Disclosure of Invention
Aiming at the 'low-low' target detection radar, the invention provides a suppression method for false tracks formed by clutter interference with Doppler frequency similar to that of the target.
The technical scheme of the invention is that the method for inhibiting false alarms of the 'low-low' target detection radar track comprises the following steps:
Step 1, starting up a radar, performing 360-degree circumferential sweeping motion on an antenna, and calculating a temporary track of a target H by a radar data processor when the target H is searched for twice continuously;
step 2, the radar searches the target again, when the target H is not searched, the temporary track of the target H is deleted, and the step 1 is returned, when the target H is searched, the radar signal processor calculates primary track information of the target H according to the received echo, calculates the radial speed of the track to be VD, calculates the reliable track of the target H according to the track information and the temporary track information of the target H, and records the track speed to be VH;
And 3, the radar data processor calculates the difference between the VD and the VH, when the VD-VH)>V Threshold value is adopted, the radar data processor judges that the target H is a clutter false target, the radar data processor deletes the reliable track of the target H, otherwise, the radar data processor judges that the target H is a real target, and the radar data processor reports the reliable track of the target H to the radar terminal for display.
In the step 1, a component ZVx of the temporary track speed filtering value in the X-axis direction of the rectangular coordinate system, a component ZVy of the temporary track speed filtering value in the Y-axis direction of the rectangular coordinate system, a component Ex of the temporary track position filtering value in the X-axis direction of the rectangular coordinate system, and a component Ey of the temporary track position filtering value in the Y-axis direction of the rectangular coordinate system are defined, and the calculation formulas of all parameters are as follows:
ZVx=(R2*sin(B2)-R1*sin(B1))/Pt;
ZVy=(R2*cos(B2)-R1*cos(B1))/Pt;
Ex=(R1*sin(B1)+ZVx*Pt)*(1.0-Ka)+R2*sin(B2)*Ka;
Ey=(R1*cos(B1)+ZVy*Pt)*(1.0-Ka)+R2*cos(B2)*Ka;
r1. Primary track-pointing distance value of target H detected by radar for the first time
B1. First detected target H by radar once trace azimuth value
R2, the distance value of the first trace point of the target H detected by the radar for the second time
B2. The radar detects the azimuth value of the first point trace of the target H for the second time
Ka Filter coefficient (0.5)
Pt is radar search period.
The further technical scheme of the invention is that in the step 2, the radial speed of the trace is VD, and the calculation formula is as follows:
VD=fd×λ÷2
Wherein fd is the Doppler frequency of the target H detected again by the radar relative to the radar
Lambda: radar emission wavelength.
In the step2, the track speed is VH;
Wherein ZVx the component of the temporary track speed filtering value in the X-axis direction of the rectangular coordinate system
ZVy component of the temporary track velocity filter in the Y-axis direction of the rectangular coordinate system
Ex component of temporary track position filtering value in X-axis direction of rectangular coordinate system
Ey component of the temporary track position filtering value in the Y-axis direction of rectangular coordinate system
R, the distance value of the first-time point trace of the target H detected by the radar again
B, the azimuth value of the first-time point trace of the target H detected by the radar again
Kb Filter coefficient (0.33)
Pt is radar search period.
Effects of the invention
The invention has the technical effect that the invention provides a method for inhibiting false alarms of low-small slow target detection radar tracks. In the prior art, the radar solves the false alarm of the flight path by detecting the radial speed difference between the target and the false alarm through a signal processing algorithm, so as to eliminate the found false alarm primary point trace, the false alarm flight path is generated by the false alarm primary point trace, the number of the false alarm primary point trace is small, and the number of the false alarm flight path is natural. However, it is sometimes difficult to eliminate the found false alarm trace once in the actual environment.
In a real environment, even if false alarm primary points are found, track processing is carried out on all target primary points (real targets and false alarms) through a data processing algorithm, and before a track is reported, whether the target track is the false alarm track is confirmed by comparing the target radial speed with the track speed, if so, the target track is discarded, and if not, the target track is reported.
Therefore, compared with the prior art, the radar false alarm reduction method reduces the primary point trace of the false alarm through the signal processor, and the false alarm reduction method reduces the flight trace of the false alarm through the data processor.
In summary, under the same environment, by adopting the method, the track false alarm displayed by the radar terminal can be effectively restrained, and the use requirement of a user is met.
Detailed Description
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
Referring to fig. 1-3, the core idea of the invention is that in a data processor, the tracks reported by all signal processors are constructed, the radial speed (also called Doppler speed and obtained by Doppler frequency calculation) of the tracks is compared with the track speed to judge, when the radial speed of the tracks is greater than a certain threshold value of the track speed, the current tracks are judged to be clutter, the clutter is deleted, otherwise, the tracks which are judged to be true targets are reported to a radar terminal to display. The judging principle is shown in the attached drawing.
The mathematical principle of the present invention is shown in the accompanying drawings, and the track velocity VH of a moving object can be decomposed into a radial velocity VD (trace doppler velocity) and a tangential velocity VQ of a relative radar, and it is known from the schematic diagram that vd=vh when the object moves in the radial direction of the radar, and VD < VH when the object moves in other directions, so that it can be considered mathematically that all objects of VD > VH are decoys (for example, for a shaky shrub or leaf, etc., they are shaky in place, vh=0 of these clutter, and doppler velocity VD > 0).
Considering that when the radar signal processor calculates VD, VD may be slightly larger than VH when the target moves along the radar radial direction, if only VD > VH is judged to be a false target, it is possible to reject the true target moving along the radar radial direction as a false target.
The method comprises the following specific steps:
Step 1, starting up a radar, performing 360-degree circular sweeping motion on an antenna, calculating a temporary navigation of a target H by a radar data processor when the target H is searched twice continuously, calculating a component ZVx of a temporary track speed filtering value in the X-axis direction of a rectangular coordinate system, a component ZVy of the temporary track speed filtering value in the Y-axis direction of the rectangular coordinate system, a component Ex of a temporary track position filtering value in the X-axis direction of the rectangular coordinate system, and a component Ey of the temporary track position filtering value in the Y-axis direction of the rectangular coordinate system, wherein the calculation formulas of all parameters are as follows:
ZVx=(R2*sin(B2)-R1*sin(B1))/Pt; (1)
ZVy=(R2*cos(B2)-R1*cos(B1))/Pt; (2)
Ex=(R1*sin(B1)+ZVx*Pt)*(1.0-Ka)+R2*sin(B2)*Ka; (3)
Ey=(R1*cos(B1)+ZVy*Pt)*(1.0-Ka)+R2*cos(B2)*Ka; (4)
r1. Primary track-pointing distance value of target H detected by radar for the first time
B1. First detected target H by radar once trace azimuth value
R2, the distance value of the first trace point of the target H detected by the radar for the second time
B2. The radar detects the azimuth value of the first point trace of the target H for the second time
Ka Filter coefficient (0.5)
Pt: radar search period
And 2, searching a target by the radar, deleting a temporary track of the target H when the target H is not searched, returning to the step 1, and calculating primary track information of the target H according to received echoes by the radar signal processor when the target H is searched, wherein the radial speed of the track is calculated as VD, and the calculation formula is as follows:
VD=fd×λ÷2 (5)
fd Doppler frequency of target H re-detected by radar relative to radar
Lambda: radar emission wavelength
According to the primary track information and the temporary track information of the target H, calculating a reliable track of the target H, and calculating the track speed as VH;
ZVx component of the temporal track velocity filter in the X-axis direction of the rectangular coordinate system
ZVy component of the temporary track velocity filter in the Y-axis direction of the rectangular coordinate system
Ex component of temporary track position filtering value in X-axis direction of rectangular coordinate system
Ey component of the temporary track position filtering value in the Y-axis direction of rectangular coordinate system
R, the distance value of the first-time point trace of the target H detected by the radar again
B, the azimuth value of the first-time point trace of the target H detected by the radar again
Kb Filter coefficient (0.33)
Pt: radar search period
And 3, before reporting the track, calculating a difference value between VD and VH by the radar data processor, when the threshold value (VD-VH) > V (Doppler resolution speed) is determined, determining that the target H is a clutter false target, deleting the reliable track of the target H by the radar data processor, otherwise, determining that the target H is a real target, and reporting the reliable track of the target H to a radar terminal by the radar data processor for display.
The following is a specific example for further explanation of the technical scheme of the present invention:
radar parameters, namely a search period Pt=3 seconds, a transmitting wavelength of 3cm and a speed resolution of 0.9m/s;
starting the radar, searching at a speed of 3 seconds for each circle, searching a target H for two circles continuously, wherein R1 of the target H searched for in the first circle is 1380m, B1 is 30 degrees, R2 of the target H searched for in the second circle is 1410m, B2 is 30.5 degrees, and ZVx, ZVy, ex, ey of the target H is calculated according to a formula 1-4;
ZVx=(1410*sin(30.5)-1380*sin(30))/3=8.543m/s;
ZVy=(1410*cos(30.5)-1380*cos(30))/3=6.594m/s;
Ex=(1380*sin(30)+8.543*3)*(1-0.5)+1410*sin(30.5)*0.5=715.6m;
Ey=(1380*cos(30)+6.594*3)*(1-0.5)+1410*cos(30.5)*0.5=1214.9m;
The third circle of radar searches that the Doppler frequency fd of the target H is 660Hz, the R3 is 1440m, the B3 is 31 degrees, and VD and VH of the target H are calculated according to formulas 5 and 6;
VD=660*0.03/2=9.9m/s;
VH=√((8.543*(1-0.33)+0.33*(1440*sin(31)-715.6)/3)2+(6.594*(1-0.33)+0.33*(1440*cos(31)-1214.9)/3)2)
=10.8m/s;
comparing VD with VH, wherein the H target VD is smaller than VH, judging the target H as a real target, and reporting the reliable track of the target H to a radar terminal by a radar data processor for display.
The radar continues searching, the target H1 is searched for in two circles continuously, R1 of the target H1 searched for in the first circle is 580m, B1 is 10 degrees, R2 of the target H1 searched for in the second circle is 560 m, B2 is 9.5 degrees, and ZVx, ZVy, ex, ey of the target H1 is calculated according to formulas 1-4;
ZVx=(590*sin(9.5)-580*sin(10))/3=-1.1126m/s;
ZVy=(590*cos(9.5)-580*cos(10))/3=3.5733m/s;
Ex=(580*sin(10)-1.1126*3)*(1-0.5)+590*sin(9.5)*0.5=97.4m;
Ey=(580*cos(10)+3.5733*3)*(1-0.5)+590*cos(9.5)*0.5=581.9m;
the third circle of radar searches that the Doppler frequency fd of the target H1 is 660Hz, R3 is 580m, B3 is 9.5 degrees, and VD and VH of the target H1 are calculated according to formulas 5 and 6;
VD=660*0.03/2=9.9m/s;
VH=√((-1.1126*(1-0.33)+0.33*(580*sin(9.5)-97.4)/3)2+(3.5733*(1-0.33)+0.33*(580*cos(9.5)-581.9)/3)2)
=1.6m/s;
Comparing VD and VH, the (VD-VH) =8.3 m/s of the target H1, which is greater than 0.9m/s of the speed resolution, determining that the target H1 is a clutter false target, and deleting the reliable track of the target H1 by the radar data processor.
Through analysis of the targets H and H1, the invention can effectively inhibit the false alarm of the flight path.
The effect pair is as follows in fig. 3:
The method comprises the steps of using a group of data, processing the data without adopting software of the invention, wherein the effect is shown as a left image, three targets are arranged in the image, two unmanned aerial vehicle targets are arranged in a yellow circle, a flight path false alarm is arranged in a blue circle, a white point is a target point trace detected by a radar, the effect is shown as a right image after the group of data is processed by adopting software of the invention, only two targets are arranged in the image, two unmanned aerial vehicle targets are arranged in the yellow circle, the flight path false alarm in the blue circle is not reported, and the flight path false alarm displayed by a radar terminal can be effectively inhibited by comparing the two images.