BDS short-burst signal anti-jamming sidelobe processing method based on correlation matching

Abstract

The application relates to a Beidou short-burst signal anti-interference sidelobe processing method based on correlation matching. The method comprises the following steps: performing frequency domain interference suppression on a Beidou short-burst signal to obtain an anti-interference signal; performing Fourier transform on a reference signal, zeroing corresponding spectral lines in the power spectrum of the reference signal according to the zeroed spectral line numbers, performing Fourier inverse transform on the anti-interference reference signal power spectrum to obtain an anti-interference reference signal; respectively performing demodulation, despreading and correlation on the anti-interference signal and the anti-interference reference signal and a local recurrence signal to obtain corresponding input signal correlation functions; performing normalized least square similarity matching on the corresponding input signal correlation functions to obtain a matching error; performing anti-interference sidelobe elimination after comparing the matching error with a pre-set threshold to obtain an anti-interference sidelobe processing result. The method can improve the user capacity and service performance of a Beidou RDSS system.

Description

Technical Field

[0001] This application relates to the field of anti-interference processing technology, and in particular to a method for anti-interference sidelobe processing of BeiDou short burst signals based on correlation matching. Background Technology

[0002] RDSS short burst signals are a unique signal mode of BeiDou, distinguishing it from other global satellite navigation systems. They provide users with active navigation and timing services, as well as satellite short message communication capabilities. With the upgrading of BeiDou RDSS service capabilities, satellite short message communication services have been gradually opened to the civilian mobile phone market, becoming an important backup communication method in emergency rescue and other application scenarios. The RDSS short burst incoming signals transmitted from the user terminal have low transmission power and long transmission distances. They need to be transmitted at a power of 2W to a geostationary satellite at an altitude of 36,000 kilometers before being relayed to the ground station, totaling a transmission distance of over 70,000 kilometers. The received signal at the ground station is very weak and susceptible to electromagnetic interference.

[0003] The RDSS ground system already possesses the capability to perform frequency-domain anti-interference processing on incoming signals. However, traditional anti-interference techniques, due to the uncertain frequency band distribution of interference, may occasionally cause the correlation function of the received signal to split, generating multiple spurious correlation peaks. Since the signal processing device cannot distinguish whether spurious correlation peaks are short burst incoming signals transmitted by other users, multiple digital processing channels are consumed during the signal tracking phase to track these spurious correlation peaks, resulting in a significant waste of processing resources and consequently a substantial reduction in the number of users that BeiDou short message communication can accommodate. This problem has become even more pronounced in recent years since BeiDou RDSS opened its services to civilian mobile phones, due to the rapid increase in the number of users. Therefore, the sidelobes of the correlation function generated by anti-interference severely restrict the user capacity and service performance of the BeiDou RDSS system. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for anti-interference sidelobe processing of BeiDou short burst signals based on correlation matching, which can improve the user capacity and service performance of the BeiDou RDSS system, in order to address the above-mentioned technical problems.

[0005] A method for anti-interference sidelobe processing of BeiDou short burst signals based on correlation matching, the method comprising:

[0006] Acquire BeiDou short burst signals and reference signals; perform frequency domain interference suppression on BeiDou short burst signals to obtain the anti-interference power spectrum and record the zeroed spectral line numbers; perform inverse Fourier transform on the anti-interference power spectrum to obtain the anti-interference signal; determine the interference state of the anti-interference signal, and if the anti-interference signal is interfered with, perform correlation function matching and sidelobe suppression.

[0007] Perform a Fourier transform on the reference signal to obtain its power spectrum; set the corresponding spectral lines in the power spectrum of the reference signal to zero according to the zeroed spectral line numbers to obtain the power spectrum of the anti-interference reference signal; perform an inverse Fourier transform on the power spectrum of the anti-interference reference signal to obtain the anti-interference reference signal; demodulate, despread, and correlate the anti-interference signal and the anti-interference reference signal with the local reproducible signal respectively to obtain the corresponding input signal correlation function;

[0008] Normalized least squares similarity matching is performed on the correlation function of the corresponding input signal to obtain the matching error; the matching error is compared with a pre-set threshold, and anti-interference sidelobe removal is performed based on the comparison result to obtain the anti-interference sidelobe processing result.

[0009] In one embodiment, frequency domain interference suppression is performed on the BeiDou short burst signal to obtain the anti-interference power spectrum and record the zeroed spectral line numbers. This includes: performing a Fourier transform on the BeiDou short burst signal to obtain the power spectrum of the signal, setting the power spectrum whose amplitude exceeds a preset anti-interference threshold to 0, obtaining the anti-interference power spectrum and recording the zeroed spectral line numbers.

[0010] In one embodiment, the matching error is compared with a preset threshold, and anti-interference sidelobe removal is performed based on the comparison result to obtain the anti-interference sidelobe processing result. This includes: comparing the matching error with a preset threshold; if the matching error is less than the preset threshold, only one tracking channel is allocated to the input BeiDou short burst signal to lock the main peak of the correlation function; if the matching error is not less than the preset threshold, multiple tracking channels are allocated to the input BeiDou short burst signal to lock all correlation peaks.

[0011] In one embodiment, the interference status of the signal after anti-interference is determined. If the signal after anti-interference is not interfered with, that is, the number of spectral lines M affected by interference is 0, then there is no need to perform correlation function matching and sidelobe suppression, and the signal can directly enter the normal acquisition and tracking stage.

[0012] In one embodiment, the anti-interference signal and the anti-interference reference signal are demodulated, despread, and correlated with the locally reproduced signal to obtain the corresponding input signal correlation function, including:

[0013] Demodulate, despread, and correlate the anti-interference signal with the locally reproduced signal to obtain the correlation function of the input signal corresponding to the anti-interference signal.

[0014]

[0015] Where y(t) represents the signal after anti-interference, x(t) represents the locally reproduced signal, T represents the coherent integration period, and t0 represents the integration start time.

[0016] In one embodiment, the anti-interference reference signal and the locally reproduced signal are demodulated, despread, and correlated to obtain the correlation function of the input signal corresponding to the anti-interference reference signal.

[0017]

[0018] Where y0(t) represents the reference signal after anti-interference.

[0019] In one embodiment, normalized least-squares similarity matching is performed on the corresponding input signal correlation function to obtain the matching error, including:

[0020] Normalized least squares similarity matching is performed on the correlation function of the corresponding input signal to obtain the matching error.

[0021]

[0022] Where L is the matching error, and N represents N-point sampling of the autocorrelation function with a sampling interval of Δτ.

[0023] In one embodiment, the pre-set threshold is determined based on empirical values ​​from long-term collected data and Monte Carlo simulations.

[0024] The aforementioned method for anti-interference sidelobe processing of BeiDou short burst signals based on correlation matching identifies and suppresses anti-interference sidelobes by comparing the similarity between the correlation function of the anti-interference processed BeiDou short burst signal and the correlation function of the locally generated reference signal processed using the same anti-interference method. This locks the main peak of the signal correlation function, avoids the erroneous occupation of digital channel resources by the correlation function sidelobes generated by anti-interference, reduces the consumption of digital processing channels by split correlation peaks, and thus improves the user capacity and service performance of the BeiDou RDSS system. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating a method for anti-interference sidelobe processing of BeiDou short burst signals based on correlation matching in one embodiment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] In one embodiment, such as Figure 1 As shown, a method for anti-interference sidelobe processing of BeiDou short burst signals based on correlation matching is provided, including the following steps:

[0028] Step 102: Obtain the BeiDou short burst signal and reference signal; perform frequency domain interference suppression on the BeiDou short burst signal to obtain the anti-interference power spectrum and record the zeroed spectral line numbers; perform inverse Fourier transform on the anti-interference power spectrum to obtain the anti-interference signal; determine the interference state of the anti-interference signal, and if the anti-interference signal is interfered with, perform correlation function matching and sidelobe suppression.

[0029] The BeiDou short burst signal obtained upon entry is

[0030]

[0031] Where x(t) is the received signal, s(t) is the BeiDou short burst signal, and j p (t) represents the narrowband interference signal, p = 1, ..., P represents P narrowband interference signals, and n(t) represents Gaussian white noise. p (t) refers to narrowband interference signals with a bandwidth not exceeding 10% of the useful signal bandwidth. For BeiDou RDSS short burst signals, the bandwidth of narrowband interference does not exceed 2MHz.

[0032] Perform a Fourier transform on the received signal x(t) to obtain the power spectrum X(f). Set the power spectral lines in X(f) whose amplitude exceeds the preset anti-interference threshold Th1 to 0 to obtain the anti-interference signal power spectrum. And record the spectral line numbers set to zero: 1, ..., M. Perform an inverse Fourier transform to obtain the interference-resistant signal. The interference status is determined. If the signal is not interfered with, that is, the number of interfered spectral lines M is 0, then there is no need to perform correlation function matching and sidelobe suppression, and the signal can directly enter the normal acquisition and tracking stage.

[0033] Step 104: Perform a Fourier transform on the reference signal to obtain the power spectrum of the reference signal; set the corresponding spectral lines in the power spectrum of the reference signal to zero according to the zeroed spectral line numbers to obtain the power spectrum of the anti-interference reference signal; perform an inverse Fourier transform on the power spectrum of the anti-interference reference signal to obtain the anti-interference reference signal; demodulate, despread, and correlate the anti-interference signal and the anti-interference reference signal with the local reproducible signal respectively to obtain the corresponding input signal correlation function.

[0034] A local reference signal x0(t) is generated, where x0(t) contains randomly generated Gaussian noise, the noise power of which is obtained from the frequency domain interference suppression module. A Fourier transform is performed on x0(t) to obtain the power spectrum X0(f) of the reference signal. Based on the power spectrum of the anti-interference signal... By setting the spectral line numbers to zero, the corresponding spectral lines in X0(f) are set to zero, thus obtaining the power spectrum of the reference signal after anti-interference processing. right Perform an inverse Fourier transform to obtain the reference signal after anti-interference processing. Signal after countering interference Reference signal after anti-interference processing Demodulate, despread, and correlate the input signal with the locally reproduced signal to obtain the correlation functions R(τ) and R0(τ).

[0035] Step 106: Perform normalized least squares similarity matching on the corresponding input signal correlation function to obtain the matching error; compare the matching error with a pre-set threshold, and perform anti-interference sidelobe removal based on the comparison result to obtain the anti-interference sidelobe processing result.

[0036] Normalized least-squares similarity matching is performed on the correlation function of the corresponding input signal to determine whether the matching error L is lower than a preset threshold Th2. If the matching error L is lower than the preset threshold Th2, only one tracking channel is allocated to the input signal x(t) to lock the main peak of the correlation function; if the matching error L is not lower than the preset threshold Th2, the device will allocate multiple tracking channels to lock all correlation peaks. By comparing the similarity between the correlation function of the BeiDou short burst signal after anti-interference processing and the correlation function of the locally generated reference signal processed using the same anti-interference method, the anti-interference sidelobes of the BeiDou short burst signal are identified and suppressed, thereby locking the main peak of the signal correlation function, avoiding the erroneous occupation of digital channel resources by the correlation function sidelobes generated by anti-interference, and reducing the consumption of digital processing channels by the split correlation peaks.

[0037] In the aforementioned method for anti-interference sidelobe processing of BeiDou short burst signals based on correlation matching, this application identifies and suppresses anti-interference sidelobes of BeiDou short burst signals by comparing the similarity between the correlation function of the anti-interference processed BeiDou short burst signals and the correlation function of locally generated reference signals processed using the same anti-interference method. This locks the main peak of the signal correlation function, avoids the erroneous occupation of digital channel resources by the correlation function sidelobes generated by anti-interference, reduces the consumption of digital processing channels by split correlation peaks, and thus improves the user capacity and service performance of the BeiDou RDSS system.

[0038] In one embodiment, frequency domain interference suppression is performed on the BeiDou short burst signal to obtain the anti-interference power spectrum and record the zeroed spectral line numbers. This includes: performing a Fourier transform on the BeiDou short burst signal to obtain the power spectrum of the signal, setting the power spectrum whose amplitude exceeds a preset anti-interference threshold to 0, obtaining the anti-interference power spectrum and recording the zeroed spectral line numbers.

[0039] In a specific embodiment, the pre-set anti-interference threshold Th1 is determined by the base noise power of long-term collected data and Monte Carlo simulation. For BeiDou short burst signals, the noise power of the incoming signal is about -130dBW, and the converted value of the spectral amplitude threshold Th1 in this application is about 8000.

[0040] In one embodiment, the matching error is compared with a preset threshold, and anti-interference sidelobe removal is performed based on the comparison result to obtain the anti-interference sidelobe processing result. This includes: comparing the matching error with a preset threshold; if the matching error is less than the preset threshold, only one tracking channel is allocated to the input BeiDou short burst signal to lock the main peak of the correlation function; if the matching error is not less than the preset threshold, multiple tracking channels are allocated to the input BeiDou short burst signal to lock all correlation peaks.

[0041] In one embodiment, the interference status of the signal after anti-interference is determined. If the signal after anti-interference is not interfered with, that is, the number of spectral lines M affected by interference is 0, then there is no need to perform correlation function matching and sidelobe suppression, and the signal can directly enter the normal acquisition and tracking stage.

[0042] In one embodiment, the anti-interference signal and the anti-interference reference signal are demodulated, despread, and correlated with the locally reproduced signal to obtain the corresponding input signal correlation function, including:

[0043] Demodulate, despread, and correlate the anti-interference signal with the locally reproduced signal to obtain the correlation function of the input signal corresponding to the anti-interference signal.

[0044]

[0045] Where y(t) represents the signal after anti-interference, x(t) represents the locally reproduced signal, T represents the coherent integration period, and t0 represents the integration start time.

[0046] In one embodiment, the anti-interference reference signal and the locally reproduced signal are demodulated, despread, and correlated to obtain the correlation function of the input signal corresponding to the anti-interference reference signal.

[0047]

[0048] Where y0(t) represents the reference signal after anti-interference.

[0049] In one embodiment, normalized least-squares similarity matching is performed on the corresponding input signal correlation function to obtain the matching error, including:

[0050] Normalized least squares similarity matching is performed on the correlation function of the corresponding input signal to obtain the matching error.

[0051]

[0052] Where L is the matching error, and N represents N-point sampling of the autocorrelation function with a sampling interval of Δτ.

[0053] In one embodiment, the pre-set threshold is determined based on empirical values ​​from long-term collected data and Monte Carlo simulations.

[0054] In a specific embodiment, the pre-set threshold Th2 is determined based on long-term collected data and empirical values ​​from Monte Carlo simulations. In this embodiment, the matching error L is set to be true when it is less than the threshold value Th2 = 10-3.

[0055] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for anti-interference sidelobe processing of BeiDou short burst signals based on correlation matching, characterized in that, The method includes: Acquire BeiDou short burst signals and reference signals; perform frequency domain interference suppression on the BeiDou short burst signals to obtain the anti-interference power spectrum and record the spectral line numbers set to zero; perform inverse Fourier transform on the anti-interference power spectrum to obtain the anti-interference signal; determine the interference state of the anti-interference signal, and if the anti-interference signal is interfered with, perform correlation function matching and sidelobe suppression. Perform a Fourier transform on the reference signal to obtain its power spectrum; set the corresponding spectral lines in the power spectrum of the reference signal to zero according to the zeroed spectral line numbers to obtain the power spectrum of the anti-interference reference signal; perform an inverse Fourier transform on the power spectrum of the anti-interference reference signal to obtain the anti-interference reference signal; demodulate, despread, and correlate the anti-interference signal and the anti-interference reference signal with the local reproducible signal to obtain the corresponding input signal correlation function; Normalized least squares similarity matching is performed on the corresponding input signal correlation function to obtain the matching error; the matching error is compared with a preset threshold, and anti-interference sidelobe removal is performed based on the comparison result to obtain the anti-interference sidelobe processing result; The matching error is compared with a preset threshold, and anti-interference sidelobe removal is performed based on the comparison result to obtain the anti-interference sidelobe processing result, including: The matching error is compared with a preset threshold. If the matching error is less than the preset threshold, only one tracking channel is allocated to the input BeiDou short burst signal to lock the main peak of the correlation function. If the matching error is not less than the preset threshold, multiple tracking channels are allocated to the input BeiDou short burst signal to lock all correlation peaks.

2. The method according to claim 1, characterized in that, Frequency domain interference suppression is performed on the BeiDou short burst signal to obtain the anti-interference power spectrum and record the zeroed spectral line numbers, including: Perform a Fourier transform on the BeiDou short burst signal to obtain the power spectrum of the signal. Set the power spectrum whose amplitude exceeds the preset anti-interference threshold to 0 to obtain the anti-interference power spectrum and record the spectral line number that is set to zero.

3. The method according to any one of claims 1 to 2, characterized in that, The method further includes: The interference status of the anti-interference signal is determined. If the anti-interference signal is not interfered with, that is, the number of interfered spectral lines M is 0, then there is no need to perform correlation function matching and sidelobe suppression, and it can directly enter the normal acquisition and tracking stage.

4. The method according to claim 1, characterized in that, The anti-interference signal and the anti-interference reference signal are demodulated, despread, and correlated with the locally reproduced signal to obtain the corresponding input signal correlation function, including: The anti-interference signal and the locally reproduced signal are demodulated, despread, and correlated to obtain the correlation function of the input signal corresponding to the anti-interference signal. in, y ( t () indicates the signal after interference suppression. x ( t This indicates a locally reproduced signal. T Indicates the period of coherent integration. t 0 indicates the start time of integration.

5. The method according to claim 4, characterized in that, The method further includes: The anti-interference reference signal and the locally reproduced signal are demodulated, despread, and correlated to obtain the correlation function of the input signal corresponding to the anti-interference reference signal. in, y 0( t ) represents the reference signal after interference suppression.

6. The method according to claim 5, characterized in that, Normalized least squares similarity matching is performed on the corresponding input signal correlation function to obtain the matching error, including: Normalized least squares similarity matching is performed on the corresponding input signal correlation function to obtain the matching error as follows: Where L is the matching error, and N represents N-point sampling of the autocorrelation function with a sampling interval of . .

7. The method according to claim 1, characterized in that, The pre-set threshold is determined based on long-term collected data and empirical values ​​from Monte Carlo simulations.

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