CN114280552A - Sidelobe cancellation method for radar strong clutter region - Google Patents
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Abstract
The invention relates to the field of radar anti-interference, in particular to a side lobe cancellation method for a strong clutter region. The method removes clutter components in the signals by making MTI on the echo signals, and removes clutter components in the signals by utilizing the frequency spectrum difference between the ground clutter and the moving target, and then makes MTD on the echo signals and performs channel cancellation, thereby avoiding the problem that the side lobe cancellation effect is influenced by the damage of the clutter on the solving condition of the side lobe cancellation value due to complex spatial characteristics and high average power of the clutter, reducing the influence of the clutter on the side lobe cancellation effect to the maximum extent, and solving the problem that the radar cannot effectively resist active interference during low altitude detection.
Description
Technical Field
The invention relates to the field of radar active interference resistance, in particular to a side lobe cancellation method in a strong clutter environment.
Background
The radar antenna side lobe cancellation technology is one of the main anti-interference technical measures of a radar system. The principle of the self-adaptive spatial filtering technology used for side lobe cancellation is that an auxiliary antenna is used for receiving an interference signal, the interference output power is minimized through self-adaptive weighting according to the azimuth and the strength of the interference signal, the combined signal of the interference and a target which can not be separated in time and frequency domains but can be separated in space is enabled to obtain the minimum interference residue after the self-adaptive filtering technology is processed, and the target signal is basically not lost. The side lobe cancellation is an anti-interference means necessary for modern radar, which greatly expands the availability of battlefield electromagnetic environment with limited time-frequency resources and ensures that the effective power range of a radar system in the interference environment can not be obviously reduced.
When low-altitude detection is carried out, the radar faces the influence of strong ground clutter, and in a clutter area, the traditional side lobe cancellation performance is greatly reduced due to the influence of the ground clutter, so that the radar is difficult to resist active interference in the clutter area. The space characteristics of the ground clutter are complex, the average power is high, the weight solving condition of side lobe cancellation is damaged, the weight calculation generates deviation, and the side lobe cancellation effect is poor. In the prior art, the MTI processing and the MTD processing are placed after the side lobe cancellation processing, so that the calculation amount is small, but the cancellation effect is poor. However, with the development of the technology, a better cancellation method needs to be provided to solve the influence of ground clutter on the side lobe cancellation effect.
Disclosure of Invention
The invention provides a side lobe cancellation method for a strong clutter region, aiming at the defects that when clutter and active interference exist in the strong clutter region at the same time, the traditional side lobe cancellation method is influenced by the clutter to cause poor cancellation effect and cannot effectively cancel the active interference. The method comprises a clutter rejection method in the echo signal and a self-adaptive side lobe cancellation implementation method, and has the advantages of good universality, good anti-interference effect, easy implementation in engineering and the like.
In order to solve the technical problems, the technical scheme of the invention is as follows: a method for canceling sidelobe of a radar strong clutter region is characterized by comprising the following steps: the method comprises the following steps:
step 1: performing in-phase accumulation on the echo signal of the main antenna;
step 2: performing in-phase accumulation on the auxiliary antenna echo signal;
and step 3: performing MTI processing on the accumulated echo signals;
and 4, step 4: performing MTD processing on the echo signal subjected to the MTI processing;
and 5: respectively calculating correlation matrixes of main antenna echo signals and auxiliary antenna echo signals of different Doppler channels:
step 6: according to the minimum mean square error criterion, the cancellation coefficient of each Doppler channel is obtained;
and 7: and performing sub-channel cancellation according to the cancellation coefficient to obtain a main channel echo matrix after cancellation.
The method for canceling the sidelobe of the strong clutter region of the radar is characterized by comprising the following steps of: vector X for echo signal of one cycle in step 11＝[x1,x2,…,xM]Is represented by the formula (I) in which x1,x2,…,xMEcho values for M range bins; vector Y for echo signal of one cycle in step 21＝[y1,y2,…,yM]Is represented by (a) in which y1,y2,…,yMEcho values for M range bins; and step 3: repeating the step 1 and the step 2, accumulating a plurality of pulse repetition periods in the wave position, and obtaining a main channel echo signal matrix A ═ X1,X2,…,XN]TThe auxiliary channel echo signal matrix B ═ Y1,Y2,…,YN]TMTI is respectively carried out on the received signals on the main channel and the auxiliary channel, and N is the number of echo signals.
The method for canceling the sidelobe of the strong clutter region of the radar is characterized by comprising the following steps of: n is greater than or equal to 8.
The method for canceling the sidelobe of the strong clutter region of the radar is characterized by comprising the following steps of: in step 4, performing MTD processing on the echo signals of the main antenna and the auxiliary antenna after MTI processing to obtain a new main antenna echo signal matrix a '([ X'1,X′2,…,X′N]TAnd auxiliary antenna signal matrix B '═ Y'1,Y′2,…,Y′N]T。
The method for canceling the sidelobe of the strong clutter region of the radar is characterized by comprising the following steps of: in step 5, according to the main antenna echo matrix A '═ X'1,X′2,…,X′N]TAnd auxiliary antenna echo matrix B '═ Y'1,Y′2,…,Y′N]TCalculating the autocorrelation matrix of the auxiliary antenna echo in sub-channels
And main antenna and auxiliary antenna echo autocorrelation matrix
The method for canceling the sidelobe of the strong clutter region of the radar is characterized by comprising the following steps of: in step 6, according to the minimum mean square error criterion, obtaining the self-adaptive side lobe cancellation coefficient W of each Doppler channeli＝Ri -1Pi。
The method for canceling the sidelobe of the strong clutter region of the radar is characterized by comprising the following steps of: in step 7, the result after the side lobe cancellation is respectively calculated for the corresponding channels of the echo signal of each main antenna and the echo signal of each auxiliary antenna, Xi″＝X′i-Wi TYi', obtaining the compensated main antenna echo matrix A ' - [ X ')1,X″2,…,X″N]T。
The invention has the beneficial effects that: the method comprises the steps of accumulating echo signals in a wave position, making MTI (maximum Transmission interference), removing clutter components in the signals by utilizing the frequency spectrum difference of ground clutter and moving targets, then making MTD (maximum Transmission Difference), enabling residual clutter and targets to be in different Doppler channels, and respectively canceling signals of main channels and auxiliary channels of different Doppler channels, so that the problem that the solution conditions of side lobe cancellation values are damaged by the clutter due to the complex spatial characteristics of the clutter and high average power to influence the side lobe cancellation effect is solved, the influence of the clutter on the side lobe cancellation effect is reduced to the maximum extent, and the problem that active interference cannot be effectively resisted by a radar during low-altitude detection is solved.
Drawings
FIG. 1 is a schematic flow chart of an embodiment of a side lobe cancellation method in a strong clutter environment;
FIG. 2 is a simulation result of antenna pattern before cancellation of side lobes in an interference and ground clutter combined environment;
FIG. 3 is a simulation result of antenna pattern after cancellation of side lobes in an interference and ground clutter combined environment;
FIG. 4 is a P-line graph before cancellation of a certain radar anti-interference test side lobe.
FIG. 5 is a P-gram of a radar after interference rejection test side lobe cancellation.
Name interpretation: MTI: displaying a moving target; MTD: and detecting a moving target.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
The embodiment of the invention provides a side lobe cancellation method in a strong clutter environment, which can be applied to the field of radar active interference resistance.
Referring to fig. 1 and fig. 2, a side lobe cancellation method in a strong clutter environment includes the following steps:
step 1: vector X for receiving echo signal of one cycle by main antenna1＝[x1,x2,…,xM]Is represented by the formula (I) in which x1,x2,…,xMEcho values for M range bins;
step 2: vector Y for one cycle of echo signal received by auxiliary antenna1＝[y1,y2,…,yM]Is represented by (a) in which y1,y2,…,yMEcho values for M range bins;
and step 3: repeating the step 1 and the step 2, accumulating a plurality of pulse repetition periods in the wave position, and obtaining a main channel echo signal matrix A ═ X1,X2,…,XN]TThe auxiliary channel echo signal matrix B ═ Y1,Y2,…,YN]TN is the number of echo signals, N is generally more than or equal to 8, and MTI is respectively carried out on the receiving signals on the main channel and the auxiliary channel. The method comprises the following steps of effectively suppressing clutter and extracting target echo information by utilizing the difference of a moving target echo and ground clutter on a frequency spectrum through MTI (maximum transmission interference) processing;
and 4, step 4: performing MTD (maximum Transmission interference) processing on echo signals of the main antenna and the auxiliary antenna after MTI processing to obtain a new main antenna echo signal matrix A ═ X'1,X′2,…,X′N]TAnd auxiliary antenna signal matrix B '═ Y'1,Y′2,…,Y′N]TThe purpose of this step is to separate the remaining clutter from the target, since the target is connected to the clutterAnd the echo signals of the main channel and the auxiliary channel are respectively subjected to MTD processing at different speeds, and the processed echo signals of the main antenna and the auxiliary antenna are in different Doppler channels with targets and clutter.
The method and the device place the MTI processing and the MTD processing before the side lobe cancellation processing, can effectively filter out clutter and separate a target signal and the residual clutter to different channels, avoid the damage of the clutter to the solving condition of the side lobe cancellation weight, and improve the interference cancellation effect.
And 5: from the new primary antenna echo matrix A '═ X'1,X′2,…,X′N]TAnd auxiliary antenna echo matrix B '═ Y'1,Y′2,…,Y′N]TCalculating the autocorrelation matrix of the auxiliary antenna echo in sub-channels
And main antenna and auxiliary antenna echo autocorrelation matrix
Step 6: obtaining the self-adaptive side lobe cancellation coefficient W of each Doppler channel according to the minimum mean square error criterioni＝Ri -1Pi(ii) a Because the clutter, the target and the interference signal are in different Doppler channels, the self-adaptive weight is calculated through the sub-channels, and the influence of the clutter with high power and complex spatial characteristics on a calculation result can be avoided;
and 7: according to the self-adaptive side lobe cancellation coefficient obtained by calculation in the step 6, the result after side lobe cancellation, X, is respectively calculated for the corresponding channels of the echo signal of each main antenna and the echo signal of each auxiliary antennai″＝X′i-Wi TY′iObtaining the echo matrix A ═ X ″, of the main antenna after cancellation1,X″2,…,X″N]T。
And 5 to 7, combining the existing self-adaptive side lobe cancellation technology, performing channel division cancellation processing on the main antenna echo and the auxiliary antenna echo, namely respectively calculating the self-adaptive weight of each Doppler channel, and reducing the influence of clutter on weight solving conditions of side lobe cancellation so that the interference cancellation performance is better.
The invention has larger calculation amount and needs to select a better hardware system, but the invention can better remove the interference of the clutter area, improve the anti-interference performance of the radar in the strong clutter area and is suitable for the existing electronic countermeasure development trend.
Fig. 2 and fig. 3 are simulation results of antenna directional diagrams before and after cancellation of side lobes in an interference and ground clutter combined environment, and fig. 4 and fig. 5 are graphs of anti-interference tests P of a certain radar.
In fig. 2 and 3, the horizontal axis is azimuth, the vertical axis is amplitude, the azimuth of the two interference sources is-80 ° and 80 °, respectively, the interference power is 76dB, the ground clutter exists in the direction of 30 ° to 60 °, the average power is 62dB, in fig. 4, the target entry angle is 325 ° direction, the height is 300m, the interference is located in the due north direction, the power spectral density is 1000W/MHz, the range from 10km to 15km from the radar in the direction of 20 ° to 30 °, and the range from 270 ° to 330 ° from 15km to 20km from the radar has strong clutter distribution. As can be seen from fig. 2 and 3, in the case where the interference signal and the clutter signal exist simultaneously, the present invention can effectively filter the interference. As can be seen from the comparison between fig. 4 and fig. 5, the method of the present invention is applied to the actual radar, and can effectively eliminate the interference in the clutter region.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (7)
1. A method for canceling sidelobe of a radar strong clutter region is characterized by comprising the following steps: the method comprises the following steps:
step 1: performing in-phase accumulation on the echo signal of the main antenna;
step 2: performing in-phase accumulation on the auxiliary antenna echo signal;
and step 3: performing MTI processing on the accumulated echo signals;
and 4, step 4: performing MTD processing on the echo signal subjected to the MTI processing;
and 5: respectively calculating correlation matrixes of main antenna echo signals and auxiliary antenna echo signals of different Doppler channels:
step 6: according to the minimum mean square error criterion, the cancellation coefficient of each Doppler channel is obtained;
and 7: and performing sub-channel cancellation according to the cancellation coefficient to obtain a main channel echo matrix after cancellation.
2. The method for canceling the sidelobe of the strong clutter region of the radar according to claim 1, wherein: vector X for echo signal of one cycle in step 11＝[x1,x2,…,xM]Is represented by the formula (I) in which x1,x2,…,xMEcho values for M range bins; vector Y for echo signal of one cycle in step 21＝[y1,y2,…,yM]Is represented by (a) in which y1,y2,…,yMEcho values for M range bins; and step 3: repeating the step 1 and the step 2, accumulating a plurality of pulse repetition periods in the wave position, and obtaining a main channel echo signal matrix A ═ X1,X2,…,XN]TThe auxiliary channel echo signal matrix B ═ Y1,Y2,…,YN]TMTI is respectively carried out on the received signals on the main channel and the auxiliary channel, and N is the number of echo signals.
3. The method for canceling the sidelobe of the strong clutter region of the radar according to claim 1, wherein: n is greater than or equal to 8.
4. The method for canceling the sidelobe of the strong clutter region of the radar according to claim 2, wherein: in step 4, performing MTD processing on the echo signals of the main antenna and the auxiliary antenna after MTI processing to obtain a new main antenna echo signal matrix a '([ X'1,X′2,…,X′N]TAnd auxiliary antennaNumber matrix B' ═ Y1′,Y′2,…,Y′N]T。
5. The method according to claim 4, wherein the cancellation method of the sidelobe of the strong clutter region of the radar comprises: in step 5, according to the main antenna echo matrix A '═ X'1,X′2,…,X′N]TAnd auxiliary antenna echo matrix B ═ Y1′,Y′2,…,Y′N]TCalculating the autocorrelation matrix R of the auxiliary antenna echo in sub-channelsi＝Yi′HYi' and main antenna and auxiliary antenna echo autocorrelation matrix
6. The method according to claim 5, wherein the cancellation method of the sidelobe of the strong clutter region of the radar comprises: in step 6, according to the minimum mean square error criterion, obtaining the self-adaptive side lobe cancellation coefficient W of each Doppler channeli＝Ri -1Pi。
7. The method according to claim 6, wherein the cancellation method of the sidelobe of the strong clutter region of the radar comprises: in step 7, the result, X', after the side lobe cancellation is respectively calculated for the corresponding channels of the echo signal of each main antenna and the echo signal of each auxiliary antennai＝X′i-Wi TYi', obtaining the compensated main antenna echo matrix A ' - [ X ')1,X″2,…,X″N]T。
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