阅读说明：本技术 跳时信号捕获装置和方法 (Time-hopping signal acquisition device and method ) 是由 姚铮 运世洁 陆明泉 于 2018-07-19 设计创作，主要内容包括：本申请涉及一种伪卫星跳时信号捕获方法和装置。根据本申请的伪卫星跳时信号捕获方法包括：捕获来自多个伪卫星的多个跳时信号中的至少一个跳时信号,以辅助捕获所述多个跳时信号中尚未捕获的跳时信号。根据本申请的实施方式,充分考虑了不同伪卫星信号之间的内在联系,捕获多个跳时信号中的至少一个跳时信号,以辅助捕获多个跳时信号中的其他跳时信号,不仅解决了跳时信号的远近问题,而且降低了信号捕获的复杂度,极大地提高了接收机的捕获灵敏度。(According to the embodiment of the application, internal links among different pseudolite signals are fully considered, at least time hopping signals among the time hopping signals are captured, other time hopping signals among the time hopping signals are captured in an auxiliary mode, the near-far problem of the time hopping signals is solved, the complexity of signal capture is reduced, and the capture sensitivity of a receiver is greatly improved.)

A method for acquiring time hopping signals, , includes acquiring at least time hopping signals from a plurality of pseudolites to assist in acquiring time hopping signals of the plurality of time hopping signals that have not been acquired.

2. The capture method of claim 1, comprising:

receiving a plurality of time hopping signals from a plurality of pseudolites;

capturing at least of the plurality of time hopped signals as index time hopped signals;

determining search position intervals of every uncaptured time-hopping signals in the time-hopping signals according to the time-hopping pulse position information of the index time-hopping signals and the time-hopping pattern prior information of each time-hopping signal, determining the search position intervals of the index time-hopping signals according to the time-hopping pulse position information of the index time-hopping signals and the time-hopping pattern prior information of each time-hopping signal, determining the search position intervals

A corresponding not yet acquired time-hopped signal is acquired every search position interval of not yet acquired time-hopped signals.

3. The capture method of claim 2, comprising:

locally reproducing a composite time-hopping pulse, said composite time-hopping pulse being accumulated from time-hopping pulses of every time-hopping signals of the received plurality of time-hopping signals, and

and carrying out correlation operation on the comprehensive time hopping pulse and the received signal to obtain an overall correlation result, and selecting at least correlation peaks according to peak values of the correlation peaks in the overall correlation result to capture at least time hopping signals corresponding to at least correlation peaks as index time hopping signals.

4. The capture method of claim 2, comprising:

determining time-hopping pulse search position intervals corresponding to every time-hopping signals which are not captured according to the time-hopping pulse position information of the index time-hopping signals and the time-hopping pattern prior information of each time-hopping signal, determining the time-hopping pulse search position intervals corresponding to each time-hopping signals which are not captured yet, and

for every time-hopped signals that have not been captured:

locally reproducing a time-hopping pulse of the time-hopping signal;

carrying out correlation operation on the time hopping pulse of the locally reproduced time hopping signal and the received signal in the time hopping pulse searching position interval corresponding to the determined time hopping signal; and

capturing the time-hopping signal within the interval according to the correlation peak.

5. The capture method of claim 4, comprising: if the time hopping signal which can not be successfully captured exists, the captured time hopping signal in the time hopping pulse searching position interval corresponding to the time hopping signal which can not be successfully captured is eliminated through an interference elimination method, and then the time hopping signal which can not be successfully captured is captured.

6. The acquisition method of claim 5, wherein the interference cancellation method comprises:

and forcibly clearing the captured time hopping signal in the time hopping pulse searching position interval corresponding to the time hopping signal which cannot be successfully captured, and capturing the time hopping signal which cannot be successfully captured.

7. The acquisition method of claim 5, wherein the interference cancellation method comprises:

and in a time hopping pulse searching position interval corresponding to the time hopping signal which can not be successfully captured, reversely offsetting the captured time hopping signal in the time hopping pulse searching position interval, and capturing the time hopping signal which can not be successfully captured.

8, , wherein the acquisition device acquires at least of the plurality of time hopping signals from the plurality of pseudolites to assist in acquiring time hopping signals of the plurality of time hopping signals that have not been acquired.

9. The capture device of claim 8, comprising:

a receiving unit that receives a plurality of time hopping signals from a plurality of pseudolites; and

and a capturing unit which captures at least time-hopping signals in the time-hopping signals as index time-hopping signals, determines search position intervals of the time-hopping signals which are not captured in the time-hopping signals according to time-hopping pulse position information of the index time-hopping signals and time-hopping pattern prior information of the time-hopping signals, and captures corresponding time-hopping signals which are not captured in each search position interval of time-hopping signals which are not captured.

10. The capturing apparatus of claim 9, wherein the capturing unit comprises a local replication module, a processing module, and a storage module that stores time hopping pattern prior information.

11. The capture device of claim 10,

the local reproduction module locally reproduces a composite time-hopping pulse accumulated from time-hopping pulses of every time-hopping signals of the received plurality of time-hopping signals, and

the processing module carries out correlation operation on the comprehensive time-hopping pulse and the received signal to obtain an overall correlation result, and selects at least correlation peaks according to peak values of the correlation peaks in the overall correlation result to capture at least time-hopping signals corresponding to at least correlation peaks as index time-hopping signals.

12. The capture device of claim 10,

the processing module determines time-hopping pulse searching position intervals corresponding to every uncaptured time-hopping signals according to the time-hopping pulse position information of the index time-hopping signal and the time-hopping pattern prior information of each time-hopping signal stored in the storage module, and

for every time-hopped signals that have not been captured:

the local reproduction module locally reproduces the time hopping pulse of the time hopping signal; and

and the processing module carries out correlation operation on the time hopping pulse of the locally reproduced time hopping signal and the received signal in the time hopping pulse searching position interval corresponding to the determined time hopping signal, and captures the time hopping signal in the interval according to a correlation peak value.

13. The capturing apparatus according to claim 12, wherein if there is a time hopping signal that cannot be successfully captured, the processing module performs capturing on the time hopping signal that cannot be successfully captured after eliminating the captured time hopping signal in the time hopping pulse searching position interval corresponding to the time hopping signal that cannot be successfully captured by an interference elimination method.

14. The capturing device according to claim 13, wherein in the time hopping pulse search position interval corresponding to the time hopping signal that cannot be successfully captured, the processing module forcibly clears the captured time hopping signal in the time hopping pulse search position interval, and captures the time hopping signal that cannot be successfully captured.

15. The capturing apparatus as claimed in claim 13, wherein, in the time hopping pulse search position interval corresponding to the time hopping signal that cannot be captured successfully, the processing module performs reverse cancellation on the captured time hopping signal in the time hopping pulse search position interval, and captures the time hopping signal that cannot be captured successfully.

Technical Field

The present application relates to the field of navigation technologies, and in particular, to a time hopping signal capturing apparatus and method.

Background

In conventional satellite navigation systems, navigation satellites use Direct Sequence Spread Spectrum (DSSS) signals, and all satellites transmit signals simultaneously on the same carrier frequency in a Code Division Multiple Access (CDMA) format by using different spreading codes.

In order to solve the problem, a time hopping pulse transmitting mechanism is introduced on the basis of the traditional GNSS signals, namely direct sequence spread spectrum-time hopping signal (TH-DSSS) systems are adopted.

Although time hopping signals employ a pulse transmission mechanism to alleviate the near-far problem, signals in adjacent time slots still interfere with the acquisition result because the acquisition process requires a search within .

Disclosure of Invention

The application aims to provide time-hopping signal capturing devices and methods.

According to aspects of the present application, methods of time hopped signal acquisition are provided, including acquiring at least of a plurality of time hopped signals from a plurality of pseudolites to assist in acquiring ones of the plurality of time hopped signals that have not been acquired.

According to another aspects of the present application, time hopped signal acquisition devices are provided, wherein the acquisition devices acquire at least of a plurality of time hopped signals from a plurality of pseudolites to assist in acquiring ones of the plurality of time hopped signals that have not been acquired.

According to the time hopping signal capturing device and the time hopping signal capturing method, prejudice in the prior art is overcome, internal relation among different pseudo satellite signals is fully considered, at least time hopping signals in the time hopping signals are captured, other time hopping signals in the time hopping signals are captured in an auxiliary mode, the problem of distance of the time hopping signals is solved, complexity of signal capturing is reduced, and capturing sensitivity of a receiver is greatly improved.

Drawings

Fig. 1 shows a schematic diagram of a pulse signal transmitted by a certain pseudolites.

Figure 2 shows a schematic diagram of signal aliasing that exists between different pseudolite signals.

Fig. 3 shows a schematic diagram of a time hopping signal acquisition method according to embodiments of the present application.

Fig. 4 shows a schematic diagram of a time hopping signal acquisition method according to another embodiments of the present application.

Fig. 5 shows a schematic diagram of a time hopped signal capture device according to embodiments of the present application.

Fig. 6 shows a schematic diagram of a time hopped signal capture device according to another embodiments of the present application.

Fig. 7 shows a schematic diagram of locally recurring integrated time hopping pulses according to another embodiments of the present application.

Fig. 8 is a schematic diagram illustrating correlation results obtained by correlating an integrated spreading code signal with a received signal according to embodiments of the present application.

Fig. 9 shows a schematic diagram of a time hopping code table according to embodiments of the present application.

Fig. 10 shows a schematic diagram of a method for capturing not yet captured time-hopping signals according to embodiments of the present application.

Fig. 11 shows a schematic diagram of a method for implementing interference cancellation by using forced zero clearing according to embodiments of the present application.

Fig. 12 shows a schematic diagram of a method for implementing interference cancellation by interference cancellation according to embodiments of the present application.

Detailed Description

The time-hopping signal acquisition apparatus and method disclosed in the present application will be described in detail below with reference to the accompanying drawings. For simplicity, the same or similar reference numbers are used for the same or similar devices in the description of the embodiments of the present application.

FIG. 1 shows direct sequence spread spectrum pulse signals transmitted by pseudolites.A direct sequence spread spectrum-time hopping signal scheme for a pseudolite system involves dividing a pseudolite signal into successive time durations T_pAnd signalsThe frame is divided into several pulse time slots averagely, every pseudo-satellites in the pseudo-satellite system only transmit direct sequence spread spectrum pulse signals in a pulse time slot of complete signal frames, thus, in transmission periods, different pseudo-satellites occupy different pulse time slots, meanwhile, in order to prevent the problem that the period of the pulse signal of a pseudo-satellite affects the frequency spectrum of a positioning signal to cause false locking of a receiver, a pseudo-satellite designer presets pseudo-random time hopping sequences for each pseudo-satellite to calibrate the time slot of the pulse signal transmitted by the satellite, and under a time hopping signal system, every pseudo-satellites transmit pulse signals according to the time slots indicated by the time hopping sequences at approximate random intervals.

In addition, different propagation distances cause the strength of different pseudolite signals to have a difference of tens of dB, which causes a near-far problem, which makes it difficult to capture weak pseudolite signals in the system, and the existing methods cannot solve the problem.

According to embodiments of the present application, pseudolite time hopping signal acquisition methods are disclosed, fig. 3 shows a schematic diagram of a pseudolite time hopping signal acquisition method according to embodiments of the present application, as shown in fig. 3, at least time hopping signals among a plurality of time hopping signals from a plurality of pseudolites are acquired in S110, and in S120, acquisition of time hopping signals among the plurality of time hopping signals, which have not been acquired, is assisted.

FIG. 4 shows a schematic diagram of a pseudo-satellite time hopping signal acquisition method according to another embodiments of the present application, as shown in FIG. 4, in S210, a plurality of time hopping signals from a plurality of pseudo-satellites can be received, and in S220, at least time hopping signals of the plurality of time hopping signals are acquired as index time hopping signals.

After capturing the index time-hopping signal, in S230, a search position interval of the time-hopping signal that has not been captured in the plurality of time-hopping signals may be determined according to the time-hopping pulse position information of the index time-hopping signal and the time-hopping pattern prior information of each time-hopping signal.

In S240, a corresponding not-yet-captured time-hopped signal is captured every search position interval of not-yet-captured time-hopped signals.

According to the embodiment of the application, the prejudice in the prior art is overcome, the internal relation among different pseudolite signals is fully considered, at least time-hopping signals in a plurality of time-hopping signals are captured as index signals, and other time-hopping signals which are not captured yet in the plurality of time-hopping signals are captured in an auxiliary manner, so that the near-far problem of the time-hopping signals is solved, the complexity of signal capture is reduced, the capture process of other time-hopping signals which are not captured yet is simplified, and the capture sensitivity of a receiver is greatly improved.

According to embodiments of the present application, pseudolite time hopping signal acquisition devices are disclosed, which acquire at least time hopping signals of a plurality of time hopping signals from a plurality of pseudolites to assist in acquiring not-yet-acquired time hopping signals of the plurality of time hopping signals, as shown in fig. 5, the acquisition devices include a receiving unit 10 and an acquisition unit 20. the receiving unit 10 receives the plurality of time hopping signals from the plurality of pseudolites. the acquisition unit 20 acquires at least time hopping signals of the plurality of time hopping signals as index time hopping signals.

According to embodiments, as shown in fig. 6, the capturing unit 20 can further include a local reproduction module 21, a processing module 22, and a storage module 23 for storing time-hopping pattern prior information.

The receiver is cold started and the acquisition device enters an index signal acquisition phase, a receiving unit of the acquisition device receives a plurality of time-hopping signals from a plurality of pseudolites and acquires at least time-hopping signals in the plurality of time-hopping signals, and the index signal can be the strongest signal or any other signal which can be successfully acquired.

Since the receiver does not know the strength of each current signal in the beginning stage, and cannot judge which signal can be normally captured, according to embodiments of the present application, it can capture signals one by the capture unit until signals are successfully captured, i.e. they can be used as index signals.

According to another embodiments of the present application, methods for fast acquisition of the index signal are also proposed.A local reproduction module 21 of the acquisition unit 20 can locally reproduce a composite time-hopping pulse accumulated from time-hopping pulses of every time-hopping signals of the received multiple time-hopping signals.As shown in FIG. 7, the local reproduction module 21 of the acquisition unit can locally reproduce time-hopping pulses of all time-hopping signals and accumulate each time-hopping pulse in pulse time slots to obtain a composite time-hopping pulse.

The processing module 22 of the capturing unit 20 performs correlation operation on the integrated time-hopping pulse and the received signal to obtain an overall correlation result, and selects at least correlation peaks according to peak values of the correlation peaks in the overall correlation result to capture at least time-hopping signals corresponding to the at least correlation peaks as index signals.

The processing module 22 performs a cyclic convolution on the locally reproduced integrated time-hopping pulse and the received signal, according to the characteristics of the time-hopping signal, it can be known that, in order to ensure that at least pulse signals can be received for the working base station, the receiver can perform a cyclic convolution on the received signal of two signal frame lengths, fig. 8 shows a schematic diagram of the correlation result obtained by performing a correlation operation on the integrated spread spectrum code signal and the received signal according to embodiments of the present application, and after maximum correlation peaks are detected, the positions of the corresponding sampling points, that is, the positions pi of the strongest pulses are recorded₀ ^ndex. And correlating the found strongest pulse with the spread spectrum code signals corresponding to different spread spectrum code numbers, and finding the spread spectrum code number corresponding to the maximum correlation value, namely determining the spread spectrum code number corresponding to the strongest pulse. Thereafter by pi₀ ^ndexThe time-hopping pulse of a plurality of time slots can be combined to estimate the Doppler shift of the current time-hopping signal, thereby successfully capturing at least time-hopping signals in the received time-hopping signals as index time-hopping signals.

After the index time-hopping signal is successfully captured, the capturing unit 20 can determine the search position interval of the time-hopping signal not yet captured in the plurality of time-hopping signals according to the time-hopping pulse position information of the index time-hopping signal and the time-hopping pattern prior information of each time-hopping signal stored in the storage module 23, for every time-hopping signals not yet captured, namely the time-hopping pulse of the time-hopping signal is locally reproduced by the receiver, the time-hopping pulse of the locally reproduced time-hopping signal is correlated with the received signal in the time-hopping pulse search position interval corresponding to the determined time-hopping signal, and the time-hopping signal in the interval is captured according to the correlation peak value.

As shown in fig. 9, the time hopping pattern prior information of the time hopping signal can be stored in the form of a time hopping code table, for example, the receiver can match the time hopping code table according to the time hopping pulse position information of the index time hopping signal, and determine the time hopping pulse search position interval corresponding to each time hopping signals which are not captured yet.

Fig. 10 shows a schematic diagram of a method for capturing not-yet-captured time-hopping signals (time-hopping signals to be captured) according to embodiments of the present application.

In S310, the start position of the signal frame of the index signal may be determined by matching the obtained time-hopping pulse position information of the index signal with the time-hopping code table.

In S320, the time-hopping pulse position corresponding to the time-hopping signal to be captured is determined according to the start position of the signal frame of the index signal and the time-hopping prior information of the time-hopping signal to be captured. The pseudo satellites in the system are time-synchronized, and can be matched with a time hopping code table according to the obtained time hopping pulse position information of the index signal to determine the time slot of the time hopping pulse of the time hopping signal to be captured, and can determine the theoretical position p of the time hopping pulse of the time hopping signal to be captured, which may appear according to the time slot of the time hopping pulse of the time hopping signal to be captured and the initial position of the current signal frame_poss。

The actual position of the time-hopping pulse may be at p, given the different propagation delays of the time-hopping signals_possAround in S330, the theoretical position p of the occurrence of the time-hopping pulse of the time-hopping signal to be captured can be determined_possAnd determining a time hopping pulse searching position interval corresponding to the time hopping signal to be captured. For example, considering the aliasing that causes the maximum number of Δ N points between different signals due to the difference of propagation distances, the signal to be captured currently appears in the search position interval [ p ]_poss-ΔN，P_poss+ΔN]At any position [ p ] is taken out_poss-ΔN，P_poss+ΔN]The signal of the point is processed by the circular convolution with the local reproduction code. The length Δ N of the aliasing interval can be determined by the signal aliasing duration and the receiver sampling rate at the extreme position.

At SAt 340, the receiver may locally reproduce the time-hopping pulses of the time-hopping signal to be acquired. The receiver can perform correlation operation on the time hopping pulse of the locally reproduced time hopping signal to be captured and the received signal in the time hopping pulse searching position interval corresponding to the determined time hopping signal, and capture the time hopping signal in the interval according to the correlation peak value. The receiver can find out the maximum correlation peak according to the correlation operation result and record the position p corresponding to the maximum correlation peak₀. Thereafter, with p₀And determining the position of the subsequent time hopping pulse as an initial position according to the time hopping code table, and detecting a correlation peak at the position. And if the correlation peaks are detected at several continuous positions, the time-hopping signal is considered to be detected. The doppler shift of the time hopped signal can be estimated, i.e., the time hopped signal is successfully acquired.

It can be understood that, because the index signal is used for indexing, and the receiver can determine the time-hopping pulse search position interval corresponding to the time-hopping signal to be captured according to the time-hopping pattern prior information of the time-hopping signal, the receiver only needs to locally reproduce the time-hopping pulse of the time-hopping signal and perform related operation with the received signal in the search position interval, thus, the pulse can be purposefully detected without traversing and searching in a grid mode for every pseudolite signals in the prior art, and therefore, the rest signals can be rapidly captured with little calculation amount, and the complexity of signal capture is greatly reduced.

According to embodiments of the present application, if there is a time-hopping signal that cannot be successfully captured, after the time-hopping signal that has been captured in the time-hopping pulse position interval corresponding to the time-hopping signal that cannot be successfully captured is removed by an interference removal method, the time-hopping signal that cannot be successfully captured is captured again.

According to embodiments, a forced clear method can be used to achieve interference cancellation, according to the present application, it can be known which positions in the received signal have time-hopping pulses of strong time-hopping signals according to the previous capturing result and the time-hopping pattern prior information (e.g. pseudolite time-hopping code table) of each time-hopping signal, in order to prevent the strong time-hopping signals which have been successfully captured from influencing the continuous capturing of weak time-hopping signals, the positions of the time-hopping pulses which have strong time-hopping signals can be all cleared to "0", then the newly obtained signals after the clearing of "0" are captured, the influence caused by the strong time-hopping signals can be avoided, and the weak time-hopping signals can be successfully detected.

The forced zero clearing of the signals is to erase all information on the positions, including information of a part of signals to be captured which are aliased in the signals, as shown in fig. 11, therefore, in the capturing process, the signals after zero clearing are correlated with the local recurrent signals, the calculation amount is small, but a reserved part of the weak signals is partially correlated with the recurrent signals, so that correlation loss determined by exists.

According to another embodiments, as shown in fig. 12, interference cancellation can be implemented by using an interference cancellation method, that is, in a time hopping pulse position interval corresponding to a time hopping signal which cannot be successfully captured, time hopping pulses of the captured time hopping signal in the time hopping pulse position interval are reversely cancelled, and the time hopping signal which cannot be successfully captured is captured.

After the elimination of the strong time-hopping signal is completed, the capture of the weak time-hopping signal can be started. At this time, after the interference elimination processing, the influence of the strong signal on the weak signal is eliminated, so that the weak time-hopping signal can be captured by utilizing the time-hopping pulse position information of the index time-hopping signal and the time-hopping pattern prior information of each time-hopping signal.

Exemplary embodiments of the present application are described above with reference to the accompanying drawings. It will be appreciated by those skilled in the art that the above-described embodiments are merely exemplary for purposes of illustration and are not intended to be limiting, and that any modifications, equivalents, etc. that fall within the teachings of this application and the scope of the claims should be construed to be covered thereby.