CN-122017786-A - Method and device for estimating two-stage distance speed for agile radar

CN122017786ACN 122017786 ACN122017786 ACN 122017786ACN-122017786-A

Abstract

The invention discloses a two-stage distance speed estimation method for a frequency agile radar, which comprises the steps of performing first-stage linear processing on echo signals, calculating the square of amplitude modulus values of all pulses, summing the sum, judging whether the signals are effective targets or not at peak points of the sum result by using a constant false alarm detector, successively detecting new targets, circularly correcting parameters of the detected targets until detection termination conditions are met, obtaining a final set of all target distances and amplitudes, performing second-stage linear processing on echoes, and estimating the accurate distance and speed of all targets by matching filtering and Newton methods according to distance units of all targets obtained in the first stage. The invention also provides a two-stage distance and speed estimation device. The method provided by the invention is used for solving the problems of poor precision, high complexity, difficult detection and the like when the frequency agile radar detects the distance and the speed of the target.

Inventors

ZHU JIANG
JIANG XING
GUO RUOHAI
ZHANG NING
WANG ZHIGANG
QU FENGZHONG
WANG XINHAI

Assignees

浙江大学
中国船舶集团有限公司第七二四研究所

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. The method for estimating the distance and speed of the agile radar in two stages is characterized by comprising the following steps: Step1, acquiring echo signals of a frequency agile radar, and performing first-stage linear processing on the echo signals to acquire first-stage target data of each target; step 2, calculating amplitude module value squares corresponding to a plurality of pulses in the target data of the first stage, and judging an effective target by using a constant false alarm detector based on the amplitude module value squares so as to obtain a first result and construct an effective target set; step 3, removing the targets stored in the effective target set from the echo signals, performing first-stage linear processing on the removed echo signals to obtain first-stage target data of the residual targets, and executing the process of step 2 to obtain a second result and storing the second result in the effective target set; Fixing a second result, correcting the first result by adopting a Newton method, and putting the corrected first result back into the effective target set; step 4, repeating the step 2-3 until the judging termination condition is met, so as to obtain a final effective target set containing the distance information and the amplitude information of all targets; Step 5, performing second-stage linear processing on the echo signals to obtain second-stage target data of each target; and 6, selecting target data of a second stage of targets based on the final effective target set obtained in the step 4, and calculating the fine resolution distance and the speed estimated value of each target.
2. The method for estimating the speed of a agile radar according to claim 1, wherein in step 2, summing is performed based on squares of amplitude modulus values corresponding to a plurality of pulses, and a highest value point of the summed result is used as a first detection unit to input a pre-constructed constant false alarm detector for judgment, if the result is determined to be an effective target, the distance and the amplitude value corresponding to the first detection unit are corrected by using a newton method to obtain a corresponding first result, and the first result is stored in an effective target set.
3. The method for estimating the range speed of the agile radar according to claim 1, wherein in step3, the square of the magnitude modulus in the first stage target data of the remaining targets is calculated and summed based on the pulse dimension; Taking the highest value point of the summation result as a second detection unit to input the constant false alarm detector for judgment: and if the effective target is judged, correcting the distance and amplitude value corresponding to the second detection unit by utilizing the Newton method to obtain a corresponding second result, and storing the second result into an effective target set.
4. The method for estimating the speed of a agile radar according to claim 1, wherein in step 6, distance information of the targets in the final effective target set is obtained based on step 4 to obtain distance units corresponding to each target, and distance units corresponding to the targets in the target data obtained in step 5 are selected, and the fine-resolution distance and speed estimation value of each target is obtained through matched filtering and newton method.
5. The method for estimating the range speed of the agile radar according to claim 1, wherein the first stage of linear processing performs pulse compression on the echo signal by using an oversampling matched filtering method to obtain pulse-compressed data.
6. The method for estimating the speed of a down-conversion radar-oriented two-stage range according to claim 1, wherein the detection process of the constant false alarm detector is as follows: Removing the protection units near the target detection unit from all training units; After rejection, calculating the average value of all data except the square maximum value of the amplitude module value to obtain the background noise; and determining a threshold value of the effective target based on the background noise size, comparing the threshold value with the threshold value through the ratio of the square maximum value of the amplitude module value to the background noise size, and if the ratio is larger than the threshold value, considering that the effective target exists, otherwise, considering that the non-effective target exists.
7. A method of estimating a range-rate in two stages for a agile radar according to claim 1,2 or 3, wherein the modified expression for newton's method is as follows: ; Wherein, the The distance units after the correction are indicated, Indicating the distance before correction by the first detection unit, Representing a cost function At the point of iteration Distance of the place Is used as a first derivative of (a), Representing a cost function At the point of iteration Distance of the place Is used for the first derivative of (c), ; Based on the corrected distance unit, the complex amplitude of the target is obtained by using a least square method, and the complex amplitude is expressed as follows: ; Wherein, the Representing the corrected complex amplitude.
8. The method for estimating the range speed of the agile radar according to claim 1, wherein the second stage of linear processing is based on pulse compression of fast fourier transform, performing fast fourier transform on an input signal, multiplying the input signal with a frequency domain representation of a matched filter, converting the result back to the time domain through inverse fast fourier transform, and extracting slow time dimension data of a range unit where the second stage of target is located according to the first stage of target range estimation value.
9. The method of two-stage range-rate estimation for a agile radar according to claim 1, wherein in step 6, the expression of the target's sub-resolution range and rate estimation is as follows: ; ; Wherein, the The distance to the target is indicated and, The speed of light is indicated as being the speed of light, Representing the carrier frequency of the carrier wave, Indicating the pulse repetition period of the pulse, The velocity of the object is indicated and, Is an integer such that the digital frequency , , , Representing a variable related to the distance estimate, Representing a variable related to the velocity estimate.
10. A two-stage range-rate estimation device, characterized by the steps for performing a two-stage range-rate estimation method for a agile radar according to any of claims 1 to 9.

Description

Method and device for estimating two-stage distance speed for agile radar Technical Field The invention belongs to the technical field of radar signal processing, and particularly relates to a method and a device for estimating a two-stage distance speed of a agile radar. Background With the rapid development of modern electronic technology, radar is an important device in electronics, the electromagnetic environment facing the radar is more and more complex, and the electronic countermeasure technology is continuously improved. As a typical pulse system radar, a agile radar is characterized by the ability to rapidly switch the carrier frequencies of pulses over the radar bandwidth. The carrier frequency of the agile radar has the characteristic of random change, and has excellent performance in the aspects of low interception, electronic countermeasures, electromagnetic compatibility and the like, so that the method has important theoretical value and practical significance for the in-depth research of the agile radar signal processing algorithm. For a long-range radar detection scenario, a agile radar system is widely used for joint estimation of target distance and speed parameters. In the existing research, when the multi-target detection problem is solved, a detection strategy based on a multi-distance unit is generally adopted, but the method has the problems of higher computational complexity and limited detection performance. From a signal processing perspective, conventional matched filtering (MATCHED FILTER, MF) techniques mainly involve two key steps, namely first performing pulse compression (pulse compression, PC) processing in the fast time domain, followed by one-dimensional discrete fourier transform (discrete Fourier transform, DFT) in the slow time domain. Notably, this approach suffers from a significant "discrete lattice" effect, i.e., when the target location deviates from a preset distance lattice or DFT lattice, it will result in significant spectral leakage of the target energy in the distance and frequency domains. The linear frequency modulation agile radar is widely applied to the military field due to high distance and speed resolution and good anti-interference performance. In a complex interference environment, the fixed-frequency radar is easy to be interfered by enemy to influence the estimation and detection of the target. The frequency agile radar works in a large bandwidth range by adopting a random frequency hopping mode, is hopeful to avoid hostile interference of enemy, and realizes target detection and estimation. In the conventional method, detection is often performed on a plurality of distance units in order to solve the problem of multi-target detection of the frequency agile radar, and the method has high computational complexity and difficult detection. The patent with publication number CN118859129A discloses an intermittent sampling interference resisting method for an inter-pulse frequency agile radar with segmented pulse pressure cancellation, which can effectively solve the challenges of intermittent sampling forwarding interference on radar target detection, tracking and identification. The invention adopts inter-pulse frequency agility-intra-pulse frequency coding signals, and realizes the suppression of interference and the reconstruction of target parameters through the steps of segmented pulse compression, interference judgment and the like. Compared with the traditional pulse pressure radar, the method has stronger electronic countermeasure capability, and can effectively reduce the interception capability of an interference machine on radar signals. However, this method still has some limitations in practical application, such as high requirements on signal processing and computing resources, and increased adaptability to complex electromagnetic environments. The patent with publication number CN116430386A discloses a high-resolution forward-looking imaging method and device of a broadband frequency agile radar, which aim to solve the problem of lattice mismatch when a traditional sparse recovery algorithm processes a sparse scene in a discrete space, so that high-resolution forward-looking imaging is difficult to realize, and the feasibility of a broadband frequency agile radar forward-looking imaging system is limited. According to the method, the collected broadband signals are directly modeled, the parameter rough estimation and the local parameter accurate estimation are carried out, the parameter estimation of a continuous space is finally realized, and the lattice point mismatch problem of the traditional method is avoided. Meanwhile, the high-resolution characteristic of the broadband signal distance is utilized, and the precision of azimuth measurement is improved, so that high-resolution forward-looking imaging of distance and azimuth is realized. However, the method needs to perform multiple iterations and parameter estimation, and has larg