CN107907878B - Method for obtaining FMCW radar distance measurement value with high precision - Google Patents
Method for obtaining FMCW radar distance measurement value with high precision Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/08—Systems for measuring distance only
- G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
- G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/35—Details of non-pulse systems
- G01S7/352—Receivers
- G01S7/354—Extracting wanted echo-signals
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Abstract
The invention discloses a method for obtaining FMCW radar distance measurement values with high precision, and aims to provide a method for obtaining FMCW radar distance measurement values with high distance measurement precision and capable of reducing spectrum errors. The invention is realized by the following technical scheme: the method comprises the steps that target beat signals which are subjected to analog-to-digital conversion are sent to four parallel time domain extraction modules, digital beat signals and sampling rate data which are obtained respectively are sent to a data zero filling module to be subjected to time domain zero filling, four time domain extraction modules obtain time domain signals with the length of Ns, discrete Fourier transformation is carried out through corresponding DFT modules, discrete frequency domain signals with the length of Ns are obtained, the four DFT modules send the discrete frequency domain signals to a data interception and splicing module at the same end to be subjected to splicing operation of frequency domain data, and FMCW radar distance measurement values are obtained through a distance measurement value obtaining module based on mathematical interpolation operation results.
Description
Technical Field
The invention relates to a method for acquiring distance measurement values with gradually improved precision in the process of moving a target from far to near, which is suitable for an FMCW radar system.
Background
Radar systems can be classified into continuous wave radars and pulse radars according to waveforms, and FMCW radars are widely used in various ranging systems due to their characteristics of high range resolution, high ranging accuracy, low power, no measured range blind area, and the like. The problem of ranging accuracy in FMCW radar ranging systems is common to all ranging systems that employ the FMCW regime. In FMCW radar ranging, the simplest method is to directly measure the difference frequency between a transmitted wave and an echo signal to obtain a distance, but the ranging accuracy is not high. At present, the FMCW radar ranging generally adopts an FFT method to obtain a power spectrum curve (distance spectrum) of an echo on a distance axis, and extracts a distance measurement value by sampling and FFT algorithm analysis of a signal, thereby achieving the purpose of obtaining high distance resolution and high measurement accuracy. But due to the "fence effect" of the FFT itself, the distance spectrum obtained by directly using the FFT has a fixed sampling interval, thereby generating a large range error, and the relative error is larger in the case of close-range measurement. In an FMCW radar signal, the frequency measurement error determines the range error. Under the condition of continuous measurement (the measured value of the difference frequency signal is continuously changed and cannot be realized in practice), after the Fourier transform is carried out on the difference frequency signal, the spectrum amplitude peak value of the difference frequency signal can be accurately found, so the measurement precision is mainly determined by the signal-to-noise ratio. However, in practice, discrete sampling is generally performed on the difference frequency signal, and then FFT transformation is performed on the sampled signal, which results in spectrum discretization, inaccurate spectrum amplitude peak finding, and frequency quantization error. The frequency modulation continuous wave distance measurement system is composed of a non-linear frequency modulation and a linear frequency modulation, the former has the advantage of easy realization, and the disadvantage of the former is that a difference frequency signal generated by each target and an information processing frequency are not single, so that targets with different distances cannot be distinguished, and the system is generally suitable for occasions with single targets; the difference frequency signal generated by each target is a single frequency (without considering Doppler frequency shift), so that targets with different distances can be easily distinguished. According to the Fourier transform theory, for a sinusoidal signal with a single frequency, the frequency corresponding to the maximum amplitude value after Fourier Transform (FT) is the frequency of the signal, and the frequency of the signal can be observed by finding the maximum amplitude value after Fourier transform. As long as there is a sufficiently high signal-to-noise ratio, a sufficiently high accuracy can be achieved by estimating the signal frequency using the fourier transformed amplitude. The range resolution of frequency modulated continuous wave radar will depend on the frequency measurement resolution, which is typically achieved by FFT processing of the difference signal. When the FFT technique is used to perform spectral analysis on a signal, the analysis accuracy is mainly limited by aliasing effect, quantization error, leakage effect, and barrier effect. Quantization errors and aliasing effects are caused by the process of digitizing analog signals, and leakage effects and fence effects are inherent to the discrete fourier transform. The distance spectrum obtained by directly using FFT has a fixed sampling interval Δ R due to the "fence effect" of FFT, resulting in a ranging error, which makes the relative error of ranging radar measurement at a short distance large. Analysis shows that increasing the number of FFT spectral lines and increasing spectral resolution can reduce the effects of leakage and shadowing, but increases the time overhead due to the increased sampling length. To increase the frequency resolution, as analyzed by the conventional FFT method, only the number of transform points is increased. Thus, the computation load and the memory capacity of the computer are greatly increased, which brings great difficulty to the hardware structure. Therefore, in the case of limited memory and sampling length, it is contradictory to increase the resolution without losing the upper limit frequency. Because the distance fixed error of the FMCW radar is limited by the frequency sweep bandwidth, the FFT (DFT) spectrum estimation precision is limited by the space frequency quantization between FFT spectral lines.
The FMCW radar has high ranging accuracy theoretically, but in an actual system, the echo signal is processed by a digital signal processing method to obtain an echo power spectrum, and further obtain distance information, so that the FMCW radar is limited by sampling and processing word length. In an actual system, due to the fence effect of Discrete Fourier Transform (DFT), the distance resolution and the ranging precision are in the same order of magnitude, and the requirement of high precision in short-distance ranging cannot be met. The root cause of the ranging error of the frequency-modulated continuous wave radar is the sampling interval on the distance spectrum, and the essence of the ranging error is caused by point equal-interval sampling of DFT on a unit circle. In order to improve the ranging accuracy of the frequency modulation continuous wave radar, the most direct method is to improve the sampling density on the distance spectrum, namely, increase the number of DFT points, at this time, the operation amount of DFT is increased from Nlog2N to MNlog2MN, which shows that the increase amplitude of the operation amount is very large, and when the speed of a processor is fixed, the operation time of signal processing can be increased, thereby affecting the real-time performance of the frequency modulation continuous wave radar system.
In the FMCW radar, in order to obtain a beat frequency and a doppler frequency corresponding to a distance, a transmitting and receiving signal is obtained by a transmitting and receiving device of a radar system to obtain a difference frequency signal, and distance information is extracted by a main frequency of the difference frequency signal. The conversion of analog and digital signals is completed on the beat signal by using an analog-digital converter ADC, the distance R and the speed V of the target are obtained by equations (1) and (2),
in the above formula, c is the transmission speed of electromagnetic wave in the uniform medium, T is the sweep frequency period, B is the signal bandwidth, FrFor range beat information, FcFor the operating frequency of the system
From the above equation, under the condition that the sweep frequency period and the signal bandwidth are fixed, accurate beat frequency must be obtained to obtain the high-precision distance information of the target. In engineering, beat frequency is obtained by using Discrete Fourier Transform (DFT) which performs mathematical transformation on a windowed and truncated digital signal in a time domain and a frequency domain, and intervals exist among discrete points and can be influenced by a fence effect, so that the interval delta f among sampling points after DFT processing enables a peak value after signal processing to be deviated to the left or right relative to a theoretical peak value, and a distance calculated by a frequency value of a maximum sampling point can generate a distance measurement error delta R/2.
The error of the frequency measurement can be expressed as the difference between the ideal continuous frequency domain and the discrete frequency domain of the beat signal. The maximum frequency measurement error is expressed as the step size of the distance and the step size of the velocity are equal to equations (3) and (4), respectively.
The error of the frequency measurement can be expressed as the difference between the ideal continuous frequency domain and the discrete frequency domain of the beat signal. The maximum frequency measurement error is expressed as
The step size of the distance and the step size of the speed are equal to equations (3) and (4), respectively.
In the above formula, c is the transmission speed of electromagnetic wave in the uniform medium, and T is the sweep periodB is the signal bandwidth, FsIs the system sampling rate, NsFor discrete data points equal to Fs x T, it can be seen that distance accuracy cannot be changed by changing FsOr the time length T is increased, and the frequency domain sampling interval is reduced only by increasing the bandwidth B of the system or increasing the number of DFT points. The improvement of the bandwidth B of the radar system can put higher requirements on hardware of the whole system, the calculation amount and the storage capacity of a computer are greatly increased, and great difficulty is brought to a hardware structure, so that hardware resources of the existing radar system cannot be changed generally. In order to improve the distance measurement accuracy of the FMCW radar, the prior art provides a zero padding method, a Chirp-Z transformation method and an FFT-DTFT combination method of a ZFT sampling sequence based on complex modulation. The disadvantage of ZFFT is that the refinement factor cannot be too large. Due to the fact that FIR filtering is carried out on the ZFFT in the 2 nd step, the order is too large due to the fact that the passband of the FIR filter is designed to be too narrow, and the design difficulty is increased, multiple times of filtering extraction are generally adopted, and the large thinning multiple is achieved through multiple times of thinning, but the calculated amount is increased due to the fact that multiple times of filtering extraction are carried out, and therefore the thinning multiple of the ZFFT cannot be too high. And when the refinement multiple is larger, the Chirp-Z transformation method has advantages, but the calculation amount of the Chirp-Z transformation method is obviously small due to the FFT-DTFT combination method when the refinement multiple is larger, and the calculation amount of the Chirp-Z is related to the refinement multiple. Because the FMCW difference frequency signal has noise interference, the improvement effect on the ranging precision is not obvious when the thinning multiple is improved to a certain limit, so the complex modulation based ZFT method is more suitable for FMCW radar real-time signal processing.
Disclosure of Invention
Based on the proportional relation between the frequency value of the echo signal of the FMCW radar system and the distance value, the sampling rate is higher when the target distance is farther and lower when the target distance is closer according to the Nyquist law, and the method for acquiring the distance measurement value of the frequency modulated continuous wave is high in distance measurement precision and capable of reducing the frequency spectrum error.
The above object of the present invention can be achieved by a method for obtaining a distance measurement value of an FMCW radar with high accuracy, characterized by comprising the steps of:
in actual echo signal processing, sampling a target beat signal by adopting an analog-digital converter (ADC) to obtain original ADC sampling data; then, the target beat signals after analog-to-digital conversion are sent to four parallel time domain extraction modules, wherein the 1 st to 3 rd time domain extraction modules extract echo data in a time domain; then, respectively sending the obtained digital beat signals with data rates of 1/8, 1/4 and 1/2 and the corresponding data with sampling rates of Fs/8, Fs/4 and Fs/2 into a data zero filling module corresponding to the time domain extraction module to perform time domain zero filling, and obtaining time domain signals with Ns sample points with sampling intervals by three paths of identical time domain extraction modules and a fourth path of time domain extraction module; the four time domain extraction modules carry out continuous discrete Fourier transform through the corresponding DFT modules to obtain Ns discrete frequency domain signals of sampling intervals of sample point frequency domains, the four DFT modules send the discrete frequency domain signals to the data interception and splicing module in a common end mode to carry out splicing operation of frequency domain data, and the result of arithmetic operation based on mathematical interpolation directly passes through the distance measurement value acquisition module to obtain the FMCW radar frequency modulation continuous wave distance measurement value.
Compared with the prior art, the invention has the following beneficial effects.
The distance measurement precision is high. The analog-digital converter ADC samples a target beat signal, sends the target beat signal after analog-digital conversion to four parallel time domain extraction modules, wherein the 1 st to 3 rd time domain extraction modules extract echo data in a time domain, respectively obtains digital beat signals with data rates of 1/8, 1/4 and 1/2, the corresponding sampling rates are Fs/8, Fs/4 and Fs/2, and sends the digital beat signals to a data zero padding module for padding to obtain a discrete point Ns time domain signal. In DFT, zero filling does not change the spectrum sample, i.e. frequency resolution, but weakens the barrier effect, improves the spectrum resolution, i.e. the spectrum sampling point increases, time domain zero filling is equivalent to frequency interpolation, and zero filling is equivalent to sampling the continuous spectrum at different sampling rates, thereby reducing the spectrum sampling interval. Under the condition that the sampling rate of an ADC (analog to digital converter) of the system and other parameters of the system are not changed, the closer the distance is, the lower the data rate is achieved through extraction, the Ns is unchanged through zero padding, the Nyquist sampling theorem is not violated, the existing resources are fully utilized, the distance precision is improved through the operation of mathematical interpolation operation software, the processing is more precise, and the distance measurement of the radar system to the high precision of a moving target is improved. Based on the time domain and frequency domain inverse interleaving method, interpolation is carried out in the frequency domain, the measurement precision of the system is improved, a more accurate distance measurement value is obtained, a plurality of adhered target echoes can be distinguished in a near zone, and the success probability of system defense is improved.
And the multi-target resolving power is enhanced. The invention is based on the time domain and inter-frequency domain inverse interleaving method, under the condition of not changing the sampling rate of an ADC, three paths of time domain data signals with the length of Ns points after extraction and zero filling processing and a fourth path of time domain data signals with the length of Ns points acquired by a time domain extraction module complete inverse interleaving between frequency domains through corresponding DFT modules, interpolation and mathematical interpolation operation are carried out in the frequency domains, and the distance measurement value of an FMCW radar is obtained through a distance measurement value acquisition module according to the operation result. The method has the advantages that the radar working mode is not changed, any resource reconstruction of the system is not carried out under the condition that effective resources are not redistributed, the specific relation between the distance and the frequency of the FMCW radar is fully utilized, limited resources are reasonably and fully utilized, a high-density frequency spectrum is provided, the real frequency spectrum is more approximate, and the multi-target resolution capability of the system is improved. Based on the time domain and frequency domain inverse interleaving method, interpolation is carried out in the frequency domain, the measurement precision of the system is improved, a more accurate distance measurement value is obtained, a plurality of adhered target echoes can be distinguished in a near zone, the closer the target distance is, the higher the distance measurement precision is, the more the multi-target distinguishing capability is enhanced, and the success probability of system defense is improved.
Reducing the spectral error. Obtaining a data rate of 1/8, a data rate of 1/4 and a data rate of 1/2 by using a decimation method on echo data in a time domain under the condition of not changing an ADC sampling rate; based on the time domain and frequency domain inverse interleaving method, the interpolation operation is completed in the frequency domain after the time domain zero padding. The result of the simulation experiment shows that interpolation is carried out in the frequency domain, the measurement precision of the system is improved, more accurate distance measurement values are obtained, a plurality of adhered target echoes can be distinguished in a near zone, and the success probability of system defense is improved.
The invention is particularly suitable for a close-range and high-precision frequency modulation continuous wave FMCW radar system, and obtains the distance measurement value with gradually improved precision in the process of moving a target from far to near relative to the radar.
Drawings
The foregoing and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
FIG. 1 is a schematic flow chart of the present invention for obtaining FMCW radar range measurements with high accuracy.
FIG. 2 is a comparison of accuracy before and after processing by the present invention.
FIG. 3 simulation graphs with higher and higher precision are obtained before and after the processing of the invention.
Detailed Description
See fig. 1. According to the invention, in the actual echo signal processing, an analog-digital converter (ADC) is adopted to sample a target beat signal to obtain original ADC sampling data; then, the target beat signals after analog-to-digital conversion are sent to four parallel time domain extraction modules, wherein the 1 st to 3 rd time domain extraction modules extract echo data in a time domain; and then respectively sending the obtained digital beat signals with data rates of 1/8, 1/4 and 1/2 and the corresponding data with sampling rates of Fs/8, Fs/4 and Fs/2 into a data zero padding module corresponding to the time domain extraction module to perform time domain zero padding, and obtaining Ns sample point discrete signals by the data zero padding module according to a sampling theorem. The three paths of same time domain extraction modules and the fourth path of time domain extraction module obtain Ns time domain signals with the sample point length as the sampling interval; the four-path time domain extraction module carries out continuous discrete Fourier transform through the corresponding DFT modules to obtain the discrete frequency domain signals of Ns sample point frequency domain sampling intervals. And performing Discrete Fourier Transform (DFT) on the Ns sample point data discrete signals in the three paths and the Ns sample point data discrete signals directly acquired by the time domain extraction module 4 in the fourth path, and performing one-time decomposition on a combined transform formula of the DFT to form a plurality of decimal points. The four DFT modules send the divided discrete frequency domain signals of a plurality of small points into the data interception and splicing module at the same end for splicing the frequency domain data, and the distance measurement value of the FMCW radar frequency modulation continuous wave is obtained by directly passing the result of the arithmetic operation based on the mathematical interpolation through the distance measurement value acquisition module.
The data zero filling module fills zero to obtain 4 groups of Ns sample point data discrete signals, and the 4 groups of Ns point data discrete signals are transformed by the DFT module to obtain four groups of data with frequency domain sampling intervals respectively
Wherein Fs is the sampling rate and Ns is the number of sample points.
In the process that a target moves from far to near relative to a radar, four parallel time domain extraction modules divide the detection range of the FMCW radar into four distance sections of a far section, a middle section, a near section and a super-near section, and when the target is in the far distance section, the distance is roughly extracted; when the target is located in the short-distance section, the 4 groups of data zero padding modules send the points of the improved FFT to the data interception and splicing module through the corresponding 4 groups of DFT modules for carrying out inverse interleaving between frequency domains, and carry out interpolation and mathematical interpolation operation in the frequency domains to obtain the distance measurement value with gradually improved precision.
Step 1: a radar system designer provides the maximum detection distance Rmax and the maximum detection speed Vmax of a target by a radar according to different application scenes of the radar system, and calculates the corresponding range frequency Fbmax and Doppler Fdmax according to the set maximum detection distance Rmax and the set detection speed Vmax;
step 2: a signal processing engineer sets the sampling rate Fs of the ADC of the receiving system to be more than or equal to 2 (Fbmax + Fdmax) according to the Nyquist law; the ADC completes analog-to-digital conversion of one modulation period T according to the set sampling frequency Fs to obtain Ns (Fs x T) echo sample points and discrete data Z;
and step 3: the time domain extraction module 1 carries out 1/8 extraction on Z to obtain Ns/8 sample points; the data zero padding module 1 performs zero padding on the Ns/8 sample points, the data length is increased to the Ns point, and the DFT module 1 performs Fourier transform on the output data of the data zero padding module 1 to obtain frequency data A; the time domain extraction module 2 carries out 1/4 extraction on the discrete data Z to obtain Ns/4 sample points; the data zero padding module 2 performs zero padding on the Ns/4 sample points, the data length is increased to the Ns point, and the DFT module 2 performs Fourier transform on the output data of the data zero padding module 2 to obtain frequency data B; the time domain extraction module 3 carries out 1/2 extraction on the discrete data Z to obtain Ns/2 sample points; the data zero padding module 3 performs zero padding on the Ns/2 sample points, the data length is increased to the Ns point, and the DFT module 3 performs Fourier transform on the output data of the data zero padding module 3 to obtain frequency data C; the time domain extraction module 4 carries out 1/1 extraction on the discrete data Z to obtain Ns sample points; the DFT module 4 performs Fourier transformation on the Ns sample points to obtain frequency data D;
and 4, step 4: the data intercepting and splicing module respectively intercepts A (Ns/4: Ns/2), B (Ns/4: Ns/2), C (Ns/4: Ns/2) and splices new data Y ═ A (Ns/4: Ns/2) and B (Ns/4: Ns/2) C (Ns/4: Ns/2) D (Ns/4: Ns/2) ];
and 5: the distance value measurement value acquisition module finishes detection on the data Y, and can acquire the distance measurement values with higher and higher target precision in the process of the target from far to near without changing any working parameter of the radar system.
As shown in fig. 2. Based on the method of the present invention, the results before and after the processing were simulated, and the results are shown in fig. 3. The system has higher and higher precision in the process of gradually approaching the target.
The present invention is based on mathematical interpolation operation, improves the distance measurement accuracy of the frequency modulated continuous wave FMCW radar, and has a plurality of methods and ways for implementing the technical scheme, and the above is only one embodiment of the present invention.
Claims (6)
1. A method for acquiring FMCW radar distance measurement values with high precision is characterized by comprising the following steps:
in actual echo signal processing, sampling a target beat signal by adopting an analog-digital converter (ADC) to obtain original ADC sampling data; then, the target beat signals after analog-to-digital conversion are sent to four parallel time domain extraction modules, wherein the 1 st to 3 rd time domain extraction modules extract echo data in a time domain; then, respectively sending the obtained digital beat signals with data rates of 1/8, 1/4 and 1/2 and the corresponding data with sampling rates of Fs/8, Fs/4 and Fs/2 into a data zero padding module corresponding to the time domain extraction module to perform time domain zero padding, so as to obtain discrete data of 4 groups of Ns sample points, wherein the data zero padding module 1 performs zero padding on Ns/8 sample points, the data length is increased to Ns point, and the DFT module 1 performs Fourier transform on the output data of the data zero padding module 1, so as to obtain frequency data A; the time domain extraction module 2 carries out 1/4 extraction on the discrete data Z to obtain Ns/4 sample points; the data zero padding module 2 performs zero padding on the Ns/4 sample points, the data length is increased to the Ns point, and the DFT module 2 performs Fourier transform on the output data of the data zero padding module 2 to obtain frequency data B; the time domain extraction module 3 carries out 1/2 extraction on the discrete data Z to obtain Ns/2 sample points; the data zero padding module 3 performs zero padding on the Ns/2 sample points, the data length is increased to the Ns point, and the DFT module 3 performs Fourier transform on the output data of the data zero padding module 3 to obtain frequency data C; the time domain extraction module 4 carries out 1/1 extraction on the discrete data Z to obtain Ns sample points; the DFT module 4 performs Fourier transformation on the Ns sample points to obtain frequency data D; three paths of discrete signals with the length of Ns sample points and Ns point data discrete signals directly obtained by a time domain extraction module 4 on the fourth path are subjected to Discrete Fourier Transform (DFT), and a combined transform formula of the DFT is subjected to one-time decomposition to form a plurality of decimal points; the three-path time domain extraction module and the fourth-path time domain extraction module obtain time domain signals with the length of Ns sample points; the four time domain extraction modules perform discrete Fourier transform through the corresponding DFT modules to obtain discrete frequency domain signals with the length of Ns sample points, the four DFT modules send the discrete frequency domain signals to the data interception and splicing module at the same end to perform splicing operation of frequency domain data, and the result of arithmetic interpolation-based operation directly passes through the distance measurement value acquisition module to obtain FMCW radar distance measurement values.
2. A method of obtaining FMCW radar range measurements with high accuracy as claimed in claim 1, wherein: the four groups of data frequency domain sampling intervals obtained by transforming the 4 groups of Ns point data discrete signals through a DFT module are respectively
Wherein Fs is the sampling rate and Ns is the number of sample points.
3. A method of obtaining FMCW radar range measurements with high accuracy as claimed in claim 1, wherein: in the process that a target moves from far to near relative to an FMCW radar, four parallel time domain extraction modules divide the detection range of the FMCW radar into four distance sections of a far section, a middle section, a near section and a super-near section, and when the target is in the far distance section, the distance is roughly extracted; when the target is located in the short-distance section, the 4 groups of data zero padding modules send the points of the improved FFT to the data interception and splicing module through the corresponding 4 groups of DFT modules for carrying out inverse interleaving between frequency domains, and carry out interpolation and mathematical interpolation operation in the frequency domains to obtain the distance measurement value with gradually improved precision.
4. A method of obtaining FMCW radar range measurements with high accuracy as claimed in claim 1, wherein: setting the sampling rate Fs of the ADC of the receiving system to be more than or equal to 2 (Fbmax + Fdmax) according to the Nyquist law; and the ADC completes analog-to-digital conversion of one modulation period T according to the set sampling frequency Fs to obtain Ns (Fs x T) echo sample points and obtain discrete data Z, wherein Fbmax and Fdmax are used for calculating corresponding range frequency Fbmax and Doppler Fdmax according to the set maximum detection range Rmax and detection speed Vmax.
5. A method of obtaining FMCW radar range measurements with high accuracy as claimed in claim 1, wherein: the time domain extraction module 1 performs 1/8 extraction on the discrete data Z to obtain Ns/8 sample points.
6. A method of obtaining FMCW radar range measurements with high accuracy as claimed in claim 1, wherein: and the data interception and splicing module respectively intercepts A (Ns/4: Ns/2), B (Ns/4: Ns/2), C (Ns/4: Ns/2) and splices the A (Ns/4: Ns/2), the B (Ns/4: Ns/2) C (Ns/4: Ns/2) D (Ns/4: Ns/2) into new data Y.
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