阅读说明：本技术 一种基于时间反转技术的频控阵时间聚焦方法 (Frequency control array time focusing method based on time reversal technology ) 是由 程婕 王文钦 张顺生 陈慧 贾文凯 侯宇典 于 2019-09-04 设计创作，主要内容包括：本发明提出一种基于时间反转技术的频控阵时间聚焦方法,该方法包括：频控阵接收设备发送第一信号；频控阵发射设备接收第二信号；将所述第一信号与所述第二信号进行去卷积,以得到多径信道；所述频控阵发射设备将发射信号通过所述多径信道发射出去。目前多径对频控阵无线传输具有信号损耗,时间反演技术可利用多径信号的损耗,时间反演信道可有效收集利用多径信号,明显改善系统的传输性能。(The invention provides a frequency control array time focusing method based on a time reversal technology, which comprises the following steps: the method comprises the steps that frequency control array receiving equipment sends a first signal; the frequency control array transmitting equipment receives a second signal; deconvolving the first signal and the second signal to obtain a multipath channel; and the frequency control array transmitting equipment transmits the transmitting signal out through the multipath channel. At present, the multipath frequency-controlled array wireless transmission has signal loss, the time reversal technology can utilize the loss of multipath signals, a time reversal channel can effectively collect and utilize the multipath signals, and the transmission performance of a system is obviously improved.)

1. The frequency control array time focusing method based on the time reversal technology is characterized by comprising the following steps:

the method comprises the steps that frequency control array receiving equipment sends a first signal;

the frequency control array transmitting equipment receives a second signal;

deconvolving the first signal and the second signal to obtain a multipath channel;

and the frequency control array transmitting equipment transmits the transmitting signal out through the multipath channel.

2. The frequency controlled array time focusing method based on the time reversal technique according to claim 1, characterized in that the first signal is:

wherein f is₀The carrier frequency of the signal transmitted by the first array element is shown, Δ f is the carrier frequency increment between different array elements, and N is the total number of the transmitted array elements.

3. The frequency controlled array time focusing method based on the time reversal technique according to claim 2, characterized in that the second signal is:

where E (r, t) represents the received signal at a distance r at time t, r is the distance of the reference array element to the target point, and c represents the speed of light.

4. The time-reversal technique-based frequency-controlled array time-focusing method according to claim 3, wherein the channels include a direct propagation path and a reflected propagation path.

5. The frequency-controlled array time focusing method based on the time reversal technique of claim 4, wherein the direct propagation path received by the target point is:

wherein E is_dn(r, t) denotes the directly propagating received signal component at a distance r at time t, r_dnIndicating the distance of the direct propagation of the nth array element from the target point.

6. The frequency control array time focusing method based on the time reversal technique of claim 5, wherein the reflection propagation path received by the target point is:

wherein E is_rn(r, t) denotes the multipath propagated received signal component at a distance r at time t, r_rnThe distance of the multipath propagation distance target point of the nth array element is shown.

7. The time-reversal technique-based frequency-controlled array time-focusing method of claim 6, wherein the target point receiving signal is expressed as:

8. the frequency controlled array time focusing method based on time reversal technique as claimed in claim 7, wherein the received signal of a certain target point is:

wherein sin (. cndot.) represents horizontal polarization, cos (. cndot.) represents vertical polarization, and E_tot(r, t) represents the received signal at a distance r at time t.

Technical Field

The invention belongs to the technical field of frequency control arrays, and particularly relates to a frequency control array time focusing method based on a time reversal technology.

Background

The array antenna technology has wide application in the fields of radar, wireless communication, sonar, navigation and the like, and the antennas can have different arrangement modes according to the requirements of practical application, and can be divided into linear arrays and area arrays at most. Compared with a single antenna, the array antenna can realize the functions of beam scanning, beam shaping, multi-beam and the like. Researchers at home and abroad often study performance and applications according to the functional classification of array antennas, such as phased array antennas, frequency scanning antennas, adaptive antennas, Multiple Input Multiple Output (MIMO) antennas, and the like. In recent years, new arrays derived from phased arrays and MIMO have attracted much attention, such as phased arrays-MIMO and differential arrays. These new arrays bring more degrees of freedom and a wide range of applications, and bring many problems to be explored and solved.

Phased array radars differ from conventional mechanical scanning radars in that they are widely used for radar target detection and imaging applications because they allow for free spatial scanning of the beam. Generally, the same signal is transmitted (received) by each array element of the phased array radar, the beam direction is controlled by accessing a phase shifter at the output end of each array element, and the spatial domain scanning of the beam can be realized by adjusting the phase shift amount of the phase shifter. Furthermore, beam scanning, i.e. frequency scanning antennas, can also be achieved by changing the operating frequency of the radar system. However, phased arrays, frequency scanning antennas and MIMO radars all suffer from one disadvantage: within each scan snapshot, the beam pointing is constant in range, i.e., the beam pointing is independent of range, and two-dimensional joint estimation of the target range and azimuth cannot be achieved with linear phased array radar.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a frequency controlled array time focusing method based on the time reversal technology.

In order to achieve the above and other related objects, the present invention provides a time focusing method of a frequency control array based on a time reversal technique, which combines a conventional frequency control array with a time reversal technique to overcome the distance periodicity of the frequency control array and focus energy at a certain time at a target distance, the focusing method comprising:

the method comprises the steps that frequency control array receiving equipment sends a first signal;

the frequency control array transmitting equipment receives a second signal;

deconvolving the first signal and the second signal to obtain a multipath channel;

and the frequency control array transmitting equipment transmits the transmitting signal out through the multipath channel.

Optionally, the receiving device first sends a probe signal, where the first signal is:

wherein f is₀The carrier frequency of the signal transmitted by the first array element is shown, Δ f is the carrier frequency increment between different array elements, and N is the total number of the transmitted array elements.

Optionally, the detection signal is received and time-reversed, and the second signal is:

where E (r, t) represents the received signal at a distance r at time t, r is the distance of the reference array element to the target point, and c represents the speed of light.

Optionally, a channel estimate of the target point (receiving device) from the transmitting device is estimated, the channel comprising a direct propagation path and a reflected propagation path.

Optionally, a received signal of a direct propagation path is obtained, and the direct propagation path received by the target point is:

wherein E is_dn(r, t) denotes the directly propagating received signal component at a distance r at time t, r_dnIndicating the distance of the direct propagation of the nth array element from the target point.

Optionally, the received signal transmitted by the reflection path, and the reflection propagation path received by the target point is:

wherein E is_rn(r, t) denotes the multipath propagated received signal component at a distance r at time t, r_rnThe distance of the multipath propagation distance target point of the nth array element is shown.

Optionally, the channel is obtained by deconvolving the transmitted signal and the target received signal, where the target received signal is represented as:

optionally, the target point received signal needs to be known, and the received signal of a certain target point is:

wherein sin (. cndot.) represents horizontal polarization, cos (. cndot.) represents vertical polarization, and E_tot(r, t) represents the received signal at a distance r at time t.

As described above, the frequency control array time focusing method based on the time reversal technology of the present invention has the following beneficial effects:

(1) at present, the multipath frequency-controlled array wireless transmission has signal loss, the time reversal technology can utilize the loss of multipath signals, a time reversal channel can effectively collect and utilize the multipath signals, and the transmission performance of a system is obviously improved.

(2) Since transmission signals are present for all range positions, time variance and range periodicity are unavoidable. The temporal variance of the frequency-controlled array is ignored in the current study. And the time-space focusing performance of the time reversal technology is utilized to realize the wave beam focusing performance of the frequency control array.

Drawings

To further illustrate the description of the present invention, the following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings. It is appreciated that these drawings are merely exemplary and are not to be considered limiting of the scope of the invention.

FIG. 1 is a schematic diagram of a frequency-controlled matrix multipath model used in the present invention;

FIG. 2 is a model diagram of a time-reversal frequency-controlled array system according to the present invention;

FIG. 3 is a horizontal polarization beam diagram of the frequency controlled array multipath model of the present invention;

FIG. 4 is a comparison graph of conventional channel response and time-reversal channel response of the frequency-controlled array of the present invention;

FIG. 5 is a comparison of response peaks for the frequency-controlled array time-reversal technique of the present invention;

FIG. 6 is a received signal diagram of a frequency-controlled array range-angle based on time-reversal technique according to the present invention;

FIG. 7 is a comparison diagram of frequency-controlled array channels with or without time reversal techniques at different frequency offsets in accordance with the present invention;

fig. 8 is a flowchart of a frequency control array time focusing method based on the time reversal technique according to the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

As shown in fig. 8, a frequency control array time focusing method based on the time reversal technique includes:

the method comprises the steps that frequency control array receiving equipment sends a first signal;

the frequency control array transmitting equipment receives a second signal;

deconvolving the first signal and the second signal to obtain a multipath channel;

and the frequency control array transmitting equipment transmits the transmitting signal out through the multipath channel.

For a linear uniform array antenna, as shown in fig. 1. Assuming that there are 12 transmitting antennas, the distance between adjacent antennas isThe carrier frequency of the transmitted signal of the first array element (reference array element) is f₀1GHz, also called the center frequency of the system, and the carrier frequency increment between different array elements is Δ f 1KHz, then the transmission signal frequency of the nth array element is expressed as:

f_n＝f₀+nΔf,n＝0,1,2,...N-1

wherein f is_nRepresenting the frequency of the transmitted signal of the nth array element, f₀The carrier frequency of the signal transmitted by the first array element (reference array element) is shown, and N is the total number of the transmitted array elements.

The waveform of the signal transmitted by the frequency control array receiving equipment is as follows:

wherein f is₀The carrier frequency of a signal transmitted by a first array element (reference array element) is shown, the increment of the carrier frequency among different array elements is delta f, and N represents the total number of the transmitted array elements.

If the distance between the reference array element and the target point is r-10 km, and the target meets a certain distance condition (d < r), the radiation beam of each array element can be regarded as a group of parallel waves, and the angles are all parallel wavesThe received signal of the frequency controlled array transmitting device (at the target) is:

where E (r, t) denotes the received signal at a distance r at time t, f₀The carrier frequency of the transmission signal of the first array element (reference array element) is shown, N is the total number of the transmission array elements, and c is the speed of light.

A uniform linear frequency controlled array is shown in fig. 1 when it is in a multipath environment (placed on a horizontal plane). Frequency-controlled array antenna distance horizontal planeSuppose there are N transmitting antennas, the distance between adjacent antennas is d, and N array elements are distributed along the x-axis with the reference array element as the center. The carrier frequency of the transmitted signal of the first array element (reference array element) is f₀Also called the center frequency of the system, the carrier frequency increment between different array elements is Δ f, and the transmission signal frequency of the nth array element is expressed as:

f_n＝f₀+nΔf,n＝0,1,2,...N-1

continuous waves are transmitted at the same amplitude and phase at the carrier frequency. The horizontal plane may be any terrain, such as a ground with large undulations or a complex dielectric constant. For ease of analysis, the horizontal plane is chosen to be a fully conductive ground plane.

There are two paths for multipath FDA (frequency controlled array), a direct propagation path and a reflected propagation path. Direct path propagation is shown in fig. 1. For a fully conductive ground plane, the reflection path can be linked to the mirror image FDA of the ground plane according to the mirror image principle. If the propagation distance of the reflected wave from the nth array element to the target point with the distance r is r_rnThis field is in anti-phase (in phase) with the original horizontal polarization (vertical polarization) of the FDA. The direct propagation path received by the target point is:

wherein E is_dn(r, t) denotes the directly propagating received signal component at a distance r at time t, r_dnRepresenting the distance of the direct propagation of the nth element from the target point, f₀The carrier frequency of the transmission signal of the first array element (reference array element) is shown, N is the total number of the transmission array elements, and c is the speed of light.

The reflected propagation path received at the target point is:

wherein E is_rn(r, t) denotes the multipath propagated received signal component at a distance r at time t, r_rnRepresenting the distance of the multipath propagation distance target point of the nth element, f₀The carrier frequency of the transmission signal of the first array element (reference array element) is shown, N is the total number of the transmission array elements, and c is the speed of light.

The target point receive signal may be expressed as:

wherein E is_tot(r, t) denotes the received signal at a distance r at time t, r_dnRepresenting the distance, r, of the direct propagation of the nth element from the target point_rnRepresenting the distance of the multipath propagation distance target point of the nth element, f₀The carrier frequency of the transmission signal of the first array element (reference array element) is shown, N is the total number of the transmission array elements, and c is the speed of light.

If r > (n-1) d + h_tThen r is_dn、r_rnIt can be simplified as:

r_dn≈r_rn≈r

θ_dn≈θ_rn≈θ

wherein the content of the first and second substances,is the directional cosine of the x-axis, and v ═ cos θ is the directional cosine of the z-axis. r is_dnRepresenting the distance, r, of the direct propagation of the nth element from the target point_rnIndicating the distance, h, of the multipath propagation distance target point of the nth element_tRepresenting the distance between the frequency controlled array antenna and the horizontal plane. Theta_dnRepresenting the angle, theta, of the direct propagation path of the nth element to the target point_rnRepresenting the angle of arrival of the multipath propagation path of the nth element at the target point,the elevation angle of the direct propagation path component of the radiation beam of the nth array element is shown,the elevation angle of the multipath propagation path component of the radiation beam of the nth array element is shown,the elevation angle of the radiation beam of the nth array element is shown. The received signal at a certain target point can be simplified as:

where sin (·)/cos (·) of the matrix is represented as horizontal/vertical polarization, respectively. E_tot(r, t) denotes the received signal at a distance r at time t, r_dnRepresenting the distance, r, of the direct propagation of the nth element from the target point_rnRepresenting the distance of the multipath propagation distance target point of the nth element, f₀Indicating the first (reference) elementThe carrier frequency of the transmitting signal, N represents the total number of transmitting array elements, and c represents the speed of light.

As shown in fig. 3, the frequency controlled array multipath model horizontally polarizes the beam pattern.

The frequency control array receiving equipment sends a detection pulse signal, and the frequency control array transmitting equipment receives the signal. Deconvolving the signal sent by the frequency control array receiving equipment and the signal received by the frequency control array transmitting equipment by using a CLEAN algorithm to obtain a multipath channel of the system model, wherein as shown in figure 4, the traditional channel response of the frequency control array and a time-reversal channel response contrast diagram of the frequency control array can be seen, and the channel response of the frequency control array based on the time-reversal technology has time focusing performance.

Fig. 5 shows the result of receiving signals by the frequency control array receiving device using the time reversal technique, which is a comparison diagram of the presence or absence of the response peak of the frequency control array using the time reversal technique. Therefore, as shown in fig. 6, which is a frequency control array distance angle receiving signal diagram based on the time reversal technology in the technical scheme of the present invention, it can be clearly seen that the wave beam of the frequency control array receiving signal through the time reversal technology has focusing performance, and the peak value is improved.

The designed frequency offset of the key factors in the frequency-controlled array wireless transmission equipment based on the time reversal technology is changed, as shown in fig. 7, a comparison graph of frequency-controlled array channels with or without the time reversal technology under different frequency offsets further illustrates that the time reversal technology is a feasible implementation mode of wave beam focusing of the frequency-controlled array.

The invention also provides a storage medium storing a computer program which, when executed by a processor, performs the method as described above.

The present invention also provides an electronic terminal, comprising:

a memory for storing a computer program;

a processor for executing the computer program stored by the memory to cause the apparatus to perform the aforementioned method.

The computer program comprises computer program code which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer readable medium may comprise any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a Random Access Memory (RAM), an electrical carrier signal, a telecommunications signal, a software distribution medium, etc.

The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory may be an internal storage unit or an external storage device, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital Card (SD), a Flash memory Card (Flash Card), and the like. Further, the memory may also include both an internal storage unit and an external storage device. The memory is used for storing the computer program and other programs and data. The memory may also be used to temporarily store data that has been or will be output.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.