CN-116047447-B - Method and device for measuring and calculating target distance and speed based on frequency modulation continuous wave radar

CN116047447BCN 116047447 BCN116047447 BCN 116047447BCN-116047447-B

Abstract

The invention discloses a target distance and speed measuring and calculating method and device based on a frequency modulation continuous wave radar, wherein the method comprises the steps of mixing a chirp transmitting signal and a receiving signal in a first frame signal to obtain an intermediate frequency signal, and obtaining spectral peak frequency and phase change; mixing the chirp transmitting signal and the receiving signal in the second frame signal to obtain intermediate frequency signal, obtaining spectral peak frequency and phase change, utilizing and obtaining accurate measured target speed, further obtaining Doppler frequency shift, correcting and finally obtaining accurate measured target distance. According to the method, the Doppler frequency shift is obtained through calculation, and the spectral peak frequency is corrected according to the Doppler frequency shift, so that errors caused by the Doppler frequency shift when the radar measures the distance are reduced. At the same time, the method can increase the maximum measurable distance and speed accuracy by increasing the chirp duration, but without compressing the measurable speed range. The method can be widely applied to the technical field of radar signal processing.

Inventors

ZHAO MINGJIAN
XIE HEQUAN
Zuo Yueling
LIU RUI

Assignees

华南理工大学

Dates

Publication Date: 20260512
Application Date: 20221229

Claims (7)

1. A target distance and speed measuring and calculating method based on a frequency modulation continuous wave radar is characterized by comprising the following steps: S1, acquiring a first frame signal transmitted by a radar, mixing a chirp transmitting signal and a receiving signal in the first frame signal to obtain an intermediate frequency signal, and acquiring the spectral peak frequency of the intermediate frequency signal spectrum according to the intermediate frequency signal And the intermediate frequency signal frequency is Phase variation of signals between adjacent chirp ; S2, acquiring a radar transmitted second frame signal transmitted by the radar, mixing a chirp transmitted signal and a received signal in the second frame signal to obtain an intermediate frequency signal, and acquiring the peak frequency of the intermediate frequency signal spectrum according to the intermediate frequency signal And the intermediate frequency signal frequency is Phase variation of signals between adjacent chirp Wherein the first frame signal and the second frame signal are two adjacent frame signals; S3, according to the spectrum peak frequency Sum spectral peak frequency Acquiring a frequency difference, and acquiring a speed with low target precision in two-frame signal time according to the frequency difference and the frame time ; S4, calculating the maximum non-fuzzy speed according to the radar emission waveform parameters According to phase change Calculating a non-ambiguous speed ; S5, according to the speed Speed of no blurring And maximum disambiguation speed Calculating the accurate speed of the measured object ; S6, according to the accurate speed And the wavelength of the center frequency of the transmitted signal Obtaining Doppler shift and correcting spectral peak frequency Thereby obtaining the corrected distance of the measured object; step S1, specifically, includes: mixing X chirp transmitting signals and receiving signals in the first frame signal to obtain X intermediate frequency signals; ADC sampling is carried out on the intermediate frequency signals, and Y points are sampled by each intermediate frequency signal to obtain an X-row Y-column matrix; Performing two-dimensional fast Fourier transform on the obtained matrix to obtain the peak frequency of the intermediate frequency signal spectrum And the intermediate frequency signal frequency is Phase variation of signals between adjacent chirp Each chirp is a continuous sine wave or cosine wave with a frequency that increases linearly with time, and the duration of each chirp Should be large enough to obtain a sufficiently large maximum measurable distance and a sufficiently high speed accuracy; Step S6, specifically comprising: Obtaining accurate speed As a target radial velocity when transmitting the previous frame signal; according to the exact speed And wavelength of center frequency Calculating Doppler shift According to Doppler shift Eliminating spectral peak frequency And calculates the accurate distance as the distance between the target and the radar when the previous frame signal is transmitted.
2. The method for measuring and calculating the target distance and speed based on the frequency modulation continuous wave radar according to claim 1, wherein the step S5 specifically comprises: According to speed Speed of no blurring And maximum disambiguation speed Calculating to obtain an integer ; Will maximum disambiguation speed Multiplied by 2 After that, and not blur the speed Adding to obtain the accurate speed of the measured object 。
3. The method for measuring and calculating the target distance and speed based on the frequency modulation continuous wave radar according to claim 1, further comprising the steps of: Due to the increase of the duration Resulting in maximum non-blurring speed Becomes smaller, i.e. the actual phase changes May exceed Obtained by two-dimensional fast Fourier transformation And (2) and Converted into speed can be expressed as Only need to find Can be obtained Corresponding precise speed To solve the problem that the maximum non-blurring speed becomes smaller.
4. The method for measuring and calculating the target distance and speed based on the frequency modulation continuous wave radar according to claim 1, wherein the speed is Obtained by calculation in the following manner: Frequency of spectral peak Sum spectral peak frequency Subtracting to obtain a frequency difference representing the change in distance of the target when transmitting the signals of the previous and subsequent frames A speed at which the target accuracy is not high during the time of transmitting the signals of the previous frame and the next frame 。
5. The method for measuring and calculating the target distance and speed based on the frequency modulation continuous wave radar according to claim 2, wherein the integer Obtained by calculation in the following manner: Speed of the speed And a non-blurring speed Divided by twice the maximum blur free speed after subtraction Rounding to obtain an integer The formula is expressed as follows: wherein the ROUND function is used to ROUND the number in brackets to a rounded integer result.
6. The method for measuring and calculating the target distance and speed based on the frequency modulation continuous wave radar according to claim 1, further comprising the steps of: after obtaining the accurate distance and speed of the first frame signal, the spectrum peak frequency is calculated Assigning spectral peak frequencies Phase change Assignment to phase change ; Acquiring a third frame signal transmitted by the radar, and acquiring a new spectral peak frequency according to the third frame signal And phase change Wherein the second frame signal and the third frame signal are two adjacent frame signals; According to the new spectral peak frequency Spectral peak frequency And phase change The exact distance and speed at the time of the second frame signal is found.
7. A target distance and speed measuring and calculating device based on a frequency modulation continuous wave radar, which is characterized by comprising: At least one processor; at least one memory for storing at least one program; The at least one program, when executed by the at least one processor, causes the at least one processor to implement the method of any one of claims 1-6.

Description

Method and device for measuring and calculating target distance and speed based on frequency modulation continuous wave radar Technical Field The invention relates to the technical field of radar signal processing, in particular to a target distance and speed measuring and calculating method and device based on a frequency modulation continuous wave radar. Background At present, with the rapid development of electronic information technology, the auxiliary driving technology in the unmanned driving field has become a popular research field. In the driving assisting technology, the frequency modulation continuous wave radar has important positions due to the characteristics of low power consumption, high integration level, small influence of weather and the like, and is particularly applied to a complex road, so that the frequency modulation continuous wave radar is highly required to accurately measure the distance and speed information of a measured target. At present, a chirp sequence modulation method is generally utilized to measure and calculate the distance and the speed of a target by the frequency modulation continuous wave radar. When the distance between the measured object and the object is calculated, the Doppler frequency shift caused by the radial speed of the object is ignored, the frequency spectrum of the intermediate frequency signal is obtained by utilizing FFT, then the peak frequency is obtained, and the frequency is regarded as being generated only by the distance between the object and the radar. However, since the vehicle is in a driving state, the radial velocity is high, and the doppler shift caused by the velocity is already reflected, if the doppler shift is ignored, the accuracy of distance measurement is affected. In addition, four indexes (maximum measurable distance, distance precision, maximum non-blurring speed and speed precision) of the conventional chirp sequence modulation method have a mutual constraint relationship, and when one of the indexes is usually improved, the other indexes are sacrificed. For example, if other parameters are unchanged, the chirp duration becomes longer, the maximum measurable distance and speed accuracy can be improved, but at the same time the maximum non-blurring speed becomes smaller. Disclosure of Invention In order to solve at least one of the technical problems existing in the prior art to a certain extent, the invention aims to provide a target distance and speed measuring and calculating method and device based on a frequency modulation continuous wave radar. The technical scheme adopted by the invention is as follows: A target distance and speed measuring and calculating method based on a frequency modulation continuous wave radar comprises the following steps: S1, acquiring a first frame signal transmitted by a radar, mixing a chirp transmitting signal and a receiving signal in the first frame signal to obtain an intermediate frequency signal, and acquiring a spectral peak frequency f TF of an intermediate frequency signal spectrum and a phase change delta phi of a signal with the intermediate frequency signal frequency f TF between adjacent chirp according to the intermediate frequency signal; S2, acquiring a radar-transmitted second frame signal transmitted by a radar, mixing a chirp-transmitted signal and a received signal in the second frame signal to obtain an intermediate frequency signal, and acquiring the spectral peak frequency f IF_next of an intermediate frequency signal spectrum and the phase change delta phi next of a signal with the intermediate frequency f TF_next between adjacent chirps according to the intermediate frequency signal, wherein the first frame signal and the second frame signal are two adjacent frame signals; S3, acquiring a frequency difference according to the spectral peak frequency f IF and the spectral peak frequency f IF_next, and acquiring a speed v ina with low target precision in two-frame signal time according to the frequency difference and the frame time; S4, calculating a maximum non-blurring speed v m_unam according to radar emission waveform parameters, and calculating a non-blurring speed v unam according to phase change delta phi; s5, calculating the accurate speed v of the measured target according to the speed v ina, the non-fuzzy speed v unam and the maximum non-fuzzy speed v m_unam; s6, according to the accurate speed v and the wavelength lambda of the center frequency of the transmitted signal, doppler frequency shift is obtained, and the spectral peak frequency f IF is corrected, so that the corrected distance of the measured object is obtained. Further, step S5 specifically includes: Calculating according to the speed v ina, the non-blurring speed v unam and the maximum non-blurring speed v m_unam to obtain an integer Z; the maximum non-blurring speed v m_unam is multiplied by 2Z and added to the non-blurring speed v unam to obtain the accurate speed v of the measured object. Fur