CN110988867B - Elliptical cross target positioning method for one-transmitting and double-receiving through-wall radar - Google Patents
Elliptical cross target positioning method for one-transmitting and double-receiving through-wall radar Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/887—Radar or analogous systems specially adapted for specific applications for detection of concealed objects, e.g. contraband or weapons
- G01S13/888—Radar or analogous systems specially adapted for specific applications for detection of concealed objects, e.g. contraband or weapons through wall detection
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/46—Indirect determination of position data
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
- G01S7/414—Discriminating targets with respect to background clutter
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
- G01S7/415—Identification of targets based on measurements of movement associated with the target
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/46—Indirect determination of position data
- G01S2013/462—Indirect determination of position data using multipath signals
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
- G01S13/46—Indirect determination of position data
- G01S2013/466—Indirect determination of position data by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
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Abstract
The invention discloses an elliptical cross positioning method suitable for a transmitting-receiving platform through-wall radar. The method can effectively eliminate the false points which may occur in the multi-target detection of the one-and-two-receiving platform through-wall radar, and improve the positioning accuracy of the radar system. Compared with the traditional double-ellipse cross positioning algorithm, the method can effectively prevent the problem of false point interference which is easy to occur in the positioning of the first-sending and second-receiving platform through-wall radar, avoids the limitation that more than 3 receivers are needed in the past, saves the actual research and development cost, improves the service performance of the first-sending and second-receiving platform through-wall radar in the actual environment, and is beneficial to the actual application of the through-wall radar.
Description
Technical Field
The invention belongs to the technical field of through-wall radars, and particularly relates to an elliptical cross target positioning method for a single-transmitting double-receiving through-wall radar.
Background
The through-wall radar mainly transmits electromagnetic wave signals of a specific frequency band to pass through barriers such as walls, doors and other non-transparent substances, and receives echo signal data reflected by a human target after passing through the barriers, so that the detection of a hidden target is realized. In recent years, the method has been widely applied in the fields of anti-terrorism battles, disaster relief, public security law enforcement and the like.
Because the electromagnetic wave transmitted by the through-wall radar system passes through the wall body in the transmission process, the echo of the wall body in the echo is stronger, the signal-to-noise ratio of a target is directly lower, when a plurality of targets are detected, when the positioning estimation is carried out through the double receivers, different matching results can be generated among the targets, the matching results can generate false points, and the radar system can directly generate larger deviation for misjudgment of the number of the targets and the association of the target motion trail. Therefore, the key for ensuring the normal work of the radar system is to eliminate false points from echo data received in a complex building environment and extract real target position information.
For the research on the detection and positioning of the hidden target after the wall-through radar detects the non-transparent substance, research institutions at home and abroad have provided a plurality of solutions. One is a target positioning technology of a through-wall radar adopting a classic BP imaging algorithm, the method utilizes a large-aperture antenna array to detect a target, target position information is obtained through coherent imaging, and pixel values of pixel points in an imaging area are obtained by performing echo delay compensation and coherent accumulation on echo signals of the array antenna, so that the accuracy of a result depends on calculating accurate echo delay. The other method is to use a wider ellipse cross positioning algorithm, the algorithm needs simpler radar physical hardware, the algorithm positioning principle is established based on a simple geometric model, the calculation is simpler, but the ellipse cross positioning algorithm realizes the positioning through ellipse group matching, so partial false points can appear when a plurality of targets exist, and the positioning accuracy is interfered, the existing mature false point elimination algorithm has a minimum distance method of a reference line, the method selects a target measuring line of a measuring station as the reference, the possible segmentation number of the whole strategy domain is reduced, and the false points are removed in groups, but the method has more than 3 antenna receivers as the precondition, and the practical application performance of the method is not good in the existing portable equipment platform establishment. Therefore, the research of a new method for removing false points by ellipse intersection positioning based on a one-sending-two-receiving platform and suitable for a portable platform has important practical application value.
Disclosure of Invention
In order to solve the above problems, the present invention provides an elliptical cross target positioning method for a transmitting-receiving dual-transmitting through-wall radar. The method comprises the steps of firstly obtaining respective distance information of each target through echo data, then obtaining a candidate point set through elliptical cross positioning, and finally eliminating false points possibly appearing in a cross network to obtain position information of each target. The method can effectively eliminate the false points which may appear in multi-target detection of the through-wall radar of the first and second receiving platforms, and improve the positioning accuracy of the radar system.
In order to achieve the above object, the present invention adopts the following technical solutions.
The method for positioning the elliptical cross target for the transmitting-receiving through-wall radar comprises the following steps:
step 1: the through-wall radar is provided with two receivers and a transmitter, and the transmitter and the receivers are horizontally arranged on the same straight line; the method comprises the steps that a transmitter transmits stepping variable frequency signals, two receivers respectively receive echo data, and the distance between each receiver and a target is extracted based on the echo data received by the two receivers;
specifically, first, the transmitter and the receiver are horizontally arranged on the same straight line; a transmitter of the through-wall radar continuously transmits step variable frequency signals outwards, two receivers of the radar continuously receive echo data, and the received echo data are subjected to frequency mixing, low-pass filtering and sampling in sequence to obtain preprocessed echo data;
the echo data comprise a target echo, an environment clutter and a wall direct echo;
secondly, performing time-dimension Fourier transform on the preprocessed echo data to obtain an original range profile; then eliminating the wall and the static target by adopting a method of data cancellation of adjacent periods, detecting the distance of the target and imaging the moving target to obtain a distance image of the moving target;
finally, carrying out Constant False Alarm Rate (CFAR) detection on the distance image of the moving target, and extracting the number N of the targets; then estimating the distance r between each target and the receiver according to the step frequency conversion signal ranging principle 11 ,...,r 1i ,...,r 1N ,r 21 ,...,r 2i ,...,r 2N ；
Wherein r is 1i Is the distance, r, from the receiver 1 to the ith target 2i Is the distance from receiver 2 to the ith target;
step 2: using an ellipse cross positioning algorithm to carry out cross pairing on the distance between a target and a receiving antenna measured by two receivers to obtain corresponding cross points, wherein all the cross points form an ellipse cross point set which is a candidate point set;
wherein N is the target number;
and 3, step 3: based on the axial deviation condition and the radial deviation condition, eliminating false target points in the candidate point set to obtain a candidate target point set;
the axial direction is the circumference where the scanning sector of the through-wall radar is located, and the radial direction is the scanning radius direction of the through-wall radar;
step 3.1: performing linear fitting on candidate points in the candidate point set, judging whether a fitted primary term coefficient f meets an axial offset condition, if so, performing axial mean processing on all the candidate points, selecting N points with maximum axial offset as candidate target points, and excluding residual false target points; otherwise, go to step 3.2;
step 3.2: judging whether candidate points in the candidate point set meet a radial offset condition or not, if so, performing radial mean processing on all the candidate points, selecting N points with minimum radial offset as candidate target points, and excluding residual false targets; otherwise, turning to step 3.3;
the step of judging whether the candidate points in the candidate point set meet the radial offset condition is to calculate the slope k of an axial dividing line in a cross network formed by each group of candidate points in the candidate point set and judge whether the slope k meets the radial offset condition;
step 3.3: and performing radial mean processing on the candidate point set, selecting N points with the minimum radial distance absolute value as candidate target points, and eliminating the residual false target points to obtain a candidate target point set.
And 4, step 4: and selecting a target point with a coordinate value positioned in the radar monitoring sector area from the candidate target point set according to the radar monitoring angle condition, wherein the target point is the real target point.
Further, the distance between each target and the receiver is estimated according to the step frequency conversion signal ranging principle, and the specific formula is as follows:
wherein c is the speed of light; b is the signal bandwidth; t is a scanning period; f. of Reconstruction Is the difference of the two frequencies after mixing.
Further, the coordinates (x, y) of the intersection in the ellipse intersection set are specifically:
wherein r is 1 ＝r 1i +r 0i ，r 2 ＝r 2i +r 0i ，i＝1,2,...,N，d 1 Horizontal distance of receiver 1 from transmitter, d 2 Is the horizontal distance, r, of the receiver 2 from the transmitter 0i The distance from the ith intersection point of the receiver 1 and transmitter ellipse and the receiver 2 and transmitter ellipse to the transmitter.
Further, the axial mean processing is performed on all candidate points, specifically:
firstly, calculating the average value of the axial coordinates of all candidate points in a candidate point set, and recording the average value as q:
q＝(x 1 +x 2 +…+x M )/M；
wherein M represents the total number of candidate points in the candidate point set, x j (ii) a Axial coordinates of the jth candidate point;
then, calculating the distance difference between each candidate point and the axial coordinate mean value q, and recording the distance difference as g (j):
g(j)＝|x j -p|,j＝1,2,…,M；
i.e. the absolute value of the axial distance corresponding to each candidate point.
Further, the radial mean processing is performed on the candidate point set, specifically:
firstly, calculating the average value of the radial coordinates of all candidate points in the candidate point set, and recording the average value as p:
p＝(y 1 +y 2 +…+y M )/M；
wherein M represents the total number of candidate points in the candidate point set; y is j Is the radial coordinate of the jth candidate point;
then, calculating the distance difference between each candidate point and the radial coordinate mean value p, and recording the distance difference as h (j):
h(j)＝|y j -p|,j＝1,2,…,M；
i.e. the absolute value of the radial distance corresponding to each candidate point.
Further, the calculation formula of the axial dividing line is as follows:
where Δ d is the radial distance difference between two targets measured by the same receiving antenna in the same group, and x c Is the abscissa, x, of the left axially displaced maximum point d The abscissa of the right axial displacement maximum point.
Further, the axial offset condition is f ∈ [ -0.0380,0.0380].
Further, the radial offset condition is k ∈ -20,20].
Further, the selecting a target point with a coordinate value located in the radar monitoring sector area from the candidate target point set specifically includes: and sequentially traversing the coordinates of all candidate points in the candidate target point set, judging whether each candidate point is positioned in a fan-shaped monitoring area of the radar system, and taking the candidate points positioned in the fan-shaped monitoring area as real target points.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides an ellipse cross positioning method suitable for a first-generation and second-generation platform through-wall radar, which can effectively eliminate false target points which may appear in multi-target detection of the first-generation and second-generation platform through-wall radar and improve the positioning accuracy of a radar system. Compared with the traditional double-ellipse cross positioning algorithm, the method can effectively prevent the problem of false point interference which is easy to occur in the positioning of the through-wall radar of the first-sending and second-receiving platform, obtains an accurate target motion track by combining with subsequent tracking work, avoids the limitation that more than 3 receivers are needed in the past, saves the actual research and development cost, improves the service performance of the through-wall radar of the first-sending and second-receiving platform in the actual environment, and is beneficial to the actual application of the through-wall radar.
Drawings
The invention is described in further detail below with reference to the figures and specific embodiments.
FIG. 1 is a schematic view of a detection scene of a step variable frequency through-wall radar configured with a one-transmitter-two-receiver platform according to the present invention;
FIG. 2 is a schematic diagram of a candidate point set according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a double ellipse cross-positioning of the present invention;
FIG. 4 is a schematic diagram of a trajectory of a real target point with a false target point removed according to an embodiment of the present invention.
Detailed Description
The embodiments and effects of the present invention will be described in further detail below with reference to the accompanying drawings.
Referring to fig. 1, the method for positioning an elliptical cross target for a transmitting-receiving through-wall radar of the present invention is implemented according to the following steps:
step 1: the through-wall radar is provided with two receivers and a transmitter, and the transmitter and the receivers are horizontally arranged on the same straight line; the method comprises the steps that a transmitter transmits stepping variable frequency signals, two receivers respectively receive echo data, and the distance between each receiver and a target is extracted based on the echo data received by the two receivers;
specifically, first, the transmitter and the receiver are horizontally arranged on the same straight line; a transmitter of the through-wall radar continuously transmits step variable frequency signals outwards, two receivers of the radar continuously receive echo data, and the received echo data are subjected to frequency mixing, low-pass filtering and sampling in sequence to obtain preprocessed echo data;
the echo data comprise a target echo, an environment clutter and a wall direct echo;
illustratively, a step frequency conversion through-wall radar detection scene configured by a one-transmitter-two-receiver platform is shown in fig. 1, wherein a target is above a wall, a transmitting antenna is FA, receiving antennas are RA and RB, a transmitter and a receiver are horizontally arranged as an x-axis, the transmitting antenna is located in the middle as an origin, the distance between the receiving antenna RA and the transmitting antenna FA is 20 cm, the distance between the receiving antenna RB and the transmitting antenna FA is 40 cm, and a through-wall radar system is placed 40 cm away from the wall, without considering wall refraction. The simulation has the situation that two target distributions start to respectively move to the coordinates (-70, 130) and (70, 130) from the coordinates (20, 20) and (-20, 20) at the same time. The radar transmitter continuously transmits step frequency signals to the outside, the two radar receivers continuously receive echo data at the same time, and the echo data after preprocessing is obtained after frequency mixing, low-pass filtering and sampling are carried out on the received data echoes;
secondly, performing time-dimension Fourier transform on the preprocessed echo data to obtain an original range profile; then eliminating the wall and the static target by adopting a method of data cancellation of adjacent periods, detecting the distance of the target and imaging the moving target to obtain a distance image of the moving target;
finally, carrying out Constant False Alarm Rate (CFAR) detection on the distance image of the moving target, and extracting the number N of the targets; then estimating the distance r between each target and the receiver according to the step frequency conversion signal ranging principle 11 ,...,r 1i ,...,r 1N ,r 21 ,...,r 2i ,...,r 2N ；
The specific formula is as follows:
wherein r is 1i Is the distance of the receiver 1 to the ith target, r 2i Is the distance from receiver 2 to the ith target; c is the speed of light; b is the signal bandwidth; t is a scanning period; f. of Reconstruction Is the difference between the two frequencies after mixing.
And 2, step: using an ellipse cross positioning algorithm to carry out cross pairing on the distance between a target and a receiving antenna measured by two receivers to obtain corresponding cross points, wherein all the cross points form an ellipse cross point set, namely a candidate point set;
wherein N is the target number.
Specifically, distances measured by two receivers are subjected to cross pairing to obtain an ellipse intersection set, a candidate point set formed by all real targets and false targets generated by the simulation is shown in fig. 2, in the figure, two lines on the outer side represent a radar sector monitoring range, each circle in the figure represents a calculated candidate point position, all circles form four tracks, a track with a solid line in the middle of the two lines on the outer side represents a target real motion track, and two tracks in the middle represent tracks formed by false points.
The coordinates (x, y) of the intersection in the ellipse intersection set are specifically:
wherein r is 1 ＝r 1i +r 0i ，r 2 ＝r 2i +r 0i ，i＝1,2,...,N，d 1 Horizontal distance of receiver 1 from transmitter, d 2 Is the horizontal distance, r, of the receiver 2 from the transmitter 0i The distance from the ith intersection point of the receiver 1 and transmitter ellipse and the receiver 2 and transmitter ellipse to the transmitter.
And 3, step 3: based on the axial deviation condition and the radial deviation condition, eliminating false target points in the candidate point set to obtain a candidate target point set;
step 3.1: performing linear fitting on candidate points in the candidate point set, judging whether a fitted primary term coefficient f meets an axial offset condition, if so, performing axial mean processing on all the candidate points, selecting N points with the maximum axial offset as candidate target points, and excluding residual false target points; otherwise, turning to step 3.2;
firstly, calculating an axial coordinate average value of all candidate points in a candidate point set, and recording the axial coordinate average value as q:
q＝(x 1 +x 2 +…+x M )/M；
wherein M represents the total number of candidate points in the candidate point set, x j Axial coordinates of the jth candidate point;
then, calculating the distance difference between each candidate point and the axial coordinate mean value q, and recording the distance difference as g (j):
g(j)＝|x j -p|,j＝1,2,…,M；
i.e. the absolute value of the axial distance corresponding to each candidate point.
Step 3.2: judging whether candidate points in the candidate point set meet a radial offset condition, if so, performing radial mean processing on all the candidate points, selecting N points with minimum radial offset as candidate target points, and excluding residual false targets; otherwise, turning to step 3.3;
the above radial mean processing on the candidate point set specifically includes:
firstly, calculating the average value of the radial coordinates of all candidate points in the candidate point set, and recording the average value as p:
p＝(y 1 +y 2 +…+y M )/M；
wherein M represents the total number of candidate points in the candidate point set; y is j Is the radial coordinate of the jth candidate point;
then, calculating the distance difference between each candidate point and the radial coordinate mean value p, and recording the distance difference as h (j):
h(j)＝|y j -p|,j＝1,2,…,M；
i.e. the absolute value of the radial distance corresponding to each candidate point.
The step of judging whether the candidate points in the candidate point set meet the radial offset condition is to calculate the slope k of an axial dividing line in a cross network formed by each group of candidate points in the candidate point set and judge whether the slope k meets the radial offset condition; the calculation formula of the axial dividing line is as follows:
where Δ d is the radial distance difference between two targets measured by the same receiving antenna in the same group, and x c Is the abscissa, x, of the left axially displaced maximum point d The abscissa of the maximum point of right axial offset.
Step 3.3: and performing radial mean processing on the candidate point set, selecting N points with the minimum radial distance absolute value as candidate target points, and eliminating the residual false target points to obtain a candidate target point set.
And 4, step 4: and selecting a target point with a coordinate value positioned in the radar monitoring sector area from the candidate target point set according to the radar monitoring angle condition, wherein the target point is the real target point.
Specifically, the specific process of selecting a target point with a coordinate value within the radar monitorable sector area from the candidate point target point set obtained through the above steps is as follows: it is determined whether the point coordinates satisfy the following set of equations:
wherein d is 1 For receiver 1Horizontal distance from transmitter, d 2 Theta is the horizontal distance of the receiver 2 from the transmitter and theta is the monitorable sector angle of the radar.
Points located in this area are taken as real target points.
Through the steps, the real target point track with the false points removed as shown in fig. 4 can be obtained finally, and as can be seen from the figure, the two tracks consisting of the false points in the middle are removed, so that the positioning accuracy of the through-wall radar system is greatly improved, and the through-wall radar with two receiving and sending platforms is favorably applied to the field of portable through-wall.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. The method for positioning the elliptical cross target for the transmitting-receiving double-through-wall radar is characterized by comprising the following steps of:
step 1: the through-wall radar is provided with two receivers and a transmitter, and the transmitter and the receivers are horizontally arranged on the same straight line; the method comprises the steps that a transmitter transmits stepping variable frequency signals, two receivers respectively receive echo data, and the distance between each receiver and a target is extracted based on the echo data received by the two receivers;
and 2, step: using an ellipse cross positioning algorithm to carry out cross pairing on the distance between a target and a receiving antenna measured by two receivers to obtain corresponding cross points, wherein all the cross points form an ellipse cross point set, namely a candidate point set;
wherein N is the target number;
and step 3: based on the axial deviation condition and the radial deviation condition, eliminating false target points in the candidate point set to obtain a candidate target point set;
the axial direction is the circumference where the scanning sector of the through-wall radar is located, and the radial direction is the scanning radius direction of the through-wall radar;
and 4, step 4: and selecting a target point with a coordinate value positioned in the radar monitoring sector area from the candidate target point set according to the radar monitoring angle condition, wherein the target point is the real target point.
2. The method as claimed in claim 1, wherein the step of extracting the distance between each receiver and the target based on the echo data received by the two receivers comprises the following steps:
firstly, two receivers of the through-wall radar continuously receive echo data, and the echo data after being received are subjected to frequency mixing, low-pass filtering and sampling in sequence to obtain preprocessed echo data;
the echo data comprise a target echo, an environment clutter and a wall direct echo;
secondly, performing time-dimension Fourier transform on the preprocessed echo data to obtain an original range profile; then eliminating the wall and the static target by adopting a method of data cancellation of adjacent periods, detecting the distance of the target and imaging the moving target to obtain a distance image of the moving target;
finally, detecting the distance image of the moving target by Constant False Alarm Rate (CFAR), and extracting the number N of the targets; then estimating the distance r between each target and the receiver according to the step frequency conversion signal ranging principle 11 ,...,r 1i ,...,r 1N ,r 21 ,...,r 2i ,...,r 2N ；
Wherein r is 1i Is the distance of the receiver 1 to the ith target, r 2i Is the distance of the receiver 2 to the ith target.
3. The method as claimed in claim 2, wherein the distance between each target and the receiver is estimated according to a step-and-frequency-converted signal ranging principle, and the specific formula is as follows:
wherein c is the speed of light; b is the signal bandwidth; t is a scanning period; f. of Reconstruction Is the difference between the two frequencies after mixing.
4. The method according to claim 3, wherein the coordinates (x, y) of the intersection in the set of elliptical intersections are specifically:
wherein r is 1 ＝r 1i +r 0i ，r 2 ＝r 2i +r 0i ，i＝1,2,...,N，d 1 Horizontal distance of receiver 1 from transmitter, d 2 Is the horizontal distance, r, of the receiver 2 from the transmitter 0i Is the distance from the receiver 1 to the transmitter at the i-th intersection of the ellipse formed by the receiver 1 and the transmitter and the ellipse formed by the receiver 2 and the transmitter.
5. The method as claimed in claim 4, wherein the step of excluding false target points from the candidate point set based on the axial offset condition and the radial offset condition comprises:
step 3.1: performing linear fitting on candidate points in the candidate point set, judging whether a fitted primary term coefficient f meets an axial offset condition, if so, performing axial mean processing on all the candidate points, selecting N points with maximum axial offset as candidate target points, and excluding residual false target points; otherwise, turning to step 3.2;
step 3.2: judging whether candidate points in the candidate point set meet a radial offset condition, if so, performing radial mean processing on all the candidate points, selecting N points with minimum radial offset as candidate target points, and excluding residual false targets; otherwise, go to step 3.3;
step 3.3: and performing radial mean processing on the candidate point set, selecting N points with the minimum radial distance absolute value as candidate target points, and eliminating the residual false target points to obtain a candidate target point set.
6. The method according to claim 5, wherein the determining whether the candidate points in the candidate point set satisfy the radial offset condition is calculating a slope k of an axial partition line in a cross network formed by each set of candidate points in the candidate point set, and determining whether the slope k satisfies the radial offset condition; the calculation formula of the axial dividing line is as follows:
where Δ d is the radial distance difference between two targets measured by the same receiving antenna in the same group, and d 1 Horizontal distance of receiver 1 from transmitter, d 2 Is the horizontal distance, x, of the receiver 2 from the transmitter c Is the abscissa, x, of the left axially displaced maximum point d The abscissa of the right axial displacement maximum point.
7. The elliptical cross-target positioning method for a transmit-receive through-wall radar according to claim 5, wherein the axial mean processing is performed on all candidate points, specifically:
firstly, calculating the average value of the axial coordinates of all candidate points in a candidate point set, and recording the average value as q:
q＝(x 1 +x 2 +…+x M )/M；
wherein M represents the total number of candidate points in the candidate point set, x j (ii) a Axial coordinates of the jth candidate point;
then, a distance difference between each candidate point and the average value q of the axial coordinates is calculated, and is recorded as g (j):
g(j)＝|x j -q|，j＝1，2，...，M；
i.e. the absolute value of the axial distance corresponding to each candidate point.
8. The method according to claim 5, wherein the radial mean processing is performed on the candidate set of points, specifically:
firstly, calculating the average value of the radial coordinates of all candidate points in the candidate point set, and recording the average value as p:
p＝(y 1 +y 2 +…+y M )/M；
wherein M represents the total number of candidate points in the candidate point set; y is j Is the radial coordinate of the jth candidate point;
then, the distance difference between each candidate point and the mean value p of the radial coordinates is calculated, and is recorded as h (j):
h(j)＝|y j -p|，j＝1，2，...，M；
i.e. the absolute value of the radial distance corresponding to each candidate point.
9. The elliptical cross-target location method for a pitch twin-pitch wall radar as defined in claim 6, wherein the axial offset condition is f e [ -0.0380,0.0380], and the radial offset condition is k e [ -20,20].
10. The method as claimed in claim 1, wherein the selecting of the target points from the candidate target point set whose coordinate values are located within the radar monitoring sector area comprises: and sequentially traversing the coordinates of all candidate points in the candidate target point set, judging whether each candidate point is positioned in a fan-shaped monitoring area of the radar system, and taking the candidate points positioned in the fan-shaped monitoring area as real target points.
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