A large-scale antenna external radiation source radar clutter cancellation and target detection method

Abstract

The application discloses a large-scale antenna external radiation source radar clutter cancellation and target detection method, comprising the following steps: acquiring three receiving channel data; performing segmented processing on receiving channel data I / II; acquiring and code loop tracking of the navigation satellite signal by using direct wave channel data, determining the matching filter function of the navigation satellite, and performing time domain correlation processing on the segmented receiving channel data I / II; constructing a compensation function D(f, t R ), multiplying echo data of echo receiving channel I / II of a target area, and correcting the traditional Keystone transformation parameter; performing Keystone transformation by using the corrected Keystone transformation; performing coherent accumulation within a segment and non-coherent accumulation between segments, and detecting the target by constant false alarm rate. By constructing the double-channel compensation function and combining with the Keystone transformation, the complex matrix operation for obtaining the compensation factor is avoided, the distance travel and the clutter phase difference are corrected at one time, and the better clutter suppression effect is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radar signal processing, and particularly relates to a large-scale antenna external source radar clutter cancellation and target detection method. BACKGROUND

[0002] The clutter received by the traditional ground-based external source radar is mainly concentrated near the Doppler zero frequency, while the ground clutter received by the airborne external source radar is Doppler spread due to the movement of the aircraft platform, and the clutter environment of the airborne external source radar based on the space-based source is more complex, not only because the platform movement of the unmanned aerial vehicle causes the broadening of the clutter spectrum, but also because the large array antenna aperture, the errors of the flight direction and speed given by the inertial navigation system will increase the additional phase difference for cancellation, and these factors all cause the traditional adaptive clutter cancellation method to be unable to directly cancel the clutter effectively, thereby affecting the target detection effect.

[0003] In order to eliminate the influence of the ground clutter on target detection, a common method is to use the signals received by the double antennas to cancel the clutter, and the basic principle of the cancellation is based on the stability of the static clutter in a short time, and the double-channel received signals are used to cancel the static clutter. The Doppler parameters of the moving target change with time, and the Doppler parameters are different in different sub-processing areas, and the positions are also different. By using the difference, the double-channel data can be used for clutter cancellation, so that the moving target is retained. But the current cancellation algorithm is based on the premise that the cancellation area is located at the center of the normal line of the double-antenna aperture, and the azimuth ±20° area, and the clutters received by the double antennas in the area are almost the same, and the influence of the additional phase error caused by the deviation of the flight direction given by the inertial navigation system from the real flight direction can be ignored. But the external source radar based on the solar unmanned aerial vehicle requires azimuth omnidirectional detection, and the antenna size is huge, so the additional phase error cannot be ignored, and the Doppler resolution is improved, and the target distance movement will further affect the target judgment effect after the clutter cancellation. SUMMARY

[0004] The technical problem of the application is to overcome the shortcomings of the prior art, and provide a large-scale antenna external source radar clutter cancellation and target detection method, which is used for solving the problems of mutual coupling of the clutter phase error and distance movement caused by the large array antenna aperture and long-time coherent accumulation, verifying the influence of the double-channel clutter cancellation effect, constructing a double-channel compensation function, combining with Keystone transformation, avoiding the complex matrix operation for obtaining the compensation factor, modifying the traditional Keystone transformation parameters, correcting the distance movement and the clutter phase difference at one time, and realizing a better clutter suppression effect.

[0005] To solve the above technical problems, the application discloses a large-scale antenna external radiation source radar clutter cancellation and target detection method, which comprises the following steps:

[0006] Step 1, the omni-directional end-fire array antenna is divided into two sub-arrays, i.e., a sub-array I and a sub-array II, by receiving the echo of a target scattering area;

[0007] Step 2, three receiving channel data, i.e., direct wave channel data, receiving channel data I and receiving channel data II, are obtained;

[0008] Step 3, the receiving channel data I and the receiving channel data II are processed in segments, and the intra-segment is fast time and the inter-segment is slow time;

[0009] Step 4, the direct wave channel data is used to capture and code loop track the navigation satellite signal, the navigation message information is solved to obtain the navigation message modulation mode and the satellite number, the navigation message data modulation stripping is performed on the receiving channel data I and the receiving channel data II by using the obtained navigation message modulation mode, and the matching filter function of the navigation satellite is determined by using the obtained satellite number; finally, the matching filter function and the receiving channel data I and the receiving channel data II processed in the step 3 are used for time domain correlation processing, and the matching filter of the echo signal is completed;

[0010] Step 5, according to the angle φ0 between the flight direction of the solar energy unmanned aerial vehicle and the initial antenna reference direction given by the inertial navigation, the estimated value of the angle between the flight direction of the solar energy unmanned aerial vehicle and the initial antenna reference direction is determined

[0011] Step 6, for the receiving channel data I and the receiving channel data II processed in the step 3, since there is no distance walk in the intra-segment and only the distance walk problem exists in the inter-segment, the phase variable is only related to the fast time and is not related to the slow time, and therefore the compensation function D(f, t R ) is constructed in the fast time frequency-slow time domain:

[0012]

[0013] wherein f represents the fast time frequency, f c represents the carrier frequency, v z represents the ground speed of the solar energy unmanned aerial vehicle platform, L represents the center distance between the sub-array I and the sub-array II, t R represents the virtual slow time, and Δt represents the change time, Δt=L / v z ;

[0014] Step 7, using the compensation function constructed in step 6, multiplying the echo data of target area echo receiving channel I and target area echo receiving channel II in step 4, and correcting the traditional Keystone transform parameters; using the corrected Keystone transform to perform Keystone transform on the echo signal obtained in this step to realize distance unit compensation and correct target distance migration and phase aperture error;

[0015] Step 8, using coherent accumulation within a segment and non-coherent accumulation between segments, detecting the target by constant false alarm, if there is no target, jumping to step 5, and Δφ n = Δφ n-1 + 0.5°; if the target is detected or Δφ n = φ max , jumping to step 3 to perform target detection processing in the next cycle.

[0016] In the above large-scale antenna external source radar clutter cancellation and target detection method, the direct wave channel data is data received through a direct wave receiving channel; the receiving channel data I is data received through a target area echo receiving channel I; and the receiving channel data II is data received through a target area echo receiving channel II.

[0017] In the above large-scale antenna external source radar clutter cancellation and target detection method, further comprising:

[0018] Determining a target area pointing angle according to current radar combat requirements;

[0019] Selecting a weight from a pre-stored weight database according to the determined target area pointing angle, and using DBF processing technology to perform weighted processing on the signals of the subarray I and the subarray II respectively to form two echo receiving channels: a target area echo receiving channel I and a target area echo receiving channel II.

[0020] In the above large-scale antenna external source radar clutter cancellation and target detection method, the weight includes: amplitude and phase.

[0021] In the above large-scale antenna external source radar clutter cancellation and target detection method, the purpose of segmenting the receiving channel data I and the receiving channel data II is to ensure that there is no distance migration caused by relative radial velocity within a segment and that the translation between segments can meet the double-channel cancellation condition.

[0022] In the above large-scale antenna external source radar clutter cancellation and target detection method,

[0023]

[0024] wherein Δφ represents an angle deviation caused by error, and is searched according to a 0.5° step, that is:

[0025] Delta phi = [- phi max : 0.5 degree: phi max ], Delta phi 0 = - phi max

[0026] Wherein, ± phi max Indicate the maximum angle error of the solar unmanned aerial vehicle.

[0027] In the above large-scale antenna external source radar clutter cancellation and target detection method, the fast time t r Of the modified Keystone transformation is:

[0028]

[0029] The present application has the following advantages:

[0030] The present application discloses a large-scale antenna external source radar clutter cancellation and target detection method, by constructing the phase deviation function caused by the omnidirectional large-size double antenna, simultaneously integrating the compensation operation and the motion compensation operation, using the modified Keystone transformation to compensate the phase deviation and target speed movement, which can effectively suppress the clutter and improve the detection ability of the moving target. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Is a coherent accumulation before amplitude diagram in the embodiment of the present application;

[0032] Figure 2 Is a coherent after multi-source fusion after amplitude diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present application more clear, the following will combine the drawings to further describe the disclosed embodiments of the present application in detail.

[0034] In the embodiment, the large-scale antenna external source radar clutter cancellation and target detection method comprises:

[0035] Step 1, by receiving the target scattering area echo, the omnidirectional end-fire array antenna is divided into two sub-arrays: sub-array I and sub-array II; wherein, the sub-array I and the sub-array II correspond to the target area echo receiving channel I and the target area echo receiving channel II respectively.

[0036] Step 2, obtain three receiving channel data: direct wave channel data, receiving channel data I and receiving channel data II.

[0037] In the embodiment, the direct wave channel data is data received through a direct wave receiving channel; the receiving channel data I is data received through a target region echo receiving channel I; and the receiving channel data II is data received through a target region echo receiving channel II.

[0038] Preferably, for the receiving channel data I and the receiving channel data II, a target region pointing angle is determined according to current radar operation requirements; and weights (including amplitudes and phases) are selected from a pre-stored weight database according to the determined target region pointing angle, and DBF processing technology is used to perform weighted processing on the subarray I and the subarray II signals respectively to form two echo receiving channels: the target region echo receiving channel I and the target region echo receiving channel II.

[0039] Step 3: The receiving channel data I and the receiving channel data II are processed in segments, and the time within a segment is fast and the time between segments is slow.

[0040] In the embodiment, the purpose of processing the receiving channel data I and the receiving channel data II in segments is to ensure that there is no distance migration caused by relative radial velocity within a segment and that the translation between segments can meet the condition of double-channel cancellation, i.e., the equivalent pulse repetition period T d of the receiving channel data I and the receiving channel data II after segmentation

[0041] T d ≤ c / (Bv max )

[0042] where c represents the speed of light.

[0043] Step 4: The direct wave channel data is used to capture and code ring track the navigation satellite signal, to solve the message information to obtain the message modulation mode and the satellite number, and to use the obtained message modulation mode to perform navigation message data modulation stripping on the receiving channel data I and the receiving channel data II, and then to use the obtained satellite number to determine the matching filter function of the navigation satellite; finally, the determined matching filter function is used for time domain correlation processing with the receiving channel data I and the receiving channel data II processed in segments in step 3 to complete the matching filtering of the echo signal.

[0044] Step 5: According to the angle φ0 between the flight direction of the solar energy unmanned aerial vehicle and the initial antenna reference direction given by the inertial navigation, an estimated value of the angle between the flight direction of the solar energy unmanned aerial vehicle and the initial antenna reference direction is determined.

[0045] In the embodiment, where Δφ represents the angle deviation caused by errors (flight instability, maneuverability, inertial navigation data delay, etc.).

[0046] The simulation analysis result shows that when the baseline length of the cancellation antenna is greater than 100λ and the angle error is greater than 2.5°, the clutter cancellation effect will affect the target detection effect. According to the maximum angle error ±φ max , the angle error can be searched in steps of 0.5° The compensation is as follows:

[0047] Δφ = [-φ max : 0.5°: φ max ], Δφ0 = -φ max

[0048] Step 6, for the received channel data I and received channel data II processed by step 3, since there is no range walk in the segment, only the range walk problem exists between the segments, therefore, the phase variable is only related to the fast time, and is not related to the slow time, so the compensation function D(f, t R ) is constructed in the fast time frequency-slow time domain:

[0049]

[0050] Wherein, f represents the fast time frequency, f c represents the carrier frequency, v z represents the ground speed of the solar unmanned aerial vehicle platform, L represents the center distance between the subarray I and the subarray II, t R represents the virtual slow time, and Δt represents the change time, Δt = L / v z .

[0051] Step 7, using the compensation function constructed in step 6, multiplying the echo data of the target area echo receiving channel I and the target area echo receiving channel II in step 4, and correcting the traditional Keystone transform parameters; using the corrected Keystone transform to perform Keystone transform on the echo signal obtained in this step, to realize the range unit compensation, and correct the target range walk and the phase aperture error.

[0052] In this embodiment, the fast time t r of the corrected Keystone transform is:

[0053]

[0054] Step 8, using coherent accumulation in the segment and using non-coherent accumulation between the segments, detecting the target with constant false alarm, if there is no target, then jumping to step 5, and Δφ n = Δφ n-1 + 0.5°; if the target is detected or Δφ n = φ max , then jumping to step 3 to perform the target detection processing of the next period.

[0055] In the embodiment, in order to verify the effectiveness of the large-scale antenna external radiation source radar clutter cancellation and target detection method proposed in the application, the target detection results before and after using the method proposed in the application are compared. Figure 1 The expression space-time clutter suppression before echo signal coherent + incoherent processing result, target signal is submerged in clutter and noise and cannot be detected; Figure 2 The expression target detection result after processing by the patent, the obvious detectable target peak value appears. The experiment shows that after the method of the application is processed, the space-time clutter in the echo signal is effectively suppressed, and the target detection of the airborne external radiation source radar is realized.

[0056] Although the application has been disclosed as above with the preferred embodiments, it is not intended to limit the application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the application by using the disclosed methods and technical contents without departing from the spirit and scope of the application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the application, which does not deviate from the technical solutions of the application, belongs to the protection scope of the technical solutions of the application.

[0057] The contents not described in detail in the specification of the application belong to the known technology of the person skilled in the art.

Claims

1. A method for clutter cancellation and target detection in large scale antenna OTHR, characterized in that, It comprises: Step 1, by receiving target scattering area echo through radar, the omni-directional end-fire array antenna is divided into two sub-arrays: sub-array I and sub-array II; wherein, sub-array I and sub-array II correspond to target area echo receiving channel I and target area echo receiving channel II respectively; Step 2, three receiving channel data are obtained: direct wave channel data, receiving channel data I and receiving channel data II; Step 3, segment processing is performed on receiving channel data I and receiving channel data II, and the segment is fast time and the segment is slow time; Step 4, direct wave channel data is used to capture and code ring track the navigation satellite signal, the navigation message information is solved to obtain the navigation message modulation mode and the satellite number, the navigation message data modulation stripping is performed on receiving channel data I and receiving channel data II by using the obtained navigation message modulation mode, and the matching filter function of the navigation satellite is determined by using the obtained satellite number; finally, the matching filter function and the segment-processed receiving channel data I and receiving channel data II in step 3 are used for time domain correlation processing, and the matching filter of the echo signal is completed; Step 5, determining an estimated value of the angle φ between the flight direction of the solar-powered unmanned aerial vehicle and the initial antenna reference direction based on the angle φ0 between the flight direction of the solar-powered unmanned aerial vehicle and the initial antenna reference direction given by the inertial navigation system Step 6, for the received channel data I and received channel data II after the segment processing in step 3, since there is no distance walk in the segment, only the distance walk problem exists between the segments, therefore, the phase variable is only related to the fast time, and is not related to the slow time, therefore, the compensation function D(f, t) is constructed in the fast time frequency domain-slow time domain R ): Wherein, f represents fast time frequency, f c represents carrier frequency, v z represents solar unmanned aerial vehicle platform ground speed, L represents the center distance between subarray I and subarray II, t R represents virtual slow time, Δt represents change time, Δt=L / v z ; Step 7, the compensation function constructed in step 6 is multiplied by the echo data of target area echo receiving channel I and target area echo receiving channel II in step 4, and the traditional Keystone transformation parameters are corrected; Keystone transformation is performed on the echo signal obtained in this step by using the corrected Keystone transformation, distance unit compensation is realized, and target distance migration and phase aperture error are corrected; Step 8, coherent accumulation within the segment, non-coherent accumulation between segments, constant false alarm detection target, if no target, jump to step 5, and Δφ n = Δφ n-1 + 0.5°; if the target is detected or Δφ n = φ max , jump to step 3 for the next cycle of target detection processing.

2. The method of clutter cancellation and target detection for large-scale antenna ODSR according to claim 1, characterized in that, The direct wave channel data is the data received through the direct wave receiving channel; the receiving channel data I is the data received through the target area echo receiving channel I; and the receiving channel data II is the data received through the target area echo receiving channel II.

3. The method of clutter cancellation and target detection for large-scale antenna ODSR according to claim 2, characterized in that, It also comprises: According to the current radar combat requirements, the target area pointing angle is determined; According to the determined target area pointing angle, the weight value is selected from the pre-stored weight value database, and the DBF processing technology is used to weight process the signals of sub-array I and sub-array II respectively, to form two echo receiving channels: target area echo receiving channel I and target area echo receiving channel II.

4. The method of clutter cancellation and target detection for large-scale antenna ODSR according to claim 3, characterized in that, The weight value comprises: amplitude and phase.

5. The method of clutter cancellation and target detection for large-scale antenna OBRadar according to claim 1, wherein, The purpose of segment processing of receiving channel data I and receiving channel data II is to make the distance migration caused by relative radial velocity in the segment, and ensure that the translation between segments can meet the condition of double-channel cancellation.

6. The large-scale antenna external radiation source radar clutter cancellation and target detection method according to claim 1, wherein, Δφ represents the angle deviation caused by the error, and the search is performed according to 0.5° step, that is: ​ Δφ = [-φ max :0.5°:φ max ], Δφ0= -φ max where ±φ max represents the maximum angular error of the solar-powered unmanned aerial vehicle.

7. The method of clutter cancellation and target detection for large-scale antenna OBRadar according to claim 1, wherein, Fast time t of the modified Keystone transform r is:

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