A real-time reconfigurable timing and control unit for Synthetic Aperture Radar

Synthetic Aperture Radar (SAR) is one of the variant of active remote sensing whereby it transmits energy and measures the return signal to obtain ground information. SAR is typically mounted on a moving platform such as an aircraft or a spacecraft. In this work, the SAR system is mounted on a small Unmanned Aerial Vehicle (UAV). One of the main obstacles faced by the UAV SAR is its instability during flight mission which causes motion errors. Theoretically, a SAR system modelling assumes that all flight path parameters (such as velocity, altitude and heading angle) are constants in generating SAR images. This would mean that ideally, the ground sampling length in between each transmission is also constant. However, this is never true in real case. These motion errors are mainly caused by wind turbulence, drag or limitations of the aircraft itself. Of all motion errors, one of the most unavoidable motion errors is the variance in velocity of the aircraft during flight which subsequently causes uneven sampling length. Velocity error causes defocussing of SAR imaging. Image with velocity error would have a “stretched” like effect in the azimuth profile