阅读说明：本技术 一种基于改进的重心插值提高雷达测距精度的方法 (Method for improving radar ranging precision based on improved gravity center interpolation ) 是由 马兰 李照照 扈月松 杨雪林 井伟 路鲲鹏 于 2020-12-09 设计创作，主要内容包括：本发明涉及一种基于改进的重心插值提高雷达测距精度的方法,属于脉冲法雷达测距技术领域。结合先验信息,当时宽、带宽和窗函数选定时,发射信号波形和回波脉冲压缩结果均是确定的。在该雷达参数设计下且不加噪声时,选择较高的采样率进行仿真实验得到脉压结果主瓣内不同位置下采样最大值和次大值点按时序的幅值比与脉压波形峰值位置的一一对应关系。再利用这一对应关系对实际采样率下且有噪声存在的脉压结果主瓣内的采样最大值和次大值点作重心插值处理,实现了对脉压波形峰值时间更精确的预估。实验结果表明,通过本发明提出的这种改进的重心插值方法,可以显著减小距离量化误差,提高雷达测距精度。(The invention relates to a method for improving radar ranging precision based on improved gravity center interpolation, and belongs to the technical field of pulse method radar ranging. In combination with prior information, the transmit signal waveform and echo pulse compression results are determined when the time width, bandwidth and window function are selected. Under the radar parameter design and when no noise is added, a higher sampling rate is selected to carry out a simulation experiment to obtain the one-to-one correspondence relationship between the amplitude ratio of the downsampling maximum value and the secondary maximum value point at different positions in the main lobe of the pulse pressure result according to the time sequence and the peak position of the pulse pressure waveform. And then the corresponding relation is utilized to carry out barycentric interpolation processing on the sampling maximum value and the secondary maximum value point in the pulse pressure result main lobe with noise under the actual sampling rate, so that the more accurate estimation of the pulse pressure waveform peak value time is realized. Experimental results show that the improved gravity center interpolation method provided by the invention can obviously reduce distance quantization errors and improve radar ranging precision.)

1. A method for improving radar ranging accuracy based on improved barycentric interpolation is characterized by comprising the following steps:

step 1: given the selected time width T, bandwidth B and sampling rate f in the project_s1And window function information, selecting a higher sampling rate f without adding noise_s2At f_s2The approximately continuous echo pulse pressure waveform is obtained through simulation experiment, and simultaneouslyUsing the real sampling rate f as the sampling time_s1Normalizing into a sampling time unit; by a peak time unit t 'of an approximately continuous echo pulse pressure waveform'_maxTo center, two sampling time intervals (2 x 1/f) were chosen_s1) The internal pulse pressure waveform;

step 2: at the actual sampling rate f on the echo pulse pressure waveform selected in step 1_s1Determining a sampling intervalSequentially taking two sampling points to enable the sampling points to be distributed over the selected pulse pressure waveform; sampling time units t 'corresponding to the two sampling points in time sequence'₁、t′₂To amplitude ratioRecording the value; and simultaneously calculating the position distribution t 'of the sampling point in sequence'₁、t′₂And waveform peak time unit t'_maxIn relation to each other, i.e. ideal amplitude ratioObtaining the amplitude ratio of the sampling pointRatio to ideal amplitudeAnd recording the data;

and step 3: for actual radar parameter time width T, bandwidth B and sampling rate f_s1Carrying out gravity center interpolation processing on the maximum sampling value and the secondary maximum sampling value point of the echo pulse pressure result under the window function and in the presence of noise; let the sampling time units corresponding to the two sampling points in time sequence be t respectively₁、t₂Amplitude ratio ofFinding the Q value closest to Q' according to the data record in the step 2, and recording the K value corresponding to the Q value at the moment; calculating echo peak value time unit according to gravity center method interpolation formula

And 4, step 4: converting the echo peak time unit into the peak time, i.e. t_maxCorresponding to a sampling time of t_max/f_s1。

2. The method for improving radar ranging accuracy based on improved barycentric interpolation as claimed in claim 1, wherein f in step 1_s2＝40f_s1。

3. The method for improving radar ranging accuracy based on the improved barycentric interpolation of claim 1, wherein the number of the two sampling points sequentially taken in step 2 is 6.

4. The method of claim 1, wherein the actual signal in step 3 is an LFM signal.

Technical Field

The invention belongs to the technical field of radar ranging by a pulse method, and particularly relates to a method for improving radar ranging precision based on improved gravity center interpolation, which is used for reducing distance quantization errors during radar ranging and improving radar ranging precision.

Background

The most basic task of the radar is to detect a target and measure the distance of the target, that is, the target is found and located by utilizing the reflection of electromagnetic waves from the target, and the ranging accuracy is one of important performance indexes of the radar.

The radio waves travel straight in a uniform medium at a fixed speed (the speed of travel in free space is approximately equal to the speed of light), and the distance from a target to a radar station can be obtained by measuring the time required for the waves to make a round trip, i.e. the delay of the echo relative to the transmitted signal, so that the distance from the target is measured to accurately determine the delay time. The delay time can be measured by pulse method, frequency method and phase method according to the difference of radar emission signal.

The invention mainly aims at pulse method distance measurement. The pulse method distance measurement is to determine the target distance by finding the distance unit number corresponding to the maximum point according to the power spectrum curve after pulse pressure processing is carried out on the target echo. However, under the constraint of the sampling rate, the pulse pressure result obtained by adding gaussian white noise to the LFM signal for pulse compression is a series of discrete sampling points, and in order to reduce the distance quantization error, the peak time of the echo pulse pressure waveform needs to be interpolated and estimated. The traditional barycenter interpolation method is to directly perform barycenter interpolation to estimate the peak position by using the amplitude information and the position information of the maximum value and the second maximum value sampling points in the echo pulse pressure result. The method has the defects that the inherent error is large, and the situation with high requirement on the distance measurement precision cannot be met, so that the method for reducing the distance quantization error is an important content for researching the radar distance measurement technology.

Disclosure of Invention

Technical problem to be solved

In order to solve the problem of inherent errors generated in the process of estimating the position of the echo peak value by the gravity center interpolation in the prior art and improve the ranging precision, the invention provides a method for improving the radar ranging precision based on the improved gravity center interpolation.

Technical scheme

A method for improving radar ranging accuracy based on improved barycentric interpolation is characterized by comprising the following steps:

step 1: given the selected time width T, bandwidth B and sampling rate f in the project_s1And window function information, selecting a higher sampling rate f without adding noise_s2At f_s2Obtaining approximate continuous echo pulse pressure waveform by simulation experiment, and simultaneously using real sampling rate f as sampling time_s1Normalizing into a sampling time unit; by a peak time unit t 'of an approximately continuous echo pulse pressure waveform'_maxTo center, two sampling time intervals (2 x 1/f) were chosen_s1) The internal pulse pressure waveform;

step 2: at the actual sampling rate f on the echo pulse pressure waveform selected in step 1_s1Determining a sampling intervalSequentially taking two sampling points to enable the sampling points to be distributed over the selected pulse pressure waveform; sampling time units t 'corresponding to the two sampling points in time sequence'₁、t′₂To amplitude ratioRecording the value; and simultaneously calculating the position distribution t 'of the sampling point in sequence'₁、t′₂And waveform peak time unit t'_maxIn relation to each other, i.e. ideal amplitude ratioObtaining the amplitude ratio of the sampling pointRatio to ideal amplitudeAnd recording the data;

and step 3: for actual radar parameter time width T, bandwidth B and sampling rate f_s1Carrying out gravity center interpolation processing on the maximum sampling value and the secondary maximum sampling value point of the echo pulse pressure result under the window function and in the presence of noise; let the sampling time units corresponding to the two sampling points in time sequence be t respectively₁、t₂Amplitude ratio ofFinding the Q value closest to Q' according to the data record in the step 2, and recording the K value corresponding to the Q value at the moment; calculating echo peak value time unit according to gravity center method interpolation formula

And 4, step 4: converting the echo peak time unit into the peak time, i.e. t_maxCorresponding to a sampling time of t_max/f_s1。

The technical scheme of the invention is further that: in step 1 f_s2＝40f_s1。

The technical scheme of the invention is further that: in step 2, the execution times of two sampling points are sequentially taken as 6 times.

The technical scheme of the invention is further that: the actual signal in step 3 is the LFM signal.

Advantageous effects

The method for improving the radar ranging precision based on the improved barycentric interpolation is combined with prior information, and when the temporal width T, the bandwidth B and the window function are selected, the transmitting signal waveform and the echo pulse compression result are determined. Under the radar parameter design and when no noise is added, a higher sampling rate is selected to carry out a simulation experiment to obtain the one-to-one correspondence relation between the amplitude ratio of the downsampling maximum value and the secondary maximum value point at different positions in the main lobe of the pulse pressure result and the peak position of the pulse pressure waveform. And then the corresponding relation is utilized to carry out barycentric interpolation processing on the sampling maximum value and the secondary maximum value point in the pulse pressure result main lobe with noise under the actual sampling rate, so that the more accurate estimation of the pulse pressure waveform peak value time is realized. Experimental results show that the improved gravity center interpolation method provided by the invention can obviously reduce distance quantization errors and improve radar ranging precision.

Drawings

FIG. 1 is a schematic diagram of the principle of the gravity center interpolation algorithm used in the present invention

FIG. 2 is a schematic diagram of a selected echo pulse pressure result main lobe waveform when using the present invention

FIG. 3 is a schematic diagram showing the relationship between the maximum value and the second maximum value in the pulse pressure result of the actual echo signal when using the present invention

FIG. 4 is a schematic diagram of the analysis of the relationship between the sampling point position and the peak position when the present invention is used

FIG. 5 is a schematic diagram showing the analysis of the amplitude ratio of the sampling points corresponding to the same sampling position under different SNR's using the present invention

FIG. 6 is a flow chart of estimating the peak time of the echo pulse pressure result using the present invention

FIG. 7 is a graph of range quantization error as a function of SNR for different offsets of a sample point from the echo peak position using the present invention

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

the invention utilizes prior information, and when the time width T, the bandwidth B and the window function are selected, the compression results of the transmitted signal waveform and the echo pulse are determined. In the radar parameter design, a higher sampling rate f is selected without adding noise_s2And obtaining the approximate continuous echo pulse pressure waveform through a simulation experiment. At the actual sampling rate f in the main lobe of the approximately continuous echo pulse pressure waveform_s1Determining a sampling intervalAnd sequentially taking two sampling points to ensure that the sampling points are distributed over the main lobe of the pulse pressure waveform. Sampling time units t 'corresponding to the two sampling points in time sequence'₁、t′₂To amplitude ratioThe value is recorded. Will be higher sampling rate f_s2The lower approximate continuous echo pulse pressure waveform peak value time unit is defined as t'_maxValue, calculating various sampling maximum values and secondary maximum value point position distribution t'₁、t′₂And waveform peak time unit t'_maxThe positional relationship therebetween. Make the ideal amplitude ratioObtaining the amplitude ratio of the sampling pointRatio to ideal amplitudeOne-to-one correspondence relationship of (a). Assuming an actual sampling rate f_s1The sampling time units corresponding to the maximum value and the second maximum value in the echo pulse pressure result with the existence of noise are respectively t according to time sequence₁、t₂The amplitude is respectively y₁、y₂Calculating the amplitude ratio at that timeReferring to fig. 5, simulation results show that the error between the Q ' value and the Q value at the corresponding position is small, so that the Q ' value at this time can be compared with the Q value to find the Q value closest to Q '. The Q value and the K value are in one-to-one correspondence, and the gravity center interpolation calculation can be carried out by combining the K value at the moment, so that the echo peak value time with the existence of noise at the moment can be estimated

In the process of the invention, the design bandwidth B of experimental parameters is 2MHz, and the sampling rate f_s1For 2.5MHz, the window function selects the Hamming window by sampling at a higher sampling rate f_s2Simulation analysis was performed at 100MHz, and the time unit of the echo peak at this time was obtained as t'_max24, so to ensure that various kinds of mining will be performed in practiceThe position distribution of the sample maximum value and the second maximum value is considered, and the sampling interval selected in the approximately continuous echo pulse pressure waveform main lobe is [23, 25 ]]Combined with the sampling rate f_s1And f_s2In terms of the actual sampling rate f_s1Determining a sampling intervalThen, the positional relationship between the sampling maximum value and the next maximum value point is divided into 41 cases. Various sampling maximum values and secondary maximum value point distribution t'₁、t′₂And waveform peak time unit t'_maxThe results of the experiment on the positional relationship between them and the amplitude ratio at this time are shown in table 1. Taking the data in the table 1 as prior information, setting the value range of the SNR (signal to noise ratio) to be 10-30 dB in an experiment, and setting the actual sampling rate f to be_s1Time-sequential amplitude ratio of sampling maximum and sub-maximum points in the presence of noiseAnd comparing with the data in the table 1, finding the Q value closest to Q', and then performing gravity center interpolation processing on the maximum sampling value and the second maximum sampling value by using the K value corresponding to the Q value at the moment to estimate the echo peak value time unit. Experimental data show that after interpolation processing is carried out by the method provided by the patent, when SNR is only 10dB, the maximum value of distance quantization error is controlled to be about 12m, and radar ranging precision is remarkably improved.

TABLE 1 analysis of the relationship between the sampling point amplitude ratio and the ideal amplitude ratio

As shown in fig. 6, the method specifically includes the following steps:

step 1, giving time width T, bandwidth B and sampling rate f selected in engineering_s1And window function information, selecting a higher sampling rate f without adding noise_s2(f_s2≈40f_s1) At f_s2The approximately continuous echo pulse pressure waveform is obtained by simulation experimentUsing real sampling rate f as time-to-time sampling time_s1Normalized to a sample time unit. Since there are typically only two samples within a 3dB beamwidth, the peak time unit t 'of the near continuous echo pulse pressure waveform is used'_maxTo center, two sampling time intervals (2 x 1/f) were chosen_s1) The internal pulse pressure waveform is analyzed. For example, t 'is obtained through simulation experiments under the radar parameters'_maxThe value is 24, and the main valve interval of the selected pulse pressure waveform is [23, 25 ]]See, fig. 2;

step 2, the actual sampling rate f is carried out on the echo pulse pressure waveform selected in the step 1_s1Determining a sampling intervalTwo sampling points are taken in sequence, with the sampling points extending over the selected pulse pressure waveform, see fig. 3. Sampling time units t 'corresponding to the two sampling points in time sequence'₁、t′₂To amplitude ratioThe value is recorded. And simultaneously calculating the position distribution t 'of the sampling point in sequence'₁、t′₂And waveform peak time unit t'_maxThe position relationship between them, see fig. 4, i.e. the ideal amplitude ratioObtaining the amplitude ratio of the sampling pointRatio to ideal amplitudeAnd recording the data. For example, under the radar parameters described above, the corresponding relationship data is obtained as shown in table 1;

step 3, for actual radar parameter time width T, bandwidth B and sampling rate f_s1And repeating the maximum value and the sub-maximum value of the sampling of the echo pulse pressure result under the window function and in the presence of noiseAnd (5) performing heart interpolation processing. Let the sampling time units corresponding to the two sampling points in time sequence be t respectively₁、t₂Amplitude ratio ofAnd (3) finding the Q value closest to Q' according to the data statistics in the step 2, and recording the K value corresponding to the Q value at the moment. Calculating echo peak value time unit according to gravity center method interpolation formula

And 4, converting the echo peak value time unit into peak value time. Since the sampling time unit is the real sampling rate f_s1Obtained by normalizing the sampling time, so t obtained in step 3_maxCorresponding to a sampling time of t_max/f_s1。

Referring to fig. 7, under the design of the radar parameters, when the SNR is between 10dB and 30dB, the distance quantization error is reduced from 12m to 0.9m, so that the ranging accuracy is significantly improved, and the requirements of actual engineering are met.

The interpolation method for reducing the distance quantization error in the radar ranging process is applied to engineering practice and achieves an obvious effect. The invention only takes the maximum value and the second maximum value sampling points in the main lobe of the echo pulse pressure result to carry out improved barycentric interpolation processing, and predicts the time of the echo peak value, thereby realizing the reduction of distance quantization error. The method solves the problem of inherent error generated in the process of estimating the echo peak value position by gravity center interpolation in the prior art.