CN111624600B - A SAR moving target detection method and system based on one-bit quantization - Google Patents

Abstract

The invention provides a SAR moving target detection method and system based on one-bit quantization. By acquiring the SAR echo data on two signal channels after de-linear frequency modulation processing, performing one-bit quantization on them, and calculating them separately The range information corresponding to the SAR echo data after one-bit quantization; repeating the above steps several times to obtain two sets of range information; according to the two sets of range information, two SAR images with azimuth dimension phase calibration are constructed; two SAR images are calculated The pixel difference between the corresponding pixels is obtained, and a difference image is obtained; the target detection is performed on the difference image, and the detection information of the target moving object is obtained. In this embodiment, the echo data is quantized by one bit, which simplifies the complexity of echo data acquisition, reduces the pressure of information processing of the terminal equipment, and saves the cost required for target detection.

Description

A SAR moving target detection method and system based on one-bit quantization

technical field

The present invention relates to the technical field of signal processing, in particular to a SAR moving target detection method and system based on one-bit quantization.

Background technique

Synthetic Aperture Radar (SAR) is an all-weather, all-weather modern remote sensing imaging radar with long-range and high-resolution detection capabilities. In the broader civil field, the vehicle-mounted SAR platform for intelligent driving is becoming a new round of research hotspots.

The airborne SAR image-based moving target detection and recognition technologies in the prior art are mainly divided into single-channel two-view processing methods, Doppler filtering and multi-view interference methods, while the multi-channel methods mainly include offset phase center antennas ( DPCA), along-track interferometry (ATI) and space-time adaptation (STAP) methods. These methods have achieved clutter suppression and moving target detection in SAR images to varying degrees. However, based on the high computational complexity and high data throughput of SAR, these methods require relatively large computational overhead, which poses a significant impact on hardware performance. high demands. Higher-resolution SAR systems often require higher signal bandwidth, and with the increase of SAR signal bandwidth, the burden of data acquisition, storage, transmission, and processing gradually increases. For vehicle-mounted SAR with limited computing resources and real-time target detection, how to simplify the system architecture and reduce the computational complexity is an urgent difficulty to be solved.

Therefore, the prior art needs to be further improved.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide users with a SAR moving target detection method and system based on one-bit quantization, to overcome the SAR echo in the prior art when SAR images are used for moving target detection. The data collection, storage and processing complexity is high, and the computing resources are limited.

The technical scheme adopted by the present invention to solve the technical problem is as follows:

In the first aspect, this embodiment discloses a SAR moving target detection method based on one-bit quantization, which includes:

Acquire the SAR echo data after dechirp processing on the two horizontal position signal channels, and perform one-bit quantization on the acquired SAR echo data to obtain the quantized one-bit echo data;

According to the one-bit echo data on the two signal channels, calculating the distance information corresponding to the one-bit echo data;

Repeat the above steps of obtaining the SAR echo data until calculating and obtaining the range information corresponding to the one-bit echo data, obtaining two sets of range information corresponding to the two position signal channels, and according to the two sets of range information Construct two SAR images that generate azimuth-dimension phase calibration;

Calculate the pixel difference value of the corresponding pixel between the two SAR images to obtain a difference value image composed of the pixel difference value;

Perform target detection on the difference image to obtain detection information of the target moving object.

Optionally, the step of acquiring dechirped SAR echo data on the two horizontal position signal channels includes:

Utilize SAR to send chirps to the detected area, and receive echo signals of the chirps on two signal channels in the horizontal direction;

The two received echo signals are respectively mixed with the transmitted signal of the chirp pulse to obtain the SAR echo data after dechirp processing.

Optionally, the step of calculating the range information corresponding to the one-bit echo data according to the one-bit echo data on the two signal channels includes:

Using the FFT algorithm to perform frequency domain conversion on the one-bit echo data on the two signal channels to obtain frequency point information;

The corresponding distance information is obtained by calculating according to the frequency point information.

Optionally, repeating the above-mentioned steps of obtaining SAR echo data until calculating the range information corresponding to the one-bit echo data, obtaining two sets of range information corresponding to the two position signal channels, and The steps of constructing and generating two SAR images with azimuth dimension phase calibration according to the two sets of range information include:

During the continuous transmission time of the chirp, repeat the above steps of calculating N+m times to obtain the range information corresponding to the one-bit echo data, and obtain N+m range directions on the two position signal channels respectively. information; where N and m are positive integers;

Obtaining the N range data matrices obtained when the m-th to N+mth echoes are extracted from the N+m range information from any signal channel, to obtain a first data set;

Extracting N distance data matrices from the 1st to Nth echoes from the N+m distance information obtained on another signal channel to obtain a second data set;

A first SAR image and a second SAR image are obtained by performing direction bit compression on the N range data matrices contained in the first data set and the second data set, respectively.

Optionally, after the step of calculating and obtaining the corresponding range information according to the frequency point information, the method further includes:

The distance warp correction is performed on the calculated distance direction information, and the distance direction information after the distance warp correction is stored according to the received time sequence.

Optionally, the step of performing target detection on the difference image and acquiring the detection information of the target moving object includes:

Target object detection is performed on the difference image by using a preset target detection algorithm, and position information of the detected target object is obtained.

Optionally, the step of performing one-bit quantization on the acquired SAR echo data, and obtaining the quantized one-bit echo data includes:

One-bit quantization sampling is performed on the SAR echo data after dechirp processing on the two information channels. If it is greater than the preset data threshold, the echo data will be stored as 1, and if it is less than or equal to the preset data threshold, the echo data will be returned. Wave data is stored as 0.

Optionally, the step of using SAR to send chirps to the detected area includes:

The SAR moves horizontally at a preset fixed speed while emitting chirps to the detected area.

Optionally, the N range data matrices obtained when the m to N+m echoes are extracted from the N+m range information obtained from any signal channel, and the step of obtaining the first data set includes: :

Arranging the distance data matrix corresponding to the N+m distance information obtained on any one of the signal channels according to the order of reception time;

According to the arrangement order, move m units to extract the distance data matrix corresponding to the echo signal received at the mth time to the echo signal received at the N+mth time

In a second aspect, this embodiment discloses a SAR moving target detection system based on one-bit quantization, which includes: a SAR receiver;

The SAR receiver includes: a data quantization module, a range calculation module, an image construction module, a difference image generation module and a motion detection module;

The data quantization module is used to obtain the SAR echo data after dechirp processing on the two horizontal position signal channels, and perform one-bit quantization on the obtained SAR echo data to obtain a quantized one-bit echo data;

The range direction calculation module is configured to calculate the range direction information corresponding to the one-bit echo data according to the one-bit echo data on the two signal channels;

The image building module is used for repeating the above steps of acquiring SAR echo data until calculating the range information corresponding to the one-bit echo data, and obtaining two sets of range information corresponding to the two position signal channels , and according to the two sets of range information, two SAR images with azimuth dimension phase calibration are constructed and generated;

The difference image generation module is used to calculate the pixel difference value of the corresponding pixel between the two SAR images, and obtain a difference value image composed of the pixel difference value;

The motion detection module is configured to perform target detection on the difference image, and obtain detection information of the target moving object.

Beneficial effects, the present invention provides a SAR moving target detection method and system based on one-bit quantization. Calculate the distance information corresponding to one bit of echo data respectively; repeat the above steps multiple times to obtain two sets of distance information corresponding to the two signal channels respectively; according to the two sets of distance information obtained from the two signal channels, obtain Two SAR images calibrated in the azimuth dimension and phase; calculate the pixel difference between the corresponding pixels in the two SAR images to obtain a difference image composed of the pixel difference; perform target detection on the difference image to obtain the target Detection information of moving objects. In this embodiment, the echo data is quantized by one bit, thereby simplifying the complexity of echo data acquisition, reducing the pressure of processing information processing of the terminal device, and saving the cost required for target detection.

Description of drawings

Fig. 1 is the step schematic diagram of the SAR moving target detection method based on one-bit quantization of the present invention;

2 is a schematic diagram of the construction structure of an offset phase center antenna in the method of the present invention;

3 is a schematic diagram of the principle of generating a SAR image based on the range information of the signal channel in the method of the present invention;

Fig. 4 is the step flow chart of the specific application embodiment in the method of the present invention;

Fig. 5 is the SAR data imaging of conventional high-precision sampling;

Fig. 6 is the result after conventional high-precision sampling DPCA;

FIG. 7 performs 1-bit sampling SAR imaging results on SAR echo data in the method of this embodiment;

FIG. 8 is the result of performing 1-bit sampling DPCA on the SAR echo data in the method of the present embodiment;

9 is a schematic diagram of detecting a target image from a SAR image in the method according to the embodiment of the present invention;

FIG. 10 is a schematic diagram of the principle of the SAR moving target detection system based on one-bit quantization according to the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer and clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

It will be understood by those skilled in the art that the singular forms "a", "an", "the" and "the" as used herein can include the plural forms as well, unless expressly stated otherwise. It should be further understood that the word "comprising" used in the description of the present invention refers to the presence of stated features, integers, steps, operations, elements and/or components, but does not exclude the presence or addition of one or more other features, Integers, steps, operations, elements, components and/or groups thereof. It will be understood that when we refer to an element as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Furthermore, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. As used herein, the term "and/or" includes all or any element and all combination of one or more of the associated listed items.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms, such as those defined in a general dictionary, should be understood to have meanings consistent with their meanings in the context of the prior art and, unless specifically defined as herein, should not be interpreted in idealistic or overly formal meaning to explain.

The inventor found that in the prior art, when detecting moving targets in SAR images, based on the characteristics of high computational complexity and high data throughput of SAR, the existing detection methods need to use higher signal bandwidth and storage resources to process acquisition. received a large amount of SAR echo data. In order to increase the signal bandwidth and increase the storage resources, it needs to increase the cost, so how to reduce the computational complexity and how to simplify the structure of the processing method is an urgent problem to be solved.

This embodiment provides a one-bit quantized SAR moving target detection method and system. By performing one-bit quantization on the received SAR echo data, the bit width is reduced, thereby reducing the complexity of data processing and improving the processing. purpose of efficiency. In this embodiment, the dual-channel DPCA technology in the field of airborne SAR-GMT I is also combined to collect the SAR echo data obtained from the two signal channels, and quantize one bit, calculate the corresponding range information, and then according to The calculated range information constructs two SAR images calibrated in the azimuth dimension and phase, calculates the difference between the corresponding pixels in the two SAR images, filters out the detection information of the stationary object, and obtains the difference containing the motion data information of the target moving object. The difference image is detected by target detection, and the detected target moving object and its motion data information are obtained.

The SAR moving target detection method and system provided by the present invention will be further described below with reference to the accompanying drawings and specific application embodiments.

This embodiment discloses a SAR moving target detection method based on one-bit quantization, as shown in FIG. 1 , including:

Step S1: Acquire SAR echo data after dechirp processing on the two signal channels, and perform one-bit quantization on the acquired SAR echo data to obtain quantized one-bit echo data.

The radar platform moves at a preset speed. The transmitting antenna of the radar platform transmits a chirp to the area where the moving object is detected, and is received by the receiving antenna of the radar platform after reflection. In order to meet the DPCA condition, The two receiving antennas are placed horizontally, and the schematic diagram is shown in Figure 2, where TX is the transmitting antenna, RX1 and RX2 are the receiving antennas, d is the distance between the centers of the two antennas, m is a positive integer, V is the speed of the radar platform, and PRF is the pulse repetition frequency.

When receiving the first echo signal, the receiving phase center of RX2 is at O ₁ point, and the receiving phase center of RX1 is at O point; after transmitting m pulses, the receiving phase center of RX2 moves to O ₁ ′, and the receiving phase center of RX1 is The center is moved to O'. If the conditions are met:

d=2mV/PRF

Then the first stationary target pulse echo received by RX2 and the m-th stationary point pulse echo received by RX1 contain the same information, and the moving point corresponding to the target moving object will generate additional information, so the moving target echo contained in both contains the same information. The wave information is different. Sliding the data received by RX1 backward by m echo times in the time dimension, and subtracting the signals of these two channels can eliminate the stationary target and leave the moving target information.

Further, the step of obtaining the dechirp-processed SAR echo data on the two signal channels includes:

The SAR is used to transmit chirps to the detected area, and the echo signals of the chirps are received on two signal channels in the horizontal direction.

The two received echo signals are respectively mixed with the transmitted signal of the chirp pulse to obtain the SAR echo data after dechirp processing.

The SAR is used to send out a pulse signal. In this embodiment, the pulse signal is a chirp. The two antennas set on the SAR in the horizontal direction are used to receive the echo signal returned by the chirp. The received echo signals are all subjected to frequency mixing processing. Specifically, each echo signal is multiplied by the conjugate of the transmitted signal to make a difference frequency, that is, after the received echo signal is subjected to frequency mixing processing, the echo signals are converted into into a single frequency signal. The frequency of the single frequency signal is proportional to the distance difference between the echo signal and the transmitted signal, which is Dechirp (de-chirp).

t_m＝mT(m＝0,1,2,…)为慢时间，

为快时间。某点目标到雷达的距离为R_t，参考中心到雷达距离为R_ref，R_Δ＝R_t-R_ref，Dechirp后差频输出为：The recorded frequency signal is

t _m =mT(m=0,1,2,...) is slow time,

for fast time. The distance from a certain point target to the radar is R _t , the distance from the reference center to the radar is R _ref , R _Δ =R _t -R _ref , the post-dechirp difference frequency output is:

f_c为中心频率，T_p为脉冲宽度，γ为LFM信号的调频率，因此，在快时间域里为频率与R_Δ成正比的单频脉冲，

其中c为光速。in,

f _c is the center frequency, T _p is the pulse width, and γ is the modulation frequency of the LFM signal. Therefore, in the fast time domain, it is a single-frequency pulse whose frequency is proportional to R _Δ ,

where c is the speed of light.

Further, the step of performing one-bit quantization on the acquired SAR echo data to obtain the quantized one-bit echo data includes:

One-bit quantization sampling is performed on the SAR echo data after dechirp processing on the two information channels. If it is greater than the preset data threshold, the echo data will be stored as 1, and if it is less than or equal to the preset data threshold, the echo data will be returned. Wave data is stored as 0.

进行一比特量化采样，若信号大于0或是预先设定的阈值，则将回波数据存储为1；若信号小于等于0或是预先设定的阈值，则将回波数据存储为0，从而可以得到由0和1组成的一比特SAR回波数据。所述SAR回波数据为复数，其对应的复信号有实部虚部，在对其进行一比特量化时，实部和虚部需要分别进行一比特量化。Time domain signal after dechirp

One-bit quantization sampling is performed. If the signal is greater than 0 or a preset threshold, the echo data is stored as 1; if the signal is less than or equal to 0 or the preset threshold, the echo data is stored as 0, thus One-bit SAR echo data consisting of 0s and 1s can be obtained. The SAR echo data is a complex number, and the corresponding complex signal has a real part and an imaginary part. When one-bit quantization is performed on it, the real part and the imaginary part need to be quantized by one-bit respectively.

Step S2: Calculate, according to the one-bit echo data on the two signal channels, distance information corresponding to the one-bit echo data.

According to the one-bit SAR echo data processed in the above-mentioned step S1, the range information contained in the echo signal is obtained, and the range information is that the echo signal contains the distance information between the transmitting point and the receiving point. In this implementation, the FFT algorithm is used to calculate the range information. Specifically, the FFT algorithm is used to perform frequency domain conversion on the one-bit echo data on the two signal channels to obtain frequency point information; and corresponding range information is obtained by calculating according to the frequency point information. Since the SAR echo data processed in this step is one-bit quantized SAR echo data, the amount of data calculated by the FFT algorithm on the echo data of the two channels is much larger than that of the previous 16-bit echo data. simplification, and then perform appropriate distance curvature correction, the data stored separately is also more compact than the previous 16-bit data processing. On the other hand, the FFT operation of the SAR echo data can also be appropriately simplified, for example, the traditional high-precision multiplier can be replaced by an exclusive OR gate in the first-stage multiplication.

Step S3, repeating the above-mentioned acquiring SAR echo data, to the step of calculating and obtaining the range information corresponding to the one-bit echo data, obtaining two sets of range information corresponding to the two position signal channels, and according to the two sets of range information. The range information is constructed to generate two SAR images that are phase-aligned in the azimuth dimension.

In the time period during which the pulses are continuously transmitted, the SAR transmits signals again, and steps S1 and S2 are repeated to store the SAR echo data after the FFT operation according to time.

As shown in Figure 3, assuming that a frame of SAR image is constructed with N echoes, after the system has processed m+N echoes, the echo time of channel 1 is shifted by m units, that is, f1(m) The data matrix to f1(m+N) is subjected to azimuthal compression imaging to obtain IM1; while channel 2 does not need time shift, the data matrix from f2(1) to f2(N) is taken for azimuthal compression imaging to obtain IM2.

The step of obtaining the distance information corresponding to the one-bit echo data by performing the above calculation repeatedly within the time that the chirp is continuously transmitted, to obtain two sets of distance information corresponding to the two position signal channels, and according to the The steps of constructing and generating azimuth-dimensional phase-calibrated SAR images from the two sets of range information include:

During the continuous transmission time of the chirp, repeat the above steps of calculating N+m times to obtain the range information corresponding to the one-bit echo data, and obtain N+m range directions on the two position signal channels respectively. information;

Obtaining the N range data matrices obtained when the m-th to N+mth echoes are extracted from the N+m range information from any signal channel, to obtain a first data set;

Extracting N distance data matrices from the 1st to Nth echoes from the N+m distance information obtained on another signal channel to obtain a second data set;

A first SAR image and a second SAR image are obtained by performing direction bit compression on the N range data matrices contained in the first data set and the second data set, respectively.

Further, the N range data matrices obtained when the m to N+m echoes are extracted from the N+m range information obtained from any signal channel, and the step of obtaining the first data set includes:

Arranging the distance data matrix corresponding to the N+m distance information obtained on any one of the signal channels according to the order of reception time;

According to the arrangement sequence, move m units, and extract the range direction data matrix corresponding to the echo signal received at the mth time to the echo signal received at the N+mth time.

Step S4: Calculate the pixel difference value of the corresponding pixels between the two SAR images to obtain a difference value image composed of the pixel difference values.

By subtracting the corresponding pixel values in the two SAR images, the stationary points corresponding to the stationary objects in the two SAR images during the pulse emission period can be filtered out, and the information of the moving target can be retained.

Step S5: Perform target detection on the difference image to obtain detection information of the target moving object.

After the difference image is obtained in the above step S4, the difference image can be imaged, and then the imaged difference image can be detected and positioned, and the image of the target moving object contained in the difference image can be obtained. location information. The image processing of the difference image may be image binarization processing, and the detection of the difference image processed by the binarization may be the use of an image target detection algorithm based on pixel connectivity to detect the location where the target moving object is located. Pixel points, and finally locate the target moving object according to the detected pixel points. In an implementation manner, a target moving object detection algorithm based on a sliding window may be used to perform target moving object detection on the difference image, to obtain position information of the detected target moving object in the difference image. In this step, other target detection algorithms may also be used to perform target detection on the difference image, so as to obtain the relevant information of the target moving object contained in the difference image.

Further, the step of using SAR to send chirps to the detected area includes:

The SAR moves horizontally at a preset fixed speed while emitting chirps to the detected area.

The method provided by this embodiment will be further explained below with reference to FIG. 4 .

Step 1: The radar platform moves in the horizontal direction at a speed V. The transmitting antenna transmits chirps to the detected target scene, and the echoes are received by the two receiving antennas of the radar after reflection.

Step 2: The received echo data of the two channels are respectively conjugated with the reference signal (transmission signal) to make a difference frequency, that is, after the frequency mixing process, the echo becomes a single-frequency signal. One-bit quantization sampling is performed on the dechirp time-domain signal.

Step 3: To obtain range information from the SAR echo data, each echo must first be converted to the frequency domain through a one-dimensional FFT, and the obtained frequency point information corresponds to the distance from the target. After the echoes of the two channels are subjected to FFT, appropriate distance curvature correction is performed and stored separately. Thanks to the one-bit quantization of the echo, the FFT operation of the echo can also be appropriately simplified, for example, the traditional high-precision multiplier can be replaced by an exclusive OR gate in the first-stage multiplication.

Step 4: The SAR transmits the signal again, repeats steps 1 to 3, and stores the data after FFT according to time. Assuming that a frame of SAR image is constructed with N echoes, after the system has processed m+N echoes, it will time-shift the echoes of channel 1 by m units, that is, take f1(m) to f1(m+N ) to perform azimuth compression imaging to obtain IM1; while channel 2 does not need time shift, take the data matrix of f2(1) to f2(N) for azimuthal compression imaging to obtain IM2.

Step 5: The two images of IM1 and IM2 are subtracted to filter out the static points of the SAR image and retain the information of the moving target. Further, the detection of the moving target can be realized by further adopting the method of image processing related target calibration. It should be pointed out that after the direct one-bit quantization of the dechirp echo, some high-order harmonics will be introduced in the imaging frequency band, which reduces the imaging quality to some extent, but still achieves better target detection performance.

The effect of the present invention can be further illustrated by the following simulation experiments, and MATLAB software is used for simulation during simulation.

The simulation constructs three different types of targets: stationary points, moving points, and walking pedestrians. The radar speed is 5m/s, and the direction is 180°; the moving point and pedestrian walking speed are 1.5m/s, and the direction is 45° and 0°, respectively. Figure 5 shows the SAR data imaging results of channel 2 data conventional high-precision sampling; Figure 6 shows the results of channel 2 and channel 1 data after conventional high-precision sampling DPCA; Figure 7 shows the channel 2 data 1-bit sampling SAR imaging results ; Figure 8 is the result of channel 1 and channel 2 data after 1-bit sampling DPCA; Figure 9 is the moving target detection result based on 1-bit sampling.

This embodiment discloses a SAR moving target detection system based on one-bit quantization, as shown in FIG. 10 , including: a SAR receiver;

The SAR receiver includes: a data quantization module 100 , a range calculation module 200 , an image construction module 300 , a difference image generation module 400 and a motion detection module 500 .

The data quantization module 100 is used for acquiring the SAR echo data after dechirp processing on the two horizontal position signal channels, and performing one-bit quantization on the acquired SAR echo data to obtain the quantized one-bit echo data. Wave data; its function is shown in step S1.

The range calculation module 200 is used for calculating the range information corresponding to the one-bit echo data according to the one-bit echo data on the two signal channels; its function is as shown in step S2.

The image construction module 300 is configured to repeatedly perform the above-mentioned steps of calculating and obtaining the range information corresponding to the one-bit echo data within the time when the chirp is continuously transmitted, and obtain the corresponding two positions on the two position signal channels. Group range information, and construct and generate two SAR images with azimuth dimension and phase calibration according to the two sets of range information; its function is shown in step S3.

The difference image generation module 400 is used to calculate the pixel difference value of the corresponding pixels between the two SAR images, and obtain a difference value image composed of the pixel difference values; its function is as shown in step S4.

The motion detection module 500 is configured to perform target detection on the difference image, and obtain detection information of the target moving object. Its function is shown in step S5.

Since the method of the present invention quantizes the SAR echo data in 16 bits, the required complexity and cost of an analog-to-digital converter (ADC) are much higher than the complexity and cost of quantizing it into 1 bit. At the same time, due to the lower complexity and cost of 1bit, its sampling rate can also be much higher than that of 16bit, which is an advantage in data acquisition.

In terms of data storage, because SAR needs to collect echoes for a period of time and then process them in the azimuth direction, the amount of echo data buffering is very large. After one-bit quantized echo, the storage overhead will be greatly reduced. Compared with 16-bit quantized data, theoretically, the storage capacity of 1-bit quantization is only 1/16.

In terms of data processing, because of the one-bit quantization of echo data, when performing distance FFT, the multiplier can be replaced by an exclusive OR gate circuit in the first-stage butterfly operation, so the method of one-bit quantization of data is performed. The complexity of data processing is reduced, and the potential for simplifying the computing architecture is improved.

The invention provides a SAR moving target detection method and system based on one-bit quantization. The obtained SAR echo data is quantized by one-bit through the SAR echo data after de-linear frequency modulation processing, and then a range information corresponding to the bit echo data; repeat the above steps for many times to obtain two sets of range information corresponding to the two signal channels respectively; according to the two sets of range information obtained from the two signal channels, when the echo is obtained Shift two SAR images at a preset number of times; calculate the pixel difference between the corresponding pixels in the two SAR images to obtain a difference image composed of the pixel difference; perform target detection on the difference image to obtain Detection information of the target moving object. In this embodiment, the echo data is quantized by one bit, thereby simplifying the complexity of echo data acquisition, reducing the pressure of processing information processing of the terminal device, and saving the cost required for target detection.

It can be understood that for those of ordinary skill in the art, equivalent replacements or changes can be made according to the technical solutions of the present invention and the inventive concept thereof, and all these changes or replacements should belong to the protection scope of the appended claims of the present invention.

Claims (9)

1. A SAR moving target detection method based on one-bit quantization is characterized by comprising the following steps:

acquiring SAR echo data subjected to de-chirp processing on two signal channels, and performing one-bit quantization on the acquired SAR echo data to obtain quantized one-bit echo data;

calculating to obtain distance direction information corresponding to the one-bit echo data according to the one-bit echo data on the two signal channels;

repeatedly executing the steps from obtaining SAR echo data to calculating to obtain distance direction information corresponding to the one-bit echo data, obtaining two groups of corresponding distance direction information on two position signal channels, and constructing and generating two SAR images with azimuth dimension phase calibration according to the two groups of distance direction information;

repeatedly executing the step of obtaining the distance direction information corresponding to the one-bit echo data by the calculation for N + m times within the continuous emission time of the linear frequency modulation pulse, and respectively obtaining N + m distance direction information on two position signal channels; wherein N and m are positive integers;

obtaining N distance direction data matrixes obtained when m-th to N + m-th echoes are extracted from the N + m distance direction information obtained from one signal channel to obtain a first data set;

extracting N distance direction data matrixes from the 1 st time echo to the Nth time echo from the N + m distance direction information obtained from the other signal channel to obtain a second data set;

respectively carrying out direction bit compression on N distance direction data matrixes contained in the first data set and the second data set to obtain a first SAR image and a second SAR image;

calculating pixel difference values of corresponding pixels between the two SAR images to obtain a difference image consisting of the pixel difference values;

and carrying out target detection on the difference image to acquire detection information of a target moving object.

2. The one-bit quantization based SAR moving target detection method of claim 1, wherein the step of obtaining the dechirped SAR echo data on the two signal channels comprises:

sending a chirp pulse to a detected area by utilizing an SAR (synthetic aperture radar), and receiving echo signals of the chirp pulse on two signal channels in the horizontal direction;

and respectively carrying out frequency mixing processing on the two received echo signals and the transmission signal of the linear frequency modulation pulse to obtain SAR echo data subjected to the de-linear frequency modulation processing.

3. The SAR moving target detection method based on one-bit quantization according to claim 1, wherein the step of calculating distance direction information corresponding to the one-bit echo data according to the one-bit echo data on two signal channels comprises:

performing frequency domain conversion on the one-bit echo data on the two signal channels by using an FFT algorithm to obtain frequency point information;

and calculating to obtain corresponding distance direction information according to the frequency point information.

4. The SAR moving target detection method based on one-bit quantization according to claim 3, wherein after the step of obtaining corresponding distance direction information by calculation according to the frequency point information, the method further comprises:

and performing distance warping correction on the calculated distance direction information, and storing the distance direction information after the distance warping correction according to the received time sequence.

5. The SAR moving target detection method based on one-bit quantization according to claim 2, wherein the step of performing target detection on the difference image and acquiring detection information of a target moving object comprises:

and carrying out target object detection on the difference image by using a preset target detection algorithm to obtain the position information of the detected target object.

6. The SAR moving target detection method based on one-bit quantization according to claim 3, wherein the step of performing one-bit quantization on the obtained SAR echo data to obtain quantized one-bit echo data comprises:

and carrying out one-bit quantitative sampling on the SAR echo data subjected to the de-chirp processing on the two information channels, if the SAR echo data is greater than a preset data threshold, storing the SAR echo data as 1, and if the SAR echo data is less than or equal to the preset data threshold, storing the SAR echo data as 0.

7. The SAR moving target detection method based on one-bit quantization of claim 2, wherein the step of sending chirp to the probed area by SAR comprises:

the SAR moves in the horizontal direction at a preset fixed speed, and simultaneously transmits a chirp pulse to the detected area.

8. The SAR moving target detection method based on one-bit quantization according to claim 1, wherein said step of obtaining a first data set by extracting N distance direction data matrices obtained from m to N + m echoes from said N + m distance direction information obtained from one signal channel comprises:

arranging distance direction data matrixes corresponding to the N + m distance direction information obtained on any one signal channel according to the front-back sequence of the receiving time;

and moving m units according to the arrangement sequence, and extracting a distance direction data matrix corresponding to the echo signal received from the mth time to the echo signal received from the (N + m) th time.

9. A SAR moving target detection system based on one-bit quantization is characterized by comprising: an SAR receiver;

the SAR receiver includes: the device comprises a data quantization module, a distance direction calculation module, an image construction module, a difference image generation module and a motion detection module;

the data quantization module is used for acquiring SAR echo data subjected to the de-chirp processing on two horizontal position signal channels, and performing one-bit quantization on the acquired SAR echo data to obtain quantized one-bit echo data;

the distance direction calculation module is used for calculating distance direction information corresponding to the one-bit echo data according to the one-bit echo data on the two signal channels;

the image construction module is used for repeatedly executing the steps of obtaining the SAR echo data and calculating to obtain the distance direction information corresponding to the one-bit echo data, obtaining two groups of corresponding distance direction information on two position signal channels, and constructing and generating two SAR images with azimuth dimension phase calibration according to the two groups of distance direction information;

repeatedly executing the step of obtaining the distance direction information corresponding to the one-bit echo data by the calculation for N + m times within the continuous emission time of the linear frequency modulation pulse, and respectively obtaining N + m distance direction information on two position signal channels; wherein N and m are positive integers;

obtaining N distance direction data matrixes obtained when m-th to N + m-th echoes are extracted from the N + m distance direction information obtained from one signal channel to obtain a first data set;

extracting N distance direction data matrixes from the 1 st time echo to the Nth time echo from the N + m distance direction information obtained from the other signal channel to obtain a second data set;

respectively carrying out direction bit compression on N distance direction data matrixes contained in the first data set and the second data set to obtain a first SAR image and a second SAR image;

the difference image generation module is used for calculating pixel difference values of corresponding pixels between the two SAR images to obtain a difference image consisting of the pixel difference values;

and the motion detection module is used for carrying out target detection on the difference image and acquiring the detection information of a target moving object.

Images