A Digital Front-End Preprocessing Method and Device for Satellite Navigation Baseband Signals

Abstract

The present invention provides a digital front-end preprocessing method and device for satellite navigation baseband signals. The method includes the following steps: S1, coding mode conversion; S2, DC removal; S3, narrowband interference detection; S4, moving narrowband interference to zero frequency; S5, moving the signal intermediate frequency back to a predetermined position; S6, spectrum shifting; S7, M / N times sampling rate conversion; S8, requantization result output. The device includes a coding mode conversion module, a DC removal module, a narrowband interference suppression module, a spectrum shifting module, a rational number factor sampling rate conversion module, and a requantization module, which are cascaded in sequence. The digital front-end preprocessing method and device for satellite navigation baseband signals described in the present invention can realize the digital front-end preprocessing function of satellite navigation baseband signals, has a simple circuit structure, is low in cost, has stable and reliable operating performance, and has a wide range of applications.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite navigation digital processing, and in particular to a satellite navigation baseband signal digital front-end preprocessing method and device thereof. Background Art

[0002] The current global satellite navigation system consists of four major systems: China's BeiDou, the United States' GPS, Europe's Galileo, and Russia's GLONASS. China's BeiDou mainly includes three frequency bands: B1, B2, and B3; the United States' GPS mainly includes three frequency bands: L1, L2, and L5; Europe's Galileo mainly includes two frequency bands: E1 and E5; and Russia's GLONASS currently mainly includes L1OF, L2OF, and L3OC signals. In terms of signal systems, there are various signal systems, including BPSK(1), BPSK(2), BPSK(10), BOC(1,1), MBOC, and AltBOC, with various bandwidths and power spectrum forms.

[0003] Under such background conditions, there may be multiple configuration schemes for the terminal products of satellite navigation receivers, which also brings serious challenges to the capture and tracking channel design of the satellite navigation receiver's dedicated integrated circuit. It would be impractical to design a corresponding set of methods and devices for each receiving mode. Summary of the Invention

[0004] The present invention aims to overcome the technical problems in the prior art where multiple signal systems are incompatible and require multiple terminal products, resulting in low efficiency and high cost. It provides a satellite navigation baseband signal digital front-end preprocessing method and device, which can realize the satellite navigation baseband signal digital front-end preprocessing function, has a simple circuit structure, low cost, stable and reliable working performance, and a wide range of applications.

[0005] The present invention provides a satellite navigation baseband signal digital front-end preprocessing method, comprising the following steps:

[0006] S1. Coding mode conversion: The coding mode conversion module converts the coded data output by the ADC into a unified 16-bit binary complement format to generate data A.

[0007] S2, DC removal: Data A is passed through a DC removal module to suppress the DC component at zero frequency, generating data B, and proceeding to step S3; data D is passed through a DC removal module to suppress the DC component at zero frequency, generating data E, and proceeding to step S5;

[0008] S3. Narrowband interference detection: Use the narrowband interference suppression module to perform a 1024-point FFT operation on the sampled signal of data B, smooth the output result, extract the noise level as the detection threshold, generate data C, and detect whether data C contains single-tone interference. If so, proceed to step S4; otherwise, proceed to step S6.

[0009] S4. Moving the narrowband interference to zero frequency: After the narrowband interference suppression module detects the frequency point of the single-tone interference of data C, the spectrum shifting module moves the single-tone interference to the zero-frequency position to generate data D, and returns to step S2;

[0010] S5. Shift the signal intermediate frequency back to the predetermined position: Pass data E through the zero-frequency notch filter of the DC removal module to suppress single-tone interference, then restore the signal intermediate frequency to the set value through the spectrum shifting module to generate data F, and proceed to step S7.

[0011] S6. Spectrum shifting: The spectrum shifting module performs orthogonal down-conversion on the data C to generate data G;

[0012] S7, M / N times sampling rate conversion: The rational number factor sampling rate conversion module performs 1 to 15 times optional zero-filling interpolation on data F or data G, passes through a 31-order low-pass filter, and then performs 1 to 15 times optional sampling to generate data H;

[0013] S8. Requantization result output: The data H is requantized by the requantization module to obtain the data result.

[0014] In the satellite navigation baseband signal digital front-end preprocessing method of the present invention, as a preferred embodiment, step S1 further includes the following steps:

[0015] S11. The electromagnetic waves of satellite navigation signals in space are converted into radio frequency electrical signals by the antenna, and then converted into 2-bit offset binary code ADC digital sampling data of IQ orthogonal quality by the radio frequency front end and input into the digital front end;

[0016] S12. The encoding mode conversion module sets the sampling signal data format to a signal representing an offset binary code, sets the sampling signal data bit width to a signal representing 2 bits, and outputs a 16-bit-wide two's complement code of the ADC digital sampling data after passing through the encoding mapper to generate data A. The corresponding relationship of the 16-bit-wide two's complement code is: 2'b00->-16d3, 2'b01->-16d1, 2'b10->16d1, and 2'b11->16d3.

[0017] The satellite navigation baseband signal digital front-end preprocessing method described in the present invention is, as a preferred embodiment, that the encoding conversion module in step S1 supports ADC sampling signals of the following encoding formats: sign-amplitude code, binary complement code, and offset binary code; the encoding conversion module supports ADC sampling signals of the following data bit widths: 1 bit, 2 bit, 4 bit, 8 bit, 10 bit, 12 bit, 14 bit, and 16 bit.

[0018] The satellite navigation baseband signal digital front-end preprocessing method of the present invention is preferably configured such that the Z domain function of the DC removal module in step S2 is:

[0019]

[0020] The present invention provides a device for implementing a satellite navigation baseband signal digital front-end preprocessing method, comprising:

[0021] Coding mode conversion module: used to receive ADC sampling data transmitted by the RF front end, convert the coding of the ADC sampling data into a unified format and generate data A, which is used to transmit data A to the DC removal module;

[0022] DC removal module: used to receive data A transmitted by the coding mode conversion module, remove the DC component in data A and generate data B, and transmit data B to the narrowband interference suppression module; used to receive data D transmitted by the spectrum shifting module, remove the DC component in data D and generate data E, and transmit data E to the spectrum shifting module;

[0023] Narrowband interference suppression module: receives data B transmitted by the DC removal module, performs a 1024-point FFT operation on data B, and smoothes the output result to generate data C. It extracts the noise level as a detection threshold to detect whether data C contains single-tone interference, and transmits data C to the spectrum shifting module.

[0024] Spectrum shifting module: used to receive data C transmitted by the narrowband interference suppression module. If there is single-tone interference in the data C, the single-tone interference is moved to the zero-frequency position and data D is generated, which is used to transmit data D to the DC removal module; if there is no single-tone interference in the data C, the data C is orthogonally down-converted to generate data G; used to receive data E transmitted by the DC removal module, used to restore the signal intermediate frequency of data E to the set value and generate data F; used to transmit data F and data G to the rational number factor sampling rate conversion module; the input signal supports single-channel intermediate frequency signal and orthogonal IQ sampling signal input selection. When in single-channel intermediate frequency signal mode, the output signals are I_out(t)=I'(t)=I(t)·cosωt, Q_out(t)=Q'(t)=I(t)·sinωt; when in orthogonal IQ sampling signal input mode, the output signals are I_out(t)=I”(t)=I(t)·cosωt-Q(t)·sinωt, Q_out(t)=Q”(t)=Q(t)·cosωt+I(t)·sinωt.

[0025] Rational number factor sampling rate conversion module: used to receive data F and data G transmitted by the spectrum shifting module, used to perform 1 to 15 times optional zero-padding interpolation on data F or data G, pass through 31-order low-pass filtering, and then perform 1 to 15 times optional sampling to generate data H; used to transmit data H to the requantization module;

[0026] Requantization module: used for receiving the data H transmitted at the rational number factor sampling rate, for requantizing the data H to obtain a data result, and for transmitting the data result to a universal satellite navigation signal tracking channel circuit and capture circuit.

[0027] The DC removal module, narrowband interference suppression module, spectrum shifting module, and rational number factor sampling rate conversion module have enable switches. Turning off the corresponding enable switch can select the pass-through mode to achieve the purpose of saving power.

[0028] In a satellite navigation baseband signal digital front-end preprocessing device described in the present invention, as an optimal embodiment, the DC removal module is a zero-frequency notch filter, the operating frequency of the zero-frequency notch filter is higher than the operating frequency of the signal sampling clock; the physical circuit of the zero-frequency notch filter can be time-division multiplexed with the narrowband interference suppression module.

[0029] In the satellite navigation baseband signal digital front-end preprocessing device described in the present invention, as an optimal mode, the operating frequency of the spectrum shifting module is higher than the operating frequency of the signal sampling clock; the physical circuit of the spectrum shifting module can be time-division multiplexed with the narrowband interference suppression module.

[0030] The satellite navigation baseband signal digital front-end preprocessing device described in the present invention is, as a preferred embodiment, a requantization module outputs a single-channel IQ orthogonal offset binary code data with a bit width of 2 bits to a capture circuit, and outputs a single-channel IQ orthogonal complement signal with a bit width of 4 bits to a universal satellite navigation signal tracking channel circuit.

[0031] In the satellite navigation baseband signal digital front-end preprocessing device of the present invention, as a preferred embodiment, the quantization threshold of the requantization module includes the following two modes: manual setting and adaptive setting.

[0032] The satellite navigation baseband signal digital front-end preprocessing device described in the present invention can be implemented in a DSP device, FPGA or ASIC as a preferred embodiment.

[0033] During use, the present invention comprises a coding mode conversion module that converts the coding of ADC output data into a unified format, and inputs the output processing result into a DC removal module. The DC removal module suppresses the DC component in the sampled signal. The sampled data after DC removal is input into a narrowband interference suppression module. The narrowband interference suppression module detects whether there is single-tone interference in the sampled signal and suppresses the interference signal if it exists. The signal after interference signal suppression is input into a spectrum shifting module. The spectrum shifting module performs spectrum shifting on a single intermediate frequency signal or an orthogonal IQ sampled signal to generate an IQ orthogonal near-zero intermediate frequency signal. The zero intermediate frequency signal is input into a rational number factor sampling rate conversion module. The rational number factor sampling rate conversion module performs M-fold interpolation, low-pass filtering, and 1 / N-fold sampling on the input signal to achieve M / N-fold rational number factor sampling rate conversion. This calculation process is achieved by selecting appropriate non-zero sampling values, multiplying them with corresponding filtering parameters, and then accumulating them. The data after sampling rate conversion is input into a requantization module to requantize the sampled signal. The quantization results are respectively output to a universal satellite navigation signal tracking channel circuit and a capture circuit.

[0034] The advantages of the present invention compared with the prior art are as follows:

[0035] (1) The present invention innovatively designs a module that can realize the conversion of commonly used ADC data encoding methods, achieving compatibility with various ADC devices;

[0036] (2) The DC removal module and spectrum shifting module provided by the present invention can be time-division multiplexed. Combined with the interference detection function of the narrowband interference suppression module, the narrowband single-tone interference suppression function can be achieved with less area resources.

[0037] (3) The rational number factor sampling rate conversion module provided by the present invention can realize M / N times sampling rate conversion with M and N values ranging from [1, 15] with relatively low area resources;

[0038] (4) The main module of the present invention can enable the pass-through mode by turning off the enable switch to achieve the purpose of reducing power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a flow chart of a satellite navigation baseband signal digital front-end preprocessing method;

[0040] Figure 2 This is a schematic diagram of the structure of a digital front-end preprocessing device for satellite navigation baseband signals;

[0041] Figure 3 This is a schematic diagram of the structure of a coding mode conversion module of a satellite navigation baseband signal digital front-end preprocessing device;

[0042] Figure 4 This is a schematic diagram of the DC removal module structure of a satellite navigation baseband signal digital front-end preprocessing device;

[0043] Figure 5 This is a schematic diagram of the structure of a narrowband interference suppression module of a satellite navigation baseband signal digital front-end preprocessing device;

[0044] Figure 6 This is a schematic diagram of the spectrum shifting module structure of a satellite navigation baseband signal digital front-end preprocessing device;

[0045] Figure 7 This is a schematic diagram of the requantization module structure of a satellite navigation baseband signal digital front-end preprocessing device;

[0046] Figure 8 Schematic diagram of the calculation principle of sampling rate conversion with rational number factor M / N=2 / 3 in Example 1. DETAILED DESCRIPTION

[0047] 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 only part of the embodiments of the present invention, rather than all the embodiments.

[0048] Example 1

[0049] like Figure 1 As shown, a satellite navigation baseband signal digital front-end preprocessing method includes the following steps:

[0050] S1, encoding mode conversion: The encoding mode conversion module converts the encoded data output by the ADC into a unified 16-bit binary complement format to generate data A; step S1 further includes the following steps:

[0051] S11. The electromagnetic waves of satellite navigation signals in space are converted into radio frequency electrical signals by the antenna, and then converted into 2-bit offset binary code ADC digital sampling data of IQ orthogonal quality by the radio frequency front end and input into the digital front end;

[0052] S12. The encoding mode conversion module sets the sampling signal data format to a signal representing an offset binary code, sets the sampling signal data bit width to a signal representing 2 bits, and outputs a 16-bit-wide two's complement code of the ADC digital sampling data after passing through the encoding mapper to generate data A. The corresponding relationship of the 16-bit-wide two's complement code is: 2'b00->-16d3, 2'b01->-16d1, 2'b10->16d1, and 2'b11->16d3.

[0053] S2, DC removal: Data A is passed through a DC removal module to suppress the DC component at zero frequency, generating data B, and proceeding to step S3; data D is passed through a DC removal module to suppress the DC component at zero frequency, generating data E, and proceeding to step S5;

[0054] S3. Narrowband interference detection: Perform a 1024-point FFT operation on the sampled signal of data B using the narrowband interference suppression module, smooth the output result, extract the noise level as the detection threshold, generate data C, and detect whether data C contains single-tone interference. If so, proceed to step S4; otherwise, proceed to step S6.

[0055] S4. Moving the narrowband interference to zero frequency: After the narrowband interference suppression module detects the frequency point of the single-tone interference of data C, the spectrum shifting module moves the single-tone interference to the zero-frequency position to generate data D, and returns to step S2;

[0056] S5. Shift the signal intermediate frequency back to the predetermined position: Pass data E through the zero-frequency notch filter of the DC removal module to suppress single-tone interference, then restore the signal intermediate frequency to the set value through the spectrum shifting module to generate data F, and proceed to step S7;

[0057] S6. Spectrum shifting: The spectrum shifting module performs orthogonal down-conversion on the data C to generate data G;

[0058] S7, M / N times sampling rate conversion: The rational number factor sampling rate conversion module performs 1 to 15 times optional zero-filling interpolation on data F or data G, passes through a 31-order low-pass filter, and then performs 1 to 15 times optional sampling to generate data H;

[0059] S8. Requantization result output: The data H is requantized by the requantization module to obtain the data result.

[0060] like Figure 2As shown, a device for implementing a digital front-end preprocessing method for satellite navigation baseband signals can be implemented in a DSP device, FPGA or ASIC, including:

[0061] Encoding conversion module: such as Figure 3 As shown, it is used to receive the ADC sampling data transmitted by the RF front end, convert the encoding of the ADC sampling data into a unified format and generate data A, which is used to transmit the data A to the DC removal module;

[0062] To DC module: Figure 4 As shown, it is used to receive data A transmitted by the coding mode conversion module, remove the DC component in the data A and generate data B, and transmit the data B to the narrowband interference suppression module; it is used to receive data D transmitted by the spectrum shifting module, remove the DC component in the data D and generate data E, and transmit the data E to the spectrum shifting module; the DC removal module is a zero-frequency notch filter, and the operating frequency of the zero-frequency notch filter is higher than the operating frequency of the signal sampling clock; the physical circuit of the zero-frequency notch filter can be time-division multiplexed with the narrowband interference suppression module;

[0063] Narrowband interference suppression module: such as Figure 5 As shown, it is used to receive data B transmitted by the DC removal module, perform a 1024-point FFT operation on the data B and smooth the output result to generate data C; extract the noise level as a detection threshold to detect whether the data C has single audio interference, and transmit the data C to the spectrum shifting module;

[0064] Spectrum shifting module: Figure 6 As shown, it is used to receive data C transmitted by the narrowband interference suppression module. If there is single-tone interference in the data C, the single-tone interference is moved to the zero-frequency position and data D is generated, which is used to transmit the data D to the DC removal module; if there is no single-tone interference in the data C, the data C is orthogonally down-converted to generate data G; it is used to receive data E transmitted by the DC removal module, and is used to restore the signal intermediate frequency of the data E to a set value and generate data F; it is used to transmit data F and data G to the rational number factor sampling rate conversion module; the input signal supports single-channel intermediate frequency signal and orthogonal IQ sampling signal input selection; when in single-channel intermediate frequency signal mode, the output The signals are I_out(t)=I'(t)=I(t)·cosωt, Q_out(t)=Q'(t)=I(t)·sinωt; when in the orthogonal IQ sampling signal input mode, the output signals are I_out(t)=I”(t)=I(t)·cosωt-Q(t)·sinωt, Q_out(t)=Q”(t)=Q(t)·cosωt+I(t)·sinωt; the operating frequency of the spectrum shifting module is higher than the operating frequency of the signal sampling clock; the physical circuit of the spectrum shifting module can be time-division multiplexed with the narrowband interference suppression module.

[0065] Rational number factor sampling rate conversion module: used to receive data F and data G transmitted by the spectrum shifting module, used to perform 1 to 15 times optional zero-padding interpolation on data F or data G, pass through 31-order low-pass filtering, and then perform 1 to 15 times optional sampling to generate data H; used to transmit data H to the requantization module;

[0066] Requantization module: such as Figure 7 As shown, it is used to receive data H transmitted at the rational number factor sampling rate, to requantize the data H to obtain a data result, and to transmit the data result to a universal satellite navigation signal tracking channel circuit and a capture circuit; the requantization module outputs a single-channel IQ orthogonal offset binary code data with a bit width of 2 bits to the capture circuit, and outputs a single-channel IQ orthogonal complement signal with a bit width of 4 bits to the universal satellite navigation signal tracking channel circuit; the quantization threshold of the requantization module includes the following two modes: manual setting and adaptive setting.

[0067] During use of this embodiment, after the electromagnetic wave of the satellite navigation signal in space is converted into a radio frequency electrical signal by the antenna, it is converted into an IQ orthogonal 2-bit offset binary code ADC digital sampling data by the radio frequency front end and input into the digital front end; the sampling signal data format is set to represent the offset binary code signal, and the sampling signal data bit width is set to represent the 2-bit signal. The 16-bit bit width binary complement code output by the ADC sampling signal after passing through the code mapper corresponds to: 2'b00->-16d3, 2'b01->-16d1, 2'b10->16d1, 2'b11->16d3; the sampled signal data encoded into the 16-bit bit width binary complement code passes through the transfer function: The DC removal process is performed and the result is output to the narrowband interference suppression module; the digital signal after DC removal is subjected to FFT processing, the result is smoothed and filtered, and the filtering result is subjected to interference detection to obtain the frequency information of the interference signal. With the help of this information, the spectrum shifting module is time-division multiplexed to shift the interference signal to zero frequency, and then the DC removal module is time-division multiplexed to suppress the interference signal at zero frequency. After suppressing the interference signal, the spectrum shifting module is time-division multiplexed again to restore the intermediate frequency of the navigation signal to its original value; the spectrum shifting module is set to the orthogonal IQ sampling signal mode, and the processing algorithm is: I_o=(u·)tω-t(·)Iω, Q_out(t)=Q(t)·cosωt+I(t)·sinωt, the intermediate frequency of the navigation signal is moved to near zero frequency; the filter bandwidth is set to the 3dB bandwidth of the navigation signal, and h(0), h(1)……h(31) are obtained through offline calculation, a total of 32 symmetrical parameters, such as Figure 7As shown in FIG, a schematic diagram of the calculation principle of the rational number factor sampling rate conversion of M / N=2 / 3 is shown. The input signal is interpolated M=2 times to obtain the sampling interpolation sequence of x(0), 0, x(1), 0, x(2), ... x(15), 0. The first 32 points are selected and multiplied with h(0), h(1), ... h(31) respectively and then accumulated to obtain the 0th interpolation filter result value. Obviously, only the non-zero sampling value needs to be calculated, and this value can also be used as the value of the 0th sample. Similarly, the next interpolation filter result value is x(1)×h(1)+x(2)×h(3)+...+x(15)×h(29)+x(16)×h(31), but this interpolation filter result will be discarded due to the extraction of N=3, so there is no need to calculate it. The result of the first sample is x (2)×h(1)+x(3)×h(3)+……+x(16)×h(29)+x(17)×h(31), the result of the second sampling is x(3)×h(0)+x(4)×h(2)+……+x(18)×h(30), and so on; first, 4 bits are intercepted from 0 to 3 bits of I(t) and Q(t), and then saturation processing is performed. If there are more than 300 values that need to be saturated in every 1024 sampling points, 4 bits are intercepted from 1 to 4 bits of I(t) and Q(t) next time. If there are still more than 300 values that need to be saturated, 4 bits are intercepted from 2 to 5 bits of I(t) and Q(t) next time, and so on, until the number of samples that need to be saturated is less than 300, and 4-bit data is output to the general satellite navigation signal tracking channel circuit. At the same time, the amplitude mean of I(t) and Q(t) is counted and used as the comparison threshold. The quantization of I(t) and Q(t) is converted into 2 bits and output to the capture module.

[0068] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A satellite navigation baseband signal digital front-end preprocessing method, characterized by: The following steps are involved: S1. Coding mode conversion: The coding mode conversion module converts the coded data output by the ADC into a unified 16-bit binary complement format to generate data A. S2, DC removal: The DC component at zero frequency is suppressed by the DC removal module on the data A to generate data B, and the process proceeds to step S3; the DC component at zero frequency is suppressed by the DC removal module on the data D to generate data E, and the process proceeds to step S5; S3, narrowband interference detection: using the narrowband interference suppression module to perform a 1024-point FFT operation on the sampled signal of data B, smoothing the output result, extracting the noise level as a detection threshold, generating data C, and detecting whether there is single-tone interference in data C. If so, proceed to step S4; otherwise, proceed to step S6; S4. Moving the narrowband interference to zero frequency: After the narrowband interference suppression module detects the frequency point of the single tone interference in the data C, the spectrum shifting module moves the single tone interference to the zero frequency position to generate data D, and then returns to step S2; S5. Shifting the signal intermediate frequency back to a predetermined position: passing the data E through the zero-frequency notch filter of the DC removal module to suppress the single-tone interference, and then restoring the signal intermediate frequency to a set value through the spectrum shifting module to generate data F, and proceeding to step S7; S6. Spectrum shifting: The spectrum shifting module performs orthogonal down-conversion on the data C to generate data G; S7, M / N times sampling rate conversion: The rational number factor sampling rate conversion module performs 1-15 times zero-padding interpolation on the data F or the data G, performs 1-15 times sampling after passing through a 31-order low-pass filter, and generates data H; S8. Requantization result output: requantize the data H through the requantization module to obtain a data result.

2. The satellite navigation baseband signal digital front-end preprocessing method according to claim 1, characterized in that: Step S1 further includes the following steps: S11. The electromagnetic waves of satellite navigation signals in space are converted into radio frequency electrical signals by the antenna, and then converted into 2-bit offset binary code ADC digital sampling data of IQ orthogonal quality by the radio frequency front end and input into the digital front end; S12. The encoding mode conversion module sets the sampling signal data format to a signal representing an offset binary code, sets the sampling signal data bit width to a signal representing 2 bits, and outputs a 16-bit binary complement of the ADC digital sampling data after passing through the encoding mapper to generate data A, where the 16-bit binary complement correspondence is: 2'b00->-16d3, 2'b01->-16d1, 2'b10->16d1, and 2'b11->16d3.

3. The satellite navigation baseband signal digital front-end preprocessing method according to claim 1, characterized in that: The encoding mode conversion module in step S1 supports ADC sampling signals of the following encoding formats: sign-amplitude code, two's complement code, offset binary code; the encoding conversion module supports ADC sampling signals of the following data bit widths: 1 bit, 2 bit, 4 bit, 8 bit, 10 bit, 12 bit, 14 bit, 16 bit.

4. The satellite navigation baseband signal digital front-end preprocessing method according to claim 1, characterized in that: The Z-domain function of the DC removal module in step S2 is: 。 5. A satellite navigation baseband signal digital front-end preprocessing device, characterized by: include: Coding mode conversion module: used to receive ADC sampling data transmitted by the RF front end, convert the coding of the ADC sampling data into a unified format and generate data A, and transmit the data A to the DC removal module; a DC removal module, configured to receive the data A transmitted by the coding mode conversion module, remove the DC component in the data A and generate data B, and transmit the data B to the narrowband interference suppression module; for receiving data D transmitted by the spectrum shifting module, for removing DC components from the data D and generating data E, and for transmitting the data E to the spectrum shifting module; Narrowband interference suppression module: used for receiving the data B transmitted by the DC removal module, performing a 1024-point FFT operation on the data B and smoothing the output result to generate data C; Extracting a noise level as a detection threshold to detect whether the data C has single-tone interference, and transmitting the data C to a spectrum shifting module; Spectrum shifting module: used to receive the data C transmitted by the narrowband interference suppression module, and if the data C has single-tone interference, move the single-tone interference to the zero-frequency position and generate the data D, and transmit the data D to the DC removal module; if the data C does not have single-tone interference, perform orthogonal down-conversion on the data C to generate data G; for receiving the data E transmitted by the DC removal module, for restoring the signal intermediate frequency of the data E to a set value and generating data F; for transmitting the data F and the data G to the rational number factor sampling rate conversion module; Rational number factor sampling rate conversion module: used to receive the data F and the data G transmitted by the spectrum shifting module, and to perform 1-15 times zero-padding interpolation on the data F or the data G, and to perform 1-15 times sampling after passing through a 31-order low-pass filter to generate data H; and to transmit the data H to the requantization module; Requantization module: used for receiving the data H transmitted at the rational number factor sampling rate, for requantizing the data H to obtain a data result, and for transmitting the data result to a universal satellite navigation signal tracking channel circuit and capture circuit.

6. The satellite navigation baseband signal digital front-end preprocessing device according to claim 5, characterized in that: The DC removal module is a zero-frequency notch filter, and the operating frequency of the zero-frequency notch filter is higher than the operating frequency of the signal sampling clock; the physical circuit of the zero-frequency notch filter can be time-division multiplexed with the narrowband interference suppression module.

7. The satellite navigation baseband signal digital front-end preprocessing device according to claim 5, characterized in that: The operating frequency of the spectrum shifting module is higher than the operating frequency of the signal sampling clock; the physical circuit of the spectrum shifting module can be time-division multiplexed with the narrowband interference suppression module.

8. The satellite navigation baseband signal digital front-end preprocessing device according to claim 5, characterized in that: The requantization module outputs a single channel of 2-bit IQ quadrature offset binary code data to the capture circuit, and outputs a single channel of 4-bit IQ quadrature complement code signal to the universal satellite navigation signal tracking channel circuit.

9. The satellite navigation baseband signal digital front-end preprocessing device according to claim 5, characterized in that: The quantization threshold of the requantization module includes the following two modes: manual setting and adaptive setting.

10. The satellite navigation baseband signal digital front-end preprocessing device according to any one of claims 5 to 9, characterized in that: It can be implemented in a DSP device, FPGA or ASIC.

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