Beidou and GPS communication and trapping integrated anti-interference digital filtering method and filter thereof

Abstract

The invention belongs to the technical field of navigation anti-interference, and particularly relates to a Beidou and GPS communication integrated anti-interference digital filtering method and a filter thereof. Comprising the following steps: generating a first band-pass FIR filter parameter corresponding to a Beidou B1 signal, generating a second band-pass FIR filter parameter corresponding to a GPS L1 signal, and respectively carrying out weighting processing on the Beidou B1 band-pass FIR filter parameter and the GPS L1 band-pass FIR filter parameter. The two independent band-pass FIR filter parameters are subjected to weighted stacking to generate a synthetic filter parameter, the parameter can meet the band-pass requirements of a Beidou B1 signal and a GPS L1 signal at the same time, a notch is formed in an intermediate frequency band, then the parameter can be effectively fused in a single FIR structure, high efficiency, anti-interference performance and hardware friendliness are achieved, and the method is suitable for large-scale popularization and application. Therefore, a traditional multi-module function is achieved, the resource efficiency is improved by more than 50%, the dynamic power adaptation effect is supported, and the method is suitable for high-precision anti-interference processing of a multi-mode satellite navigation receiver.

Description

Technical Field

[0001] The invention belongs to the technical field of navigation anti-interference, and in particular relates to a Beidou and GPS integrated anti-interference digital filtering method and a filter thereof. Background Art

[0002] With the comprehensive networking of the Beidou satellite navigation system and its compatible application with the GPS system, the dual-mode navigation terminal faces higher requirements for anti-interference ability in complex electromagnetic environments. The Beidou system has significant advantages in functional diversity (such as short message communication and high-precision positioning), but the frequency band difference between it and the GPS signal (Beidou B1: 1561.098MHz±2MHz, GPS L1: 1575.42MHz±2MHz) and the need for mixed signal processing make the traditional anti-interference technology have the following prominent problems: The traditional solution uses a dual independent filter architecture (such as Figure 3 As shown in the figure, it is necessary to design bandpass filters for Beidou B1 and GPS L1 signals respectively (e.g., Beidou B1 filter passband 1560-1562MHz, GPS L1 filter passband 1574-1576MHz). This design doubles the hardware resources (e.g., FPGA's DSP unit), and the parallel operation of the two filters places extremely high demands on real-time performance (e.g., high-precision positioning scenarios require millisecond-level response). In addition, the simple superposition of the two filter outputs does not take into account the signal power difference (e.g., GPS signals are more severely attenuated in urban canyons), which may cause weak signals to be submerged by noise and significantly degrade the signal-to-noise ratio. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the problems of high hardware resource occupancy, lack of intermediate frequency band interference suppression, and insufficient dynamic adaptation of signal power caused by the traditional dual independent filter architecture, the present invention provides a Beidou and GPS integrated anti-interference digital filtering method and its filter, which realizes dual-band signal extraction, out-of-band suppression and intermediate frequency band notch functions through a single filter structure, and supports dynamic adaptation of signal power ratio to optimize signal-to-noise ratio and resource efficiency.

[0004] (II) Technical solution The present invention is implemented by the following technical scheme: The present invention proposes a Beidou and GPS integrated anti-interference digital filtering method, comprising the following steps (Beidou positioning system B1 signal and satellite navigation system L1 signal are collectively referred to as Beidou B1 signal and GPS L1 signal hereinafter): Step 1: Generate the first bandpass FIR filter parameters corresponding to the Beidou B1 signal, the passband of the first bandpass FIR filter covers the Beidou B1 signal frequency band, and the stopband covers the frequency band below the lower limit of the Beidou B1 signal and above its upper limit; the first bandpass FIR filter parameters usually include a passband range and a stopband range, and can be designed according to the sampling rate Fs, the cutoff frequency Fstop1 / Fstop2 and the passband insertion loss Apass with the help of MATLAB's fdatool tool; MATLAB (Matrix Laboratory) is a high-performance language used for technical calculations, including matrix calculations, function and data plotting, algorithm implementation, user interface creation, and interfaces with other programming languages; fdatool is a graphical user interface (GUI) tool in MATLAB for designing, analyzing and visualizing digital filters; Fs represents the sampling rate, that is, the number of samples collected per second; Fstop1 and Fstop2 represent the stopband start frequency and stopband end frequency (or stopband edge frequency) of the filter respectively; Step 2: Generate the parameters of the second bandpass FIR filter corresponding to the GPS L1 signal. The passband of the second bandpass FIR filter covers the frequency band of the GPS L1 signal, and the stopband covers the frequency band below the lower limit of the GPS L1 signal and above its upper limit. The parameters of the second bandpass FIR filter usually also include a passband range and a stopband range, and the same parameters can also be designed with the same tools and methods as in step 1. Step 3: Perform weighted processing on the Beidou B1 bandpass FIR filter parameters and the GPS L1 bandpass FIR filter parameters respectively (the weighted processing here is: Beidou B1 bandpass FIR filter parameters and K B The product of the product results, as well as the GPS L1 bandpass FIR filter parameters and K G The product of is obtained by multiplying the product result), where the weighting coefficient of the Beidou B1 bandpass FIR filter parameter is K B , the weighting coefficient of GPS L1 bandpass FIR filter parameters is K G , and the following constraints must be met at the same time: Normalization constraint: K B +K G =1, power ratio constraint: K B ÷K G =P B ÷P G , where P B , P Gare the power values ​​of Beidou B1 signal and GPS L1 signal respectively. The power values ​​of Beidou B1 signal and GPS L1 signal may be different in each system. They can usually be obtained by measuring the signals in the channel with a spectrum analyzer. In most cases, they can be regarded as K1=K2=0.5. Step 4: superimpose the weighted first bandpass FIR filter parameters and the second bandpass FIR filter parameters by position (i.e., add the two product results of step 3) to generate synthetic filter parameters; Step 5: construct a pass-and-trap integrated digital filter based on the synthetic filter parameters (the digital shaping filter uses the synthetic filter parameters to construct a pass-and-trap integrated digital filter), and realize the following functions: Passes Beidou B1 signal band and GPS L1 signal band at the same time; Suppress the frequency band below the lower limit of Beidou B1 signal and above the upper limit of GPS L1 signal; The middle frequency band between Beidou B1 signal and GPS L1 signal is notched.

[0005] Preferably, the stopband attenuation values ​​of the first bandpass FIR filter and the second bandpass FIR filter are not less than 30 dB.

[0006] Preferably, the intermediate frequency band is a non-overlapping frequency band between Beidou B1 signal and GPS L1 signal.

[0007] Preferably, the pass-and-rejection integrated digital filter is a FIR structure, and its order is dynamically adjusted according to the stopband attenuation requirement.

[0008] The present invention also provides a pass-and-trap integrated digital filter, which is used to implement any of the filtering methods described above, comprising: A Beidou B1 bandpass FIR filter parameter generator is used to generate a first bandpass FIR filter parameter corresponding to a Beidou B1 signal, wherein the passband of the Beidou B1 bandpass FIR filter parameter generator covers the Beidou B1 signal frequency band, and the stopband covers the frequency band below the lower limit of the Beidou B1 signal and above its upper limit; A GPS L1 bandpass FIR filter parameter generator, used to generate a second bandpass FIR filter parameter corresponding to the GPS L1 signal, wherein the passband of the GPS L1 bandpass FIR filter parameter generator covers the GPS L1 signal frequency band, and the stopband covers the frequency band below the lower limit of the GPS L1 signal and above its upper limit; There are two multipliers, which are used to perform weighted processing on the Beidou B1 bandpass FIR filter parameters and the GPS L1 bandpass FIR filter parameters, respectively, wherein the weighted coefficient of the Beidou B1 bandpass FIR filter parameters is K B , the weighting coefficient of GPS L1 bandpass FIR filter parameters is KG , and the following constraints must be met at the same time: Normalization constraint: K B +K G =1, power ratio constraint: K B ÷K G =P B ÷P G , where P B , P G They are the power values ​​of Beidou B1 signal and GPS L1 signal respectively; A vector adder, used for superimposing the weighted first bandpass FIR filter parameters and the second bandpass FIR filter parameters according to positions to generate composite filter parameters; The digital filter former is used to construct a pass-through and trap-integrated digital filter according to the synthetic filter parameters. The pass-through and trap-integrated digital filter realizes the following functions: Passes Beidou B1 signal band and GPS L1 signal band at the same time; Suppress the frequency band below the lower limit of Beidou B1 signal and above the upper limit of GPS L1 signal; The middle frequency band between Beidou B1 signal and GPS L1 signal is notched.

[0009] Preferably, the filtering execution module is a FPGA or ASIC hardware logic unit.

[0010] (III) Beneficial effects Compared with the prior art, the present invention has the following beneficial effects: The present invention generates a synthetic filter parameter by weighted superposition of two independent bandpass FIR filter parameters. The parameter can simultaneously meet the bandpass requirements of Beidou B1 signal and GPS L1 signal, and form a notch in the intermediate frequency band, so that it can be effectively integrated into a single FIR structure, with high efficiency, anti-interference and hardware friendliness, thereby realizing the traditional multi-module function, improving resource efficiency by more than 50%, and supporting the effect of dynamic power adaptation, which is suitable for high-precision anti-interference processing of multi-mode satellite navigation receivers. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 Flow chart of the filtering method of the present invention.

[0012] Figure 2 This is a functional structure diagram of the filter of the present invention.

[0013] Figure 3 This is a diagram of the traditional dual independent filter architecture.

[0014] Figure 4 FIG. 4 is a diagram showing the structure of the filter of the present invention.

[0015] Figure 5 It is a simulation diagram of the pass-and-trap integrated digital filter constructed in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In this technical solution: In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] Reference Figure 1 As shown, the present invention proposes a Beidou and GPS integrated anti-interference digital filtering method, comprising the following steps (Beidou positioning system B1 signal and satellite navigation system L1 signal are collectively referred to as Beidou B1 signal and GPS L1 signal hereinafter): Step 1: Generate the first bandpass FIR filter parameters corresponding to the Beidou B1 signal, the passband of the first bandpass FIR filter covers the Beidou B1 signal frequency band, and the stopband covers the frequency band below the lower limit of the Beidou B1 signal and above its upper limit; the first bandpass FIR filter parameters usually include a passband range and a stopband range, and can be designed according to the sampling rate Fs, the cutoff frequency Fstop1 / Fstop2 and the passband insertion loss Apass with the help of MATLAB's fdatool tool; MATLAB (Matrix Laboratory) is a high-performance language used for technical calculations, including matrix calculations, function and data plotting, algorithm implementation, user interface creation, and interfaces with other programming languages; fdatool is a graphical user interface (GUI) tool in MATLAB for designing, analyzing and visualizing digital filters; Fs represents the sampling rate, that is, the number of samples collected per second; Fstop1 and Fstop2 represent the stopband start frequency and stopband end frequency (or stopband edge frequency) of the filter respectively; Step 2: Generate the parameters of the second bandpass FIR filter corresponding to the GPS L1 signal. The passband of the second bandpass FIR filter covers the frequency band of the GPS L1 signal, and the stopband covers the frequency band below the lower limit of the GPS L1 signal and above its upper limit. The parameters of the second bandpass FIR filter usually also include a passband range and a stopband range, and the same parameters can also be designed with the same tools and methods as in step 1. Step 3: Perform weighted processing on the Beidou B1 bandpass FIR filter parameters and the GPS L1 bandpass FIR filter parameters respectively (the weighted processing here is: Beidou B1 bandpass FIR filter parameters and K BThe product of the product results, as well as the GPS L1 bandpass FIR filter parameters and K G The product of is obtained by multiplying the product result), where the weighting coefficient of the Beidou B1 bandpass FIR filter parameter is K B , the weighting coefficient of GPS L1 bandpass FIR filter parameters is K G , and the following constraints must be met at the same time: Normalization constraint: K B +K G =1, power ratio constraint: K B ÷K G =P B ÷P G , where P B , P G are the power values ​​of Beidou B1 signal and GPS L1 signal respectively. The power values ​​of Beidou B1 signal and GPS L1 signal may be different in each system. They can usually be obtained by measuring the signals in the channel with a spectrum analyzer. In most cases, they can be regarded as K1=K2=0.5. Step 4: superimpose the weighted first bandpass FIR filter parameters and the second bandpass FIR filter parameters by position (i.e., add the two product results of step 3) to generate synthetic filter parameters; Step 5: construct a pass-and-trap integrated digital filter based on the synthetic filter parameters (the digital shaping filter uses the synthetic filter parameters to construct a pass-and-trap integrated digital filter), and realize the following functions: At the same time, it passes through the Beidou B1 signal band and the GPS L1 signal band (that is, input signal (Beidou B1 signal + GPS L1 signal + interference signal) → ADC sampling → pass-through filter → output signal (pure Beidou B1 + GPSL1, out-of-band and intermediate frequency band suppression), such as Figure 4 shown); Suppress the frequency band below the lower limit of Beidou B1 signal and above the upper limit of GPS L1 signal; The middle frequency band between Beidou B1 signal and GPS L1 signal is notched.

[0018] Wherein, the stopband attenuation values ​​of the first bandpass FIR filter and the second bandpass FIR filter are not less than 30 dB.

[0019] The intermediate frequency band is a non-overlapping frequency band between the Beidou B1 signal and the GPS L1 signal.

[0020] The pass-and-rejection integrated digital filter is a FIR structure, and its order is dynamically adjusted according to the stop-band attenuation requirement.

[0021] like Figure 2As shown, the present invention also provides a pass-and-trap integrated digital filter, which is used to implement any of the filtering methods described above, including: A Beidou B1 bandpass FIR filter parameter generator is used to generate a first bandpass FIR filter parameter corresponding to a Beidou B1 signal, wherein the passband of the Beidou B1 bandpass FIR filter parameter generator covers the Beidou B1 signal frequency band, and the stopband covers the frequency band below the lower limit of the Beidou B1 signal and above its upper limit; A GPS L1 bandpass FIR filter parameter generator, used to generate a second bandpass FIR filter parameter corresponding to the GPS L1 signal, wherein the passband of the GPS L1 bandpass FIR filter parameter generator covers the GPS L1 signal frequency band, and the stopband covers the frequency band below the lower limit of the GPS L1 signal and above its upper limit; There are two multipliers, which are used to perform weighted processing on the Beidou B1 bandpass FIR filter parameters and the GPS L1 bandpass FIR filter parameters, respectively, wherein the weighted coefficient of the Beidou B1 bandpass FIR filter parameters is K B , the weighting coefficient of GPS L1 bandpass FIR filter parameters is K G , and the following constraints must be met at the same time: Normalization constraint: K B +K G =1, power ratio constraint: K B ÷K G =P B ÷P G , where P B , P G They are the power values ​​of Beidou B1 signal and GPS L1 signal respectively; A vector adder, used for superimposing the weighted first bandpass FIR filter parameters and the second bandpass FIR filter parameters according to positions to generate composite filter parameters; The digital filter former is used to construct a pass-through and trap-integrated digital filter according to the synthetic filter parameters. The pass-through and trap-integrated digital filter realizes the following functions: Passes Beidou B1 signal band and GPS L1 signal band at the same time; Suppress the frequency band below the lower limit of Beidou B1 signal and above the upper limit of GPS L1 signal; The middle frequency band between Beidou B1 signal and GPS L1 signal is notched.

[0022] Wherein, the filtering execution module is an FPGA or ASIC hardware logic unit.

[0023] The present invention generates a synthetic filter parameter by weighted superposition of two independent bandpass FIR filter parameters. The parameter can simultaneously meet the bandpass requirements of Beidou B1 signal and GPS L1 signal, and form a notch in the intermediate frequency band, so that it can be effectively integrated into a single FIR structure, with high efficiency, anti-interference and hardware friendliness, thereby realizing the traditional multi-module function, improving resource efficiency by more than 50%, and supporting the effect of dynamic power adaptation, which is suitable for high-precision anti-interference processing of multi-mode satellite navigation receivers; The following are the detailed implementation steps and feature descriptions: Generation of sub-filter parameters: Beidou B1 signal bandpass FIR filter parameter generation: Design a bandpass filter whose passband covers the BeiDou B1 frequency band (e.g. 1561.098±2.046 MHz); The stopband is designed in the frequency band outside the upper and lower limits of the passband, ensuring that the stopband attenuation is at least 30dB; GPS L1 signal bandpass FIR filter parameter generation: Design a bandpass filter whose passband covers the GPS L1 band (e.g. 1575.42 ± 1.023 MHz); Stopband design also follows the principle of ensuring sufficient attenuation; Tool support: Using MATLAB's fdatool tool, the parameters of the FIR filter are automatically generated according to the given sampling rate Fs, cutoff frequency Fstop1 / Fstop2 and passband insertion loss Apass; Weighted processing (satisfying both of the following conditions): Normalization constraint (K B +K G =1), to ensure the stability of the synthesis filter gain and avoid amplitude distortion; Power ratio constraint (K B ÷K G =P B ÷P G ), adjust the weighting coefficient according to the actual signal power (for example, a weak Beidou signal requires a higher gain) to ensure balanced output signal power; Parameter stacking and synthesis filter construction: Add the two weighted filter coefficients point by point to generate a composite coefficient; Frequency response superposition effect: Passband preservation: Beidou B1 and GPS L1 passbands are preserved due to coefficient superposition.

[0024] Notch formation: The middle frequency band (such as the upper limit of Beidou B1 to the lower limit of GPS L1) forms a high attenuation area (notch) due to the superposition of the two filter stop bands; Out-of-band suppression: The frequency bands below Beidou B1 and above GPS L1 are suppressed by the joint stopband; Hardware Execution: FPGA / ASIC implementation: The synthesis coefficients are loaded into a digital filter shaper (such as a FIR convolution engine) to perform real-time filtering on the mixed signal sampled by the ADC; Dynamic adjustment: Dynamically adapt to different frequency band requirements or interference environments by updating the coefficient table; As can be seen from the above, the present invention has the following positive effects: Efficient design of integrated ventilation and sinking Functional integration: A single filter is used to simultaneously implement passband filtering (retaining Beidou B1 and GPS L1 signals) and notching (suppressing interference in the intermediate frequency band), avoiding the complexity of traditional multi-stage cascade filtering and reducing hardware resource consumption; Dynamic adaptation: The filter order can be dynamically adjusted according to the stopband attenuation requirements to flexibly respond to interference intensity in different environments; Outstanding anti-interference ability High stopband attenuation: The stopband attenuation of the two sub-filters is not less than 30dB, effectively suppressing out-of-band noise and adjacent frequency band interference; Precise notching: Actively suppress the non-overlapping intermediate frequency band between Beidou B1 and GPS L1 to reduce crosstalk between signals; Power ratio adaptive Weighted optimization, that is, ensuring that the synthesis filter parameters match the signal power through normalization constraints and power ratio constraints to avoid signal distortion or power imbalance; Strong environmental adaptability: Supports dynamic measurement of power values ​​through spectrum analyzer to adapt to changes in signal strength in different scenarios (such as urban multipath, electromagnetic interference, etc.); Hardware implementation is efficient Modular design: parameter generation, weighting, superposition and filter shaping modules are separated, which is convenient for FPGA or ASIC hardware logic implementation to meet real-time processing requirements; Resource reuse: Beidou B1 and GPS L1 filter parameters can reuse the same design tools (such as MATLAB fdatool), reducing development costs; Compatibility and scalability Multi-system support: can be expanded to other satellite navigation bands (such as GLONASS, Galileo) by simply adjusting the filter parameters; Mature software tool chain: Standardized filter design process based on MATLAB, shortening the development cycle.

[0025] Example: Based on a fixed power ratio (K B =K G = 0.5) filter synthesis Parameter configuration and implementation steps Beidou B1 signal bandpass FIR filter parameter generation: Tools: MATLAB fdatool; Parameter settings: Sampling rate Fs = 200 MHz; Stopband frequency: low frequency cutoff frequency Fstop1 is 35.098MHz, high frequency cutoff frequency Fstop2 is 43.098MHz; Passband frequency: low frequency pass frequency Fpass1 is 37.098MHz, high frequency pass frequency Fpass2 is 41.098MHz; Stopband attenuation: Astop1=Astop2=30dB; Passband insertion loss: Apass is 1dB; Generate BeiDou B1 signal bandpass FIR filter parameters (partial example) Fir1_num1=-0.00320358466750386; Fir1_num2=-0.0212100617063406; … … Fir1_num201=-0.00320358466750386; GPS L1 signal bandpass FIR filter parameter generation: Tools: MATLAB fdatool; Parameter settings: Sampling rate Fs = 200 MHz; Stopband frequency: low frequency cutoff frequency Fstop1 is 49.42MHz, high frequency cutoff frequency Fstop2 is 57.42MHz; Passband frequency: low frequency pass frequency Fpass1 is 51.42MHz, high frequency pass frequency Fpass2 is 55.42MHz; Stopband attenuation: Astop1=Astop2=30dB; Passband insertion loss: Apass is 1dB; Generate GPS L1 signal bandpass FIR filter parameters (partial example) Fir2_num1=-0.000266055525037489; Fir2_num2=-0.00145016021200931; … … Fir2_num201=-0.000266055525037489; Parameter weighting (K B =K G =0.5): Beidou B1 signal bandpass FIR filter parameter weighting (partial example): Fir1_factor1 = Fir1_num1 × 0.5 = -0.00160179233375193; Fir1_factor2 = Fir1_num2 × 0.5 = -0.0106050308531703; ...; GPS L1 signal bandpass FIR filter parameter weighting (partial example); Fir2_factor1 = Fir2_num1 × 0.5 = -0.000133027762518745; Fir2_factor2 = Fir2_num2 × 0.5 = -0.000725080106004655; ... ; Parameter synthesis Fir_data1=Fir1_factor1+Fir2_factor1=-0.00160179233375193+(-0.000133027762518745)=-0.00173482009627068; Fir_data2=Fir1_factor2+Fir2_factor2=-0.0106050308531703+(-0.000725080106004655)=-0.0113301109591749; ...; Fir_data201=Fir1_num201×0.5+Fir2_num201×0.5=0.00320358466750386×0.5+(0.000266055525037489)×0.5=0.00173482009627068; Finally, the digital shaping filter uses the parameters (Fir_data1, Fir_data2, ..., Fir_data201) generated by the vector adder to design a pass-and-trap integrated digital filter, thereby completing the filtering method.

[0026] The performance of the pass-and-traps integrated digital filter in the embodiment is verified. Figure 5From the simulation diagram of the pass-and-trap integrated digital filter, it can be seen that the filter realizes the function of simultaneously passing the Beidou B1 signal of 39.098±2MHz and the GPS L1 signal of 53.42±2MHz, and realizes the stopband suppression capability below 35.098MHz and above 57.42MHz, and realizes the notch function of the signal between 45MHz and 50MHz. Compared with the traditional method, only one digital filter is needed to realize it, that is, the dual filter (450 order) is compressed into a single filter (201 order) through parameter synthesis, saving more than 50% of logic resources. In addition, dynamic parameter adaptation, that is, K can be adjusted in real time according to the signal power. B With K G ,Adapt to complex electromagnetic environment, and,enhance anti-interference: the synthesized intermediate notch depth is ≥30dB, which is better than the traditional combiner solution.

[0027] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices stated in the device claim can also be implemented by one unit or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

[0028] Finally, it should be noted that the above is only a specific example of the present invention. Obviously, the present invention is not limited to the above example, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A Beidou and GPS integrated anti-interference digital filtering method, characterized in that: The following steps are involved: Step 1: Generate the first bandpass FIR filter parameters corresponding to the Beidou B1 signal; Step 2: Generate the second bandpass FIR filter parameters corresponding to the GPS L1 signal; Step 3: Weighting the Beidou B1 bandpass FIR filter parameters and the GPS L1 bandpass FIR filter parameters, respectively, where the weighting coefficient of the Beidou B1 bandpass FIR filter parameters is K B , the weighting coefficient of GPS L1 bandpass FIR filter parameters is K G , and the following constraints must be met at the same time: Normalization constraint: K B +K G =1, power ratio constraint: K B ÷K G =P B ÷P G , where P B , P G They are the power values ​​of Beidou B1 signal and GPS L1 signal respectively; Step 4: superimposing the weighted first bandpass FIR filter parameters and the second bandpass FIR filter parameters according to positions to generate composite filter parameters; Step 5: construct a pass-through and trap-integrated digital filter based on the synthetic filter parameters, and the pass-through and trap-integrated digital filter realizes the following functions: Passes Beidou B1 signal band and GPS L1 signal band at the same time; Suppress the frequency band below the lower limit of Beidou B1 signal and above the upper limit of GPS L1 signal; The middle frequency band between Beidou B1 signal and GPS L1 signal is notched.

2. The Beidou and GPS integrated anti-interference digital filtering method according to claim 1 is characterized in that: The stopband attenuation values ​​of the first bandpass FIR filter and the second bandpass FIR filter are not less than 30 dB.

3. The Beidou and GPS integrated anti-interference digital filtering method according to claim 1 is characterized in that: The intermediate frequency band is a non-overlapping frequency band between the Beidou B1 signal and the GPS L1 signal.

4. The Beidou and GPS integrated anti-interference digital filtering method according to claim 1 is characterized in that: The pass-and-trap integrated digital filter is a FIR structure, and its order is dynamically adjusted according to the stop-band attenuation requirement.

5. A digital filter for implementing the Beidou and GPS anti-interference digital filtering method according to any one of claims 1 to 4, characterized in that: include: A Beidou B1 bandpass FIR filter parameter generator is used to generate a first bandpass FIR filter parameter corresponding to a Beidou B1 signal, wherein the passband of the Beidou B1 bandpass FIR filter parameter generator covers the Beidou B1 signal frequency band, and the stopband covers the frequency band below the lower limit of the Beidou B1 signal and above its upper limit; A GPS L1 bandpass FIR filter parameter generator, used to generate a second bandpass FIR filter parameter corresponding to the GPS L1 signal, wherein the passband of the GPS L1 bandpass FIR filter parameter generator covers the GPS L1 signal frequency band, and the stopband covers the frequency band below the lower limit of the GPS L1 signal and above its upper limit; There are two multipliers, which are used to perform weighted processing on the Beidou B1 bandpass FIR filter parameters and the GPS L1 bandpass FIR filter parameters, respectively, wherein the weighted coefficient of the Beidou B1 bandpass FIR filter parameters is K B , the weighting coefficient of GPS L1 bandpass FIR filter parameters is K G , and the following constraints must be met at the same time: Normalization constraint: K B +K G =1, power ratio constraint: K B ÷K G =P B ÷P G , where P B , P G They are the power values ​​of Beidou B1 signal and GPS L1 signal respectively; A vector adder, used for superimposing the weighted first bandpass FIR filter parameters and the second bandpass FIR filter parameters according to positions to generate composite filter parameters; The digital filter former is used to construct a pass-through and trap-integrated digital filter according to the synthetic filter parameters. The pass-through and trap-integrated digital filter realizes the following functions: Passes Beidou B1 signal band and GPS L1 signal band at the same time; Suppress the frequency band below the lower limit of Beidou B1 signal and above the upper limit of GPS L1 signal; The middle frequency band between Beidou B1 signal and GPS L1 signal is notched.

6. The pass-and-trap integrated digital filter according to claim 5, characterized in that: The filtering execution module is a FPGA or ASIC hardware logic unit.

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