High-precision distance measurement method based on distance sum-difference channel

Abstract

The high-precision distance measurement method based on the distance sum-difference channel is suitable for detection of an aerial carrier radar, a controller and a plurality of filters are installed on an aerial carrier, and the method comprises the steps that S101, echo signals obtained after radar preprocessing are obtained, and a corresponding matched filter is designed according to a waveform emitted by the radar; s102, carrying out decomposition by the matched filter; s103, performing matched filtering processing on the decomposed matched filter to determine a matched filtering result; and S104, the target distance is quickly calculated according to the matched filtering result, and difference distance channel processing is added, so that the distance measurement precision of the target can be improved, and meanwhile, a relatively small calculation amount is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of radar, and in particular relates to a high-precision distance measurement method based on distance and difference channels. Background Art

[0002] In radar detection, linear frequency modulation (LFM) signals can ensure radar detection power while having a certain distance resolution. The distance measurement accuracy is related to the resolution of the waveform and the target signal-to-noise ratio. The smaller the resolution, the higher the signal-to-noise ratio, and the higher the distance measurement accuracy. The distance measurement accuracy improves the target association tracking effect, reduces false alarms, and improves the target track stability.

[0003] The existing high-precision ranging method uses the filter group method to calculate the corresponding distance offset to obtain a high-precision ranging result. This method requires a traversal search of all filters on the carrier. Although the accuracy is high, the amount of calculation is large and requires high hardware processing resources. It is not suitable for engineering applications. In addition, the energy centroid method is used for ranging. Although the calculation is simple, the ranging accuracy is poor.

[0004] In summary, the existing ranging methods have low efficiency. Summary of the invention

[0005] In view of this, the high-precision distance measurement method based on the distance and difference channel of the present invention solves the technical problem of low efficiency of distance measurement in the existing method.

[0006] A high-precision distance measurement method based on distance and difference channels is suitable for detection of aircraft radar. A controller and multiple filters are installed on the aircraft. The method includes:

[0007] S101: Obtain the radar pre-processed echo signal and design a corresponding matched filter according to the waveform transmitted by the radar;

[0008] S102: The matched filter performs decomposition;

[0009] S103: performing matched filtering processing on the decomposed matched filter to determine a matched filtering result;

[0010] S104: Rapidly calculate the target distance according to the matched filtering result.

[0011] Beneficial Effects

[0012] The present invention utilizes the phase change relationship of the LFM signal at different distance offsets when the range gate is matched filtered, and proposes a high-precision ranging method based on the distance and difference channels. This method can add the difference distance channel processing on the basis of the normal target detection processing process, which can improve the ranging accuracy of the target while ensuring a small amount of calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 is the distance and difference channel characteristic of the present invention;

[0015] Figure 2 is the distance and difference channel ranging result of the present invention;

[0016] Figure 3 It is the result of the distance measurement error varying with the signal-to-noise ratio described in the present invention;

[0017] Figure 4 It is the result of the distance measurement error changing with the distance deviation described in the present invention. DETAILED DESCRIPTION

[0018] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0019] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0020] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0021] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure, and only show the components related to the present disclosure rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout type may also be more complicated.

[0022] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, one skilled in the art will appreciate that aspects may be practiced without these specific details.

[0023] like Figures 1 to 4 The high-precision ranging method based on distance and difference channels is suitable for detection of aircraft radar, and a controller and multiple filters are installed on the aircraft. The method includes:

[0024] S101: Obtain the echo signal after radar preprocessing (for example, A / D sampling), and design a corresponding "matched filter" according to the waveform emitted by the radar. Specifically,

[0025] The echo signal is x, and x=[x1,x2,...,x L ], where L is the number of range gates;

[0026] Get the radar waveform information parameters, including signal bandwidth B, signal pulse width τ, sampling frequency F s and frequency modulation slope u=B / τ. Preferably, the waveform emitted by the radar is an LFM waveform, and a corresponding matched filter is designed according to the parameters of the LFM waveform;

[0027] S102: Matched filter decomposition, specifically,

[0028] The “matched filter” of the LFM waveform h=[h1,h2,...,h N ] is decomposed into filters h1 = [h1,h2,...,h N / 2 ,0 1×(N / 2) ] and filter h2 = [0 1×(N / 2) ,h N / 2+1 ,...,h N ], where N = F s *τ is the length of the matched filter, 0 1×(N / 2) Represents a one-dimensional vector with a value of 0 and a length of N / 2;

[0029] S103: The decomposed matched filter is subjected to matched filtering processing to determine a matched filtering result. Specifically,

[0030] The echo signal x is processed by matched filtering according to the filter h1 to obtain the matched filtering result y1, which is expressed as:

[0031] y1 = IFFT(FFT(x) * FFT(h1)), where * represents convolution, IFFT represents inverse fast Fourier transform, and FFT represents Fourier transform;

[0032] Perform matched filtering on the echo signal x according to the filter h2 to obtain the matched filtering result y2:

[0033] y2 = IFFT(FFT(x) * FFT(h2));

[0034] According to the matched filtering result y1 and the matched filtering result y2, calculate the "sum distance" channel data Σ and the "difference distance" channel data Δ of the radar, where

[0035] Σ = y2 + y1 and Δ = y2 - y1;

[0036] S104: Rapidly calculate the target distance based on the matched filtering result. Specifically,

[0037] S201: Perform target detection on the "sum distance" channel data Σ to obtain the target distance gate k, and the distance corresponding to the distance gate is R k , (R k is the distance measured by the radar. Generally, there is a certain error), the target distance R t is used as the accurate value, and the true target distance R t and the measured distance R k The distance deviation is ΔR = R t -R k ;

[0038] S202: Judge the "sum-difference contradiction" for the target distance gate k. When |Σ(k)| ≥ |Δ(k)| is satisfied, where Σ(k) is the "sum distance" channel data of the k-th distance gate and Δ(k) is the "difference distance" channel data of the k-th distance gate, perform ranging on the "sum distance" channel and the "difference distance" channel to obtain the distance deviation ΔR of the target;

[0039] S203: After summing and expanding according to the Fourier transform, the "sum distance" channel data Σ(k) and the "difference distance" channel data Δ(k) are specifically expressed as:

[0040] In the formula, a is the amplitude of the echo signal, c is the speed of light, and R = R t is the true distance of the target;

[0041] S204: The distance deviation ΔR of the target is expressed as:

[0042]

[0043] Rt =R k +ΔR, where imag is the imaginary part operation;

[0044] S205: Compare or divide the “sum distance” channel data Σ and the “difference distance” channel data Δ, expressed as:

[0045]

[0046] S206: extracting the “imaginary part” of the comparison value result to obtain tan(πBΔR / c);

[0047] The extracted "imaginary part" is subjected to inverse tangent operation to obtain πBΔR / c. Since π, B and c are all known, the distance deviation ΔR can be inferred in reverse, avoiding high-order calculations and increased hardware costs. In addition, by combining the imaginary part operation with the above-mentioned sum and difference of the two sets of data, high accuracy is guaranteed while achieving rapid solution of the target distance.

[0048] For example:

[0049] The present invention uses the distance and difference channel to calculate the target distance and realize high-precision distance measurement. The simulation parameters are as follows: the pulse width of the LFM signal emitted by the radar is set to τ = 2us, the signal bandwidth is set to B = 3.6MHz, the sampling rate is set to Fs = 4MHz, and the distance resolution is set to c / (2B) = 41.7m.

[0050] In order to prove that the present invention can use the distance and difference channels for high-precision ranging, the characteristics of the sum channel and the difference channel under different distance deviations are simulated and analyzed. The results are as follows: Figure 1 and Figure 2 As shown in the figure, it can be seen that the distance deviation between the target and the range gate can be estimated through the calculation of the sum and difference channels.

[0051] In order to analyze the influence of signal-to-noise ratio on distance and difference channel ranging, the ranging error is simulated and analyzed. The results are as follows: Figure 3 As shown in the figure, the ranging error is the standard deviation. It can be seen that as the signal-to-noise ratio increases, the ranging error decreases. When the signal-to-noise ratio is 10dB, the ranging error is about 5.9m; when the signal-to-noise ratio is 15dB, the ranging error is about 3.3m. The ranging accuracy can reach 1 / 10× the range resolution.

[0052] In order to analyze the influence of distance deviation on distance and difference channel ranging, the ranging error is simulated and analyzed. The results are as follows: Figure 4 As shown in the figure, it can be seen that the distance measurement error is basically the same under different distance deviations. Therefore, the measurement error is independent of the distance deviation and can be calculated quickly and accurately.

[0053] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A high-precision distance measurement method based on distance and difference channels, suitable for detection of aircraft radar, the aircraft is equipped with a controller and multiple filters, characterized in that: The methods include: S101: Obtain the radar pre-processed echo signal and design a corresponding matched filter according to the waveform transmitted by the radar; S102: The matched filter performs decomposition; S103: performing matched filtering processing on the decomposed matched filter to determine a matched filtering result; S104: Rapidly calculate the target distance according to the matched filtering result.

2. The high-precision distance measurement method according to claim 1, characterized in that: S101 includes, The echo signal is x, and x=[x1,x2,...,x L ], where L is the number of range gates; Obtain radar waveform information parameters, including signal bandwidth B, signal pulse width τ, sampling frequency F s And the frequency modulation slope u = B / τ.

3. The high-precision distance measurement method according to claim 2, characterized in that: The waveform emitted by the radar is an LFM waveform, and the corresponding matched filter is designed according to the parameters of the LFM waveform.

4. The high-precision distance measurement method according to claim 3, characterized in that: S102 includes: The matched filter h of the LFM waveform is h=[h1,h2,...,h N ] is decomposed into filters h1 = [h1,h2,...,h N / 2 ,0 1×(N / 2) ] and filter h2 = [0 1×(N / 2) ,h N / 2+1 ,...,h N ], where N = F s *τ is the length of the matched filter, 0 1×(N / 2) Represents a one-dimensional vector with a value of 0 and a length of N / 2.

5. The high-precision distance measurement method according to claim 4, characterized in that: S103 includes: The echo signal X is subjected to matched filtering according to the filter h1 to obtain a matched filtering result y1, which is expressed as: y1 = IFFT(FFT(x)*FFT(h1)), * represents convolution, IFFT represents inverse fast Fourier transform, and FFT represents Fourier transform; The echo signal x is subjected to matched filtering according to the filter h2 to obtain a matched filtering result y2: y2 = IFFT(FFT(x)*FFT(h2)); According to the matched filtering result y1 and the matched filtering result y2, the radar sum range channel data ∑ and difference range channel data Δ are calculated, where: ∑=y2+y1 and Δ=y2-y1.

6. The high-precision distance measurement method according to claim 5, characterized in that: S104 includes: S201: Perform target detection on the sum range channel data ∑ to obtain a target range gate k, where the distance corresponding to the range gate is R k , target distance R t As an accurate value, the target's true distance R t The measured distance R k The distance deviation is ΔR=R t -R k ; S202: Perform sum and difference contradiction judgment on the target range gate k. When |∑(k)|≥|Δ(k)| is satisfied, ∑(k) is the sum range channel data of the kth range gate, Δ(k) is the difference range channel data of the kth range gate, and ranging is performed on the sum range channel and the difference range channel to obtain the target range deviation ΔR. S203: The sum distance channel data Σ(k) and the difference distance channel data Δ(k) obtained by Fourier transform summation are specifically expressed as: In the formula, a is the amplitude of the echo signal, c is the speed of light, and R = R t The actual distance to the target; S204: The distance deviation ΔR of the target is expressed as: Among them, imag is the operation of taking the imaginary part; S205: Compare or divide the sum distance channel data Σ and the difference distance channel data Δ, expressed as: S206: extracting the imaginary part of the comparison value result to obtain tan(πBΔR / c); The extracted imaginary part is subjected to arc tangent operation to obtain πBΔR / c, from which the distance deviation is deduced.

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