Advances on the Frequency Scan for Time-of-Echo Compression Synthetic Aperture Radar Imaging Mode

Abstract

The Frequency Scan for Time-of-Echo Compression (f-STEC) imaging mode uses a narrow beam, the steering angle of which is a function of the transmitted frequency. The bandwidth of the system is utilized to scan the beam over the swath from far to near range, resulting in a compression of the echo in the time domain. By distributing the frequency spectrum over the imaged swath f-STEC effectively trades (worsens) range resolution for (improved) swath width and signal-to-noise ratio. This paper derives an expression relating the instantaneous frequency to the echo arrival time, which is then used to explore the f-STEC timing and nadir echo constraints, enabling imaging under timing constraints that conventional pulsed SAR systems cannot accommodate. Further, findings about the optimization of the data rate are reported.