Double-base SAR (Synthetic Aperture Radar) synchronization-free echo focus imaging method based on direct wave
A bistatic, direct-wave signal technology, applied in radio wave reflection/re-radiation, radio wave measurement systems, special data processing applications, etc., can solve problems affecting imaging processing, complex time synchronization and phase synchronization, and inability to obtain transmitters Orbit parameters and other issues, to achieve the effect of precise focus imaging and fast rough imaging
Active Publication Date: 2014-05-07
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology
[0008] In the actual passive SAR system of spaceborne radiation source, the space synchronization can be controlled through the coordination between the transmitter and the receiver, but the problems of time synchronization and phase synchronization are more complicated, and if the synchronization problem is not solved, then Will affect the next step of imaging processing
[0009] Since it is often impossible to obtain accurate transmitter orbit parameters, oblique angles and other parameters in practice, it is impossible to synchronize the target echo
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[0029] The method of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.
[0030] The experimental system works in the mode of bistatic one station fixed (receiver fixed), and the following parameters are set: the transmitter oblique angle is θ, and the azimuth Doppler center frequency is f dc , the azimuth Doppler modulation frequency is f dr , the operating speed of the transmitter is V, the operating wavelength of the transmitter is λ, and the pulse width of the transmitted signal is T p , c is the speed of light, and the modulation frequency of the quadratic range compression matched filter is k src , the sum of the two-station distance of the target is R, and the sum of the two-station distance of the target at the center of the azimuth is R 0 , the azimuth time is η, and the azimuth frequency is f η , the pulse repetition frequency is PRF, and the transmitted signal is a chirp signal s(t)=ex p...
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The invention provides a double-base SAR (Synthetic Aperture Radar) synchronization-free echo focus imaging method based on a direct wave. The method is characterized by comprising the following steps of: setting M squint angles theta and N Doppler center frequencies fdc; selecting one squint angle and the N Doppler center frequencies fdc to form N secondary matched filters to carry out secondary distance compression on target echoes so as to obtain an optimal Doppler center frequency fdc_best; forming M secondary matched filters by the optimal Doppler center frequency fdc_best and the M squint angles theta to carry out the secondary distance compression on the target echoes to obtain an optimal squint angle theta_best; utilizing to forming an optimal secondary matched filter by utilizing the optimal Doppler center frequency fdc_best and the optimalsquint angle theta_best to realize the secondary distance compression on the target echoes; and carrying out further treatment on the compressed target echoes to obtain an SAR ground distance image. According to the method disclosed by the invention, under the conditions of time synchronization and phase synchronization of releasing complexity of echo data, a target image is rapidly obtained.
Description
technical field [0001] The invention relates to a direct wave-based bistatic SAR non-synchronous echo focusing imaging method, which belongs to the technical field of synthetic aperture radar data processing. Background technique [0002] Compared with monostatic radar, bistatic radar has the advantages of flexible configuration, rich information acquisition, anti-interception and anti-interference due to the special configuration of bistatic radar. These advantages and application prospects have made bistatic radar more and more popular in recent years. favor. Bistatic radar includes a variety of configuration modes. According to the type of transceiver platform, it mainly includes space-borne bistatic SAR, airborne bistatic SAR, star-machine bistatic SAR, ground-machine bistatic SAR, etc. [0003] Passive SAR based on spaceborne radiation sources is one of the research hotspots at home and abroad. The system has many advantages, especially low implementation cost and di...
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IPC IPC(8): G01S13/90G01S7/41G06F17/50
Inventor 曾涛胡程吴立薪刘飞峰倪崇
Owner BEIJING INSTITUTE OF TECHNOLOGYGY