A device and method for improving the anti-interference performance of Beidou nulling antenna

Abstract

The present invention discloses a device and method for improving the anti-interference performance of a Beidou nulling antenna. The device includes a Beidou nulling antenna, and the Beidou nulling antenna includes an FFT conversion circuit and an adaptive anti-interference processing circuit. A frequency domain data smoothing circuit is provided between the FFT conversion circuit and the adaptive anti-interference processing circuit. For out-of-band signals, the circuit is directly set to zero and does not participate in the convergence of weight coefficients. For in-band signals, multiple groups of memories are added to store data before and after the current frame, and the current frame data is smoothed and weighted with the previous and next frame data to stabilize the input signal of the LMS algorithm and improve the anti-interference performance. The present invention reduces the jitter of the data participating in the LMS algorithm by optimizing the implementation mode of the weight convergence circuit, and the weights finally converged tend to be more stable, thereby improving the robustness of the adaptive algorithm and improving the anti-interference index of the Beidou nulling antenna.

Description

Technical Field

[0001] The present invention relates to the technical field of nulling antennas, and in particular to a device and method for improving the anti-interference performance of a Beidou nulling antenna. Background Art

[0002] With the full completion of my country's Beidou-3 satellite navigation system, its application is becoming more and more extensive around the world, especially in the field of national defense applications, and the requirements for the anti-interference performance of Beidou navigation equipment are becoming higher and higher. At present, most of the mainstream anti-interference solutions use space-time adaptive filtering technology, which can effectively suppress narrowband interference, broadband interference, pulse interference, swept frequency interference and other types of interference in the space environment. Space-time adaptive filtering technology generally adopts the minimum mean square error criterion. Based on the complexity of algorithm implementation and hardware cost considerations, the specific implementation adopts the least mean square (LMS) algorithm, which has the advantages of stable performance, low computational complexity and easy engineering implementation, but the disadvantage is that it cannot achieve a faster convergence speed and a smaller mean square error.

[0003] The general process of Beidou nulling antenna anti-interference is as follows Figure 2 As shown. Figure 2 It can be seen that the adaptive anti-interference processing (LMS algorithm) is performed in the frequency domain. From the measured data, for the stable interference signal in the space environment, after the fast Fourier transform, the amplitude of the sampling data at the same frequency point and at different times has large fluctuations. Using this kind of data with large fluctuations for the LMS adaptive iterative algorithm has the following two effects on the convergence of the weight coefficients: first, the convergence speed will be slower and it will not converge to the optimal value in time; second, the fluctuation of the weights is relatively large after the convergence is completed, resulting in unstable anti-interference output, which ultimately restricts the improvement of anti-interference performance. Summary of the invention

[0004] The purpose of the present invention is to provide a device and method for improving the anti-interference performance of a Beidou nulling antenna, so as to solve the technical problem of how to improve the anti-interference performance of a Beidou anti-interference antenna.

[0005] The present invention is implemented by adopting the following technical scheme: a device for improving the anti-interference performance of Beidou nulling antenna, comprising Beidou nulling antenna, wherein the Beidou nulling antenna comprises an FFT transformation circuit and an adaptive anti-interference processing circuit, wherein a frequency domain data smoothing circuit is arranged between the FFT transformation circuit and the adaptive anti-interference processing circuit, wherein for out-of-band signals, zero is directly set and the convergence of weight coefficients is not involved; for in-band signals, multiple groups of memories are added to store data before and after the current frame, and the current frame data is smoothed and weighted by using the data of the previous and next frames, so as to stabilize the input signal of the LMS algorithm and improve the anti-interference performance.

[0006] Furthermore, the Beidou nulling antenna also includes an array antenna, an RF radio frequency circuit and an analog-to-digital converter ADC connected in sequence, and the analog-to-digital converter ADC is connected to the FFT conversion circuit.

[0007] Furthermore, the Beidou nulling antenna also includes an IFFT conversion circuit, a digital AGC circuit, a digital-to-analog converter DAC and an up-conversion circuit connected in sequence, and the IFFT conversion circuit is connected to the adaptive anti-interference processing circuit.

[0008] A method for improving the anti-interference performance of a Beidou nulling antenna comprises the following steps:

[0009] S1: Build a multi-channel broadband signal receiving device, debug each circuit, and ensure that each circuit can work normally and reliably;

[0010] S2: receiving the spatial signal through a signal receiving device and performing FFT transformation on the signal;

[0011] S3: After FFT transformation, the data of each frequency point of the in-band signal is stored, and the data is smoothed and weighted iteration of the adaptive LMS algorithm is performed;

[0012] S4: Weighting coefficient ω according to LMS algorithm Ai , take out one frame of data, perform adaptive filtering on each frequency point in the band, and then perform IFFT transformation;

[0013] S5: After the digital AGC stabilizes the signal amplitude, the digital signal is converted into an analog signal through the DAC, and finally output after up-conversion.

[0014] Furthermore, step S3 includes the following sub-steps:

[0015] S31: After the FFT transformation, each channel opens multiple memory RAMs for storing in-band signal data;

[0016] S32: When new data is updated, the write address of the RAM is controlled, the latest data is put into the first memory RAM, and the data of the previous memory RAM is put into the next memory RAM in sequence, and the data of the last memory RAM is discarded;

[0017] S33: Control the read address of the memory RAM, take out the data in all the memory RAMs, and use the data in the front and back memory RAMs to smooth the data in the intermediate memory RAM;

[0018] S34: sending the smoothed data in the intermediate memory RAM to the LMS algorithm circuit for weight iterative calculation to obtain the optimal weight.

[0019] Further, step S32 includes the following sub-steps:

[0020] S321: After FFT transformation, each point of data represents a specific frequency. When storing and reading data, data at different frequencies cannot be smoothed;

[0021] S322: According to the start mark and signal bandwidth during FFT transformation, the write addresses of all memory RAMs are controlled to put the data of different frequency points into the designated memory RAMs;

[0022] S323: When a new frame of data is updated, it is necessary to accurately complete the update of the data in each memory RAM, and control the read and write addresses of each memory RAM at the same time.

[0023] Furthermore, the read address of the control memory RAM and the write address of the control memory RAM cannot be performed at the same time.

[0024] Furthermore, step S4 includes the following sub-steps:

[0025] S41: weighting coefficient ω according to LMS algorithm Ai , control the read address of the intermediate memory RAM, and read the data from the intermediate memory RAM in sequence;

[0026] S42: The read data cannot be smoothed, and the weighting coefficient ω of the corresponding frequency point is directly used. Ai The data is weighted and processed by adaptive filtering to obtain the output with frequency domain anti-interference;

[0027] S43: The weighted data is amplitude adjusted and IFFT transformed to obtain an output with time domain anti-interference.

[0028] The beneficial effects of the present invention are as follows: the present invention optimizes the implementation mode of the weight convergence circuit, increases limited hardware resources, reduces the data jitter involved in the LMS algorithm, makes the final converged weight more stable, improves the robustness of the adaptive algorithm, and improves the anti-interference index of the Beidou nulling antenna; the present invention improves the weight convergence time, enables the Beidou nulling antenna to be suitable for larger dynamics, and broadens the application range of the Beidou nulling antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0030] Figure 1 It is the principle diagram of the present invention;

[0031] Figure 2 This is the general processing flow chart for Beidou nulling antenna anti-interference. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0034] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0035] Example 1

[0036] See also Figure 1 A device for improving the anti-interference performance of a Beidou nulling antenna comprises a Beidou nulling antenna, wherein the Beidou nulling antenna comprises an FFT transformation circuit and an adaptive anti-interference processing circuit, wherein a frequency domain data smoothing circuit is arranged between the FFT transformation circuit and the adaptive anti-interference processing circuit, wherein for out-of-band signals, the circuit is directly set to zero and does not participate in the convergence of weight coefficients; for in-band signals, multiple groups of memories are added to store data before and after a current frame, and the current frame data is smoothed and weighted with the data of the previous and next frames, so as to stabilize the input signal of an LMS algorithm and improve the anti-interference performance.

[0037] In this embodiment, the Beidou zeroing antenna also includes an array antenna, an RF radio frequency circuit and an analog-to-digital converter ADC connected in sequence, and the analog-to-digital converter ADC is connected to the FFT conversion circuit. Further, the Beidou zeroing antenna also includes an IFFT conversion circuit, a digital AGC circuit, a digital-to-analog converter DAC and an up-conversion circuit connected in sequence, and the IFFT conversion circuit is connected to an adaptive anti-interference processing circuit. The present invention is used on the Beidou adaptive zeroing antenna to smooth the input signal of the LMS algorithm and improve the convergence time and stability of the adaptive weight coefficient. After the fast Fourier transform and before the adaptive processing, a frequency domain data smoothing circuit is added. For out-of-band signals, it is directly set to zero and does not participate in the convergence of the weight coefficient; for in-band signals, multiple groups of memories are added to store data before and after the current frame, and the current frame data is smoothed and weighted with the previous and next frame data to stabilize the input signal of the LMS algorithm and improve the anti-interference performance.

[0038] In the present invention, the array antenna is responsible for receiving the spatial signal, the RF radio frequency circuit converts the radio frequency signal into an intermediate frequency signal and amplifies and filters it, the analog-to-digital converter ADC converts the analog signal into a digital signal, the FFT conversion circuit converts the signal from the time domain to the frequency domain, the adaptive filtering completes the suppression of the interference signal, the IFFT conversion circuit converts the data after anti-interference back to the time domain, the digital AGC circuit outputs the signal amplitude steadily, the digital-to-analog converter DAC converts the digital signal into an analog signal, the up-conversion circuit completes the conversion of the signal from the intermediate frequency to the radio frequency, and completes the amplification and filtering.

[0039] A method for improving the anti-interference performance of a Beidou nulling antenna comprises the following steps:

[0040] S1: Build a multi-channel broadband signal receiving device, debug each circuit, and ensure that each circuit can work normally and reliably;

[0041] S2: receiving the spatial signal through a signal receiving device and performing FFT (time domain-frequency domain) transformation on the signal;

[0042] S3: After FFT transformation, for the in-band signal, three frames of data are stored at each frequency point, and smoothing is performed on the three frames of data, and adaptive LMS algorithm weighted iteration is performed;

[0043] S4: Weighting coefficient ω according to LMS algorithm Ai , take out the second frame of data, perform adaptive filtering on each frequency point in the band, and then perform IFFT (frequency domain-time domain) transformation;

[0044] S5: After the digital AGC stabilizes the signal amplitude, the digital signal is converted into an analog signal through the DAC, and finally output after up-conversion.

[0045] After anti-interference, the amplitude difference of signals at different frequencies in the band is detected, a frame of signal is stored, and the weighting coefficient ω of each frequency point in the band is calculated. Ai .

[0046] In this embodiment, step S3 includes the following sub-steps:

[0047] S31: After the FFT transformation, three memories are opened for each channel to store the in-band signal data, and three frames of in-band data are continuously stored (e.g., for a 1024-point FFT, the number of points of the in-band signal is 400, then the storage depth of the memory is 400), which are placed in RAM1, RAM2 and RAM3 respectively;

[0048] S32: When new data is updated, the write address of RAM is controlled, the latest data is put into RAM1, the original data of RAM1 is put into RAM2, the original data of RAM2 is put into RAM3, and the original data of RAM3 is discarded;

[0049] S33: Control the read address of RAM, take out the data in RAM1, RAM2 and RAM3, and use the data in RAM1 and RAM3 to smooth the data in RAM2;

[0050] S34: Send the smoothed data in RAM2 to the LMS algorithm circuit for weight iterative calculation to obtain the optimal weight.

[0051] Further, step S32 includes the following sub-steps:

[0052] S321: After FFT transformation, each point of data represents a specific frequency. When storing and reading data, the write address must be strictly controlled. Data at different frequencies cannot be smoothed.

[0053] S322: According to the start mark and useful signal bandwidth during FFT transformation, the write addresses of RAM1, RAM2, and RAM3 are controlled to put the data of different frequency points into the designated memory;

[0054] S323: When a new frame of data is updated, the data in each RAM must be updated accurately, and the read and write addresses of each RAM must be controlled at the same time. Reading and writing cannot be performed at the same time.

[0055] In this embodiment, step S4 includes the following sub-steps:

[0056] S41: weighting coefficient ω calculated according to step S3 Ai , control the read address addr2 of RAM2, and read the data from RAM2 in sequence;

[0057] S42: The read data cannot be smoothed, and the weighting coefficient ω of the corresponding frequency point is directly used. Ai The data is weighted and processed by adaptive filtering to obtain the output with frequency domain anti-interference;

[0058] S43: The weighted data is amplitude adjusted and IFFT transformed to obtain an output with time domain anti-interference.

[0059] The working process of the present invention is further explained: after the spatial signal is received by the array antenna, it is first down-converted, filtered and amplified in the radio frequency channel, and the analog signal is converted into a digital signal through the ADC; then the signal is converted to the frequency domain through the FFT transformation, and a frequency domain data smoothing circuit is added. For out-of-band signals, it is directly set to zero and does not participate in the convergence of the weight coefficient; for in-band signals, multiple groups of memories are added to store the data before and after the current frame, and the current frame data is smoothed and weighted with the previous and next frame data to stabilize the input signal of the LMS algorithm and improve the anti-interference performance. After the IFFT transformation is returned to the time domain, the amplitude is stabilized by the digital AGC, and the DAC is converted into an analog signal, and finally converted to the radio frequency output through up-conversion.

[0060] The present invention has at least the following technical effects:

[0061] The present invention reduces the data jitter involved in the LMS algorithm by optimizing the implementation mode of the weight convergence circuit, makes the final converged weight more stable, improves the robustness of the adaptive algorithm, and improves the anti-interference index of the Beidou nulling antenna; improves the weight convergence time, enables the Beidou nulling antenna to be suitable for larger dynamics, and broadens the application range of the Beidou nulling antenna.

[0062] It should be noted that, for the above embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification belong to preferred embodiments, and the actions involved are not necessarily required by the present application.

[0063] The above embodiments describe the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the changes and modifications made by those skilled in the art shall be within the scope of protection of the appended claims of the present invention without departing from the spirit and scope of the present invention.

Claims

1. A method for improving the anti-interference performance of Beidou nulling antenna, based on a device for improving the anti-interference performance of Beidou nulling antenna, characterized in that: The steps include: S1: Build a multi-channel broadband signal receiving device, debug each circuit, and ensure that each circuit can work normally and reliably; S2: receiving the spatial signal through a signal receiving device and performing FFT transformation on the signal; S3: After the FFT transformation, for the in-band signal, data is stored at each frequency point, and the data is smoothed and weighted iteration of the adaptive LMS algorithm is performed; step S3 includes the following sub-steps: S31: After the FFT transformation, each channel opens multiple memory RAMs for storing in-band signal data; S32: When new data is updated, the write address of the RAM is controlled, the latest data is put into the first memory RAM, and the data of the previous memory RAM is put into the next memory RAM in sequence, and the data of the last memory RAM is discarded; S33: Control the read address of the memory RAM, take out the data in all the memory RAMs, and use the data in the front and back memory RAMs to smooth the data in the intermediate memory RAM; S34: sending the smoothed data in the intermediate memory RAM to the LMS algorithm circuit for weight iterative calculation to obtain the optimal weight; S4: Weighting coefficient according to LMS algorithm , take out one frame of data, perform adaptive filtering on each frequency point in the band, and then perform IFFT transformation; S5: After the digital AGC stabilizes the signal amplitude, the digital signal is converted into an analog signal through the DAC, and finally output after up-conversion.

2. A method for improving the anti-interference performance of Beidou nulling antenna according to claim 1, characterized in that: Step S32 includes the following sub-steps: S321: After FFT transformation, each point of data represents a frequency. When storing and reading data, data at different frequencies cannot be smoothed; S322: According to the start mark and signal bandwidth during FFT transformation, the write addresses of all memory RAMs are controlled to put the data of different frequency points into the designated memory RAMs; S323: When a new frame of data is updated, it is necessary to accurately complete the update of the data in each memory RAM, and control the read and write addresses of each memory RAM at the same time.

3. A method for improving the anti-interference performance of Beidou nulling antenna as claimed in claim 2, characterized in that: The read address of the control memory RAM and the write address of the control memory RAM cannot be performed at the same time.

4. A method for improving the anti-interference performance of Beidou nulling antenna as claimed in claim 1, characterized in that: Step S4 includes the following sub-steps: S41: Weighting coefficient according to LMS algorithm , control the read address of the intermediate memory RAM, and read the data from the intermediate memory RAM in sequence; S42: The read data cannot be smoothed, and the weighting coefficient of the corresponding frequency point is used directly The data is weighted and adaptively filtered to obtain frequency domain anti-interference output; S43: The weighted data is amplitude adjusted and IFFT transformed to obtain an output with time domain anti-interference.

5. A method for improving the anti-interference performance of Beidou nulling antenna as claimed in claim 1, characterized in that: The device for improving the anti-interference performance of a Beidou nulling antenna comprises a Beidou nulling antenna, wherein the Beidou nulling antenna comprises an FFT transformation circuit and an adaptive anti-interference processing circuit, wherein a frequency domain data smoothing circuit is arranged between the FFT transformation circuit and the adaptive anti-interference processing circuit, wherein for out-of-band signals, the circuit is directly set to zero and does not participate in the convergence of weight coefficients; and for in-band signals, multiple groups of memories are added to store data before and after a current frame, and the current frame data is smoothed and weighted using the data of the previous and next frames, thereby stabilizing the input signal of an LMS algorithm and improving the anti-interference performance.

6. A method for improving the anti-interference performance of Beidou nulling antenna as claimed in claim 5, characterized in that: The Beidou nulling antenna also includes an array antenna, an RF radio frequency circuit and an analog-to-digital converter ADC which are connected in sequence, and the analog-to-digital converter ADC is connected to the FFT conversion circuit.

7. A method for improving the anti-interference performance of Beidou nulling antenna as claimed in claim 6, characterized in that: The Beidou nulling antenna also includes an IFFT conversion circuit, a digital AGC circuit, a digital-to-analog converter DAC and an up-conversion circuit which are connected in sequence, and the IFFT conversion circuit is connected to an adaptive anti-interference processing circuit.

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