阅读说明：本技术 一种雷达信号发射和接收方法及装置 (Radar signal transmitting and receiving method and device ) 是由 劳大鹏 刘劲楠 刘荣江 杨晨 朱金台 李德建 于 2020-05-30 设计创作，主要内容包括：一种雷达信号发射和接收方法及装置,应用于雷达装置,包括：S个时隙中发送第一信号以及第二信号；第一信号的相位在S个时隙中不变,可以相当于是一种SIMO信号；第二信号采用时分方式或码分方式中的至少一种方式发送；第二信号中通过m根发射天线中的每根发射天线发送的信号采用2πk-y/P的步长进行相位调制,相当于是一种MIMO信号。其中,P＝2时,MIMO信号采用时分方式发送,P>2时,MIMO信号采用时分方式和码分方式发送。上述方法中,由于在S个时隙中同时发送第一信号和第二信号,因此通过第一信号和第二信号检测目标所需的时长明显减少,可以提高检测效率。(A method and a device for transmitting and receiving radar signals are applied to a radar device and comprise the following steps: sending a first signal and a second signal in S time slots; the phase of the first signal is unchanged in S slots and may correspond to an SIMO signal; the second signal is sent in at least one of a time division mode or a code division mode; the signal transmitted by each transmitting antenna in the m transmitting antennas in the second signal adopts 2 pi k y The step size of/P is phase modulated, corresponding to a MIMO signal. When P is 2, the MIMO signal is transmitted in time division mode, P>And 2, transmitting the MIMO signal by adopting a time division mode and a code division mode. In the method, because the first signal and the second signal are simultaneously transmitted in S time slots, the time length required for detecting the target through the first signal and the second signal is obviously reduced, and the detection can be improvedEfficiency.)

1. A radar signal transmitting method is applied to a radar device, wherein the radar device comprises N transmitting antennas, N is an integer greater than 2, and the method comprises the following steps:

transmitting a first signal through 1 transmitting antenna in the N transmitting antennas in S time slots; the phase of the first signal is unchanged in the S slots; s is an integer greater than or equal to 4;

transmitting a second signal in the S time slots by using m transmitting antennas in the N transmitting antennas in a time division mode or a code division mode; m is an integer greater than or equal to 2 and less than N;

the signals sent by each transmitting antenna in the m transmitting antennas in the second signals adopt 2 pi k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs an integer greater than 0 and less than P, where k_yAnd y is 1, …, m, which represents the phase modulation step adopted by the y-th transmitting antenna in the m transmitting antennas.

2. The method of claim 1, wherein (Nd +1) P M > S > -Nd P M, where Nd represents a number of repetitions of a transmission pattern of the M transmit antennas, Nd being greater than or equal to 1;

the transmitting pattern represents that signals of transmitting antennas adopting a time division mode occupy P time slots with M time slots and without conflict, M is the number of time slots which are separated from adjacent time slots in the time slots occupied by one transmitting antenna in the M transmitting antennas, and M is an integer which is greater than or equal to M/(P-1).

3. The method according to claim 1, wherein the signals transmitted by the transmitting antennas occupying the same time slot of the m transmitting antennas adopt 2 π k_yWhen the step size of/P is phase modulated, k_yThe values are different.

4. A method according to any one of claims 1 to 3, wherein said P phases are produced by a phase shifter comprising [0, 2 pi/P, 4 pi/P, 6 pi/P, …, (P-1) × 2 pi/P ] phases.

5. The method of any of claims 1 to 4, further comprising:

transmitting a third signal in a time division manner through the m transmitting antennas in S0 time slots after the S time slots, wherein S0 is an integer greater than 1;

the transmission pattern of the third signal in S0 time slots is the same as the transmission pattern of the second signal in S time slots, S Nd P M being an integer greater than or equal to M/(P-1).

6. The method of claim 1, wherein m-N1 + N2, N1> -2, N2> -1;

the sending a second signal in the S time slots by using at least one of a time division manner and a code division manner through m transmitting antennas of the N transmitting antennas includes:

in the first S1 time slots of the S time slots, P M1 time slots are taken as a period through N1 transmitting antennas of the M transmitting antennas, and P time slots which are not conflicted and are separated by M1 are selected from P M1 time slots of one period to respectively transmit the second signals;

in the last S2 timeslots of the S timeslots, selecting, by using P × M2 timeslots as a cycle, P timeslots spaced by M2 and not colliding among the P × M2 timeslots of one cycle, through N2 ones of the M transmit antennas except the N1 transmit antennas, and respectively transmitting the second signal;

wherein, S is S1+ S2, M1 is not equal to M2, M1> -N1/(P-1), and M2> -N2/(P-1).

7. The method according to any one of claims 1 to 6, wherein the signal waveform of the first signal in the S time slots is a Frequency Modulated Continuous Wave (FMCW);

the signal waveform of the second signal in the S time slots is FMCW.

8. The method of any one of claims 1 to 7, wherein P-2, 3, or 4.

9. The method of any of claims 1 to 8, wherein the m transmit antennas transmitting the second signal and the 1 transmit antenna transmitting the first signal are different transmit antennas of the N transmit antennas.

10. A radar signal receiving method, applied to a radar apparatus including N transmitting antennas and at least one receiving antenna, where N is an integer greater than 2, and m is an integer greater than or equal to 2 and less than N, the method comprising:

obtaining M sub-range-Doppler (RD) maps of each receiving antenna in the at least one receiving antenna; the ith sub-RD pattern in the M sub-RD patterns of each receiving antenna is a result of two-dimensional fast fourier transform 2D-FFT of signals every M time slots, where the initial time slot of each receiving antenna in the echo signals of S time slots is i, and i is any integer of 1,2, …, M; the echo signal is formed by reflecting a first signal and a second signal by at least one target; wherein the first signal is transmitted through 1 of the N transmit antennas in S time slots, and a phase of the first signal is unchanged in the S time slots; the second signal is acquired in the S time slots through m transmitting antennas in the N transmitting antennasTransmitting in at least one of time division and code division modes; the signals sent by each transmitting antenna in the m transmitting antennas in the second signals adopt 2 pi k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs an integer greater than 0 and less than P, where k_yThe phase modulation step adopted by the y-th transmitting antenna in the m transmitting antennas is represented, wherein y is 1, …, m;

detecting a first target according to the sub-RD images accumulated by the M sub-RD images of each receiving antenna, and obtaining the distance information of the first target; the first target is one or more targets of the at least one target.

11. The method of claim 10, further comprising:

and obtaining a total distance-Doppler (RD) graph which is the result of executing 2D-FFT on all the adjacent time slots in the S time slots.

12. The method of claim 10, further comprising:

determining at least one doppler index Vind _ sub of the aliased velocity of the first signal of the first target on the accumulated sub-RD map, the at least one doppler index Vind _ sub of the aliased velocity of the first signal of the first target on the accumulated sub-RD map being located in P possible positions spaced by Nfft/P, where Nfft is a dimension of the 2D-FFT of the accumulated sub-RD map.

13. The method according to claim 10 or 11, characterized in that the method further comprises:

and matching according to the accumulated sub-RD diagram and the total RD diagram, and determining at least one Doppler index Vind _ total of the unaliased velocity of the first target and at least one Doppler index Vind _ sub of the corresponding aliased velocity of the first target on the accumulated sub-RD diagram.

14. The method of claim 10, further comprising:

and compensating Doppler phase deviation caused by time division and phase deviation caused by code division of the m transmitting antennas, and obtaining angle information of the first target.

15. A radar apparatus comprising an antenna array, a processor and a microwave integrated circuit, the antenna array comprising N transmit antennas, N being an integer greater than 2, wherein:

the processor for determining a first signal and a second signal as claimed in any one of claims 1 to 9;

the microwave integrated circuit is used for generating the first signal and the second signal determined by the processor;

the antenna array is used for transmitting the first signal and the second signal generated by the microwave integrated circuit.

16. A radar apparatus, comprising a receiver and a processor, the receiver comprising at least one receive antenna, wherein:

the receiver for receiving the echo signal according to any one of claims 10 to 14;

the processor configured to perform the method of any one of claims 10 to 14.

17. A radar apparatus, comprising: a memory for storing instructions and a processor for executing the instructions stored by the memory, and execution of the instructions stored in the memory causes the processor to perform the method of any of claims 10 to 14.

18. A readable storage medium, comprising a computer program or instructions which, when executed, perform the method of any of claims 1 to 9 or 10 to 14.

19. A computer program product comprising computer readable instructions which, when read and executed by a radar apparatus, cause the radar apparatus to perform the method of any one of claims 1 to 9 or 10 to 14.

Technical Field

The present disclosure relates to radar technologies, and in particular, to a method and an apparatus for transmitting and receiving radar signals.

Background

Vehicle-mounted radars are indispensable sensors in autonomous driving systems, by which obstacle (also referred to as target) detection can be provided for a vehicle. Specifically, the vehicle-mounted radar may transmit a Frequency Modulated Continuous Wave (FMCW), and measure a distance, a speed, and an azimuth of an obstacle by detecting a reflected echo of the obstacle.

In recent years, the technology of vehicle-mounted radar is continuously evolving, the performance of the vehicle-mounted radar is continuously improved, and the technology can be embodied in the following aspects: the frequency band gradually evolves from 24GHz to 77GHz/79GHz, so that higher distance resolution is obtained through larger scanning bandwidth; the scanning period of chirp (chirp) on the waveform is several ms, and is reduced to a mu s level, so that the measurement distance and the measurement speed are decoupled, and the probability of false targets is reduced; the number of channels is evolved from a Single Input Multiple Output (SIMO) mode to a Multiple Input Multiple Output (MIMO) mode, and the antenna scale is continuously enlarged, so that the aperture of the virtual antenna is enlarged, the angular resolution is improved, and the requirement of realizing automatic driving for higher spatial resolution of a target can be met. Since obtaining the target angle requires separating signals of a plurality of transmitting antennas, it is necessary to design orthogonal waveforms of the plurality of transmitting antennas.

The multiple transmit antennas of the MIMO radar may use a Time Division Multiplexing (TDM) method to send chirp (chirp) signals to achieve the effect of extending the aperture of the virtual antenna, i.e. TDM MIMO waveform. However, the TDM MIMO waveform has a maximum velocity measurement range Vmax _ MIMO drop, where Vmax _ MIMO is Vmax _ SIMO/Ntx, where Ntx is the number of transmitting antennas.

In addition, there is also a method of simultaneously transmitting signals of a plurality of transmitting antennas by using Code Division Multiple Access (CDM), and the CDM is also known as Doppler Division Multiple (DDM) or Doppler Division Multiple Access (DDMA). In The document "automatic Fast-Chirp MIMO Radar with Simultaneous Transmission in a Doppler-Multiplex, The 19th International Radar Symposium IRS, 2018", a 2-antenna MIMO Radar is realized with two phases. Meanwhile, the document, "automatic radio Radar Doppler Division MIMO With Velocity amplitude Resolving Capabilities, 16th European radio Conference (EuRAD), 2019" realizes simultaneous transmission of 3 transmitting antennas by using two phases. The two modes are limited, the phase shifter in the chip can accurately control the signal phase, more antenna orthogonal transmission cannot be realized, and the requirements on the speed measurement range and the angular resolution cannot be realized simultaneously.

Disclosure of Invention

The application aims to provide a method and a device for transmitting and receiving radar signals, and the problem that orthogonal waveforms transmitted by an existing radar device cannot meet requirements for a speed measurement range and angular resolution at the same time is solved.

In a first aspect, the present application provides a radar signal transmitting method, applied to a radar apparatus, where the radar apparatus includes N transmitting antennas, N is an integer greater than 2, m is an integer greater than or equal to 2 and less than N, and the method includes: simultaneously transmitting a first signal and a second signal in S time slots; wherein the first signal is transmitted through 1 transmitting antenna of the N transmitting antennas; the phase of the first signal is unchanged in S time slots; the second signal is sent in S time slots by at least one of a time division mode or a code division mode through m transmitting antennas in the N transmitting antennas, and the signal sent by each transmitting antenna in the m transmitting antennas in the second signal adopts 2 pi k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs greater than 0 and smallAn integer of P, wherein k_yAnd y is 1, … and m, which represents the phase modulation step adopted by the y-th transmitting antenna in the m transmitting antennas.

In the above method, since the first signal only includes a signal of one transmitting antenna and occupies S consecutive time slots, the first signal may be an SIMO signal, which has the advantage of a larger speed measurement range. The second signal includes signals transmitted by m transmitting antennas, and can be understood as a MIMO signal, which has the advantage of larger angular resolution of measurement. The first signal and the second signal are transmitted in at least one of a time division mode or a code division mode, so that a larger speed measurement range and a larger angle resolution ratio can be obtained at the same time.

In one possible design, S may have a range of values, that is, (Nd +1) × P > S > ═ Nd × P × M, where Nd denotes the number of repetitions of a transmission pattern of M transmit antennas, Nd is greater than or equal to 1, the transmission pattern denotes that signals of the transmit antennas in a time division manner occupy P time slots that are not in conflict and are separated by M time slots, M is the number of time slots separated by adjacent time slots in the time slots occupied by one of the M transmit antennas, and M is an integer greater than or equal to M/(P-1). Wherein, the phase and amplitude relation of signal modulation in P M time slots can be represented by the emission pattern; from P, Nd and the range of M, that is, P is 2, M/(P-1) is 2, Nd is 1, the minimum value of S can be 4.

In the above method, since the speed resolution of the speed of the measurement target is λ/(2 × S × Tchip), which is inversely proportional to the magnitude of S, the larger S, the smaller the speed resolution, and the more accurate the speed of the measurement target is. λ is the wavelength of the modulation frequency and Tchip is the duration of one time slot.

In one possible design, 2 pi k is adopted for signals transmitted by transmitting antennas occupying the same time slot in m transmitting antennas_yWhen the step size of/P is phase modulated, k_yThe values are different. For example, one transmit antenna is phase modulated with a step size of 2 pi/P and the other transmit antenna is phase modulated with a step size of 4 pi/P.

In the method, the transmitting antennas occupying the same time slot adopt different step lengths for phase modulation, so that signals transmitted by different transmitting antennas can be distinguished through the phase, and the accuracy of target detection is improved.

In one possible design, the P phases are produced by a phase shifter comprising [0, 2 π/P, 4 π/P, 6 π/P, …, (P-1) × 2 π/P ] phases.

In one possible design, the third signal may also be transmitted in a time division manner through m transmit antennas in S0 time slots after S time slots, where S0 is an integer greater than 1. The waveform of the third signal is the same as that of the second signal, that is, the transmission pattern of the third signal in S0 time slots is the same as that of the second signal in S time slots, and S is Nd P M, where M is an integer greater than or equal to M/(P-1).

In the above method, by transmitting the third signal of S0 time slots after the first signal, the velocity of the target and the doppler phase corresponding to the velocity of the target can be obtained in conjunction with the velocity resolution of the first signal.

In one possible design, transmitting the second signal in S timeslots through m transmit antennas of the N transmit antennas in at least one of a time division manner and a code division manner includes: in the first S1 time slots of the S time slots, P M1 time slots are used as the period through N1 transmitting antennas of the M transmitting antennas, and P time slots which are not conflicted and are separated by M1 are selected from P M1 time slots of one period to respectively transmit second signals; in the last S2 time slots of the S time slots, P M2 time slots are used as a period through N2 transmitting antennas except N1 transmitting antennas in the M transmitting antennas, and P non-conflicting time slots which are separated by M2 are selected from the P M2 time slots of one period to respectively transmit second signals; wherein, m is N1+ N2, N1 is 2, N2 is 1; S-S1 + S2, M1 ≠ M2, M1> -N1/(P-1), and M2> -N2/(P-1).

In the method, the maximum velocity measurement range is different because the M1 and the M2 are configured differently, and two targets aliasing at the echo velocity of the interval M1 can be easily distinguished in the echo of the interval M2. Vice versa, two targets with velocity aliasing in the echo with interval M2 can be easily distinguished in the echo with interval M1. Therefore, by setting different slot intervals M1 and M2, it is easier to determine the actual number of targets, avoiding missing targets with weak reflected echoes.

In one possible design, the signal waveform of the first signal in S time slots may be FMCW; the signal waveform of the second signal in S time slots may also be FMCW. Alternatively, a waveform used for another MIMO radar may be used, and for example, a pulse waveform or a waveform such as Orthogonal Frequency Division Multiplex (OFDM) may be used.

In one possible design, P ═ 2, 3, or 4.

In the method, the first signal and the second signal respectively adopt different phase modulation codes, and only less than or equal to 4 phases are used, so that the precision requirement on the phase modulator is reduced, and the requirement on a chip is reduced.

In one possible design, the intersection between the m transmit antennas sending the second signal and the 1 transmit antenna sending the first signal is 0, that is, the m transmit antennas sending the second signal and the 1 transmit antenna sending the first signal are different transmit antennas of the N transmit antennas.

In a second aspect, the present application provides a radar signal receiving method, which is applied to a radar device, where the radar device includes N transmitting antennas and at least one receiving antenna, m is an integer greater than or equal to 2 and less than N, and N is an integer greater than 2, and the method includes: obtaining M sub-range-Doppler (RD) graphs of each receiving antenna in at least one receiving antenna; detecting a first target according to the sub-RD images accumulated by the M sub-RD images of each receiving antenna, and obtaining the distance information of the first target; the first target is one or more of the at least one target. The ith sub-RD diagram of the M sub-RD diagrams of each receiving antenna is the initial time slot of the receiving antenna in the echo signals of S time slots, i is the result of two-dimensional fast Fourier transform (2D-FFT) of signals of every M time slots, and i is any integer of 1,2, … and M; the echo signal is formed by the first signal and the second signal after being reflected by at least one target; wherein the first signal passes through 1 of the N transmit antennas in S time slotsThe transmitting antenna transmits, the phase of the first signal is unchanged in S time slots; the second signal is sent in S time slots by m transmitting antennas in the N transmitting antennas in at least one of time division and code division modes; the signal transmitted by each transmitting antenna in the m transmitting antennas in the second signal adopts 2 pi k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs an integer greater than 0 and less than P, where k_yAnd y is 1, … and m, which represents the phase modulation step adopted by the y-th transmitting antenna in the m transmitting antennas.

In the prior art, the total RD pattern is used to detect doppler spectral lines of aliasing velocity of a target, and there are (P-1) × M +1 doppler spectral lines to be matched. In the method, the accumulated sub-RD graphs are used for detecting one target, and because the number of corresponding doppler spectral lines of the same target is only P and is much smaller than the number of corresponding doppler spectral lines when the total RD graph is used for detection, the sub-RD graphs are used for more easily detecting the doppler spectral lines of the aliasing velocity of one target than the total RD graph.

Note that, RD diagram: one dimension is distance information, and the other dimension is a radar output graph of Doppler information. Extraction from the Range dimension is called Range bin, extraction from the Doppler dimension is called Doppler bin, and extraction from both the Range and Doppler dimensions is called Range-Doppler Cell.

In one possible design, an overall RD map may also be obtained, which may be the result of performing a two-dimensional FFT (2D-FFT) on all adjacent slots within S slots.

In one possible design, the method further includes: at least one doppler index Vind _ sub of the aliased velocity of the first signal of the first object on the accumulated sub-RD-map is determined, the at least one doppler index Vind _ sub of the aliased velocity of the first signal of the first object on the accumulated sub-RD-map being located in P possible positions spaced by Nfft/P, where Nfft is the dimension of the 2D-FFT of the accumulated sub-RD-map.

In one possible design, the method further includes: and matching according to the accumulated sub-RD diagram and the total RD diagram, and determining at least one Doppler index Vind _ total of the unaliased velocity of the first target and at least one Doppler index Vind _ sub of the corresponding aliased velocity of the first target on the accumulated sub-RD diagram.

In one possible design, the method further includes: doppler phase deviation caused by time division and phase deviation caused by code division of the m transmitting antennas are compensated, and angle information of the first target is obtained. By compensating for the phase deviation, more accurate angle information can be obtained.

In a third aspect, a radar apparatus is provided, where the radar apparatus includes an antenna array, a processor, and a microwave integrated circuit, where the antenna array includes N transmit antennas, where N is an integer greater than 2, where:

a processor for determining the first signal and the second signal as in any one of the possible designs of the first aspect;

a microwave integrated circuit for generating a first signal and a second signal determined by a processor;

and the antenna array is used for transmitting the first signal and the second signal generated by the microwave integrated circuit.

In a fourth aspect, a radar apparatus is provided, the radar apparatus comprising a receiver and a processor, the receiver comprising at least one receiving antenna, wherein: a receiver for receiving echo signals as in any one of the possible designs of the second aspect;

a processor for performing the method according to any one of the two possible designs based on the echo signal.

In a fifth aspect, there is provided a radar apparatus comprising: a memory for storing instructions and a processor for executing the instructions stored by the memory, and execution of the instructions stored by the memory causes the processor to generate the first signal and the second signal as in any one of the possible designs of the first aspect.

In a sixth aspect, there is provided a radar apparatus comprising: a memory for storing instructions and a processor for executing the instructions stored by the memory, and execution of the instructions stored by the memory causes the processor to perform the method of any one of the possible designs of the second aspect.

In a seventh aspect, there is provided a readable storage medium comprising a computer program or instructions which, when executed, performs the method of any one of the possible designs of the first or second aspect.

In an eighth aspect, there is provided a computer program product comprising computer readable instructions which, when read and executed by a radar apparatus, cause the radar apparatus to perform the method of any one of the possible designs of the first or second aspect.

Drawings

Fig. 1(a) to 1(b) are schematic structural diagrams of a radar apparatus suitable for use in the embodiments of the present application;

FIG. 2 is a schematic structural diagram of a vehicle according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of a radar signal transmission process provided in an embodiment of the present application;

fig. 4 is a schematic diagram of a radar signal provided in an embodiment of the present application;

FIG. 5 is a schematic diagram of another radar signal provided by an embodiment of the present application;

FIG. 6 is a schematic diagram of another radar signal provided by an embodiment of the present application;

fig. 7 is a schematic diagram of a radar signal receiving process according to an embodiment of the present disclosure;

fig. 8 is a schematic diagram of another radar signal receiving process provided in the embodiment of the present application;

fig. 9 is a schematic diagram of another radar signal receiving process provided in the embodiment of the present application;

FIGS. 10(a) to 10(c) are schematic Doppler line diagrams provided in the embodiments of the present application;

FIG. 11 is a Doppler spectrum diagram provided by an embodiment of the present application;

FIG. 12 is a Doppler spectrum diagram provided by an embodiment of the present application;

FIG. 13 is a Doppler line diagram provided in accordance with an embodiment of the present application;

FIG. 14 is a Doppler line diagram provided by an embodiment of the present application;

FIG. 15 is a Doppler spectrum diagram provided by an embodiment of the present application;

FIG. 16 is a Doppler line diagram provided by an embodiment of the present application;

fig. 17 is a schematic structural diagram of a radar apparatus according to an embodiment of the present application;

fig. 18 is a schematic structural diagram of a radar apparatus according to an embodiment of the present application.

Detailed Description

Embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

Fig. 1(a) is a schematic view of a radar apparatus according to an embodiment of the present disclosure. The radar apparatus in fig. 1(a) may be a MIMO radar, and may include an antenna array 101, a microwave integrated circuit (MMIC) 102, and a processor 103. Antenna array 101 may include multiple transmit antennas and multiple receive antennas.

The microwave integrated circuit 102 is configured to generate a radar signal, and then transmit the radar signal through one or more transmitting antennas in the transmitting antenna array 101. It should be noted that in the embodiment of the present application, the waveform of the signal transmitted by the transmitting antenna of the radar apparatus is FMCW, and the frequency of the signal is modulated by increasing and decreasing the frequency of the signal with time, and such signal generally includes one or more "chirp (chirp) signals". One time slot can be expressed as the occupied time, T, of a single transmitting antenna for transmitting a chirp signal_SIMO＝T_ramp+T_otherWherein T is_rampRepresenting the time, T, of the swept frequency signal actually used for the measurement_otherRepresents the additional time overhead introduced by practical devices such as analog to Digital converters (ADCs), Phase Locked Loops (PLLs). It will be appreciated that, since time division and phase modulation techniques are used in the present application, the radio frequency link of each transmitting antenna in the radar apparatus further includes a switch and a phase shifter.

For example, as shown in fig. 1(b), a schematic diagram of a microwave integrated circuit according to an embodiment of the present application is provided. In fig. 1(b), the microwave integrated circuit may include one or more rf receive channels and an rf transmit channel. The rf transmission channel may include a waveform generator, a phase shifter, a switch, and a Power Amplifier (PA). The rf receiving channel may include a Low Noise Amplifier (LNA), a down mixer (mixer), a filter, and an analog to digital converter (ADC).

Fig. 1(b) is an example, and other forms of the microwave integrated circuit may exist, which is not limited in the embodiments of the present application.

Before transmitting the radar signal, the processor realizes the waveform of the configured radar signal through a waveform generator in the radio frequency transmission channel. In the embodiment of the present application, the orthogonal transmit waveforms of multiple transmit antennas may be preconfigured by the processor, and are not limited to the name of the processor, and only indicate functions of implementing the preconfigured waveforms. In the embodiment of the application, the radar signals can be sent in different transmitting antennas in a time division mode, so that the transmitting antennas needing to send the radar signals can be gated through the switch. Also, the radar signals may be code-division transmitted in different transmit antennas, with the corresponding phase being modulated by phase shifters connected to the transmit antennas. Wherein the switch and phase shifter connect the antenna and the waveform transmitter in series, but wherein the order of the switch and phase shifter may be interchanged.

After the radar signal is sent out, the radar signal is reflected by one or more targets to form an echo signal, and the echo signal is received by the receiving antenna. The microwave integrated circuit 102 is further configured to perform processing such as mixing and sampling on echo signals received by some or all of the receiving antennas in the antenna array 101, and transmit the sampled echo signals to the processor 103.

The processor 103 is configured to perform Fast Fourier Transform (FFT), signal processing, and the like on the echo signal, so as to determine information such as a distance, a speed, and an angle of a target according to the received echo signal. Specifically, the processor 103 may be a device having a processing function, such as a Microprocessor (MCU), a Central Processing Unit (CPU), a Digital Signal Processor (DSP), a field-programmable gate array (FPGA), or a dedicated accelerator.

In addition, the radar system shown in fig. 1(a) may further include an Electronic Control Unit (ECU) 104 for controlling the vehicle, such as determining a driving route of the vehicle, controlling the speed of the vehicle, and the like, according to information such as a target distance, a speed, an angle, and the like processed by the processor 103.

The transmitter in the embodiment of the present application may include a transmitting antenna and a transmitting channel in the microwave integrated circuit 102, and the receiver includes a receiving antenna and a receiving channel in the microwave integrated circuit 102. The transmitting antenna and the receiving antenna may be located on a Printed Circuit Board (PCB), and the transmitting channel and the receiving channel may be located in a chip, that is, an aob (antenna on PCB); alternatively, the transmitting antenna and the receiving antenna may be located in a chip package, and the transmitting channel and the receiving channel may be located in the chip, i.e., an Antenna In Package (AIP). The combination form in the embodiments of the present application is not particularly limited. It should be understood that, in the embodiment of the present application, specific structures of the transmitting channel and the receiving channel are not limited as long as corresponding transmitting and receiving functions can be achieved.

In addition, because the channel specification ratio of a single microwave integrated circuit (radio frequency chip) is relatively limited, when the number of the receiving and transmitting channels required by the system is larger than that of a single radio frequency chip, a plurality of radio frequency chips are required to be cascaded. Thus, the entire radar system may include multiple rf chip cascades, for example, the transmit antenna array and the receive antenna array are multiple MIMO cascades, and data output from Analog Digital Converter (ADC) channels is interfaced to a processor 103, such as an MCU, a DSP, an FPGA, a General Processing Unit (GPU), and the like. Also for example, the MMIC and DSP may be integrated in one chip, called a System On Chip (SOC). Also for example, MMIC and ADC, the processor 103 may be integrated in one chip, constituting a SOC. In addition, the entire vehicle may be equipped with one or more radar systems and connected to the central processor via a vehicle bus. The central processor controls one or more vehicle-mounted sensors, including one or more millimeter wave radar sensors.

An application scenario of the embodiment of the present application is described below. The radar device shown in fig. 1(a) may be applied to a vehicle having an automatic driving function. Referring to fig. 2, a functional block diagram of a vehicle 200 with an automatic driving function according to an embodiment of the present application is provided. In one embodiment, the vehicle 200 is configured in a fully or partially autonomous driving mode. For example, the vehicle 200 may control itself while in the autonomous driving mode, and may determine a current state of the vehicle and its surroundings by human operation, determine a possible behavior of at least one other vehicle in the surroundings, and determine a confidence level corresponding to the possibility that the other vehicle performs the possible behavior, and control the vehicle 200 based on the determined information. When the vehicle 200 is in the autonomous driving mode, the vehicle 200 may be placed into operation without human interaction.

The vehicle 200 may include various subsystems such as a travel system 202, a sensor system 204, a control system 206, one or more peripherals 208, as well as a power source 210, a computer system 212, and a user interface 216. Alternatively, vehicle 200 may include more or fewer subsystems, and each subsystem may include multiple elements. In addition, each of the sub-systems and elements of the vehicle 200 may be interconnected by wire or wirelessly.

The travel system 202 may include components that provide powered motion to the vehicle 200. In one embodiment, the travel system 202 may include an engine 218, an energy source 219, a transmission 220, and wheels/tires 221. The engine 218 may be an internal combustion engine, an electric motor, an air compression engine, or other type of engine combination, such as a hybrid engine of a gasoline engine and an electric motor, or a hybrid engine of an internal combustion engine and an air compression engine. The engine 218 converts the energy source 219 into mechanical energy.

Examples of energy sources 219 include gasoline, diesel, other petroleum-based fuels, propane, other compressed gas-based fuels, ethanol, solar panels, batteries, and other sources of electrical power. The energy source 219 may also provide energy to other systems of the vehicle 200.

The transmission 220 may transmit mechanical power from the engine 218 to the wheels 221. The transmission 220 may include a gearbox, a differential, and a drive shaft. In one embodiment, the transmission 220 may also include other devices, such as a clutch. Wherein the drive shaft may comprise one or more shafts that may be coupled to one or more wheels 221.

The sensor system 204 may include several sensors that sense information about the environment surrounding the vehicle 200. For example, the sensor system 204 may include a positioning system 222 (which may be a Global Positioning System (GPS) system, a Beidou system, or other positioning system), an Inertial Measurement Unit (IMU) 224, a radar 226, a laser range finder 228, and a camera 230. The sensor system 204 may also include sensors of internal systems of the monitored vehicle 200 (e.g., an in-vehicle air quality monitor, a fuel gauge, an oil temperature gauge, etc.). Sensor data from one or more of these sensors may be used to detect the object and its corresponding characteristics (position, shape, orientation, velocity, etc.). Such detection and identification is a critical function of the safe operation of the vehicle 200.

The positioning system 222 may be used to estimate the geographic location of the vehicle 200. The IMU 224 is used to sense position and orientation changes of the vehicle 200 based on inertial acceleration. In one embodiment, the IMU 224 may be a combination of an accelerometer and a gyroscope.

The radar 226 may utilize radio signals to sense targets within the surrounding environment of the vehicle 200. In some embodiments, in addition to sensing a target, radar 226 may also be used to sense the speed and/or heading of a target. In one specific example, the radar 226 may be implemented using the radar apparatus shown in fig. 1 (a).

The laser rangefinder 228 may utilize a laser to sense a target in the environment in which the vehicle 100 is located. In some embodiments, laser rangefinder 228 may include one or more laser sources, laser scanners, and one or more detectors, among other system components.

The camera 230 may be used to capture multiple images of the surrounding environment of the vehicle 200. The camera 230 may be a still camera or a video camera.

The control system 206 is for controlling the operation of the vehicle 200 and its components. The control system 206 may include various elements including a steering system 232, a throttle 234, a braking unit 236, a sensor fusion algorithm 238, a computer vision system 240, a route control system 242, and an obstacle avoidance system 244.

The steering system 232 is operable to adjust the heading of the vehicle 200. For example, in one embodiment, a steering wheel system.

The throttle 234 is used to control the operating speed of the engine 218 and thus the speed of the vehicle 200.

The brake unit 236 is used to control the vehicle 200 to decelerate. The brake unit 236 may use friction to slow the wheel 221. In other embodiments, the brake unit 236 may convert the kinetic energy of the wheel 221 into an electrical current. The brake unit 236 may take other forms to slow the rotational speed of the wheel 221 to control the speed of the vehicle 200.

The computer vision system 240 may be operable to process and analyze images captured by the camera 230 in order to identify objects and/or features in the environment surrounding the vehicle 200. The objects and/or features may include traffic signals, road boundaries, and obstacles. The computer vision system 240 may use target recognition algorithms, motion from motion (SFM) algorithms, video tracking, and other computer vision techniques. In some embodiments, the computer vision system 240 may be used to map an environment, track a target, estimate a speed of a target, and the like.

The route control system 242 is used to determine a travel route of the vehicle 200. In some embodiments, the route control system 142 may combine data from the sensors 238, the GPS 222, and one or more predetermined maps to determine a travel route for the vehicle 200.

The obstacle avoidance system 244 is used to identify, assess, and avoid or otherwise negotiate potential obstacles in the environment of the vehicle 200.

Of course, in one example, the control system 206 may additionally or alternatively include components other than those shown and described. Or may reduce some of the components shown above.

The vehicle 200 interacts with external sensors, other vehicles, other computer systems, or users through peripherals 208. Peripheral devices 208 may include a wireless communication system 246, an in-vehicle computer 248, a microphone 250, and/or a speaker 252.

In some embodiments, the peripheral device 208 provides a means for a user of the vehicle 200 to interact with the user interface 216. For example, the onboard computer 248 may provide information to a user of the vehicle 200. The user interface 216 may also operate the in-vehicle computer 248 to receive user input. The in-vehicle computer 248 can be operated through a touch screen. In other cases, the peripheral device 208 may provide a means for the vehicle 200 to communicate with other devices located within the vehicle. For example, the microphone 250 may receive audio (e.g., voice commands or other audio input) from a user of the vehicle 200. Similarly, the speaker 252 may output audio to a user of the vehicle 200.

The wireless communication system 246 may communicate wirelessly with one or more devices, either directly or via a communication network. For example, the wireless communication system 246 may use 3G cellular communication such as Code Division Multiple Access (CDMA), EVD0, global system for mobile communications (GSM)/General Packet Radio Service (GPRS), or 4G cellular communication such as Long Term Evolution (LTE), or 5G cellular communication. The wireless communication system 246 may communicate with a Wireless Local Area Network (WLAN) using WiFi. In some embodiments, the wireless communication system 246 may communicate directly with the device using an infrared link, bluetooth, or ZigBee. Other wireless protocols, such as various vehicular communication systems, for example, the wireless communication system 246 may include one or more Dedicated Short Range Communications (DSRC) devices that may include public and/or private data communications between vehicles and/or roadside stations.

The power supply 210 may provide power to various components of the vehicle 200. In one embodiment, power source 210 may be a rechargeable lithium ion or lead acid battery. One or more battery packs of such batteries may be configured as a power source to provide power to various components of the vehicle 200. In some embodiments, the power source 210 and the energy source 219 may be implemented together, such as in some all-electric vehicles.

Some or all of the functions of the vehicle 200 are controlled by the computer system 212. The computer system 212 may include at least one processor 223, the processor 223 executing instructions 225 stored in a non-transitory computer-readable medium, such as the memory 214. The computer system 212 may also be a plurality of computing devices that control individual components or subsystems of the vehicle 200 in a distributed manner.

Processor 223 may be any conventional processor, such as a commercially available Central Processing Unit (CPU). Alternatively, the processor may be a dedicated device such as an Application Specific Integrated Circuit (ASIC) or other hardware-based processor. Although fig. 2 functionally illustrates a processor, memory, and other elements of the computer 210 in the same block, those skilled in the art will appreciate that the processor, computer, or memory may actually comprise multiple processors, computers, or memories that may or may not be stored within the same physical housing. For example, the memory may be a hard drive or other storage medium located in a different enclosure than the computer 210. Thus, references to a processor or computer are to be understood as including references to a collection of processors or computers or memories which may or may not operate in parallel. Rather than using a single processor to perform the steps described herein, some components, such as the steering component and the retarding component, may each have their own processor that performs only computations related to the component-specific functions.

In various aspects described herein, the processor may be located remotely from the vehicle and in wireless communication with the vehicle. In other aspects, some of the processes described herein are executed on a processor disposed within the vehicle and others are executed by a remote processor, including taking the steps necessary to perform a single maneuver.

In some embodiments, the memory 214 may contain instructions 225 (e.g., program logic), which instructions 225 may be executed by the processor 223 to perform various functions of the vehicle 200, including those described above. The memory 214 may also contain additional instructions, including instructions to send data to, receive data from, interact with, and/or control one or more of the travel system 202, the sensor system 204, the control system 206, and the peripheral devices 208.

In addition to instructions 225, memory 214 may also store data such as road maps, route information, location, direction, speed of the vehicle, and other such vehicle data, among other information. Such information may be used by the vehicle 200 and the computer system 212 during operation of the vehicle 200 in autonomous, semi-autonomous, and/or manual modes.

A user interface 216 for providing information to or receiving information from a user of the vehicle 200. Optionally, the user interface 216 may include one or more input/output devices within the collection of peripheral devices 208, such as a wireless communication system 246, an in-vehicle computer 248, a microphone 250, and a speaker 252.

The computer system 212 may control the functions of the vehicle 200 based on inputs received from various subsystems (e.g., the travel system 202, the sensor system 204, and the control system 206) and from the user interface 216. For example, the computer system 212 may utilize input from the control system 206 to control the steering unit 232 to avoid obstacles detected by the sensor system 204 and the obstacle avoidance system 244. In some embodiments, the computer system 212 is operable to provide control over many aspects of the vehicle 200 and its subsystems.

Alternatively, one or more of these components described above may be mounted or associated separately from the vehicle 200. For example, the memory 214 may exist partially or completely separate from the vehicle 200. The above components may be communicatively coupled together in a wired and/or wireless manner.

Optionally, the above components are only an example, in an actual application, components in the above modules may be added or deleted according to an actual need, and fig. 2 should not be construed as limiting the embodiment of the present application.

An autonomous automobile traveling on a roadway, such as vehicle 200 above, may identify targets within its surrounding environment to determine adjustments to the current speed. The target may be another vehicle, a traffic control device, or another type of target. In some examples, each identified target may be considered independently, and based on the respective characteristics of the target, such as its current speed, acceleration, separation from the vehicle, etc., may be used to determine the speed at which the autonomous vehicle is to be adjusted.

Optionally, the autonomous vehicle 200 or a computing device associated with the autonomous vehicle 200 (e.g., computer system 212, computer vision system 240, memory 214 of fig. 2) may predict behavior of the identified target based on characteristics of the identified target and the state of the surrounding environment (e.g., traffic, rain, ice on the road, etc.). Optionally, each identified target is dependent on each other's behavior, so it is also possible to consider all identified targets together to predict the behavior of a single identified target. The vehicle 200 is able to adjust its speed based on the predicted behavior of the identified target. In other words, the autonomous vehicle is able to determine what steady state the vehicle will need to adjust to (e.g., accelerate, decelerate, or stop) based on the predicted behavior of the target. Other factors may also be considered in this process to determine the speed of the vehicle 200, such as the lateral position of the vehicle 200 in the road being traveled, the curvature of the road, the proximity of static and dynamic objects, and so forth.

In addition to providing instructions to adjust the speed of the autonomous vehicle, the computing device may also provide instructions to modify the steering angle of the vehicle 200 to cause the autonomous vehicle to follow a given trajectory and/or maintain a safe lateral and longitudinal distance from a target near the autonomous vehicle (e.g., a car in an adjacent lane on the road).

The vehicle 200 may be a car, a truck, a motorcycle, a bus, a boat, an airplane, a helicopter, a lawn mower, an amusement car, a playground vehicle, construction equipment, a trolley, a golf cart, a train, a trolley, etc., and the embodiment of the present invention is not particularly limited.

In addition, it should also be noted that the radar system in the embodiment of the present application may be applied to various fields, for example, the radar system in the embodiment of the present application includes, but is not limited to, a vehicle-mounted radar, a roadside traffic radar, and an unmanned aerial vehicle radar.

In the present embodiment, a plurality means two or more. In addition, it is to be understood that the terms first, second, etc. in the description of the present application are used for distinguishing between the descriptions and not necessarily for describing a sequential or chronological order.

In combination with the foregoing description, the present application provides a radar signal transmitting and receiving method, which is applied to a radar apparatus including N transmitting antennas, N > m, m being an integer greater than or equal to 2. It should be understood that the specific structure of the radar apparatus may be as shown in fig. 1(a), and may not be limited to the specific structure of fig. 1(a), which is not limited in the present application.

Referring to fig. 3, on the transmitting side, the method includes:

step 301: the first signal is transmitted through 1 of the N transmit antennas in S time slots.

In the embodiment of the present application, the phase of the first signal is not changed in S slots. For example, the phase of the first signal in the first slot of the S slots isThen the phases in the other time slots are all

Illustratively, the signal waveform of the first signal in S slots is FMCW.

Step 302: and in S time slots, sending a second signal by m transmitting antennas in the N transmitting antennas in a time division mode or a code division mode.

Wherein, the signal waveform of the second signal in S time slots is also FMCW, and the first signal and the second signal adopt different phase modulation codes.

The Code Division scheme represents a scheme of forming a Code by modulating a phase of a signal in Code Division Multiple Access (CDM), Doppler Division Multiple Access (DDM), or Doppler Division Multiple Access (DDMA), that is, phase modulation coding.

The second signal is transmitted through m transmit antennas, corresponding to a superposition of the signals transmitted by the m transmit antennas. The signal transmitted by each transmitting antenna in the m transmitting antennas in the second signal adopts 2 pi k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs an integer greater than 0 and less than P, where k_yAnd the phase modulation step adopted by the y-th transmitting antenna in the m transmitting antennas is represented, wherein y is 1, …, m and P are integers which are larger than 1. In this embodiment, the modulation phase of the second signal may include P phases, where the P phases are P phases that are uniform in [0, 2 pi ], and the corresponding phase set may be [0, 2 pi/P, 4 pi/P, 6 pi/P, …, (P-1) × 2 pi/P]. Since P is at least equal to 2, for example, for P ═ 2, then the P phases are 0 and pi, respectively, as shown in fig. 1 (b); it will be appreciated that for P4, then the P phases are 0, pi/2, pi and 3 pi/2 respectively, i.e. the phase shifter in fig. 1(b) can provide a high accuracy of 0, pi/2, pi and 3 pi/2 for a total of 4 phases over the entire FMCW frequency sweep slope range. It is worth noting that for complex signals, phase modulation is equivalent to signal multiplication by exp (j φ), with the equivalent of a 2 π period rotation. Therefore, the practical system only uses P phases, and can realize other phase modulation of integral multiple of 2 pi. That is, 2 π/P phase modulation can be used instead of 2 π/P + u by 2 π phase modulation, u being an integer.

It should be noted that, since the second signal and the first signal both occupy S slots for transmission, the steps 301 and 302 are not in sequence. Indicating that only the first and second signals use different code division, i.e. different dopplerOffset 2 π k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs an integer greater than or equal to 0 and less than P. When k is_yEqual to 0, it can be understood that the signal variation occupied by the transmitting antenna in a plurality of time slots, i.e. between adjacent time slots, is zero.

Since the first signal only includes the signal of one transmitting antenna and occupies S consecutive time slots, the first signal may be an SIMO signal, which has the advantage of a larger speed measurement range. The second signal includes signals of m transmitting antennas, and can be understood as a TDM MIMO signal, which has the advantage of larger angular resolution of measurement. Since the target moves during measurement, the SIMO signal and the TDM MIMO signal obtain the target non-aliasing velocity by matching the velocity index on the same range unit. If the first signal and the second signal are not transmitted simultaneously, SIMO signals and MIMO signals transmitted before and after may cause that the targets are not matched to the same range bin, that is, the observation time of the targets is different, resulting in that the velocity of the targets cannot be measured accurately. In the application, the first signal and the second signal are transmitted simultaneously, so that the problem that the speed of the target cannot be accurately measured due to different observation times of the high-speed moving target when the SIMO signal and the TDM MIMO signal are transmitted in a time division mode in the prior art is solved.

When P is 2, i.e. two-Phase modulation, (also known as bpsk (binary Phase Shift keying), the embodiment of the present application is not particularly limited), the first signal and the second signal respectively adopt 2 pik k_y/P，k_yThe phase modulation is performed in arbitrary steps of 0 and 1. It can be understood that k_yWhen the phase step size in the adjacent time slots is 0, i.e. the phase in S time slots is not changed, it can be understood that the phase modulation code is [1,1]Where the elements in this sequence represent the modulation phase of the signal, 1 represents a modulation phase of 0, -1 represents a modulation phase of pi. When k is_yWhen the signal is 1, the signal transmitted by each transmitting antenna is phase modulated by a step length of pi, that is, the phase modulation code of each transmitting antenna in the second signal is the same, that is, 1, -1]. Therefore, to distinguish m hairs in the second signalAnd in the orthogonal waveform of the transmitting antenna, m transmitting antennas further adopt a time division mode to transmit signals in the second signal. Since TDM MIMO transmission is not limited by phase control, the number of transmit antennas of the radar system can be easily extended by multiple transmit antennas in the second signal, i.e., m can be any integer greater than or equal to 2. By the method, the problem that orthogonal transmission of more transmitting antennas cannot be realized by the conventional two-phase DDM waveform is solved. And the first signal is continuously transmitted in S time slots, so that the maximum speed measurement range of the radar system is ensured. The problem that the speed measuring range of a radar system is reduced due to the adoption of TDM MIMO transmission is avoided.

In practice, when P is 2, the first signal may also be phase modulated with steps of pi. The signals of the plurality of transmitting antennas in the second signal are all transmitted in a 0 step size, namely in a phase-invariant manner. However, the velocity measurement range of the first signal is large, so if the first signal is phase-modulated with a 0 step length, the echo signal of the first signal at the receiving end can obtain a large velocity measurement range, and there is no extra doppler shift caused by a non-zero phase modulation step length, thereby further simplifying the receiving processing flow. Therefore, the following embodiments are described by taking the first signal as an example of performing phase modulation with 0 step size.

For example, each of the M transmit antennas repeats transmission in a period of P × M slots. Because 2 π k is used in the second signal_yThe multiple transmitting antennas performing phase modulation with a/P step length need P time slots to complete uniform Doppler modulation. And a plurality of transmitting antennas adopting time division require a time slot with M being more than or equal to 2 to complete time division transmission. Thus, here expressed, each transmit antenna repeats transmissions in a period of P x M slots. For example, when P is 2, N is 3, and m is N-1 is 2, transmission is performed at least 1 time in a period of 4 slots.

When each transmitting antenna repeatedly transmits in a period of P M time slots, one transmitting antenna transmits in each period according to a transmitting pattern, the transmitting pattern represents the relation between the phase and amplitude of the modulated signal, the signals of the transmitting antennas are transmitted in a time division mode, P time slots which are separated by M time slots and do not conflict are occupied, M is the number of the time slots separated by adjacent time slots in the time slots occupied by one transmitting antenna in the M transmitting antennas, and M is an integer which is larger than or equal to M/(P-1).

In order to improve the speed resolution, further, (Nd +1) × P × M > S > ═ Nd × P × M, where Nd denotes the number of transmission cycles of the M transmission antennas in the period of P × M slots, and Nd is an integer greater than or equal to 1. The specific value of M can be determined according to actual conditions, and M is an integer which is greater than or equal to M/(P-1). It is noted that S may not be equal to an integer multiple of Nd × P × M, and zero padding may be performed at the receiving end, which is not limited herein.

In conjunction with the foregoing description, since P is an integer greater than 1, Nd is an integer greater than or equal to 1, and M is an integer greater than 1, S is an integer greater than or equal to 4. The specific value of S may be determined according to actual conditions, and is not limited herein.

In this embodiment of the application, signals sent by each of the m transmitting antennas may be distinguished in a time division manner or a code division manner, that is, signals sent by different transmitting antennas occupy different time slots, or signals sent by transmitting antennas occupying the same time slot among the m transmitting antennas adopt 2 pi k_yWhen the step size of/P is phase modulated, k_yThe values are different. Thus, even if the number of P is not large, for example, P is less than or equal to 4, the signals of N transmitting antennas can still realize orthogonal transmission.

For example, the signals transmitted by the transmitting antennas occupying the same time slot in m transmitting antennas adopt 2 π k_yWhen the step size of/P is phase modulated, k_yThe values are different. For example, when the transmitting antenna 1 and the transmitting antenna 2 transmit signals in the same time slot, and P is 4, k corresponding to the transmitting antenna 1_yThe value of (1) is 1, namely the phase of the signal sent by the transmitting antenna 1 circulates by 0, pi/2, pi and 3 pi/2 in sequence; k corresponding to transmitting antenna 2_yA value of 3, i.e. the phase of the signal transmitted by the transmitting antenna 2 cycles sequentially by 0, 3 pi/2, 3 pi-2 pi + pi and 9 pi/2-4 pi + pi/2. For convenience of description, the combination of the phases of signals transmitted by one transmitting antenna in one period may be referred to as the transmitting antennaThe emission pattern of the line, then according to the Euler formulaThat is, the phase of the signal of the transmitting antenna 1 in 4 occupied time slots is sequentially circulated by 0, pi/2, pi and 3 pi/2, and is expressed in a complex form, and the phase of the transmitting antenna 1 in P time slots occupying the interval M in P x M time slots can be expressed as [1, j, -1, -j](ii) a Similarly, for the transmitting antenna 2, the phase in P slots occupying the interval M among P × M slots can be represented as [1, -j, -1, j]. However, it is understood that the transmission pattern herein can only represent phase modulation, and cannot represent time-division antennas. Therefore, in the embodiment of the present application, x is introduced to indicate silence, and no signal is transmitted in the time slot, which may also be indicated by 0, and it can be understood that the amplitude of the signal is set to zero in this time slot, and an actual system may be implemented by setting the switch to an off state. It can be calculated that when P is 4 and M is 2, M is less than or equal to M (P-1), the maximum value M of M is 6, and N is M +1, the antenna can be extended to 7 transmitting antennas. Specific embodiments may be referenced for specific emission patterns.

In the embodiment of the present application, for convenience of description, a transmission antenna for transmitting a first signal is denoted as Tx0, and transmission antennas for transmitting a second signal are denoted as Tx1 to Txm.

Further, in this embodiment of the application, the m transmitting antennas for sending the second signal and the 1 transmitting antenna for sending the first signal may be different transmitting antennas among the N transmitting antennas. Then Tx0 transmitting the first signal occupies all of the S time slots. It can be understood that when P is 2, M > M/(P-1) M, M signals in the second signal do not occupy all of S time slots, and only the first signal exists in some time slots. For example, when P is 2, N is 3, M is N-1 is 2, and M is 3, then it is assumed that Tx1 occupies slot 1 and slot 4, Tx2 occupies slot 2 and slot 5, and only the first signal, i.e., the signal transmitted by Tx0, exists in slot 3 and slot 6.

Alternatively, the 1 transmitting antenna for transmitting the first signal may be one transmitting antenna of the m transmitting antennas, and the embodiment of the present application is not limited. Then, in response to a collision, the transmitting antenna transmits with the phase code of the second signal, and the corresponding time slot in the first signal may similarly have a small number of signal gaps in the time slot. For example, when P is 2, N is 3, M is 3, and M is 3, then it is assumed that Tx1 occupies slot 1 and slot 4, Tx2 occupies slot 2 and slot 5, and the signals transmitted by Tx0 in slot 3 and slot 6 transmit Tx0 if the rule of the second signal, i.e., the step size is pi. Then the regularly transmitted first signal, which uses the second signal, has a gap in each of 3 of the S time slots. Of course, when M is small, it can be seen that the ratio of antenna nulls transmitted according to the first signal characteristic is close to 1/M in S slots, resulting in an SIMO signal that is equivalent to being down-sampled. Therefore, this transmission mode is suitable for use when M is relatively large, for example, M is greater than 3.

For example, the signals transmitted by the transmitting antennas occupying the same time slot of the m transmitting antennas adopt 2 π k_yWhen the step size of/P is phase modulated, k_yOf different values, e.g. k_y1,2, …, P-1. For example, when P is 3, k of m antennas in the second signal_yValue is 1,2, k corresponding to transmitting antenna 1_yThe value of (1) is 1, namely the phase of the signal sent by the transmitting antenna 1 circulates by 0, 2 pi/3 and 4 pi/3 in sequence; k corresponding to transmitting antenna 2_yThe value of (2) is that the phase of the signal transmitted by the transmitting antenna 2 cycles through 0, 4 pi/3, 8 pi/3 to 2 pi +2 pi/3 in sequence. Wherein, for the convenience of description, the combination of the phases of the signals transmitted by one transmitting antenna in one period may be referred to as the transmission pattern of the transmitting antenna, and then the phase of the signal in 3 occupied time slots of the transmitting antenna 1 is sequentially circulated by 0, 2 pi/3, 4 pi/3 according to the euler's formula exp (j ψ), and the phase of the transmitting antenna 1 in P time slots occupying the interval M among P × M time slots may be represented as [1, exp (j2 pi/3), exp (j4 pi/3)](ii) a Similarly, for the transmit antenna 2, the phase in the P slots occupying the M interval in the P M slots can be expressed as [1, exp (j4 π/3), exp (j2 π/3)]. However, it is understood that the transmission pattern herein can only represent phase modulation, and cannot represent time-division antennas. Therefore, in the embodiment of the present application, x is introduced to indicate silence, and no signal is transmitted in the time slot, which can also be indicated by 0, and it can be understood that this is the caseThe amplitude of the signal in each time slot is set to zero, and the actual system can be realized by setting the switch to be in an off state. It can be calculated that when P is 3 and M is 2, M is less than or equal to M (P-1), the maximum value M of M is 4, and N is M +1 is 5, and the antenna can be extended to 5 transmitting antennas. If M takes a larger value, it can be easily extended to more values of N. The specific transmission pattern is not described in detail.

Different first and second signals are described below with specific N, M, P value embodiments.

The first embodiment is as follows:

fig. 4 is a schematic signal diagram provided in the embodiment of the present application. In fig. 4, N is 3, that is, there are 3 transmitting antennas for transmitting radar signals, P is 2, that is, the phase shifter can provide at least stable phase modulation of 0 and pi, m is 2, and the second signal includes two transmitting antennas. According to the preceding description, M is an integer greater than or equal to M/(P-1). Then M may be calculated to be greater than or equal to 2, taking the minimum value of M, and M is described as 2. In fig. 4, the first signal is transmitted through a transmitting antenna Tx0, and in S time slots, the first signal includes S chirp signals, and the phase between each chirp signal is not changed.

The second signal includes a plurality of chirp signals, the second signal is transmitted by time division through a transmitting antenna Tx1 and a transmitting antenna Tx2, the period of the signals transmitted by Tx1 and Tx2 is 4 time slots, the transmission pattern of Tx1 in each period may indicate that the phase and amplitude relationship of the signals modulated is [1, x, -1, x ], and the signal of the transmission pattern of Tx2 in each period may indicate that the phase and amplitude relationship of the signals modulated is [ x,1, x, -1 ]. Wherein x represents silence, and no signal is transmitted in the time slot, or 0, that is, the transmission pattern of Tx1 in each period can be written as [1,0, -1,0], the transmission pattern of Tx2 in each period can be written as [0,1,0, -1], it can be understood that the amplitude of the signal in this time slot is set to zero, and the actual system can be realized by setting the switch to the off state; 1 indicates that the phase of the chirp signal in the slot is modulated by 0 radians; -1 indicates that the phase of the chirp signal in the time slot is modulated by pi radians, which can be implemented in practical systems by setting the switch to a closed state and selecting the phase of the phase shifter accordingly. As can be seen from fig. 4, the time slot occupied by the signal transmitted by Tx1 is different from the time slot occupied by the signal transmitted by Tx 2; in the time slots occupied by the signal transmitted by Tx1, adjacent time slots are separated by 2 time slots; the signal transmitted by Tx2 occupies 2 slots apart from adjacent slots.

It should be noted that the chirp signal shown in fig. 4 is a rising chirp, and the chirp signal may also be a falling chirp, and the embodiment of the present application is not limited thereto.

Because the first signal and the second signal respectively adopt different phase modulation codes and only use 0 and pi phases, the first signal and the second signal can be transmitted only by a relatively stable two-phase modulator, and the requirement on a chip is reduced. To improve the speed resolution, further, the time length occupied by S slots may be increased, and S > -Nd x P x M, where Nd denotes the number of repetitions of the transmission pattern of M transmission antennas, and Nd is greater than or equal to 1. The transmission pattern represents that signals of the transmitting antennas adopting the time division mode occupy P time slots with M time slots and without conflict, M is the number of time slots which are separated between adjacent time slots in the time slots occupied by one transmitting antenna in the M transmitting antennas, and M is an integer which is greater than or equal to M/(P-1). The specific value of M can be determined according to actual conditions, and M is an integer which is greater than or equal to M/(P-1).

In this embodiment, M/(P-1) is taken, and it is understood that the maximum speed measurement range corresponding to the second signal is taken to be the maximum value. M may also be an integer greater than M/(P-1), for example, N is 3, P is 2, and M is 3, which reduces the maximum velocity measurement range of the second signal, but in some time slots, the number of phase steps used by the first signal and the second signal may be smaller than P, so that the receiving end may use the vacant phase steps to determine the doppler frequency of the first signal, and further simplify the received signal processing. Specifically, the first signal is transmitted every time slot, and the transmission pattern of the transmitting antenna Tx0 for transmitting the first signal can be written as 6 time slots denoted as [1,1,1,1,1,1 ]; the transmission patterns of the plurality of transmitting antennas for transmitting the second signal are respectively as follows: the Tx1 transmission pattern may be written as 6 slots and denoted as [1, x, x, -1, x x ], the Tx2 transmission pattern is denoted as [ x,1, x, x, -1, x ] in 6 slots, then only the transmit antenna signal in the first signal is present in the 3 rd slot and the 6th slot, and the signal of the second transmit antenna is gated by the switch in the 3 rd slot and the 6th slot, and no antenna is gated. Then the echo signals in the 3 rd time slot and the 6th time slot are extracted, and the observed doppler frequency is the echo signal of the transmitting antenna signal in the first signal. And the Doppler frequency in the 1 st time slot, the 4 th time slot, the 2 nd time slot and the 5 th time slot comprises the echo signal of the transmitting antenna signal in the first signal and the second signal. By comparing the sub-RD patterns in different time slots, the doppler frequency corresponding to the transmitting antenna in the first signal can be easily found.

In this embodiment, the size of Nd may be further constrained according to the requirements for resolution accuracy. Given here by way of example Nd 32, the minimum value of S32 × 2 × 128 can be obtained from S > ═ Nd × P × M, i.e. the transmission pattern of each of the above-mentioned transmit antennas in 4 time slots is transmitted repeatedly 32 times. It is understood that Nd may take any other integer value, and will not be described herein.

Actually, according to the above description, the emission pattern when P is 2, N is 12, and M is 11 can be as shown in table 1.

TABLE 1

Each bin in the first row of table 1 represents 1 time slot and each bin in the first column represents 1 transmit antenna. The numbers of the transmitting antennas in table 1 are only logical numbers, and the transmitting antennas adjacent in number do not represent actual spatial adjacency. The transmit antenna for the first signal is designated Tx0 and employs a 0 phase modulated signal. The transmitting antenna for the second signal is designated as Tx1-Tx11, since P is 2, k_yThe signals transmitted by 11 transmitting antennas in the second signal are all 2 pi k, where m is 1, N-1 is 11_yAnd modulating the signal by pi step. In which it transmitsThe two-signal transmitting antennas Tx1-Tx11 are time division transmitting antennas, and occupy non-conflicting P2 time slots with M/(P-1) 11 time slots.

Example two:

in the second embodiment, in addition to simultaneously transmitting the first signal and the second signal in S time slots, further in S0 time slots after S time slots, the third signal may be transmitted in a time division manner through m transmitting antennas, and S0 is an integer greater than 1.

The transmission pattern of the third signal in S0 time slots is the same as the transmission pattern of the second signal in S time slots, S Nd P M being an integer greater than or equal to M/(P-1).

The first signal does not exist in the S0 time slots, and the first signal transmitted by the Tx0 exists only in the S time slot, so that the doppler frequency of the target can be determined by comparing the doppler frequency in the received echo signal in the S0 time slots with the doppler frequency in the received echo signal in the S time slots, the doppler index position corresponding to the Tx0 in the S time slots is determined, and the flow of obtaining the target speed on the receiving side is further simplified.

For example, referring to fig. 4, as shown in fig. 5, a signal diagram provided by the embodiment of the present application is shown. In fig. 5, M ═ 2, P ═ 2, and M ═ 2 are described as examples. In fig. 5, the first signal and the second signal transmitted in the previous S slots may be referred to as shown in fig. 4. The third signal is transmitted through Tx1 and Tx2 in S0 time slots after S time slots. The transmission pattern of the third signal is the same as that of the second signal, that is, the period of the signals transmitted by Tx1 and Tx2 is 4 slots, the signal of the transmission pattern of Tx1 in each period may indicate that the signal is modulated with the phase and amplitude relationship of [1, x, -1, x ], and the signal of the transmission pattern of Tx2 in each period may indicate that the signal is modulated with the phase and amplitude relationship of [ x,1, x, -1 ]. As can be seen from fig. 5, the Tx1 transmits the same signal in S0 slots as it transmits in S slots, and the Tx2 transmits the same signal pattern in S0 slots as it transmits in S slots. Wherein, x represents silence, and no signal is sent in the time slot, or 0 is used for representing the silence, it can be understood that the amplitude of the signal in the time slot is set to zero, and the actual system can be realized by setting the switch to an off state; 1 indicates that the phase of the chirp signal in the slot is modulated by 0 radians; -1 indicates that the phase of the chirp signal in the time slot is modulated by pi radians, which can be implemented in practical systems by setting the switch to a closed state and selecting the phase of the phase shifter accordingly. As can be seen from fig. 5, the time slot occupied by the signal transmitted by Tx1 is different from the time slot occupied by the signal transmitted by Tx 2; in the time slots occupied by the signal transmitted by Tx1, adjacent time slots are separated by 2 time slots; the signal transmitted by Tx2 occupies 2 slots apart from adjacent slots.

When S128 and S0 are 128, it is understood that 2 transmitting antennas in the second signal repeatedly transmit 32 × 2 × 64 times using a predetermined transmission pattern in 4 time slots. And 1 transmit antenna in the first signal is repeatedly transmitted 32 times using a predetermined transmission pattern in 4 slots. Since the velocity resolution of the velocity of the measurement target is inversely proportional to the magnitudes of S and S0, it can be understood that S and S0 may take other integer values greater than 0, and the larger the value, the higher the velocity resolution.

Example three:

in the foregoing embodiments, P ═ 2 is described as an example. The number of phases P included in the second signal may also be other values, for example, when P is 4, as shown in fig. 6, which is a signal diagram provided in the embodiment of the present application. In fig. 6, M is 6, P is 4, and M is 2. In fig. 6, a first signal is transmitted through a transmission antenna Tx0, the first signal including S chirp signals, the phase of each chirp signal being maintained.

The second signal is transmitted through the transmit antenna Tx1 to the transmit antenna Tx6, where each transmit antenna transmits a signal with a period of 8 slots. The 6 transmit antennas may be divided into 2 groups, one group including Tx1, Tx2, and Tx3, and the other group including Tx4, Tx5, and Tx 6.

Tx1, Tx2, and Tx3 may occupy the same time slot but transmit signals with different phase modulation codes, respectively. Specifically, the signal of the Tx1 transmission pattern in each period may indicate that the signal is modulated with a phase and amplitude relationship of [1, x, j, x, -1, x, -j, x ], i.e., a step size of pi/2, the signal of the Tx2 transmission pattern in each period may indicate that the signal is modulated with a phase and amplitude relationship of [1, x, -1, x,1, x, -1, x ], i.e., a modulation step size of pi, and the signal of the Tx3 transmission pattern in each period may indicate that the signal is modulated with a phase and amplitude relationship of [1, x, -j, x, -1, x, j, x ], i.e., a modulation step size of 3 pi/2. Wherein x represents silence, and no signal is transmitted in the time slot; 1 indicates that the phase of the chirp signal in the slot is modulated by 0 radians; j indicates that the phase of the chirp signal in the time slot is modulated by pi/2 radians; -1 indicates that the phase of the chirp signal within the time slot is modulated by pi radians; -j indicates that the phase of the chirp signal within the slot is modulated by 3 pi/2 radians.

The Tx4, Tx5 and Tx6 in the first group and the Tx1, Tx2 and Tx3 in the second group occupy different time slots for transmitting signals, i.e., are time-division orthogonal. Similarly, the signal of the Tx4 transmission pattern in each period may indicate that the signal is modulated with a phase and amplitude relationship of [ x,1, x, j, x, -1, x, -j ], i.e., a modulation step size of π/2, and the signal of the Tx5 transmission pattern in each period may indicate that the signal is modulated with a phase and amplitude relationship of [ x,1, x, -1, x,1, x, -1], i.e., a modulation step size of π, and the signal of the Tx6 transmission pattern in each period may indicate that the signal is modulated with a phase and amplitude relationship of [ x,1, x, -j, x, -1, x, j ], i.e., a modulation step size of 3 π/2.

It should be noted that the transmission pattern of the signal transmitted by Tx4 may be a cyclic shift sequence of the transmission pattern of the signal transmitted by Tx 1. The cyclically shifted sequence may refer to a new sequence obtained by shifting a base sequence clockwise or counterclockwise. If the sequence is a cyclic shift sequence with the sequence of [1, x, j, x, -1, x, -j, x ], the sequence can be obtained as [ x,1, x, j, x, -1, x, -j ] according to the anticlockwise cyclic shift of 1 time; the sequence can be obtained by clockwise cyclic shift 2 times, and is [ j, x, -1, x, -j, x,1, x ], and the like. Accordingly, the signal transmitted by Tx5 may be a cyclically shifted sequence of the signal transmitted by Tx2, and the signal transmitted by Tx6 may be a cyclically shifted sequence pattern of the signal transmitted by Tx 3. The specific phase step length selected by each transmitting antenna in a group of antennas occupying the same time slot is only different, and the specific phase step length corresponding to the transmitting antenna sequence given in the embodiment is not limited in the application.

Further, the transmission pattern when P-4 and N-16 can be represented by table 2.

TABLE 2

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
																					Tx0	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
Tx1	1					j					-1					j
																					Tx2	1					-1					1					-1
Tx3	1					-j					-1					j
																					Tx4		1					j					-1					j
Tx5		1					-1					1					-1
																					Tx6		1					-j					-1					j
Tx7			1					j					-1					j
																					Tx8			1					-1					1					-1
Tx9			1					-j					-1					j
																					Tx10				1					j					-1					j
Tx11				1					-1					1					-1
																					Tx 12				1					-j					-1					j
Tx 13					1					j					-1					j
																					Tx 14					1					-1					1					-1
Tx 15					1					-j					-1					j

Each bin in the first row in table 2 represents 1 time slot and each bin in the first column represents 1 transmit antenna. The numbers of the transmitting antennas in table 2 are only logical numbers, and the transmitting antennas adjacent in number do not represent actual spatial adjacency. The transmit antenna for the first signal is designated Tx0 and employs a 0 phase modulated signal. The transmit antennas for the second signal are denoted as Tx1 through Tx 15. If P is 4, the transmission from the N16 transmitting antenna is implemented, and M is at least (N-1)/(P-1) 5, then the transmission pattern represents 4 × 5 to 20 time slots of P × M, the transmitting antenna of the first signal is denoted as Tx0, and a 0-phase modulated signal is used, [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1] represents a modulated signal of 20 time slots; the second signals are transmitted by Tx1 to Tx15 using time division or code division, respectively, i.e., the code-divided antennas use pi/2, pi, 3 pi/2 as step modulation, and the time-divided antennas occupy non-colliding P-4 slots with a spacing of M-5 slots (N-1)/(P-1), respectively. Tx1 and Tx2, Tx3 may be transmitted with different phase modulation codes, respectively, and the transmitted 20-slot modulated signals are denoted as [1, x, x, x, j, x, x, x, x, -1, x, x, x, x, -j, x, x, x, x, x ], [1, x, x, x,1, x, x, x, x, x, -1, x, x, x, x ], [1, x, x, x, x, x, -j, x, x, x, x, -1, x, x, x, j, x, x, x. Tx4 and Tx5, Tx6 may be cyclically shifted 1 slot counter-clockwise from Tx1-Tx3 using different time slots, e.g., phase-coded as Tx1-Tx3, and the transmitted 20-slot modulated signal is denoted as [ x,1, x, x, x, x, x, j, x, x, x, x, -1, x, x, x ], [ x,1, x, x, x, -j, x, x, x, x, -1, x, x, x, x, x, j, x, x, x, x. Similar Tx7 Tx9 phase-codes are cyclically shifted 2 slots counter-clockwise for Tx1 Tx3, Tx10 Tx12 phase-codes are cyclically shifted 3 slots counter-clockwise for Tx1 Tx3, and Tx13 Tx15 phase-codes are cyclically shifted 4 slots counter-clockwise for Tx1 Tx 3.

It should be noted that, when P is equal to other values, the specific structures of the first signal and the second signal may refer to the foregoing description, and are not described herein again.

Example four:

in the foregoing description, the m transmit antennas transmitting the second signal transmit the signals in the same configuration in S slots. The M transmitting antennas can also be in S time slots, the M transmitting antennas in the second signal are divided into different groups, and each group selects different M_iOr m_iI takes at least two configurations of 1, 2.

For example, in the first S1 timeslots of S timeslots, N1 ones of M transmit antennas may select, in the P × M1 timeslots of one cycle, non-colliding P timeslots spaced by M1 to transmit the second signal, respectively, with P × M1 timeslots as a cycle; in the last S2 time slots of the S time slots, N2 transmitting antennas except N1 transmitting antennas in the M transmitting antennas take P × M2 time slots as a period, and P time slots which are not conflicted and are separated by M2 are selected from P × M2 time slots of one period to respectively transmit second signals; wherein, m is N1+ N2, N1 is 2, N2 is 1; S-S1 + S2, M1 ≠ M2, M1> -N1/(P-1), and M2> -N2/(P-1).

For example, N-5, M-N-1-4, P-2, N1-2, N2-2, M1-2, and M2-3 are described as examples. The first signal is transmitted through the transmitting antenna Tx0, and the first signal includes S chirp signals, the phase of each chirp signal being maintained.

The second signal is transmitted through the transmitting antenna Tx1 to the transmitting antenna Tx2, the transmitting pattern of Tx1 in each period may indicate that the signal is modulated with a phase and amplitude relationship of [1, x, -1, x ], and the transmitting pattern of Tx2 in each period may indicate that the signal is modulated with a phase and amplitude relationship of [ x,1, x, -1 ]. The Tx4 transmission pattern in each period may indicate that the signal is modulated with a phase and amplitude relationship of [1, x, x, -1, x, x ], the Tx4 transmission pattern in each period may indicate that the signals transmitted by the Tx1 and Tx2 are modulated with a phase and amplitude relationship of [ x,1, x, x, -1, x ] with a period of 4 slots, and repeatedly transmitted Nd1 times, and the signals transmitted by Tx3 and Tx4 with a period of 6 slots, and repeatedly transmitted Nd2 times, wherein Nd1 and Nd2 are both greater than or equal to 2. I.e. S — Nd1 × 4, S2 — Nd2 × 6.

Similar to other embodiments, Nd1 and Nd2 may be larger integers to further improve velocity resolution, for example, Nd1 — Nd2 — 32. Such a multiple configuration can avoid two targets with velocities that differ by half of the maximum velocimetry range, where the doppler index of the echo signal of the Tx0 signal of target 1 falls exactly the same as the doppler index of the echo signal of the Tx1 and Tx2 signals where target 2 is modulated to pi phase. Since M1 and M2 of configuration 1 and configuration 2 are different, the maximum velocity measurement range in configuration 1 is different from the maximum velocity measurement range in configuration 2, and even if the echoes of the Tx0 signal of the target 1 and the target 2 in configuration 1 are difficult to distinguish into two targets, in configuration 2, they can be easily identified. Therefore, the echo signal of the Tx0 signal is prevented from containing aliasing of a plurality of targets with Doppler frequency difference Vmax k/P. Due to the different configurations of Vmax ═ λ/(4 × T), for different configurations of M, a transmission repetition period T ═ M × T results_SIMODifferent. Here, the transmission repetition period T1 of configuration 1 is 2 × T_SIMOAnd the transmission repetition period T1 of configuration 2 is 3 × T_SIMOIn configuration 1, the two targets where doppler lines collide can be separated in configuration 2.

The above is merely an example, and other different configurations may be adopted in S time slots, or the case of expanding to P ═ 4 may be adopted, and no further description is given here.

Corresponding to the signal transmission method shown in fig. 3, an embodiment of the present application further provides a method for processing an echo signal formed by reflecting the first signal and the second signal by one or more targets, so as to obtain the velocity of the one or more targets, and further obtain angle information (e.g., a horizontal azimuth angle and a vertical azimuth angle) of the one or more targets.

The method may be applied to radar devices, in particular MIMO radars. The radar apparatus comprises N transmit antennas and at least one receive antenna, see fig. 7, the method comprising the steps of:

step 701: and receiving echo signals formed by the first signals and the second signals after the first signals and the second signals are reflected by at least one target.

The specific content of the first signal and the second signal can be shown with reference to the flow shown in fig. 3.

Namely receiving echo signals formed by the first signals and the second signals after being reflected by at least one target; the first signal is sent through 1 transmitting antenna in N transmitting antennas in S time slots, and the phase of the first signal is unchanged in the S time slots; the second signal is sent in S time slots by m transmitting antennas in the N transmitting antennas in at least one of time division and code division modes; the signal transmitted by each transmitting antenna in the m transmitting antennas in the second signal adopts 2 pi k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs an integer greater than 0 and less than P, where k_yThe phase modulation step adopted by the y-th transmitting antenna in the m transmitting antennas is represented, wherein y is 1, …, m; s is an integer greater than or equal to 4;

step 702: m sub range doppler maps (RD maps) are obtained for each receive antenna.

Each receiving antenna here refers to each of all receiving antennas included in the radar apparatus. The ith sub-RD pattern in the M sub-RD patterns of each receiving antenna is a result of 2D-FFT of the signal every M time slots, where the initial time slot of the echo signal of S time slots of the receiving antenna is i, and i is an arbitrary integer of 1,2, …, M.

Step 703: and detecting a first target according to the sub-RD images accumulated by the M sub-RD images of each receiving antenna, and obtaining the distance information of the first target.

Wherein the first target is one or more of the at least one target.

The distance information of the first target can be obtained through the process shown in fig. 7, and the angle information and the speed information of the first target can also be obtained in the embodiment of the present application, which may be specifically shown in fig. 8.

Step 801: a one-dimensional Fast Fourier Transform (FFT) (1D-FFT), i.e., a Fast Fourier transform in the range dimension, is performed in each time slot, respectively, based on the difference frequency signal of the received echo signal.

Assuming that a plurality of sampling signals are obtained by Nrx receiving antennas in each time slot, the distance dimension FFT is Nrange, FFT operation is performed on the plurality of sampling signals of one receiving antenna in each time slot, and the obtained complex matrix dimension is Nrange S Nrx.

Step 802: on the basis of the result of the 1D-FFT, signals of every M time slots with the initial time slots from 1 to M are extracted in each distance unit one by one to be subjected to two-dimensional FFT (2D-FFT), namely Doppler Fourier transform, and complex values of M sub-RD images are obtained on Nrx receiving antennas respectively, so that M sub-RD images of each receiving antenna are obtained.

Wherein, RD diagram: one dimension is distance information, and the other dimension is a radar output graph of Doppler information. Extraction from the Range dimension is called Range bin, extraction from the Doppler dimension is called Doppler bin, and extraction from both the Range and Doppler dimensions is called Range-Doppler Cell.

It should be noted that, in the process of obtaining the sub-RD graph, there may be operations performed on the echo signal, such as signal Windowing (Windowing), transmit/receive channel Calibration (Tx/Rx Calibration), Zero-padding (Zero-padding), and the like.

Further, after obtaining the M sub-RD patterns of each receiving antenna, in step 703, a first target may be detected according to the M sub-RD patterns of each receiving antenna, and distance information of the first target may be obtained, which specifically includes the following steps:

step 803: and accumulating the M sub-RD diagrams obtained from the multiple receiving antennas to obtain the accumulated sub-RD diagrams, and detecting the accumulated sub-RD diagrams to obtain a distance index Rind of the first target, namely the distance information of the first target.

Specifically, a distance index Rind and a doppler index Vind of the first target are obtained, Vind being the doppler index of the detected target in the range of [1, Nfft/P ]. And carrying out target detection according to coherent accumulation values or incoherent accumulation values of the M sub-RD graphs of the Nrx receiving antennas. The coherent accumulation value is accumulated for different transmitting antennas or receiving antennas in the same phase, that is, the maximum value in the beam direction of the selected predetermined angle is selected. And non-coherent accumulation value, and the signal accumulation mode of different transmitting antennas or receiving antennas adopts the value of amplitude superposition.

Threshold detection can be performed in the distance dimension, which is not limited to obtaining the distance index Rind of the first target by using Constant False-Alarm Rate (CFAR), and other detection methods, such as a method based on a noise threshold, may also be used.

Step 804 a: and performing 2D-FFT on the Doppler domain by using all S time slots to obtain complex values of a total range Doppler Map (RD Map).

Specifically, two-dimensional FFT (2D-FFT), i.e. fast fourier transform of doppler dimension, is performed on the results of S time slots 1D-FFT to obtain complex values of total range doppler maps (RD maps) of signals on multiple receiving channels.

The signals on a plurality of receiving channels are accumulated to obtain the energy of each range-Doppler unit in a total RD diagram. It is understood that the dimension of the total RD map is Nrange (M × Nfft), i.e., the distance dimension is the same as the dimension of the sub-RD map, and the doppler dimension is M times the dimension of the sub-RD map.

The total RD pattern is a 2D-FFT performed at M x Nfft points on the doppler domain using all S time slots based on step 801, and M interval decimation is not performed any more. Only Nrx receive antennas are non-coherently superimposed.

Further, to simplify the calculation, as shown in fig. 9, step 804a may be replaced by step 804 b: the sub RD graph is calculated to detect the 2D-FFT doppler spectrum within S slots at the distance index Rind of the first target.

In order to determine the doppler in the echo signal of the first signal reflected by the target, a number of different processes may be performed in conjunction with the transmit waveform.

Step 805: at least one doppler index Vind _ sub of the aliased velocity of the first signal of the first target on the accumulated sub-RD map is determined, i.e. the doppler index Vind _ sub in the accumulated sub-RD map of Tx0 is obtained. The doppler index Vind _ sub of the first signal of the first target on the accumulated sub-RD map is one of P possible positions spaced by Nfft/P, where Nfft is the dimension of the 2D-FFT of the accumulated sub-RD map.

And extracting Doppler values on the sub RD image for detection on a distance unit Rind of the first target, namely performing threshold detection on a Doppler domain to obtain the velocity of the first target in an aliasing Vmax/M range or at least one Doppler index Vind _ sub of the aliasing velocity of the first signal.

But since the signals of the different antennas are modulated by 2 π k_yPhase of/P, k_yPhase modulation in 0,1, … P-1. At least one Doppler index Vind _ sub of the aliased velocity of the first signal of the first target on the accumulated sub-RD map is not directly obtained, but is located in P lines separated by Nfft/P, including Vind, Nfft/P + Vind, …, (P-1) Nfft/P + Vind, where Nfft is the dimension of the 2D-FFT of the accumulated sub-RD map, VindIs at [1, Nfft/P]Target index values detected within the range. In fact, since the doppler spectrum has a 2 pi cycle characteristic, the specific detection here can also detect any sub-range of P sub-intervals of the accumulated sub-RD graph. For example, select [ Nfft/P +1, 2Nfft/P]And Vind in the interval, the positions corresponding to the P spectral lines are Vind-Nfft/P, Vind, …, (P-2) Nfft/P + Vind.

The embodiment of the present application proposes a plurality of methods for determining the spectral line position of the spectral line Tx0, one of which is the method in step 805, and only uses the information of M sub-RD graphs. Another method may utilize the total RD map and the sub-RD map, with particular reference to step 806.

The method in step 805: only M sub-RD maps are utilized. Specifically, the amplitude difference of a pair of spectral lines corresponding to P spectral lines in each of the M sub-RD patterns of the same receiving antenna is compared, and the sub-RD pattern corresponding to the pair of spectral lines with the smaller amplitude difference is the spectral line position where Tx0 is located, that is, the doppler index corresponding to Tx0 antenna in the sub-RD pattern is determined.

The spectral lines of Tx 1-Txm correspond to different channels respectively, so that the amplitude difference is large, and the spectral line of Tx0 is the same channel, so that the amplitude difference is small, and the spectral line position of Tx0 can be determined according to the amplitude difference. Wherein Tx 1-Txm are m transmitting antennas respectively for transmitting the second signal.

Step 806: and (3) extracting the complex values of P spectral lines in each sub RD image one by one, wherein the P spectral lines are P spectral lines with Doppler index values of Vind and Nfft/P + Vind … (P-1) Nfft/P + Vind in the sub RD images, matching the complex values of the P spectral lines with the total RD image, and determining the speed of the first target and the corresponding speed of Tx0 on the accumulated sub RD images. Where Vind is the target index value detected in the [1, Nfft/P ] range.

It should be noted that, by this step, Tx0 corresponding spectral lines on the accumulated sub-RD graphs and corresponding spectral lines on the total RD graph can be determined. That is, both the velocity of the first target and the corresponding velocity of Tx0 on the accumulated sub-RD map are determined.

Where Vind is the actual process, since the speed itself is directional, i.e. far from or close to the radarA positive or negative number may be taken to indicate whether the object is far or close. The maximum speed measurement range Vmax _ total of the radar apparatus, which is determined by the transmission waveform parameters, is usually in the form of positive and negative values in the directions of approaching and separating from two speeds, i.e., ± Vmax _ total ═ λ/(4 × T ═ T-_SIMO) λ is the wavelength of the modulation frequency, T_SIMOFor a single continuous transmit antenna, one slot length, is referred to herein as the repetition period for the transmit antenna Tx0 to transmit a signal, and the transmit antenna Tx0 is the transmit antenna to transmit the first signal. The first target is any one of the at least one target. And the second signal is extracted every M time slots, ± Vmax _ sub ═ λ/(4 × M ═ T)_SIMO) Since λ is the wavelength of the modulation frequency, the doppler index value of the Tx0 antenna determined on the sub-RD diagram needs to be converted to a velocity index value in the Vmax range. The doppler index for the unaliased velocity of the first target Vind _ total ═ Vind _ sub + kk Nfft-Nfft/2, where kk denotes the aliased value since the sub-RD map is the per M down-sampled doppler index of the total RD map, and kk takes the value 0, …, M-1. Note that Vind _ sub in RD is fftshift operated by-Nfft/2, which represents positive and negative speeds, while Vind _ total in total RD can obtain positive and negative speeds by the fftshift operation. The embodiments of the present application are not limited because different applications have different positive and negative speed definitions.

Specifically, the number of targets on the range cell is obtained by using the sub-RD map, and on the total RD map, a spectral line with the largest energy on the same range cell, that is, a doppler index Vind _ total of the unaliased velocity of the first target, and a doppler index Vind _ sub _ mod (Vind _ total, Nfft) + Nfft/2 of the aliased velocity matched on the sub-RD map are located. And sequentially iterating the spectral lines and the number of the targets according to the number.

Wherein, because only the Tx0 signal is transmitted all the time during the total transmission time, the Tx0 spectral line of one target has higher energy than the spectral lines of other transmitting antennas of the same target in the total RD diagram.

As shown in fig. 10(a) to 10(c), the doppler spectrum corresponding to one 3 transmitting antennas is illustrated, and in fig. 10(a) to 10(c), in S time slots, the modulation phase of the second signal includes P phases, and each transmitting antenna transmitting the second signal performs repeated transmission with P × M time slots as a cycle. Taking P-2 and M-2 as an example, a total S-256 time slot is transmitted, Nfft-S/2-128 is taken, and the real speed is 0. Fig. 10(a) is a doppler spectrum of all slots, i.e., a total RD diagram. Fig. 10(b) shows doppler spectra corresponding to time slot 1 and time slot 3. Fig. 10(c) shows doppler spectra corresponding to time slot 2 and time slot 4. In fig. 10(a), in the total RD diagram, at a certain target distance unit Rind, there may be one spectral line at each of the doppler indices Vind _ total ═ 129 (the identifier of Nfft/P ═ 128/2 ═ 64) of the unaliased velocity, that is, at 129-64 ═ 65 and 129+65 ═ 184, the target can be detected, that is, the doppler value of the detected target is high.

In FIG. 10(b), the Doppler spectrum for the odd slots has a line at 1 and 65, respectively; in fig. 10(c), the doppler spectrum for the even slots has a spectral line at 1 and 65, respectively. Then instead of the index being 1, the doppler index Vind _ sub-mod (129, Nfft 128) + Nfft/2 65 for the location of the line on the sub-RD graph for Tx0 as the aliased velocity can be obtained.

As can be seen from fig. 10(a) to 10(c), the following rule exists for the intervals of the spectral lines when P is 2: spectral lines exist at the left and right intervals Nfft/2 of the real Doppler index Vind, namely Vind _ total + Nfft/2 or Vind _ total-Nfft/2, and other spectral lines are at the left and right integer multiples of Nfft interval. It will also be appreciated that even if there is only one target doppler velocity, the time and code division transmitted second signal will form multiple doppler lines, it is very difficult to detect the aliasing velocity of a target at Tx0 directly on the total RD pattern if the total RD pattern is used to detect (P-1) × M +1 corresponding doppler lines for a target according to the prior art method. When the speed measurement range of the sub-RD diagram is reduced to 1/M of the total RD diagram, P spectral lines with larger amplitude values and different Nfft/P relation always exist, the number of the spectral lines in the sub-RD diagram cannot be increased along with the increase of the number of the transmitting antennas of the second signal, and the sub-RD diagram only sums with the phase modulation step length k adopted in the phase modulation_yAre related to the number of different values. Thus, the sub-RD map is used to determine at least one Doppler index Vind _ sub of the aliased velocity of an object, matching only PThe number of spectral lines with larger amplitude is far smaller than the number of Doppler spectral lines to be matched in the total RD diagram.

Step 807: and according to the Doppler index Vind _ sub of the aliasing velocity of the Tx0 in the accumulated sub RD image, matching the total RD image to obtain the Doppler index Vind _ total of the unaliased velocity of the first target.

Specifically, the doppler index Vind _ sub of the unaliased velocity of Tx0 and the formula Vind _ total of Vind _ sub + kk Nfft-Nfft/2 obtained from the accumulated sub-RD graph are traversed to match the different kk values to the doppler index value with the maximum amplitude value on the corresponding possibility of the total RD graph, so as to obtain the doppler index Vind _ total of the first target unaliased velocity, where kk is an aliasing velocity coefficient, and kk is 0,1, …, and M-1. Similar to the reverse process in step 806. The velocity at which the first object does not alias is the velocity information of the first object.

As shown in fig. 10(a) to 10(c), actually, the doppler index Vind _ sub of the velocity aliased on the sub-RD map by Tx0 is 65, the doppler index Vind _ total of the velocity unaliased is 129, and kk is 1. It can also be seen that when kk is 0, Vind _ total is 65-64 is 1, and the energy on the doppler spectrum line with index Vind _ total being 1 is much lower than Vind _ total being 129 on the total RD graph, so it can also be confirmed that kk is 1 instead of being 0. Note that the values of 0, … and M-1 used for the value of kk also have a mode of representing the value of kk in the positive and negative intervals, and the embodiment of the present application is not particularly limited.

Steps 805-807 are repeatedly executed according to the detected plurality of distance units where the at least one target is located until the traversal is completed.

Further, the method can also comprise the following steps:

step 808: the 2D-FFT transformed complex signals of the transmit antenna Tx0 on different receive antennas are obtained.

It will be appreciated that the complex signal is extracted from the RD cells corresponding to the distance index Rind of the M sub-RD maps of Nrx receive antennas and the doppler index Vind _ sub of the aliased velocity.

Step 809: and compensating Doppler phase deviation caused by time division and code division of the m transmitting antennas Tx 1-Txm to obtain complex signals after 2D-FFT conversion of the m transmitting antennas Tx 1-Txm on different receiving antennas.

Note that M is 0,1 … M-1, and M is 0 for the first slot, and there are cases where the doppler phase shift caused by the code division and the phase shift caused by the code division are merely divided. When m takes other values, there are doppler phase deviation due to time division and phase deviation due to code division.

The phase to be compensated due to the selection of the transmitting antenna of the mth time slot can be represented by a function of Vind _ sub or Vind _ total. Wherein f (V)_{ind_total}) Denotes the complex value of the RD cell with index (Rind, Vind _ total) of the 2D-FFT on the overall RD plot, f (V) if the antenna is aligned to the transmit time and phase of Tx0_{ind_sub}) Indicating transmission in the m-th time slot, usingFor a phase modulated antenna, the signal with velocity aliasing coefficient kk is indexed on the mth sub-RD graph as the complex value of the RD cell of (Rind, Vind _ sub).

Wherein, the phase compensation quantity introduced by the antennas transmitted in the TDM time division time slot m and the velocity aliasing coefficient isAnd variations caused by phase modulationWherein k is_mThe value of k in the phase modulation step adopted by the transmitting waveform adopted by the transmitting antenna in the m time slot.

In this step, by calculating the doppler phase shift between different time slots of each target, the separated complex signal of each receiving antenna can be obtained after phase compensation.

Specifically, there may be two methods:

method 9-1: and determining Doppler compensation values of the transmitting antennas at different moments according to the phase difference of the spectral line phases where Tx0 is located in the N-1 sub-RD diagrams.

Due to the line in which Tx0 is located, only the phase introduced due to the time difference on the different sub-RD patterns is compensated as a compensation value to the other time-divided antennas, so that the signals are equivalent to simultaneous transmission. I.e. equivalent to that in the formulaAnd (4) partial.

Method 9-2: and compensating the corresponding phase difference to Doppler compensation values of the transmitting antenna at different moments according to the obtained Doppler phase of the first target.

The phase to be compensated can be represented by Vind _ sub or Vind _ total due to the selection of the transmitting antenna of the mth time slot.

Step 810: and acquiring the angle information of the first target according to the compensated signals on the virtual receiving antenna formed by the different transmitting antennas and the receiving antenna.

The antenna synthesized by the transmitting antenna and the receiving antenna is a Virtual receiving antenna (Virtual Receiver antenna), which can be described as a Virtual receiving array synthesized by the transmitting antenna and the receiving antenna. According to the arrangement of the virtual receiving antennas, the angle information of the first target is obtained by using FFT, Digital Beamforming (DBF), Multiple Signal Classification (MUSIC), or other common angle spectrum analysis algorithms, which is not described herein again.

It should be noted that, in step 810, the distance information and the speed information determined in step 807 can also be obtained.

It should be noted that steps 808-810 are repeated on the first target output in step 807.

It should be noted that the present application is also applicable to the case where the number of transmission antennas is larger. For example, as shown in fig. 11, a diagram of doppler lines of a range cell containing a target in the overall RD diagram is shown. In the leftmost total RD pattern of fig. 11, at least 6 time slots are required for 4 transmitting antennas, and the total RD pattern includes 4 spectral lines; in the middle of fig. 11, 5 transmitting antennas require at least 8 time slots on the total RD diagram, which includes 5 spectral lines; in the right-most overall RD diagram of fig. 11, at least 10 time slots are required for 6 transmitting antennas, and the overall RD diagram includes 6 spectral lines. Other cases will not be described in detail. From this figure it can be seen that if the target is detected on the total RD pattern, due to the periodic continuation of the antenna speed for discontinuous transmission, there will be multiple spectral lines, which are difficult to detect, even if the phase is selected only P different steps. Therefore, the sub-RD diagram is adopted to detect the target in the method, and the processing of the receiving side can be simplified.

Further, when M is 8, N is 9, P is 2, S is 1024, and Nfft is 1024/8 is 128, there are two target scenes, that is, 2 situations of Vind _ sub are detected on Rind. As shown in fig. 12, a diagram of a total RD of two phases of 16 slots containing 2 target doppler lines in one range bin is shown. In fig. 12, the velocity resolution of the total RD pattern and the sub-RD pattern is dv, but the velocity range of the total RD pattern is 8 × 2 × 64 × dv 1024 × dv, and the velocity range of the sub-RD pattern is 2 × 64 × dv 128 × dv.

In the sub-RD graph, the peak index in the doppler domain after the detection of Tx0 is Vind 96 or 83, and the interval between two peaks in the sub-RD graph is 13.

In the total RD diagram, a local peak value method is adopted to obtain a Doppler index 544 of a first large peak value, which is 96+128 × 3+ 64; thus matching 544 x dv to the velocity of the first target; since the two peak separation in the sub-RD plots is 13, the doppler index of the second peak in the total RD plot does not satisfy the integer aliasing relationship for this separation, and at the third largest peak doppler index of magnitude 659, the match 96-83 ═ 544-.

In fact, although this example is illustrated on the same distance index Rind, this corresponds to the case where there are two targets. The embodiments of the present application are not limited thereto and may be iterated multiple times until the matching peak is below the predetermined threshold.

Further, the method 9-1 or 9-2 compensates for Doppler phase differences between different antennas based on velocity compensation for Doppler phase differences due to different time instants.

Furthermore, the signals of the antennas transmitted at different time instants are transmitted at the same time instant after compensation, and the phase difference on the antennas is only the phase difference introduced by the time delay on the space of the antennas. And calculating the angle information of the target according to the phase difference. Since the calculation here is related to the arrangement of the antennas, there is no particular limitation here.

Further, in combination with the second embodiment, when a third signal is further included in S0 time slots after S time slots, the steps executed by the corresponding receiving side are the same except for step 806, and reference may be specifically made to the foregoing description.

In conjunction with the second embodiment, the previous step 806 can be implemented as follows:

when m transmit antennas are also transmitting a third signal in S0 slots, the doppler position of Tx0 in the sub-RD pattern, i.e., the doppler index Vind _ sub of the aliased velocity, and the target true velocity, corresponding doppler index Vind _ total of the unaliased velocity, can be determined by comparing the spectral lines in S slots with the positions of the spectral lines in S0 slots.

Specifically, it is assumed that M is 8, N is 9, M is 8, P is 2, S is S0 is 512, the transmitting antennas are Tx0 to Tx8, Tx0 transmits the first signal, Tx1 to Tx8 transmits the second signal and the third signal. The doppler spectrum of the signals in the first S time slots in the corresponding distance unit is obtained, as shown in fig. 13, which is a doppler spectrum diagram provided in the embodiment of the present application. In total, 9 spectral lines, the signal transmitted by Tx0, and other Tx1 to Tx8, are obtained in fig. 13 (c) (bottom left diagram in fig. 13), which are a plurality of overlapped spectral lines appearing on the spectral lines due to time division. If the range bin corresponding to the signal in the following S0 time slots is doppler-spectrally obtained, 8 spectral lines can be obtained, specifically, refer to (d) in fig. 13 (the lower right diagram in fig. 13). Due to the absence of the signal of Tx0, multiple aliased spectral lines appear on the spectral line only from Tx1 to Tx8 due to time division. Then subtracting the two spectral amplitudes can obtain the line position corresponding to the velocity of the target at 256, which can be referred to as (b) in fig. 13 (upper right diagram in fig. 13). Fig. 13 (a), i.e., the upper left diagram in fig. 13, is doppler spectrum obtained by FFT of the entire S + S0 time slots.

Since the sum of the durations of the second signal and the third signal is longer than the duration of the first signal, the signal transmitted by Tx0 occupies only the first S time slots, and the signals transmitted by Tx1 to Tx8 occupy S + S0 time slots, so that the velocity resolution obtained by Tx0 is actually lower than those of Tx1 to Tx8, i.e., dv _ Tx0 is S dv _ txi/(S + S0), where dv _ Tx0 and dv _ txi respectively represent the velocity resolution corresponding to Tx0, and the actual target velocity and the doppler phase corresponding to the target velocity can be obtained by simple conversion, which is not repeated here.

Further, in combination with the previous third embodiment, when P is greater than 2, the specific steps of the receiving side are the same except for the step 806 and the step 809, and the step 806 and the step 809 are respectively described below.

Step 806: and (4) extracting spectral lines of Vind, Nfft/4+ Vind, Nfft/2+ Vind and 3 Nfft/4+ Vind in the sub RD diagram, and determining the spectral line position of the sub RD diagram where Tx0 is located, namely the Doppler index Vind _ sub of the aliasing speed.

It should be noted that this case is difficult to distinguish by doppler using the information of the multiple transmitting antennas in the total RD diagram. The phase of the transmitting antennas Tx1, Tx2 and Tx3 for simultaneously transmitting signals in the same group is f0- (2 pi ii + Q)/(2 pi M T)_SIMO) And f0 is the frequency of the signal transmitted by Tx 0. When M-N-1-2 and P-4, then Q has 3 possible values, i.e., pi/2 or pi or 3 pi/2, the 0 phase is occupied by Tx0, ii has 2 possible values of 0 or 1, a total of 2 x 3-6 possible spectral lines, plus the spectral line in which Tx0 is located, for a total of 7 spectral lines. As shown in the first left panel of fig. 11. Therefore, in this embodiment, the spectral line where Tx0 is located may be obtained by the sub-RD pattern auxiliary target information.

Specifically, the method one: only the child RD map is utilized, step 805 a. Comparing the amplitude differences of the plurality of sub RD patterns, wherein P is the amplitude difference of 4 spectral lines, and the smaller amplitude difference is the spectral line where Tx0 is located.

Since the channels other than the channel Tx0 in the plurality of sub-RD graphs are time-divided, the amplitude difference is large. In fig. 11, the amplitude of Vind ═ 129 in the sub RD graph is 256, and the position of the spectrum line where Tx0 is located is 129.

The second method comprises the following steps: the total RD map and the sub-RD maps are utilized, step 806. And obtaining the number of targets on the range unit by using the sub RD diagram, and matching the position of aliasing mod (Vind _ total, Nfft) + Nfft/2 on the sub RD diagram by using a spectral line with the maximum energy on the same range unit, namely the Doppler index Vind _ total of the unaliased speed on the total RD diagram. And sequentially iterating the spectral lines and the target number according to the number, thereby determining the position of the spectral line where Tx0 is located.

Fig. 14 is a diagram of a doppler spectrum provided in an embodiment of the present application. Fig. 14 illustrates doppler lines in the total RD pattern and the sub-RD pattern for a target in a range unit in a 4 phase 8 slot. In fig. 14, a case where the total radial velocity is 0 and only one target exists in the 0-degree direction is described as an example. The total RD pattern has 7 lines separated by Nfft/4-64. Each object has 4 spectral lines spaced 64 apart in the sub-RD pattern. Where the doppler index of the unaliased velocity of the first target Vind total 257 is highest in energy, mod (257, 256) +256/2 129, the doppler index position 129 can be determined to be the spectral line of Tx 0.

Further, step 809: the Doppler frequency difference of the time slots where Tx 1-Txm is located is compensated, and the fixed phase difference j, -1 and-j is added with Tx 0. And obtaining complex signals after 2D-FFT transformation of Tx 1-Txm antennas on different receiving antennas.

Similarly, the third embodiment can also be generalized to the case where M is other values, such as N ≦ (P-1) × M + 1. The different antennas in the same group (i.e., the antennas occupying the same time slot for transmission) have different phases, and the positions in different groups that are silent periods have cyclic shifts.

Furthermore, when M is other values and P is greater than or equal to 3, the number of simultaneously transmitting antennas in at least one group (antennas simultaneously transmitting in the same time slot) of the second signal is less than P-1.

Correspondingly on the receive side, step 805 may be as follows:

step 805 b: as an alternative to step 805a, a method of determining the doppler signature of Tx0 in a sub-RD map using only the sub-RD map. Similarly, in the second embodiment, when P ≧ 3, if the signal is modulated within a group (antennas transmitting simultaneously in the same timeslot) with only part of the phases in the set as the step size, the identification of the vacant phase-resolved Tx0 can be used. Or when P is 2 and M is larger than the integer of M/(P-1), P phase modulation steps are not occupied in the partial sub RD diagram. Therefore, the phase missing from a certain sub-RD pattern can be used to identify the doppler line position where Tx0 is located, i.e. the doppler index Vind _ sub of the aliasing velocity.

Specifically, in the example of P ═ 4 phases, the phase of the signal transmitted in each cycle in P slots occupying the interval M among P × M slots may be represented as [1,1,1,1], and the phase of the signal transmitted in each cycle in P slots occupying the interval M among P × M slots may be selected from [1, j, -1, -j ], [1, -1,1, -1], [1, -j, -1, j ], and less than 4-1 ═ 3(P ═ 4) transmit antennas simultaneously, for example, when transmitting only [1, j, -1, -j ], [1, -j, -1, j ], then the spectral line of f0-fvmax/2 does not exist, and the correct position of Tx0 can be determined by this method. I.e. spectral lines are present only at f0, f0-fvmax/4, f0-3 fvmax/4. In M groups of time-division multiplexed antennas, the sub-RD pattern of the corresponding time slot can be used to determine the line position of Tx0 on the receiving side whenever some groups are transmitted in this way. Similarly, P is 4, M is 2, M is 5, N is M +1 is 6, Tx1 to Tx3 occupy slots 1,3, Tx4 to Tx5 occupy slots 2,4, and then only signals of 3 transmitting antennas, namely Tx0, Tx4, Tx5 antennas, exist in 2,4 slots, and according to the step size of phase modulation, there may be one missing line, namely f0-fvmax/2 line, among P evenly distributed lines according to the phase of the missing line.

Or it can be understood that when P is 2, M > M/(P-1) M, M signals in the second signal do not occupy all of S time slots, and only the first signal exists in some time slots. For example, if P is 2, N is 3, M is N-1 is 2, and M is 3, then Tx1 occupies 1,4 time slots, Tx2 occupies 2,5 time slots, and only the first signal, i.e., the signal of Tx0, and the second signal is located in the empty spectral line position in time slots 3, 6. The line position for Tx0 may be determined using the corresponding sub-RD plots for slots 3, 6.

Further, at present, in some special cases, only 1 pair of spectral lines can be observed on the sub-RD-map, but actually 2 target velocities can be observed from the overall RD-map. For example, as shown in fig. 15, there is a diagram of the total RD pattern and the doppler lines in the sub-RD patterns of the overlapped objects for 2 sub-RD patterns in a range unit of 2 phase 4 slots. In fig. 16, the corresponding velocity Vind 59 and Vind 251, the corresponding two targets Tx0 are the left and right spectral lines, respectively, in the sub-RD graph, and it is possible to miss weaker targets, such as the target with the velocity Vind 251.

To solve the problem, the signal transmission method in the fourth embodiment may be adopted, that is, M transmitting antennas in the second signal are divided into different groups, and each group selects different M_iOr m_i. With reference to the fourth embodiment, when m transmitting antennas transmit the second signal in different configurations in S time slots, on the receiving side, there may be the following differences in the previous steps 803, 806, and 809:

step 803: a plurality of sub-RD maps are extracted according to M1 and M2, respectively.

For example, when M1 is 2 and M2 is 3, as shown in fig. 16, a doppler spectrum diagram is provided for the embodiment of the present application. Fig. 16 illustrates a diagram of doppler lines in a total RD pattern and sub-RD patterns for an object with doppler overlap in 4 slots for 2 sub-RD patterns in a 2-phase 6-slot range unit.

Using d in conjunction with FIG. 16_vM2＝M1*d_vM1The M2 translates into different configured speed identifiers, specifically, since M2 is 3 and the maximum speed measurement range is a single chirp scanning time, the speed resolution d for the case of using 6 time slots_v6And 4 slot down speed resolution d_v4There may be a reduced relationship d_v6＝4*d_v4/6＝M1*d_v4/M2。

Step 806: the spectral line in which Tx0 is located is determined from the plurality of differently configured sub-RD plots and the total RD plot.

In contrast to the embodiment, the number of targets is the largest target in the plurality of sub-RD graphs. For example, in the sub-RD graph of M1 ═ 2, only one object is determined, and in the sub-RD graph of M2 ═ 3, two objects are determined, and then the spectral lines of Tx0 of the two objects need to be searched respectively. Specifically, the Tx0 spectral line positions of multiple targets are further determined using 805 and 806.

Whether Tx0 of multiple targets alias to one of the same or different P positions at the current distance index Rind can be easily obtained by waveform configuration at the transmitting side.

Step 809: compensating the Doppler frequency difference of the time slots of Tx 1-Txm.

The N1 transmitting antennas and the N2 transmitting antennas transmit signals in a time division mode, and when the designed total transmitting time length of the N1 transmitting antennas and the N2 transmitting antennas does not exceed one range cell even if the target moves at the maximum speed, the target reflected by the signals transmitted by the N1 transmitting antennas and the N2 transmitting antennas is still in one range cell. Therefore, only the phase difference may be considered. In a vehicle-mounted scenario, it can be considered that the total duration of S1 time slots in which N1 transmit signals does not exceed 10ms, and the total duration of S2 time slots in which N2 transmit signals does not exceed 10 ms. The embodiment of the present application also provides a radar apparatus, which can be used to execute the method shown in fig. 3. Referring to fig. 17, the radar apparatus includes an antenna array 1701, a microwave integrated circuit 1702, and a processor 1703, the antenna array 1701 including N transmit antennas, N being an integer greater than 2, where:

a processor 1703 for determining a first signal and a second signal;

a microwave integrated circuit 1702 for generating a first signal and a second signal determined by a processor 1703;

an antenna array 1701 for transmitting a first signal through 1 of the N transmit antennas in S slots; the phase of the first signal is unchanged in S time slots; in S time slots, sending a second signal by m transmitting antennas in N transmitting antennas in a time division mode or a code division mode; s is an integer greater than or equal to 4; m is an integer greater than 2 and less than N; the signal transmitted by each transmitting antenna in the m transmitting antennas in the second signal adopts 2 pi k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs greater than 0 and less thanP is an integer, where k_yAnd y is 1, … and m, which represents the phase modulation step adopted by the y-th transmitting antenna in the m transmitting antennas.

Optionally, (Nd +1) × P > S > ═ Nd × P × M, where Nd denotes the number of repetitions of the transmission pattern of the M transmission antennas, Nd being greater than or equal to 1;

the transmission pattern represents signals of the transmitting antennas adopting a time division mode, and occupies non-conflicted P time slots with the interval of M time slots, wherein M is the number of time slots which are separated from each other in the time slots occupied by one transmitting antenna in M transmitting antennas, and M is an integer which is greater than or equal to M/(P-1).

Optionally, 2 pi k is adopted by signals sent by transmitting antennas occupying the same time slot in m transmitting antennas_yWhen the step size of/P is phase modulated, k_yThe values are different.

Optionally, the microwave integrated circuit is further configured to: in S0 time slots after the S time slots, sending a third signal in a time division mode through m transmitting antennas, wherein S0 is an integer larger than 1; the transmission pattern of the third signal in S0 time slots is the same as the transmission pattern of the second signal in S time slots, S Nd P M being an integer greater than or equal to M/(P-1).

Optionally, m is N1+ N2, N1 is 2, and N2 is 1; microwave integrated circuits are specifically used for:

in the first S1 time slots of the S time slots, P M1 time slots are used as the period through N1 transmitting antennas of the M transmitting antennas, and P time slots which are not conflicted and are separated by M1 are selected from P M1 time slots of one period to respectively transmit second signals; the last S2 time slots in the S time slots use P M2 time slots as a period through N2 transmitting antennas except N1 transmitting antennas in the M transmitting antennas, and P time slots which are not conflicted and are separated by M2 are selected from the P M2 time slots in one period to respectively transmit second signals; wherein, S is S1+ S2, M1 is not equal to M2, M1> -N1/(P-1), and M2> -N2/(P-1).

Optionally, P ═ 2, 3, or 4.

Optionally, the m transmitting antennas for sending the second signal and the 1 transmitting antenna for sending the first signal are different transmitting antennas among the N transmitting antennas.

The embodiment of the application also provides a radar device which can be used for executing the method shown in the figure 7. Referring to fig. 18, the radar apparatus comprises a receiver 1801 comprising at least one receiving antenna, and a processor 1802, wherein:

a receiver for receiving an echo signal, the echo signal being formed by a first signal and a second signal reflected by at least one target; the first signal is sent through 1 transmitting antenna in N transmitting antennas in S time slots, and the phase of the first signal is unchanged in the S time slots; the second signal is sent in S time slots by m transmitting antennas in the N transmitting antennas in at least one of time division and code division modes, wherein m is an integer greater than or equal to 2 and less than N; the signal transmitted by each transmitting antenna in the m transmitting antennas in the second signal adopts 2 pi k_yStep size of/P is phase modulated, P is an integer greater than 1, k_yIs an integer greater than 0 and less than P, where k_yThe phase modulation step adopted by the y-th transmitting antenna in the m transmitting antennas is represented, wherein y is 1, …, m; s is an integer greater than or equal to 4;

a processor for obtaining M sub-range-doppler RD maps for each of at least one receive antenna; the ith sub-RD diagram of the M sub-RD diagrams of each receiving antenna is the initial time slot of the receiving antenna in the echo signals of S time slots, i is the result of two-dimensional fast Fourier transform (2D-FFT) of signals of every M time slots, and i is any integer of 1,2, … and M; detecting a first target according to the sub-RD images accumulated by the M sub-RD images of each receiving antenna, and obtaining the distance information of the first target; the first target is one or more of the at least one target.

Optionally, the processor is further configured to: and obtaining a corresponding total distance-Doppler RD diagram, wherein the total RD diagram is the result of executing 2D-FFT on all the adjacent time slots in the S time slots.

Optionally, the processor is further configured to: at least one doppler index Vind _ sub of the aliased velocity of the first signal of the first object on the accumulated sub-RD-map is determined, the at least one doppler index Vind _ sub of the aliased velocity of the first signal of the first object on the accumulated sub-RD-map being located in P possible positions spaced by Nfft/P, where Nfft is the dimension of the 2D-FFT of the accumulated sub-RD-map.

Optionally, the processor is further configured to: and matching according to the accumulated sub-RD diagram and the total RD diagram, and determining at least one Doppler index Vind _ total of the unaliased velocity of the first target and at least one Doppler index Vind _ sub of the corresponding aliased velocity of the first target on the accumulated sub-RD diagram.

Optionally, the processor is further configured to: doppler phase deviation caused by time division and phase deviation caused by code division of the m transmitting antennas are compensated, and angle information of the first target is obtained.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.