A single-bit radar quantization method and system based on frequency modulation threshold

Abstract

The present invention provides a single-bit radar quantization method and system based on frequency modulation thresholds, belonging to the field of signal processing technology. The method comprises: a main control MCU controls a DAC to generate a sawtooth signal, which in turn controls a voltage-controlled oscillator to generate a frequency-modulated continuous wave, which is then amplified by a power amplifier and transmitted by a transmitting antenna as a linear frequency modulation signal. The receiving antenna acquires the echo signal reflected by the target, amplifies it by a low-noise amplifier, and then mixes it with the linear frequency modulation signal in a mixer to extract the intermediate frequency signal. The signal is then automatically amplified and limited by an AGC to obtain a single-frequency intermediate frequency signal. The main control MCU generates a frequency modulation threshold signal through a DAC or oscillator, and the amplitudes of the two are compared by a voltage comparator to generate a binary signal. The signal is then sampled at high speed through a digital IO port to obtain single-bit quantized data. Finally, the signal is quantized through frequency domain transformation and rectangular window function filtering. The present invention solves the problems of harmonic interference, false target influence, and insufficient retention of signal amplitude and phase information in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of signal processing technology, and in particular to a single-bit radar quantization method and system based on frequency modulation threshold. Background Art

[0002] With the development of drones, airborne radars are becoming increasingly smaller and lighter. High-resolution imaging is achieved by leveraging their flexibility and close-range observation capabilities. Airborne SAR is also maneuverable and flexible, with flight routes adjustable according to mission requirements, allowing for rapid deployment to target areas for observation. Internationally, several countries have developed unique micro-UAV-mounted SAR systems. However, the large amount of echo data imposes a heavy burden on the system for data acquisition, storage, transmission, and processing, resulting in high system complexity and cost. Single-bit radar imaging technology can address these issues. This technology not only reduces the amount of data the system must process, but also lowers system costs. Therefore, research on single-bit radar imaging technology is of great significance for both military and civilian applications.

[0003] G. Franceschetti et al. successfully performed single-bit quantization on SAR echo signals, preserving the original signal's phase information. However, this method failed to address issues such as harmonic interference and amplitude distortion. Furthermore, under a de-skewed scheme, zero-threshold single-bit quantization generated a large number of false targets due to harmonic interference, significantly impacting target recognition and detection. C. Gianelli et al. employed a time-varying Gaussian threshold to perform single-bit quantization on the signal, effectively preserving the original signal's amplitude and phase information. However, this method also introduced significant noise. Furthermore, in conventional applications, this method introduces the issue of high-precision storage of the quantization threshold and fails to effectively simplify the system architecture, contradicting the original purpose of single-bit sampling quantization. B. Zhao et al. proposed a single-bit quantization method based on a single-frequency threshold. This paper demonstrated that the use of a single-frequency threshold can suppress harmonics and restore signal amplitude information. However, under a de-skewed scheme, the intermodulation between the threshold and the signal introduces a large number of false targets, further impacting target detection and recognition. T. Pan et al. proposed a single-bit frequency shift method to move harmonics in the spectrum to reduce the impact on imaging components. However, although this method can effectively reduce the impact of false targets generated by harmonics, it still has a strong false target impact.

[0004] Therefore, it is of great practical significance to provide a single-bit radar quantization method and system based on frequency modulation threshold. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide a single-bit radar quantization method and system based on frequency modulation threshold, which effectively reduces the amount of radar echo data and system complexity, preserves signal amplitude and phase information, suppresses harmonic interference and false targets, and improves the signal-to-noise ratio and target detection accuracy.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A single-bit radar quantization method based on frequency modulation threshold comprises the following steps:

[0008] S1, the main control MCU controls the DAC to generate a sawtooth signal, and controls the voltage-controlled oscillator to generate a frequency-modulated continuous wave. After amplification by the power amplifier, the linear frequency modulation signal is transmitted to the detection area through the transmitting antenna;

[0009] S2. The radar obtains the echo signal reflected by the target through the receiving antenna, amplifies it through the low-noise amplifier, mixes it with the linear frequency modulation signal in the mixer, extracts the intermediate frequency signal, and performs automatic gain amplification and limiting through the AGC to obtain a single-frequency intermediate frequency signal;

[0010] S3, the main control MCU dynamically generates the frequency modulation threshold signal through the DAC or oscillator;

[0011] S4, inputting the single-frequency intermediate frequency signal and the frequency modulation threshold signal into a voltage comparator, generating a binary signal through amplitude comparison, and performing high-speed sampling on the binary signal using a digital IO port to obtain single-bit quantized data;

[0012] S5. Perform frequency domain transformation on the single-bit quantized data and then apply a rectangular window function to perform filtering processing to remove strong harmonic components generated by the frequency modulation threshold signal, retain the effective spectral components of the target echo, and complete single-bit radar quantization based on the frequency modulation threshold.

[0013] Preferably, in S1, the mathematical expression of the linear frequency modulation signal is:

[0014] ;

[0015] Where, In the form of a transmitted signal; is the signal carrier frequency; is the frequency modulation slope; is the signal duration, that is, the time it takes for the linear frequency modulation signal to be received by the radar after being reflected by the target; is the signal amplitude; is the initial phase.

[0016] Preferably, in S2, the mathematical expression for obtaining the echo signal reflected by the target through the receiving antenna by the radar is:

[0017] ;

[0018] Where, is the echo delay function, and the signal moving speed is V , the signal distance radar is , then the real-time distance between the target signal and the radar is , then the echo delay function , c is the speed of light; is the signal amplitude, which is related to the signal attenuation coefficient of the target scattering cross-section; is the phase shift after reflection.

[0019] Preferably, in S2, the echo signal is amplified by a low noise amplifier and then mixed with the linear frequency modulation signal in a mixer to extract the intermediate frequency signal. The mathematical expression is:

[0020] ;

[0021] Through AGC automatic gain amplification and limiting, a single-frequency intermediate frequency signal is obtained. The mathematical expression is:

[0022] ;

[0023] Where, is the signal amplitude after AGC automatic gain; is the carrier frequency of the intermediate frequency signal; is the total phase of the signal.

[0024] Preferably, in S3, the frequency modulation threshold signal is generated by the main control MCU through a DAC peripheral or a control oscillator, and the mathematical expression of the frequency modulation threshold signal is:

[0025] ;

[0026] Where, is the threshold amplitude, is the threshold carrier frequency, is the frequency modulation slope of the threshold; is the total phase of the FM threshold signal; For the initial phase, is the order of transmitting pulses, specifically:

[0027] ;

[0028] Where, PRF is the pulse repetition frequency; is the equivalent frequency parameter, where v is the radar movement speed, is the signal wavelength, is the angle between the receiving antenna beam and the radar movement direction, is the main lobe width of the radar antenna.

[0029] Preferably, in S4, the single-frequency intermediate frequency signal and the frequency modulation threshold signal are input into a voltage comparator, and a binary signal is generated by amplitude comparison, that is, the portion of the single-frequency intermediate frequency signal that is greater than the frequency modulation threshold signal is 1, and the portion of the single-frequency intermediate frequency signal that is less than the frequency modulation threshold signal is 0. Subsequently, sampling is performed to obtain a single-bit signal, and the signal characteristics are divided into two parts: the amplitude between different harmonics and the position of the harmonic spectrum. The mathematical expression is:

[0030] ;

[0031] It represents the amplitude of the harmonic component, which is related to the amplitude of the FM threshold and the amplitude of the signal. At this time, the frequency of the target echo is , the frequency of the FM threshold signal is , ,in T P is the threshold duration, and the harmonic distribution after single-bit quantization is:

[0032] ;

[0033] It indicates the position of the harmonics after they are moved due to intermodulation between different harmonics. is the harmonic order of the FM threshold signal, It is the harmonic order generated by the intermodulation of the target echo signal and the FM threshold signal.

[0034] Preferably, S4 further includes: reducing the influence of harmonic noise brought by harmonics on the observation area by moving the stronger threshold; wherein, when When it is an even number, ;when , When , it is the target echo signal; when , is the first harmonic generated by the frequency modulation threshold signal. At this time, most of the threshold energy is concentrated in the first harmonic generated by the frequency modulation threshold. At this time, the maximum observation distance is , the maximum bandwidth of the intermediate frequency signal after mixing is ; To reduce the amount of data, the sampling frequency is ;

[0035] when , When , the threshold is moved outside the observation distance to avoid spectrum aliasing due to the Nyquist sampling theorem. The threshold frequency distribution requirement is:

[0036] ;

[0037] in, , we can get the threshold carrier frequency as .

[0038] Preferably, in S4, in order to preserve the integrity of the signal amplitude and also to suppress the generation of false targets, appropriate signal amplitude and threshold amplitude are set, and the signal threshold ratio is defined as STR , the expression is:

[0039] ;

[0040] ;

[0041] in, is the signal amplitude after AGC automatic gain, and , threshold amplitude , based on this range, the amplitude of the false target generated by the single-bit quantization intermodulation is lower than the amplitude of the FM threshold signal harmonic.

[0042] Preferably, in S5, in the process of applying a rectangular window function to filter the single-bit quantized data after frequency domain transformation, the range of the rectangular window is ,in , is the maximum observation distance, and the specific expression is:

[0043] ;

[0044] Where, is a rectangular window with a length of , for The corresponding spectrum is used to filter out the strong harmonic components generated by the FM threshold signal and retain the effective spectrum components of the target echo.

[0045] The present invention further provides a single-bit radar quantization system based on a frequency modulation threshold, which is used to execute the above-mentioned single-bit radar quantization method based on a frequency modulation threshold, comprising:

[0046] The signal transmission module is used to generate and transmit linear frequency modulation signals, including a main control MCU, a DAC, a voltage-controlled oscillator, a power amplifier and a transmitting antenna;

[0047] The echo receiving module is used to receive the echo signal and perform frequency mixing and limiting processing, including a receiving antenna, a low-noise amplifier, a mixer and an AGC module;

[0048] The FM threshold generation module is controlled by the main MCU and is used to generate the FM threshold signal, including a DAC or an oscillator;

[0049] Single-bit quantization module, used to compare the echo signal with the frequency modulation threshold and sample it, including a voltage comparator and a digital IO port;

[0050] The frequency domain processing module is used to perform frequency domain windowing filtering on single-bit data to suppress harmonic components.

[0051] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0052] The present invention adopts a time-varying threshold method to perform single-bit quantization on radar echoes, obtains single-bit data in hardware with the help of a voltage comparator, and logically collects logic levels through an IO port. This reduces the amount of radar system echo data, significantly increases the sampling rate, and greatly reduces system complexity, making the radar system more lightweight and miniaturized.

[0053] The present invention effectively retains the amplitude and phase information of the signal and reduces the effect of signal distortion by using a time-varying threshold; at the same time, by adopting a frequency modulation threshold method, it effectively reduces the problem of false targets caused by signal harmonic intermodulation and suppresses the generation of false targets.

[0054] The present invention achieves the purpose of suppressing the influence of the reference Pulser component caused by the threshold by adopting a time-varying initial phase, that is, different pulses adopt different initial phases, and the initial phase changes with the pulse emission sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0056] Figure 1 A schematic diagram of the single-bit quantization principle provided by the present invention;

[0057] Figure 2 A block diagram of the radar system provided by the present invention;

[0058] Figure 3 The high-precision quantized one-dimensional range image provided by the present invention;

[0059] Figure 4 The one-dimensional distance image after single-bit quantization provided by the present invention; wherein, Figure 4 (a) is the one-dimensional distance image after zero threshold single-bit quantization. Figure 4 (b) is the one-dimensional distance image after Gaussian threshold single-bit quantization. Figure 4(c) is the one-dimensional distance image after single-frequency threshold single-bit quantization. Figure 4 (d) is the one-dimensional range image after frequency shift single-bit quantization;

[0060] Figure 5 The one-dimensional distance image of the frequency modulation threshold provided by the present invention;

[0061] Figure 6 This is a graph showing the constant false alarm detection results under different single-bit quantization thresholds provided by the present invention;

[0062] Figure 7 This is a cross-sectional diagram of different single-bit quantization thresholds provided by the present invention. DETAILED DESCRIPTION

[0063] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0064] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0065] like Figure 1 As shown, the present invention provides a single-bit radar quantization method based on frequency modulation threshold, comprising the following steps:

[0066] S1, the main control MCU controls the DAC to generate a sawtooth signal, and controls the voltage-controlled oscillator to generate a frequency-modulated continuous wave. After amplification by the power amplifier, the linear frequency modulation signal is transmitted to the detection area through the transmitting antenna;

[0067] S2. The radar obtains the echo signal reflected by the target through the receiving antenna, amplifies it through the low-noise amplifier, mixes it with the linear frequency modulation signal in the mixer, extracts the intermediate frequency signal, and performs automatic gain amplification and limiting through the AGC to obtain a single-frequency intermediate frequency signal;

[0068] S3, the main control MCU dynamically generates the frequency modulation threshold signal through the DAC or oscillator;

[0069] S4, inputting the single-frequency intermediate frequency signal and the frequency modulation threshold signal into a voltage comparator, generating a binary signal through amplitude comparison, and performing high-speed sampling on the binary signal using a digital IO port to obtain single-bit quantized data;

[0070] S5. Perform frequency domain transformation on the single-bit quantized data and then apply a rectangular window function to perform filtering processing to remove strong harmonic components generated by the frequency modulation threshold signal, retain the effective spectral components of the target echo, and complete single-bit radar quantization based on the frequency modulation threshold.

[0071] The present invention uses a frequency modulation threshold method to compare the radar intermediate frequency signal in a de-slanted radar system with a threshold to obtain single-bit data. This method uses the frequency modulation signal as a threshold to perform single-bit quantization on the echo, effectively preserving the signal's amplitude and phase information while suppressing the generation of false targets. Compared to a Gaussian threshold, it reduces floor noise, improves the signal-to-noise ratio, and significantly enhances the quality of radar echo recovery. Furthermore, in S1, the mathematical expression of the linear frequency modulation signal is:

[0072] ;

[0073] Where, In the form of a transmitted signal; is the signal carrier frequency; is the frequency modulation slope; is the signal duration, that is, the time it takes for the linear frequency modulation signal to be received by the radar after being reflected by the target; is the signal amplitude; is the initial phase.

[0074] Furthermore, in S2, the mathematical expression for the radar to obtain the echo signal reflected by the target through the receiving antenna is:

[0075] ;

[0076] Where, is the echo delay function, and the signal moving speed is V , the signal distance radar is , then the real-time distance between the target signal and the radar is , then the echo delay function , c is the speed of light; is the signal amplitude, which is related to the signal attenuation coefficient of the target scattering cross-section; is the phase shift after reflection.

[0077] Furthermore, in S2, the echo signal is amplified by a low-noise amplifier and then mixed with the linear frequency modulation signal in a mixer. After the mixing is completed, the right band is extracted, and the signal is limited by AGC automatic gain amplification to obtain the required signal amplitude, and the intermediate frequency signal is extracted. The mathematical expression is:

[0078] ;

[0079] Through AGC automatic gain amplification and limiting, a single-frequency intermediate frequency signal is obtained. The mathematical expression is:

[0080] ;

[0081] Where, is the signal amplitude after AGC automatic gain; is the carrier frequency of the intermediate frequency signal; is the total phase of the signal.

[0082] Furthermore, in S3, the frequency modulation threshold signal is generated by the main control MCU through a DAC peripheral or a control oscillator, and the mathematical expression of the frequency modulation threshold signal is:

[0083] ;

[0084] Where, is the threshold amplitude, is the threshold carrier frequency, is the frequency modulation slope of the threshold; is the total phase of the FM threshold signal; For the initial phase, is the order of transmitting pulses, specifically:

[0085] ;

[0086] Where, PRF is the pulse repetition frequency; is the equivalent frequency parameter, where v is the radar movement speed, is the signal wavelength, is the angle between the receiving antenna beam and the radar movement direction, is the main lobe width of the radar antenna.

[0087] Furthermore, in S4, the single-frequency intermediate frequency signal and the frequency modulation threshold signal are input into a voltage comparator, and a binary signal is generated by amplitude comparison, that is, the portion of the single-frequency intermediate frequency signal that is greater than the frequency modulation threshold signal is 1, and the portion of the single-frequency intermediate frequency signal that is less than the frequency modulation threshold signal is 0. Subsequently, they are sampled to obtain a single-bit signal. The signal characteristics are divided into two parts: the amplitude between different harmonics and the position of the harmonic spectrum. The mathematical expression is:

[0088] ;

[0089] It represents the amplitude of the harmonic component, which is related to the amplitude of the FM threshold and the amplitude of the signal. At this time, the frequency of the target echo is , the frequency of the FM threshold signal is , ,in TP is the threshold duration, and the harmonic distribution after single-bit quantization is:

[0090] ;

[0091] It indicates the position of the harmonics after they are moved due to intermodulation between different harmonics. is the harmonic order of the FM threshold signal, It is the harmonic order generated by the intermodulation of the target echo signal and the FM threshold signal.

[0092] In order to reduce the impact of harmonics on strong targets, it is necessary to adjust the signal amplitude and threshold amplitude so that the false target is submerged in the bottom noise and reduce the amplitude of the bottom noise. By moving the stronger threshold, the impact of harmonic noise on the observation area can be reduced; among them, when When it is an even number, ;when , When , it is the target echo signal; when , is the first harmonic generated by the frequency modulation threshold signal. At this time, most of the threshold energy is concentrated in the first harmonic generated by the frequency modulation threshold. At this time, the maximum observation distance is , the maximum bandwidth of the intermediate frequency signal after mixing is ; To reduce the amount of data, the sampling frequency is ;

[0093] when , When , the threshold is moved outside the observation distance to avoid spectrum aliasing due to the Nyquist sampling theorem. The threshold frequency distribution requirement is:

[0094] ;

[0095] in, , we can get the threshold carrier frequency as Since most of the harmonic energy is contained only in the first harmonic of the FM threshold, the first harmonic of the FM threshold is also moved outside the observation range due to the influence of the threshold carrier frequency. At this time, the influence of other intermodulation is very weak.

[0096] Furthermore, in S4, in order to preserve the integrity of the signal amplitude and suppress the generation of false targets, the appropriate signal amplitude and threshold amplitude are set, and the signal threshold ratio is defined as STR , the expression is:

[0097] ;

[0098] ;

[0099] in, is the signal amplitude after AGC automatic gain, and , the amplitude information can be restored well within this range. Threshold amplitude , based on this range, the amplitude of the false target generated by the single-bit quantization intermodulation is lower than the amplitude of the FM threshold signal harmonic.

[0100] Furthermore, in S5, after the single-bit quantized data is subjected to frequency domain transformation and then subjected to a rectangular window function for filtering, the range of the rectangular window is ,in , is the maximum observation distance, and the specific expression is:

[0101] ;

[0102] Where, is a rectangular window with a length of , for The corresponding spectrum is used to filter out the strong harmonic components generated by the FM threshold signal and retain the effective spectrum components of the target echo.

[0103] Reference Figure 2 The present invention further provides a single-bit radar quantization system based on a frequency modulation threshold, which is used to execute the above-mentioned single-bit radar quantization method based on a frequency modulation threshold, comprising:

[0104] The signal transmission module is used to generate and transmit linear frequency modulation signals, including a main control MCU, a DAC, a voltage-controlled oscillator, a power amplifier and a transmitting antenna;

[0105] The echo receiving module is used to receive the echo signal and perform frequency mixing and limiting processing, including a receiving antenna, a low-noise amplifier, a mixer and an AGC module;

[0106] The FM threshold generation module is controlled by the main MCU and is used to generate the FM threshold signal, including a DAC or an oscillator;

[0107] Single-bit quantization module, used to compare the echo signal with the frequency modulation threshold and sample it, including a voltage comparator and a digital IO port;

[0108] The frequency domain processing module is used to perform frequency domain windowing filtering on single-bit data to suppress harmonic components.

[0109] In order to further verify the effect of the present invention, a simulation experiment is performed to illustrate the data. MATLAB software is used for data processing, wherein the simulation data parameters are as follows:

[0110] The radar operates in a de-slant system with a carrier frequency of , the radar bandwidth is , the pulse duration is , pulse repetition frequency , , , The maximum observation distance is 200m, and the radar frequency modulation slope , the sampling rate is Set five target points at 20m, 40m, 60m, 80m, and 100m respectively. The signal threshold ratio is -1.5dB.

[0111] Among them, the parameters of the single-frequency threshold are as follows: the frequency is , the frequency modulation threshold parameters are as follows: carrier frequency , the bandwidth is .

[0112] Reference Figure 3 After high-precision sampling, fast Fourier transform is performed to find the spectrum position and amplitude information of the five targets. Then, the radar echo is quantized by the existing single-bit method. Figure 4 From (a) in the figure, we can see that the zero threshold can well restore the echo phase information, but it will also bring harmonic effects and signal amplitude distortion. Figure 4 From (b) in the figure, we can see that although the Gaussian threshold can retain the phase and amplitude information of the echo, it brings a lot of noise. Figure 4 From (c) in the figure, we can see that although the single-frequency threshold can well preserve the phase and amplitude information of the echo, it will bring a large number of false targets due to the influence of harmonic intermodulation. Figure 4 In (d), we can see that the frequency shift single bit can well separate the third harmonic and the fifth harmonic, but there is still a lot of harmonic interference and amplitude distortion. Based on this, Figure 5 The method of frequency modulation threshold is used to quantize the signal into single bits. Figure 5 It can be seen that the spectrum after single-bit quantization can well restore the amplitude and phase information of the original echo, while reducing harmonic interference.

[0113] Finally, the constant false alarm detection method is used to evaluate the echo after single-bit quantization under different signal threshold ratios. Figure 6 It is obvious that the single-frequency threshold brings a large number of false targets, the Gaussian threshold causes the detection results to fluctuate due to the influence of noise, and the zero threshold and frequency shift single bit also have the interference of false targets. Figure 6 The results shown in Figure 2 show that the frequency modulation threshold can detect the target correctly. Figure 7 ,Comparing different quantization methods, the FM threshold can still maintain a good ,mainlobe width and sidelobe height.

[0114] Therefore, the above-mentioned single-bit radar quantization method and system based on frequency modulation threshold are adopted to effectively reduce the amount of radar echo data and system complexity, retain signal amplitude and phase information, suppress harmonic interference and false targets, and improve the signal-to-noise ratio and target detection accuracy.

[0115] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A single-bit radar quantization method based on frequency modulation threshold, characterized in that: The following steps are involved: S1, the main control MCU controls the DAC to generate a sawtooth signal, and controls the voltage-controlled oscillator to generate a frequency-modulated continuous wave. After amplification by the power amplifier, the linear frequency modulation signal is transmitted to the detection area through the transmitting antenna; S2. The radar obtains the echo signal reflected by the target through the receiving antenna, amplifies it through the low-noise amplifier, mixes it with the linear frequency modulation signal in the mixer, extracts the intermediate frequency signal, and performs automatic gain amplification and limiting through the AGC to obtain a single-frequency intermediate frequency signal; S3, the main control MCU dynamically generates the frequency modulation threshold signal through the DAC or oscillator; In S3, the frequency modulation threshold signal is generated by the main control MCU through the DAC peripheral or the control oscillator. The mathematical expression of the frequency modulation threshold signal is: ； Where, is the threshold amplitude, is the threshold carrier frequency, is the frequency modulation slope of the threshold; is the total phase of the FM threshold signal; For the initial phase, is the order of transmitting pulses, specifically: ； Where, PRF is the pulse repetition frequency; is the equivalent frequency parameter, where v is the radar movement speed, is the signal wavelength, is the angle between the receiving antenna beam and the radar movement direction, is the main lobe width of the radar antenna; S4, inputting the single-frequency intermediate frequency signal and the frequency modulation threshold signal into a voltage comparator, generating a binary signal through amplitude comparison, and performing high-speed sampling on the binary signal using a digital IO port to obtain single-bit quantized data; S5. After performing frequency domain transformation on the single-bit quantized data, a rectangular window function is applied to perform filtering processing to filter out strong harmonic components generated by the frequency modulation threshold signal, retain the effective spectral components of the target echo, and complete single-bit radar quantization based on the frequency modulation threshold.

2. The single-bit radar quantization method based on frequency modulation threshold according to claim 1, characterized in that: In S1, the mathematical expression of the linear frequency modulation signal is: ； Where, In the form of a transmitted signal; is the signal carrier frequency; is the frequency modulation slope; is the signal duration, that is, the time it takes for the linear frequency modulation signal to be received by the radar after being reflected by the target; is the signal amplitude; is the initial phase.

3. The single-bit radar quantization method based on frequency modulation threshold according to claim 2, characterized in that: In S2, the mathematical expression for the radar to obtain the echo signal reflected by the target through the receiving antenna is: ； Where, is the echo delay function, and the signal moving speed is V , the signal distance radar is , then the real-time distance between the target signal and the radar is , then the echo delay function , c is the speed of light; is the signal amplitude, which is related to the signal attenuation coefficient of the target scattering cross-section; is the phase shift after reflection.

4. The single-bit radar quantization method based on frequency modulation threshold according to claim 3, characterized in that: In S2, the echo signal is amplified by a low noise amplifier and then mixed with the linear frequency modulation signal in a mixer to extract the intermediate frequency signal. The mathematical expression is: ； Through AGC automatic gain amplification and limiting, a single-frequency intermediate frequency signal is obtained. The mathematical expression is: ； Where, is the signal amplitude after AGC automatic gain; is the carrier frequency of the intermediate frequency signal; is the total phase of the signal.

5. The single-bit radar quantization method based on frequency modulation threshold according to claim 4, characterized in that: In S4, the single-frequency intermediate frequency signal and the frequency modulation threshold signal are input into a voltage comparator, and a binary signal is generated by amplitude comparison. That is, the portion of the single-frequency intermediate frequency signal that is greater than the frequency modulation threshold signal is 1, and the portion of the single-frequency intermediate frequency signal that is less than the frequency modulation threshold signal is 0. Subsequently, they are sampled to obtain a single-bit signal. The signal characteristics are divided into two parts: the amplitude between different harmonics and the position of the harmonic spectrum. The mathematical expression is: ； It represents the amplitude of the harmonic component, which is related to the amplitude of the FM threshold and the amplitude of the signal. At this time, the frequency of the target echo is , the frequency of the FM threshold signal is , ,in T P is the threshold duration, and the harmonic distribution after single-bit quantization is: ； It indicates the position of the harmonics after they are moved due to intermodulation between different harmonics. is the harmonic order of the FM threshold signal, It is the harmonic order generated by the intermodulation of the target echo signal and the FM threshold signal.

6. The single-bit radar quantization method based on frequency modulation threshold according to claim 5, characterized in that: S4 also includes: reducing the impact of harmonic noise on the observation area by moving the stronger threshold; wherein, when When it is an even number, ;when , When , it is the target echo signal; when , is the first harmonic generated by the frequency modulation threshold signal. At this time, most of the threshold energy is concentrated in the first harmonic generated by the frequency modulation threshold. At this time, the maximum observation distance is , the maximum bandwidth of the intermediate frequency signal after mixing is ; To reduce the amount of data, the sampling frequency is ; when , When , the threshold is moved outside the observation distance to avoid spectrum aliasing due to the Nyquist sampling theorem. The threshold frequency distribution requirement is: ； in, , we can get the threshold carrier frequency as .

7. The single-bit radar quantization method based on frequency modulation threshold according to claim 6, characterized in that: In S4, in order to preserve the integrity of the signal amplitude and suppress the generation of false targets, the appropriate signal amplitude and threshold amplitude are set, and the signal threshold ratio is defined as STR , the expression is: ； ； in, is the signal amplitude after AGC automatic gain, and , threshold amplitude , based on this range, the amplitude of the false target generated by the single-bit quantization intermodulation is lower than the amplitude of the FM threshold signal harmonic.

8. The single-bit radar quantization method based on frequency modulation threshold according to claim 7, characterized in that: In S5, after the single-bit quantized data is subjected to frequency domain transformation and then subjected to a rectangular window function for filtering, the range of the rectangular window is ,in , is the maximum observation distance, and the specific expression is: ； Where, is a rectangular window with a length of , for The corresponding spectrum is used to filter out the strong harmonic components generated by the FM threshold signal and retain the effective spectrum components of the target echo.

9. A single-bit radar quantization system based on frequency modulation threshold, characterized in that: The method for executing the single-bit radar quantization method based on frequency modulation threshold according to any one of claims 1 to 8 comprises: The signal transmission module is used to generate and transmit linear frequency modulation signals, including a main control MCU, a DAC, a voltage-controlled oscillator, a power amplifier and a transmitting antenna; The echo receiving module is used to receive the echo signal and perform frequency mixing and limiting processing, including a receiving antenna, a low-noise amplifier, a mixer and an AGC module; The FM threshold generation module is controlled by the main MCU and is used to generate the FM threshold signal, including a DAC or an oscillator; Single-bit quantization module, used to compare the echo signal with the frequency modulation threshold and sample it, including a voltage comparator and a digital IO port; The frequency domain processing module is used to perform frequency domain windowing filtering on single-bit data to suppress harmonic components.

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