Signal processing system and method

Abstract

The invention discloses a signal processing system and method, and the method comprises the steps: carrying out the processing of a received radio frequency signal based on a signal receiving module, and obtaining a baseband discrete signal of an orthogonal frequency division multiplexing time domain; performing down-sampling on the baseband discrete signal based on a non-recursive CIC filter to generate a down-sampled signal; compensating a passband of the down-sampling signal based on an index compensation filter to obtain a compensation signal; and attenuating the compensation signal based on a comb filter to obtain a target signal. According to the signal processing method provided by the embodiment of the invention, the high performance of the down-sampling filter is ensured, the calculation amount of the filter is reduced, and the filtering efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of digital signal processing, and in particular to a signal processing system and method. Background Art

[0002] In wireless communication systems, one of the core aspects of signal processing is to sample and transform signals in order to efficiently utilize spectrum resources and ensure accurate data transmission. Current communication systems usually need to upsample signals at the transmitter to meet bandwidth requirements, while downsampling is used to restore signals at the receiver to reduce processing burden and data storage requirements. However, when downsampling is performed at the receiver, the change in frequency range may cause aliasing and signal distortion due to the reduction in sampling rate. Therefore, in the process of downsampling, an anti-aliasing filter needs to be introduced to limit the signal spectrum to filter out high-frequency components outside the bandwidth and ensure the integrity and quality of the signal after downsampling.

[0003] Downsampling filters play an important role in the signal chain at the receiving end, and their design has a profound impact on system performance. Traditional downsampling filters mostly use finite impulse response (FIR) or infinite impulse response (IIR) structures. Although these filters can theoretically meet the requirements of signal bandwidth, their implementation often requires high computing and storage resources, especially in high-sampling rate communication systems. For example, although FIR filters can achieve accurate linear phase response, they require more filter orders to ensure high out-of-band attenuation, thereby increasing the system's computational workload and hardware cost. On the other hand, IIR filters have higher implementation efficiency, but face nonlinear phase problems in design, which may affect signal synchronization. The academic community has unanimously recognized that the cascaded integral comb filter has good performance in multi-rate processing, but the filter itself also has some shortcomings, such as attenuation in the passband and slow roll-off in the transition band. To address this problem, a well-known method is to use sharpening technology based on amplitude transfer function to improve the amplitude-frequency characteristics of the device. Although this method improves the characteristics of the cascaded integral comb filter, the amount of calculation has also increased, that is, high performance is exchanged for the amount of calculation; another study proposed to use an improved technology based on interpolated second-order polynomials to improve the amplitude-frequency characteristics of the filter. Cascading it with a cascaded integral comb filter can reduce the passband fluctuation of the filter and reduce the distortion of high-frequency signals in the passband. At the same time, it also reduces the stopband attenuation and increases the impact of useless signal aliasing.

[0004] The signal processing methods in the prior art have the problems of large amount of calculation and poor processing performance.

[0005] Therefore the prior art needs further development. Summary of the invention

[0006] In view of the above technical problems, the embodiments of the present invention provide a signal processing system and method, which can solve the technical problems of large calculation amount and poor processing performance in the signal processing method in the prior art.

[0007] A first aspect of an embodiment of the present invention provides a signal processing system, the system comprising: The signal receiving module is used to process the received radio frequency signal to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain; A non-recursive CIC filter, used for downsampling the baseband discrete signal to generate a downsampled signal; An exponential compensation filter, used for compensating the passband of the down-sampled signal to obtain a compensated signal; The comb filter is used to attenuate the compensation signal to obtain the target signal.

[0008] Optionally, the signal receiving module includes: A radio frequency circuit processing unit, used to extract a signal from the received radio frequency signal and suppress the noise and interference of the extracted signal to obtain a preprocessed signal; An analog-to-digital conversion unit, used for converting the preprocessed signal into a digital signal; The digital intermediate frequency unit is used to filter, demodulate and down-convert the digital signal in sequence, restore the down-converted signal to the baseband, and obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain.

[0009] A second aspect of an embodiment of the present invention provides a signal processing method based on the above signal processing system, the method comprising: Processing the received radio frequency signal based on the signal receiving module to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain; Downsampling the baseband discrete signal based on a non-recursive CIC filter to generate a downsampled signal; Compensating the passband of the downsampled signal based on an exponential compensation filter to obtain a compensated signal; The compensation signal is attenuated based on the comb filter to obtain the target signal.

[0010] Optionally, the received radio frequency signal is processed based on the signal receiving module to obtain a baseband discrete signal in an orthogonal frequency division multiplexing time domain, including: Extracting a signal from the received radio frequency signal and suppressing the noise and interference of the extracted signal to obtain a preprocessed signal; Converting the preprocessed signal into a digital signal; The digital signal is filtered, demodulated and down-converted in sequence, and the down-converted signal is restored to the baseband to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain.

[0011] Alternatively, the transfer function of the non-recursive CIC filter is:

[0012] Where R is the downsampling factor, M is the order of the non-recursive CIC filter, n is the index, and z is the complex exponential.

[0013] Optionally, the exponential compensation filter is a FIR compensation filter.

[0014] Optionally, the compensation function of the FIR compensation filter is:

[0015] in, is an exponential function, is the gain factor, , is the cutoff frequency of the passband to be compensated, .

[0016] Optionally, the transfer function of the comb filter is: ; Where K is the order of the filter.

[0017] Optionally, the method for obtaining the coefficients of the compensation function of the FIR compensation filter is to call a specific coefficient formula, and the specific coefficient formula is: ; Among them, L is the number of coefficients of the filter, x is the frequency value, y is the spectrum response function value of the compensation filter corresponding to the frequency value, and window is the window coefficient.

[0018] Optionally, the coefficients of the exponential function are: ; Among them, m and n are indices, M is the cutoff frequency corresponding to w, , represents rounding down, N is the number of points of the inverse Fourier transform, It is the degree to which the parameter controls the compensation value.

[0019] In the technical solution provided by the embodiment of the present invention, the received RF signal is processed based on the signal receiving module to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain; the baseband discrete signal is downsampled based on the non-recursive CIC filter to generate a downsampled signal; the passband of the downsampled signal is compensated based on the exponential compensation filter to obtain a compensated signal; the compensated signal is attenuated based on the comb filter to obtain a target signal. The signal processing method of the embodiment of the present invention ensures the high performance of the downsampling filter, reduces the calculation amount of the filter, and improves the filtering efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a module of a preferred embodiment of a signal processing system in an embodiment of the present invention; Figure 2 A flow chart of a preferred embodiment of a signal processing method in an embodiment of the present invention; Figure 3 A hierarchical schematic diagram of a preferred embodiment of a signal processing method in an embodiment of the present invention; Figure 4 A schematic diagram of a CIC filter implementation method of a preferred embodiment of a signal processing method in an embodiment of the present invention; Figure 5 It is a schematic diagram of exponential function compensation values ​​corresponding to different parameters of a preferred embodiment of a signal processing method in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0022] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0023] See also Figure 1 , Figure 1 FIG. 1 is a schematic diagram of a module of an embodiment of a signal processing system in an embodiment of the present invention. Figure 1 As shown, the system includes: The signal receiving module 100 is used to process the received radio frequency signal to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain; A non-recursive CIC filter 200, configured to downsample the baseband discrete signal to generate a downsampled signal; An exponential compensation filter 300, used to compensate the passband of the down-sampled signal to obtain a compensated signal; The comb filter 400 is used to attenuate the compensation signal to obtain a target signal.

[0024] In specific implementation, the signal processing system of the present invention uses a non-recursive CIC filter to downsample the baseband signal, thereby reducing the computational complexity; at the same time, the attenuation introduced by the CIC filter in the passband is compensated by a compensation filter to ensure that the signal amplitude is fully restored in the passband. In addition, the steepness of the transition band is further improved by cascading comb filters, and the stopband attenuation is increased. The comb filter adopts a unit gain coefficient (that is, each tap coefficient is 1), which does not increase the additional computational complexity while meeting high performance.

[0025] Furthermore, the signal receiving module 100 includes: A radio frequency circuit processing unit, used to extract a signal from the received radio frequency signal and suppress the noise and interference of the extracted signal to obtain a preprocessed signal; An analog-to-digital conversion unit, used for converting the preprocessed signal into a digital signal; The digital intermediate frequency unit is used to filter, demodulate and down-convert the digital signal in sequence, restore the down-converted signal to the baseband, and obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain.

[0026] In specific implementation, the receiver performs RF circuit processing, analog-to-digital conversion processing and digital intermediate frequency processing on the received RF signal in sequence to obtain a baseband discrete signal in the OFDM time domain. RF circuit processing: RF circuit processing is the front-end module of the receiver. Its task is to extract signals from the received radio waves while suppressing interference and noise. It mainly includes the following steps: Antenna receiving RF signals - the antenna captures RF signals from the air and sends them to the RF circuit; RF amplification - amplifying weak RF signals through a low noise amplifier (LNA) to ensure that the signal strength is sufficient for subsequent processing; filtering - using a bandpass filter to remove out-of-band interference signals and retain the frequency band where the target signal is located; mixing and down-conversion - the RF signal passes through the mixer and is mixed with the intrinsic signal of the local oscillator (LO) to complete the down-conversion processing and convert the high-frequency signal into an intermediate frequency signal; automatic gain control - dynamically adjust the amplifier gain to ensure that the signal strength adapts to the output range of the post-analog-to-digital conversion (ADC).

[0027] Analog-to-digital conversion processing: RF processed models are usually in analog form and need to be digitized by an analog-to-digital converter (ADC).

[0028] Digital IF processing: The digital IF processing module further filters, demodulates and down-converts the digitized signal to restore the signal to baseband. It mainly includes: digital down-conversion - moving the IF signal to baseband and frequency-shifting the signal through a digital mixer.

[0029] See also Figure 2 , Figure 2 FIG. 1 is a flow chart of an embodiment of a signal processing method in an embodiment of the present invention. Figure 2 As shown, including: Step S100: Processing the received radio frequency signal based on the signal receiving module to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain; Step S200, downsampling the baseband discrete signal based on a non-recursive CIC filter to generate a downsampled signal; Step S300, compensating the passband of the down-sampled signal based on an exponential compensation filter to obtain a compensated signal; Step S400: attenuate the compensation signal based on the comb filter to obtain a target signal.

[0030] In specific implementation, the embodiment of the present invention uses a non-recursive CIC filter to downsample the baseband signal. The non-recursive CIC filter uses an FIR structure to complete the filtering process. Correspondingly, there is a recursive CIC filter that uses an IIR structure to complete the filtering process. There is an integrator in the recursive CIC filter structure, which will always accumulate, so the bit width of the accumulated result is infinitely increased. In order to solve this problem, the accumulation process needs to perform a binary complement accumulation operation. However, there is no integrator in the non-recursive CIC filter, so the accumulated bit width is limited and does not require a binary complement operation. ) Thereby reducing the computational complexity; At the same time, the attenuation introduced by the CIC filter in the passband is compensated by the compensation filter to ensure that the signal amplitude is fully restored in the passband. (The spectrum of the CIC filter is downward attenuated, and the compensation filter spectrum is the reciprocal of the spectrum of the CIC filter, so the product of the two spectra is 1. The compensation can be completed by cascading the two.

[0031] After obtaining the spectrum function of the compensation filter, different frequency points are substituted into the spectrum function to obtain the corresponding spectrum function values. The frequency point values ​​and spectrum function values ​​are substituted into the fir2 function in matlab to obtain the coefficient values ​​of the compensation filter. These coefficient values ​​are given according to the FIR filter structure, so the output result of the CIC filter is input into this FIR filter to complete the compensation of the passband attenuation.

[0032] The steepness of the transition band is further improved by cascading comb filters, and the stopband attenuation is increased. Because the passband of the cascaded comb filter is attenuated from zero frequency, cascading multiple can attenuate faster. By cascading multiple cascaded comb filters and CIC filters, that is, multiplying the spectrum, the combined filter will naturally attenuate faster. To achieve fast stopband attenuation, the stopband attenuation can be achieved by sharpening the ordinary FIR filter (that is, cascading multiple FIR filters, the filter coefficient is not 1), but the area will be larger, the comb filter coefficient is 1, and the calculation is simpler.) The comb filter uses a unit gain coefficient (that is, each tap coefficient is 1), which does not increase the amount of additional calculation while meeting high performance.

[0033] The embodiment of the present invention aims at solving the problems of passband attenuation and slow transition band roll-off speed of a CIC filter, and cascades a compensation filter and a comb filter. The passband attenuation of the CIC filter is compensated by the compensation filter, and the transition band roll-off speed is accelerated by the comb filter to increase the stopband attenuation.

[0034] Further, the received radio frequency signal is processed based on the signal receiving module to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain, including: Extracting a signal from the received radio frequency signal and suppressing the noise and interference of the extracted signal to obtain a preprocessed signal; Converting the preprocessed signal into a digital signal; The digital signal is filtered, demodulated and down-converted in sequence, and the down-converted signal is restored to the baseband to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain.

[0035] In specific implementation, RF circuit processing is the front-end module of the receiver. Its task is to extract signals from the received radio waves while suppressing interference and noise. It mainly includes the following steps: antenna receives RF signal - the antenna captures RF signal from the air and sends it to the RF circuit; RF amplification - amplifies weak RF signal through a low noise amplifier (LNA) to ensure that the signal strength is sufficient for subsequent processing; filtering - uses a bandpass filter to remove out-of-band interference signals and retains the frequency band where the target signal is located; mixing and down-conversion - the RF signal passes through the mixer and is mixed with the intrinsic signal of the local oscillator (LO) to complete the down-conversion processing and convert the high-frequency signal into an intermediate-frequency signal; automatic gain control - dynamically adjusts the amplifier gain to ensure that the signal strength adapts to the output range of the subsequent analog-to-digital conversion (ADC).

[0036] Analog-to-digital conversion processing: RF processed models are usually in analog form and need to be digitized by an analog-to-digital converter (ADC).

[0037] Digital IF processing: The digital IF processing module further filters, demodulates and down-converts the digitized signal to restore the signal to baseband. It mainly includes: digital down-conversion - moving the IF signal to baseband and frequency-shifting the signal through a digital mixer.

[0038] Furthermore, the transfer function of the non-recursive CIC filter is:

[0039] Where R is the downsampling factor, M is the order of the non-recursive CIC filter, n is the index, and z is the complex exponential.

[0040] In specific implementation, due to the word length growth problem of the accumulator in the recursive CIC filter, the required bit width of the intermediate cache register is larger, while the non-recursive CIC filter can perform hierarchical down sampling, so the word length growth problem can be solved. The transfer function of the non-recursive CIC filter is shown in the above formula.

[0041] If the sampling rate conversion factor R is a positive integer power of 2, that is, K is a positive integer, then the transfer function It can be broken down into: ; Based on this decomposition, the CIC filter can be implemented in a K-fold non-recursive form. The specific classification is shown in Figure 3 shown.

[0042] If the sampling filter transform factor R is not an integer power of 2, factorize R into the product of prime numbers, that is, , the corresponding CIC filter implementation method is shown in Figure 4 As shown in the figure Represents the non-recursive CIC filter transfer function when R is 2, 3, and 5 respectively ; Furthermore, the exponential compensation filter is a FIR compensation filter.

[0043] In specific implementation, FIR compensation filter refers to a finite impulse response filter, which is a finite length unit impulse response filter, also known as a non-recursive filter. It is the most basic component in the digital signal processing system. It can have a strict linear phase-frequency characteristic while ensuring arbitrary amplitude-frequency characteristics. At the same time, its unit sampling response is finite length, so the filter is a stable system.

[0044] Furthermore, the compensation function of the FIR compensation filter is:

[0045] in, is an exponential function, is the gain factor, , is the cutoff frequency of the passband to be compensated, .

[0046] In a specific implementation, the FIR compensation filter is used to compensate for the passband attenuation of the CIC filter.

[0047] is the gain factor. The larger the value, the greater the compensation value. The coefficients of the corresponding compensation filter can be obtained by performing Fourier inverse transformation on the above spectrum response function. Since the compensation filter does not attenuate the stopband sufficiently, a comb filter is used to further attenuate the stopband of the compensation filter.

[0048] Since the recursive CIC filter will cause attenuation in the passband, a compensation filter is used to compensate the passband. The spectrum response function of the non-recursive CIC filter is:

[0049] Therefore, the spectral response function of the compensation filter is the inverse of the spectral response function of the CIC filter, which can be obtained:

[0050] Since the comb filter will cause attenuation, an exponential function is added to the spectrum response function of the compensation filter to compensate for the attenuation, and the following compensation function can be obtained: . Furthermore, the method for obtaining the coefficients of the compensation function of the FIR compensation filter is to call a specific coefficient formula, and the specific coefficient formula is: ; Among them, L is the number of coefficients of the filter, x is the frequency value, y is the spectrum response function value of the compensation filter corresponding to the frequency value, and window is the window coefficient.

[0051] In the specific implementation, the coefficients of the compensation filter can be obtained by calling the function in Matlab Obtain, L is the number of filter coefficients, x is the frequency value, y is the spectral response function value of the compensation filter corresponding to the frequency value, and window is the window coefficient, corresponding to the coefficient of the exponential function.

[0052] Furthermore, the coefficients of the exponential function are:

[0053] Among them, m and n are indices, M is the cutoff frequency corresponding to w, , represents rounding down, N is the number of points of the inverse Fourier transform, It is the degree to which the parameter controls the compensation value.

[0054] In a specific implementation, the coefficients corresponding to the exponential function can be obtained according to the process: the exponential function is discretized, and the frequency spectrum value of the discretized exponential function is subjected to inverse Fourier transform to obtain the corresponding coefficient value.

[0055] In the formula, m is the index, M is the cutoff frequency corresponding to w, , Indicates rounding down, N is the number of points of the inverse Fourier transform. After the inverse Fourier transform, N coefficient values ​​are obtained, and the first L values ​​are intercepted as the coefficient values ​​of the exponential function. The parameter controls the degree of compensation value. The larger the value, the greater the exponential function compensation value. Figure 5 yes and The corresponding spectrum value.

[0056] Furthermore, the transfer function of the comb filter is: ; Where K is the order of the filter.

[0057] In specific implementation, K is the order of the filter. The larger the K value, the better the attenuation effect. The attenuation of a single comb filter is slow, and multiple comb filters are usually cascaded. The transfer function of a comb filter is as follows:

[0058] Assume The frequency of the comb filter The attenuation value is ,in , , so the cascaded comb filter is The attenuation at the frequency should be equal to the exponential compensation filter at The compensation amount under frequency, based on which the following constraints can be obtained: ;

[0059] Where: is a non-negative integer, indicating the number of comb filters at each level, and the constraints can be obtained: ; Too many will also increase the complexity, so the sum of constraints for each filter level is: ; Based on the above constraints, we can get The value of .

[0060] It can be seen from the above embodiments that the embodiments of the present invention can use a CIC filter to downsample the communication baseband signal, use an exponential compensation filter to compensate for the passband attenuation of the CIC filter, and use a comb filter to accelerate the transition band roll-off speed of the CIC filter, increase the stopband attenuation, and greatly reduce the influence of the out-of-band component. The stopband attenuation is increased by using a comb filter, and the order of the compensation filter can be reduced. In addition, the comb filter coefficients are all 1, so the multiplication calculation amount will not increase. The cascaded down-sampling filter of the present invention has a low calculation amount and can simultaneously meet the performance indicators in the passband and out-of-band.

[0061] It should be noted that there is not necessarily a certain order between the above-mentioned steps. A person skilled in the art can understand, based on the description of the embodiments of the present invention, that in different embodiments, the above-mentioned steps may have different execution orders, that is, they may be executed in parallel, may be executed interchangeably, and so on.

[0062] An embodiment of the present invention provides a non-volatile computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are executed by one or more processors, for example, to execute the above-described Figure 2 The method comprises steps S100 to S400.

[0063] As an example, non-volatile storage media can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) as external cache memory. By way of illustration and not limitation, RAM can be obtained in many forms such as synchronous RAM (SRAM), dynamic RAM, DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM) and direct Rambus RAM (DRRAM). The disclosed memory components or memories of the operating environment described in the embodiments of the present invention are intended to include one or more of these and / or any other suitable types of memories.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A signal processing system, characterized in that: The system includes: The signal receiving module is used to process the received radio frequency signal to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain; A non-recursive CIC filter, used for downsampling the baseband discrete signal to generate a downsampled signal; An exponential compensation filter, used for compensating the passband of the down-sampled signal to obtain a compensated signal; The comb filter is used to attenuate the compensation signal to obtain the target signal.

2. The signal processing system according to claim 1, characterized in that The signal receiving module comprises: A radio frequency circuit processing unit, used to extract a signal from the received radio frequency signal and suppress the noise and interference of the extracted signal to obtain a preprocessed signal; An analog-to-digital conversion unit, used for converting the preprocessed signal into a digital signal; The digital intermediate frequency unit is used to filter, demodulate and down-convert the digital signal in sequence, restore the down-converted signal to the baseband, and obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain.

3. A signal processing method based on the signal processing system according to claim 1 or 2, characterized in that: Methods include: Processing the received radio frequency signal based on the signal receiving module to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain; Downsampling the baseband discrete signal based on a non-recursive CIC filter to generate a downsampled signal; Compensating the passband of the downsampled signal based on an exponential compensation filter to obtain a compensated signal; The compensation signal is attenuated based on the comb filter to obtain the target signal.

4. The signal processing method according to claim 3, characterized in that: The signal receiving module processes the received radio frequency signal to obtain a baseband discrete signal in an orthogonal frequency division multiplexing time domain, including: Extracting a signal from the received radio frequency signal and suppressing the noise and interference of the extracted signal to obtain a preprocessed signal; Converting the preprocessed signal into a digital signal; The digital signal is filtered, demodulated and down-converted in sequence, and the down-converted signal is restored to the baseband to obtain a baseband discrete signal in the orthogonal frequency division multiplexing time domain.

5. The signal processing method according to claim 4, characterized in that: The transfer function of the non-recursive CIC filter is: ； Where R is the downsampling factor, M is the order of the non-recursive CIC filter, n is the index, and z is the complex exponential.

6. The signal processing method according to claim 5, characterized in that: The exponential compensation filter is a FIR compensation filter.

7. The signal processing method according to claim 6, characterized in that: The compensation function of the FIR compensation filter is: ； in, is an exponential function, is the gain factor, , is the cutoff frequency of the passband to be compensated, .

8. The signal processing method according to claim 7, characterized in that: The transfer function of the comb filter is: ; Where K is the order of the filter.

9. The signal processing method according to claim 8, characterized in that: The method for obtaining the coefficients of the compensation function of the FIR compensation filter is to call a specific coefficient formula, and the specific coefficient formula is: ; Among them, L is the number of coefficients of the filter, x is the frequency value, y is the spectrum response function value of the compensation filter corresponding to the frequency value, and window is the window coefficient.

10. The signal processing method according to claim 9, characterized in that: The coefficients of the exponential function are: ； Among them, m and n are indices, M is the cutoff frequency corresponding to w, , represents rounding down, N is the number of points of the inverse Fourier transform, It is the degree to which the parameter controls the compensation value.

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