US Patent 10955546 Synthetic aperture radar imaging apparatus and methods

A synthetic aperture radar (SAR) is operable in an interrogation mode and in a self-imaging mode, the self-imaging mode entered in response to determining a response to interrogation pulses have been received from a ground terminal and position information specifying a ground location has been received from the ground terminal. A ground terminal is operable to receive interrogation pulses transmitted by a SAR, transmit responses, and transmit position information to cause the SAR to enter a self-imaging mode. The ground terminal receives first and subsequent pulses from the SAR where subsequent pulses include backscatter and are encoded. The ground terminal generates a range line by range compression.