GB-SAR deformation monitoring method based on triple stepping

Abstract

The invention provides a GB-SAR deformation monitoring method based on triple stepping. According to radar system design, GB-SAR based on triple stepping is utilized for deformation measurement; for first stepping, stepped frequency continuous wave (SFCW) signals are employed to synthesize large signal bandwidth, isolation is improved through transceiver antenna separation; for second stepping, a radar device is mounted on a linear guide rail and does stepping motion in a stop-go-stop mode, orientation resolution is improved through relatively large aperture synthesis, signals are emitted and received by the radar device in stop periods, so a phase error caused by signal transceiving in motion periods is avoided; for third stepping, radar device antennas do stepping motion sequentially along the orientation, a relatively wide monitoring area is covered, and data at different antenna positions are spliced and are used for imaging processing. Imaging processing on acquired data is carried out based on echo signal characteristics of the GB-SAR system, compensation for an instantaneous slant range difference between pulses is not necessary, computational complexity is relatively low, and timeliness requirement of the GB-SAR system can be satisfied.

Description

technical field [0001] The invention relates to a synthetic aperture radar SAR imaging technology. Background technique [0002] Stepped Frequency Continuous Wave (Stepped Frequency Continuous Wave, SFCW) GB-SAR (Ground-Based SAR) is a ground-based synthetic aperture imaging radar placed on orbit, which obtains large bandwidth and high distance by continuously transmitting and receiving stepped frequency continuous wave signals Through the stepping movement of the radar on the guide rail, the large aperture and high azimuth resolution are synthesized, and the deformation or micro-displacement measurement value of the target is obtained through the imaging of the two movements for interference processing. Since the radar and the guide rail are installed on a fixed The position can be continuously measured with high precision to realize the monitoring of specific areas or targets, and early warning of possible natural disasters or infrastructure dangers. The radar system has ...

AI Technical Summary

Problems solved by technology

[0004] The difficulty of GB-SAR deformation monitoring radar lies in: (1) Affected by factors such as field operations, installation and cost, the track for placing the radar cannot be too long, but if the track is too short, the length of the synthetic hole will be small, the azimuth resolution will be low, and the azimuth resolution will be low. The size of the unit in the direction is large, resulting in a rough deformation map, which cannot reflect the specific deformation position

Reducing the radar wavelength can also improve the azimuth resolution, but if the wavelength is too short, it will be sensitive to meteorological conditions, reduce the measurement distance and increase the atmospheric phase error

(2) To improve the range resolution, a large signal bandwidth is required, and the cost of conventional pulse SAR is relatively high, and its imaging algorithm cannot be used for stepping frequency continuous wave radar

(3) The monitoring range is a fan-shaped area centered on the radar. Usually, the beam width of the antenna azimuth is only a few degrees, resulting in too small a monitoring area, and only strip area monitoring can be done.

Reducing the antenna size can increase the beam width. For example, when the beam width is 1 radian or 57.3°, the antenna size is only equivalent to the wavelength. Too small antenna size will result in reduced antenna gain and poor performance

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