Airborne aircraft phase-sweeping radar SAR mode beam control method

Abstract

The invention belongs to the technical field of airborne aircraft phase-sweeping Reida SAR mode beam control, particularly relates to an airborne aircraft phase-sweeping Reida SAR mode beam control method, and relates to an antenna azimuth beam and pitching beam pointing electric scanning and mechanical scanning control method. In a bunching SAR mode, an azimuth wave beam and a pitching wave beam in the same aperture time can always cover the center of an imaging area well, and the SAR image quality and the azimuth resolution are ensured; in the strip SAR mode, the azimuth wave beam can be always well orthogonal to the imaging track angle, and the SAR image quality and the moving target positioning precision are ensured.

Description

Technical Field

[0001] The present application belongs to the technical field of airborne phase-scanned radar (SAR) mode beam control, and specifically relates to an airborne phase-scanned radar (SAR) mode beam control method, and relates to an electronic scanning and mechanical scanning control method for antenna azimuth beam and elevation beam pointing. Background Art

[0002] As radar usage scenarios become increasingly complex, in addition to the traditional detection and surveillance capabilities of ground and low-altitude targets, it is also necessary to have high-resolution imaging capabilities for ground targets, such as helicopter-mounted surveillance and early warning radars.

[0003] In the specified mission airspace, the aircraft usually needs to make multiple round trips to perform reconnaissance and surveillance missions. The aircraft trajectory consists of turning segments and straight segments. Usually, the radar can only output high-quality SAR images on the straight segment route.

[0004] The SAR mode is composed of multiple continuous apertures. In the spotlight SAR mode, the antenna beam must always cover the same target area within each aperture time so that the radar can output high-quality spotlight SAR images. In the strip SAR mode, the antenna beam pointing angle must always maintain an orthogonal relationship with the imaging track angle within each aperture time so that the radar can output high-quality strip SAR images and moving targets can be superimposed on the SAR image with higher positioning accuracy.

[0005] The mechanical phase-scanning radar has the functional features of mechanical azimuth 360-degree scanning, azimuth + elevation two-dimensional radio beam scanning, etc. Due to atmospheric disturbances on the straight route, the heading of the aircraft fluctuates irregularly. In this regard, the mechanical phase-scanning radar currently uses a servo motor to adjust the antenna beam pointing in real time. For large-caliber and high-inertia radar antennas, this technical solution has the following defects:

[0006] 1) Antenna beam pointing lags due to inertia, and the antenna cannot rotate to the azimuth command angle position in time. In the spotlight mode, the radar antenna azimuth beam does not cover the same target within the same aperture time. In the strip SAR mode, the radar antenna azimuth beam pointing does not maintain an orthogonal relationship with the imaging track angle.

[0007] 2) The antenna beam pointing appears to be ahead due to inertia. The antenna rotates past the azimuth command angle position. The radar antenna azimuth beam does not cover the same target within the same aperture time in the spotlight mode. The radar antenna azimuth beam pointing does not maintain an orthogonal relationship with the imaging track angle in the strip SAR mode.

[0008] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0009] The purpose of the present application is to provide a beam control method for an airborne phase-scanning radar (SAR) mode, so as to overcome or alleviate at least one of the known technical defects.

[0010] The technical solution of this application is:

[0011] A beam control method for an airborne phase-scanning radar SAR mode, for a spotlight SAR mode, comprising:

[0012] S11, real-time reception of inertial navigation data, including inertial navigation longitude Lon ins , Latitude ins , height H ins , roll γ, pitch θ, heading C;

[0013] S12, using inertial navigation longitude Lon ins , Latitude ins , height H ins and the longitude lon of the imaging area sar , Latitude sar , height H sar Data, to calculate the geographic azimuth command angle Az_geo_ctr and elevation command angle El_geo_ctr of the radar antenna beam;

[0014] S13, transforming the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr into the radar system azimuth initial command angle Az_rd_ctr0 and the elevation initial command angle El_rd_ctr0 through the coordinate system conversion matrix;

[0015] S14, compare the radar system azimuth initial command angle Az_rd_ctr0 with the radar system mechanical azimuth angle Az_serv, and the servo controls the radar antenna through the motor according to the difference to make an initial adjustment on the mechanical azimuth angle, and compares the radar system elevation initial command angle El_rd_ctr0 with the radio beam elevation angle El_rd, and uses the beam control module to make an initial control on the radio beam elevation direction according to the difference;

[0016] S15, according to the timing relationship between the nth aperture frame Ap_frame(n) pulse moment and the mth processing frame pulse Prc_frame(m), the mth processing frame corresponds to the start of the nth aperture frame, and the m+k-1th processing frame corresponds to the end of the nth aperture frame, and the processing frame mapping division within the aperture frame time is performed, wherein k is the ratio of the aperture frame period to the processing frame period;

[0017] S16. For the 1st to nth imaging apertures, the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr are calculated in real time according to the processing frame period, the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr are transformed into the radar system azimuth command angle Az_rd_ctr and the radar system elevation command angle El_rd_ctr through the coordinate system conversion matrix, the radar system azimuth command angle Az_rd_ctr is compared with the radar system azimuth angle Az_rd, when the difference exceeds the first angle threshold, the servo controls the radar antenna through the motor to make a rough adjustment on the mechanical azimuth angle, when the difference is less than the first angle threshold of 30°, the mechanical azimuth angle is not adjusted, and the beam control module is used to make a fine adjustment on the azimuth angle of the electric beam;

[0018] S17. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr in real time according to the processing frame period, transform the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the pitch command angle El_rd_ctr through the system conversion matrix, compare the radar system pitch command angle El_rd_ctr with the radio beam pitch angle El_rd, and when the difference exceeds the second angle threshold, adjust the radio beam pitch angle with the beam control module, and when the difference is less than the second angle threshold, do not adjust the radio beam pitch angle.

[0019] According to at least one embodiment of the present application, in the above-mentioned airborne phase-scanning radar SAR mode beam control method, in S1, the inertial navigation longitude Lon ins , Latitude ins , height H ins and the longitude lon of the imaging area sar , Latitude sar , height H sar Data, real-time calculation of the geographic azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr of the radar antenna beam, specifically:

[0020]

[0021]

[0022] Detx= (N1+H sar )cos(Lat sar )cos(Lon sar )-(N2+H ins )cos(lat sar )cos(lonsar );

[0023] Dety= (N1+H sar )cos(Lat sar )sin(Lon sar )-(N2+H ins )cos(lat sar )sin(lon sar );

[0024]

[0025] Wayp x = -Detx*sin(Lat ins )cos(Lon ins )-Dety*sin(Lat ins )sin(Lon ins )+Detz* cos(Lat ins );

[0026] Wayp y =-Detx*sin(Lon ins )+Dety*cos(Lon ins );

[0027] Wayp z = Detx*cos(Lat ins )cos(Lon ins )+Dety*cos(Lat ins )sin(Lon ins )+Detz* sin(Lat ins );

[0028]

[0029]

[0030] in:

[0031] R a is the Earth's semi-major axis;

[0032] R b is the Earth's semi-minor axis;

[0033] N1, N2, Detx, Dety, Detz, Wayp x 、Wayp y、Wayp z It is the intermediate calculation amount.

[0034] According to at least one embodiment of the present application, in the above-mentioned airborne phase-scanning radar SAR mode beam control method, in S13, the coordinate system conversion matrix is

[0035] According to at least one embodiment of the present application, in the above-mentioned airborne phase scan radar SAR mode beam control method, in S16, the first angle threshold is 30°.

[0036] According to at least one embodiment of the present application, in the above-mentioned airborne phase-scanning radar SAR mode beam control method, in S17, the second angle threshold is 1°.

[0037] According to at least one embodiment of the present application, in the above-mentioned airborne phase-scanning radar SAR mode beam control method, for the strip SAR mode, it includes:

[0038] S21, real-time reception of inertial navigation data, including inertial navigation longitude Lon ins , Latitude ins , height H ins , roll γ, pitch θ, heading C;

[0039] S22, real-time receiving imaging track angle Ang_trace_SARctrl;

[0040] S23, calculate the geographic system azimuth command angle Az_geo_ctr using the image track angle Ang_trace_SARctrl, and use the inertial navigation altitude H ins , imaging area height H sar , calculate the radar antenna beam geographic system elevation command angle El_geo_ctr in real time;

[0041] S24, transforming the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr into the radar system azimuth initial command angle Az_rd_ctr0 and the elevation initial command angle El_rd_ctr0 through the coordinate system conversion matrix;

[0042] S25. For imaging in the right viewing direction, the servo controls the mechanical angle of the radar antenna azimuth at the radar system 90° position through the motor. For imaging in the left viewing direction, the servo controls the mechanical angle of the radar antenna azimuth at the radar system -90° position through the motor. The radar system azimuth initial command angle Az_rd_ctr0 is compared with the radar system mechanical azimuth angle Az_serv. The beam control module performs initial adjustment of the azimuth direction of the radio beam according to the difference. The radar system pitch initial command angle El_rd_ctr0 is compared with the radio beam pitch angle El_bk. The beam control module performs initial control of the pitch direction of the radio beam according to the difference.

[0043] S26, according to the timing relationship between the nth aperture frame Ap_frame(n) pulse moment and the mth processing frame pulse Prc_frame(m), the mth processing frame corresponds to the start of the nth aperture frame, and the m+k-1th processing frame corresponds to the end of the nth aperture frame, and the processing frame mapping division within the aperture frame time is performed, wherein k is the ratio of the aperture frame period to the processing frame period;

[0044] S27. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr in real time according to the processing frame period, transform the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the elevation command angle El_rd_ctr through the coordinate system conversion matrix, compare the radar system azimuth command angle Az_rd_ctr with the radar system azimuth angle Az_rd, and adjust the azimuth angle of the electric beam according to the difference by the beam control module;

[0045] S28. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr in real time according to the processing frame period, transform the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the pitch command angle El_rd_ctr through the coordinate system conversion matrix, compare the radar system pitch command angle El_rd_ctr with the radar system pitch angle El_rd, and when the difference exceeds the third angle threshold, adjust the pitch angle of the radio beam by the beam control module; when the difference is less than the third angle threshold, do not adjust the pitch angle of the radio beam.

[0046] According to at least one embodiment of the present application, in the above-mentioned airborne phase-scanning radar SAR mode beam control method, in S23, the geographic system azimuth command angle Az_geo_ctr is calculated using the image track angle Ang_trace_SARctrl:

[0047] For the right viewing direction imaging, Az_geo_ctrl=Ang_trace_SARctrl+90;

[0048] For the left viewing direction, Az_geo_ctrl=Ang_trace_SARctrl-90.

[0049] According to at least one embodiment of the present application, in the above-mentioned airborne phase-scanning radar SAR mode beam control method, in S23, the radar antenna beam geographic system pitch command angle El_geo_ctr is calculated, specifically:

[0050]

[0051] According to at least one embodiment of the present application, in the above-mentioned airborne phase-scanning radar SAR mode beam control method, in S24, the coordinate system conversion matrix is

[0052] According to at least one embodiment of the present application, in the above-mentioned airborne phase-scanning radar SAR mode beam control method, the third angle threshold is 1°.

[0053] This application has at least the following beneficial technical effects:

[0054] A beam control method for an aircraft-borne phase-scanning radar (SAR) mode is provided. In the spotlight SAR mode, the azimuth beam and the elevation beam can always well cover the center of the imaging area within the same aperture time, thereby ensuring the SAR image quality and azimuth resolution; in the strip SAR mode, the azimuth beam can always well be orthogonal to the imaging track angle, thereby ensuring the SAR image quality and the positioning accuracy of moving targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic diagram of a beam control method of an airborne phase-scanning radar SAR mode provided in an embodiment of the present application;

[0056] Figure 2 is a schematic diagram of processing frame mapping division within the aperture frame time provided by an embodiment of the present application;

[0057] Figure 3 This is a diagram showing the implementation effect of beam control in the airborne phase-scanning radar spotlight SAR mode provided in an embodiment of the present application;

[0058] Figure 4 This is a diagram showing the implementation effect of the strip SAR mode beam control of an airborne phase-scanned radar provided in an embodiment of the present application.

[0059] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be construed as limitations on the present application. DETAILED DESCRIPTION

[0060] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0061] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall have the usual meanings understood by those of ordinary skill in the art to which this application belongs. The words used in the description of this application to indicate orientation are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application indicates that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0062] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0063] Provided is a beam control method for an airborne phase-scanning radar SAR mode, such as Figure 1 As shown, the servo motor is used to control the azimuth beam of the radar antenna to complete the pointing adjustment of the large deflection angle, and the synchronization and proportional relationship between the aperture frame and the processing frame are used to divide the processing frame of the aperture frame time. In the spotlight SAR mode, the inertial navigation longitude, latitude, altitude and the longitude, latitude and altitude data of the imaging area are used to complete the geographic system azimuth and pitch command angle solution of the radar antenna azimuth beam. In the strip SAR mode, the aircraft-borne inertial navigation altitude, imaging distance, and imaging area altitude data are used to complete the geographic system pitch command angle solution. The geographic system azimuth and pitch command angles are transformed into radar system azimuth and pitch command angles through a coordinate system conversion matrix. The difference between the azimuth command angle and the antenna azimuth angle is used to complete the adjustment of the azimuth radio wave beam, and the difference between the pitch command angle and the antenna pitch angle is used to complete the adjustment of the pitch radio wave beam.

[0064] In Spotlight SAR mode:

[0065] S11, real-time reception of inertial navigation data on aircraft 429 bus, including inertial navigation longitude Lon ins , Latitude ins , height H ins , roll γ, pitch θ, heading C and other data.

[0066] S12, using inertial navigation longitude Lon ins , Latitude ins , height H ins and the longitude lon of the imaging area sar , Latitude sar , height H sar The data is used to calculate the geographic azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr of the radar antenna beam in real time by referring to formulas 1 to 10.

[0067]

[0068]

[0069] Detx= (N1+H sar )cos(Lat sar )cos(Lon sar )-(N2+H ins )cos(lat sar )cos(lon sar )...Formula 3

[0070] Dety= (N1+H sar )cos(Lat sar )sin(Lon sar )-(N2+H ins )cos(lat sar )sin(lon sar )...Formula 4

[0071]

[0072] Wayp x = -Detx*sin(Lat ins )cos(Lon ins )-Dety*sin(Lat ins )sin(Lon ins )+Detz* cos(Lat ins )...Formula 6

[0073] Wayp y =-Detx*sin(Lon ins )+Dety*cos(Lon ins )...Formula 7

[0074] Wayp z = Detx*cos(Lat ins )cos(Lon ins )+Dety*cos(Lat ins )sin(Lon ins )+Detz* sin(Lat ins )...Formula 8

[0075]

[0076]

[0077] in:

[0078] R a is the Earth's semi-major axis;

[0079] R b is the Earth's semi-minor axis;

[0080] N1, N2, Detx, Dety, Detz, Wayp x 、Wayp y 、Wayp z It is the intermediate calculation amount.

[0081] S13, transforming the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr into the radar system azimuth initial command angle Az_rd_ctr0 and the elevation initial command angle El_rd_ctr0 through the coordinate system conversion matrix.

[0082]

[0083] in: are the coordinates of the radar system, are the coordinates of the geography department.

[0084] S14. Compare the radar system azimuth initial command angle Az_rd_ctr0 with the radar system mechanical azimuth angle Az_serv. The servo controls the radar antenna through a motor according to the difference delta_Az = (Az_rd_ctr0-Az_serv) to make initial adjustments to the mechanical azimuth angle. Compare the radar system elevation initial command angle El_rd_ctr0 with the radio beam elevation angle El_rd. The beam control module performs initial control of the radio beam elevation pointing according to the difference delta_El = (El_rd_ctr0-El_rd).

[0085] S15. According to the timing relationship between the pulse moment of the nth aperture frame Ap_frame(n) and the pulse moment of the mth processing frame Prc_frame(m), the processing frame mapping division within the aperture frame time is completed. The ratio of the aperture frame period T to the processing frame period t is T=k*t, where k is the ratio of the aperture frame period to the processing frame period. The mapping relationship between the processing frame and the aperture frame is completed. The mth processing frame corresponds to the start of the nth aperture frame, and the m+k-1th processing frame corresponds to the end of the nth aperture frame. Ap_frame(n)-->[prc_frame(m)prc_frame(m+k-1)], as shown in Figure 2 shown.

[0086] S16. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr in real time according to the processing frame period and with reference to formulas 1 to 10, transform the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the radar system elevation command angle El_rd_ctr through the coordinate system conversion matrix of formula 11, compare the radar system azimuth command angle Az_rd_ctr with the radar system azimuth angle Az_rd, and when the difference deltaAz=Az_rd_ctr-Az_rd exceeds the first angle threshold of 30°, the servo controls the radar antenna through the motor to make a rough adjustment on the mechanical azimuth angle, and when the difference deltaAz=Az_rd_ctr-Az_rd is less than the first angle threshold of 30°, no mechanical azimuth angle adjustment is made, and the beam control module is used to make a fine adjustment on the azimuth angle of the electric beam.

[0087] S17. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr in real time according to the processing frame period formulas 1 to 10, transform the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the pitch command angle El_rd_ctr through the coordinate system conversion matrix of formula 11, compare the radar system pitch command angle El_rd_ctr with the radio beam pitch angle El_rd, and when the difference deltaEl=(El_rd_ctr-El_rd) exceeds the second angle threshold of 1°, adjust the radio beam pitch angle by the beam control module, and when the difference is less than the second angle threshold of 1°, do not adjust the radio beam pitch angle.

[0088] In Strip SAR mode:

[0089] S21, real-time reception of inertial navigation data on aircraft 429 bus, including inertial navigation longitude Lon ins , Latitude ins , height H ins , roll γ, pitch θ, heading C and other data;

[0090] S22, receiving the imaging track angle Ang_trace_SARctrl on the control bus in real time.

[0091] S23, calculate the geographic system azimuth command angle Az_geo_ctr with the image track angle Ang_trace_SARctrl, calculate the geographic system azimuth command angle Az_geo_ctr with reference to formula 12 for imaging in the right viewing direction, and calculate the geographic system azimuth command angle Az_geo_ctr with reference to formula 13 for imaging in the left viewing direction, and use the inertial navigation altitude H ins , imaging area height H sar , refer to formula 14 to calculate the radar antenna beam geographic system pitch command angle El_geo_ctr in real time.

[0092] Az_geo_ctrl=Ang_trace_SARctrl+90......Formula 12

[0093] Az_geo_ctrl=Ang_trace_SARctrl-90...Formula 13

[0094]

[0095] S24. The geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr are transformed into the radar system azimuth initial command angle Az_rd_ctr0 and the elevation initial command angle El_rd_ctr0 through the coordinate system conversion matrix of formula 11.

[0096] S25, for imaging in the right viewing direction, the servo controls the mechanical angle of the radar antenna azimuth at the radar system 90° position through the motor, for imaging in the left viewing direction, the servo controls the mechanical angle of the radar antenna azimuth at the radar system -90° position through the motor, compares the initial command angle of the radar system azimuth Az_rd_ctr0 with the mechanical azimuth angle of the radar system Az_serv, and uses the difference delta_Az= The size of Az_rd_ctr0-Az_serv is used to perform initial adjustment of the azimuth pointing of the radio beam. The radar system pitch initial command angle El_rd_ctr0 is compared with the radio beam pitch angle El_bk, and the beam control module performs initial control of the pitch pointing of the radio beam based on the difference delta_El=El_rd_ctr0-El_bk.

[0097] S26. According to the timing relationship between the pulse moment of the nth aperture frame Ap_frame(n) and the alignment of the mth processing frame pulse Prc_frame(m), the processing frame mapping division within the aperture frame time is completed. The ratio of the aperture frame period T to the processing frame period t is T=k*t, where k is the ratio of the aperture frame period to the processing frame period. The mapping relationship between the processing frame and the aperture frame is completed. The mth processing frame corresponds to the start of the nth aperture frame, and the m+k-1th processing frame corresponds to the end of the nth aperture frame. Ap_frame(n)-->[prc_frame(m)prc_frame(m+k-1)].

[0098] S27. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr in real time according to the processing frame period and with reference to formulas 12 to 14, and transform the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the pitch command angle El_rd_ctr through the coordinate system conversion matrix of formula 11. When the side view direction changes (left-side imaging becomes right-side imaging or right-side imaging becomes left-side imaging), the servo controls the mechanical azimuth angle of the radar antenna to 90° or -90° of the radar system through the motor, and compares the radar system azimuth command angle Az_rd_ctr with the radar system azimuth angle Az_rd, and adjusts the azimuth angle of the radio beam according to the difference deltaAz=Az_rd_ctr-Az_rd by the beam control module.

[0099] S28. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr in real time according to the processing frame period and with reference to Formulas 12 to 14, transform the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the pitch command angle El_rd_ctr through the coordinate system conversion matrix of Formula 11, compare the radar system pitch command angle El_rd_ctr with the radar system pitch angle El_rd, and when the difference deltaEl=(El_rd_ctr-El_rd) exceeds the third angle threshold of 1°, adjust the pitch angle of the radio beam by the beam control module; when the difference is less than the third angle threshold of 1°, do not adjust the pitch angle of the radio beam.

[0100] Figure 3 This is the effect diagram of the beam control implementation in the spotlight SAR mode. It can be seen that the antenna azimuth beam at different positions in the same aperture time on the route can always be well focused on the imaging center area. Figure 4 This is the effect diagram of the implementation of beam control in the strip SAR mode. It can be seen that the electric axis of the radar antenna azimuth beam at different positions on the route within the same aperture time can be well orthogonal to the imaging track angle.

[0101] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A beam control method for airborne phase scanning radar SAR mode, characterized in that: For Spotlight SAR mode, these include: S11, real-time reception of inertial navigation data, including inertial navigation longitude Lon ins , Latitude ins , height H ins , roll γ, pitch θ, heading C; S12, using inertial navigation longitude Lon ins , Latitude ins , height H ins and the longitude lon of the imaging area sar , Latitude sar , height H sar Data, to calculate the geographic azimuth command angle Az_geo_ctr and elevation command angle El_geo_ctr of the radar antenna beam; S13, transforming the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr into the radar system azimuth initial command angle Az_rd_ctr0 and the elevation initial command angle El_rd_ctr0 through the coordinate system conversion matrix; S14, compare the radar system azimuth initial command angle Az_rd_ctr0 with the radar system mechanical azimuth angle Az_serv, and the servo controls the radar antenna through the motor according to the difference to make an initial adjustment on the mechanical azimuth angle, and compares the radar system elevation initial command angle El_rd_ctr0 with the radio beam elevation angle El_rd, and uses the beam control module to make an initial control on the radio beam elevation direction according to the difference; S15, according to the timing relationship between the nth aperture frame Ap_frame(n) pulse moment and the mth processing frame pulse Prc_frame(m), the mth processing frame corresponds to the start of the nth aperture frame, and the m+k-1th processing frame corresponds to the end of the nth aperture frame, and the processing frame mapping division within the aperture frame time is performed, wherein k is the ratio of the aperture frame period to the processing frame period; S16. For the 1st to nth imaging apertures, the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr are calculated in real time according to the processing frame period, the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr are transformed into the radar system azimuth command angle Az_rd_ctr and the radar system elevation command angle El_rd_ctr through the coordinate system conversion matrix, the radar system azimuth command angle Az_rd_ctr is compared with the radar system azimuth angle Az_rd, when the difference exceeds the first angle threshold, the servo controls the radar antenna through the motor to make a rough adjustment on the mechanical azimuth angle, when the difference is less than the first angle threshold of 30°, the mechanical azimuth angle is not adjusted, and the beam control module is used to make a fine adjustment on the azimuth angle of the electric beam; S17. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr in real time according to the processing frame period, transform the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the pitch command angle El_rd_ctr through the system conversion matrix, compare the radar system pitch command angle El_rd_ctr with the radio beam pitch angle El_rd, and when the difference exceeds the second angle threshold, adjust the radio beam pitch angle with the beam control module, and when the difference is less than the second angle threshold, do not adjust the radio beam pitch angle.

2. The airborne phase-scanning radar SAR mode beam control method according to claim 1, characterized in that: In S1, the inertial longitude Lon is used ins , Latitude ins , height H ins and the longitude lon of the imaging area sar , Latitude sar , height H sar Data, real-time calculation of the geographic azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr of the radar antenna beam, specifically: Detx= (N1+H sar )cos(Lat sar )cos(Lon sar )-(N2+H ins )cos(lat sar )cos(lon sar ); Dety= (N1+H sar )cos(Lat sar )sin(Lon sar )-(N2+H ins )cos(lat sar )sin(lon sar ); Wayp x = -Detx*sin(Lat ins )cos(Lon ins )-Dety*sin(Lat ins )sin(Lon ins )+Ten* basket(Width ins ); Wayp y =-Detx*sin(Lon ins )+Dety*cos(Lon ins ); Wayp z = Detx*cos(Lat ins )cos(Lon ins )+Dety*cos(Lat ins )sin(Lon ins )+Ten* sin(Lat ins ); in: R a is the Earth's semi-major axis; R b is the Earth's semi-minor axis; N1, N2, Detx, Dety, Detz, Wayp x 、Wayp y 、Wayp z It is the intermediate calculation amount.

3. The airborne phase-scanning radar SAR mode beam control method according to claim 2, characterized in that: In S13, the coordinate system transformation matrix is 4. The airborne phase-scanning radar SAR mode beam control method according to claim 3 is characterized in that: In S16, the first angle threshold is 30°.

5. The airborne phase-scanning radar SAR mode beam control method according to claim 4, characterized in that: In S17, the second angle threshold is 1°.

6. The airborne phase-scanning radar SAR mode beam control method according to claim 5, characterized in that: For Strip SAR mode, it includes: S21, real-time reception of inertial navigation data, including inertial navigation longitude Lon ins , Latitude ins , height H ins , roll γ, pitch θ, heading C; S22, real-time receiving imaging track angle Ang_trace_SARctrl; S23, calculate the geographic system azimuth command angle Az_geo_ctr using the image track angle Ang_trace_SARctrl, and use the inertial navigation altitude H ins , imaging area height H sar , calculate the radar antenna beam geographic system elevation command angle El_geo_ctr in real time; S24, transforming the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr into the radar system azimuth initial command angle Az_rd_ctr0 and the elevation initial command angle El_rd_ctr0 through the coordinate system conversion matrix; S25. For imaging in the right viewing direction, the servo controls the mechanical angle of the radar antenna azimuth at the radar system 90° position through the motor. For imaging in the left viewing direction, the servo controls the mechanical angle of the radar antenna azimuth at the radar system -90° position through the motor. The radar system azimuth initial command angle Az_rd_ctr0 is compared with the radar system mechanical azimuth angle Az_serv. The beam control module performs initial adjustment of the azimuth direction of the radio beam according to the difference. The radar system pitch initial command angle El_rd_ctr0 is compared with the radio beam pitch angle El_bk. The beam control module performs initial control of the pitch direction of the radio beam according to the difference. S26, according to the timing relationship between the nth aperture frame Ap_frame(n) pulse moment and the mth processing frame pulse Prc_frame(m), the mth processing frame corresponds to the start of the nth aperture frame, and the m+k-1th processing frame corresponds to the end of the nth aperture frame, and the processing frame mapping division within the aperture frame time is performed, wherein k is the ratio of the aperture frame period to the processing frame period; S27. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr in real time according to the processing frame period, transform the geographic system azimuth command angle Az_geo_ctr and the elevation command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the elevation command angle El_rd_ctr through the coordinate system conversion matrix, compare the radar system azimuth command angle Az_rd_ctr with the radar system azimuth angle Az_rd, and adjust the azimuth angle of the electric beam according to the difference by the beam control module; S28. For the 1st to nth imaging apertures, calculate the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr in real time according to the processing frame period, transform the geographic system azimuth command angle Az_geo_ctr and the pitch command angle El_geo_ctr into the radar system azimuth command angle Az_rd_ctr and the pitch command angle El_rd_ctr through the coordinate system conversion matrix, compare the radar system pitch command angle El_rd_ctr with the radar system pitch angle El_rd, and when the difference exceeds the third angle threshold, adjust the pitch angle of the radio beam by the beam control module; when the difference is less than the third angle threshold, do not adjust the pitch angle of the radio beam.

7. The airborne phase-scanning radar SAR mode beam control method according to claim 6, characterized in that: In S23, the geographic system azimuth command angle Az_geo_ctr is calculated using the image track angle Ang_trace_SARctrl: For the right viewing direction imaging, Az_geo_ctrl=Ang_trace_SARctrl+90; For the left viewing direction, Az_geo_ctrl=Ang_trace_SARctrl-90.

8. The airborne phase-scanning radar SAR mode beam control method according to claim 7, characterized in that: In S23, the radar antenna beam geographic system pitch command angle El_geo_ctr is calculated, specifically:

9. The airborne phase-scanning radar SAR mode beam control method according to claim 8, characterized in that: In S24, the coordinate system transformation matrix is 10. The airborne phase scan radar SAR mode beam control method according to claim 9, characterized in that: The third angle threshold is 1°.

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