Direct signal synchronization for staring passive bistatic radar

Passive bistatic radar that use radar as the illuminator of opportunity are particularly attractive as the waveform is optimized for detecting and locating moving targets. Staring radar with the broad beam transmitter and use of digital waveform overcome typical issues with Passive Bistatic radar (PBR) especially beam chasing with a scanning radar system and obtaining a clean reference for matched filtering. Further, in the absence of any direct synchronization, the local oscillator in each radar is mis-aligned in both time and frequency. In this paper we find the clock frequency and timing offset that can be applied to compensate for the lack of synchronization and propose a method for estimating these in software using the direct signal. Results are presented from real drone flights that show that after compensation the passive bistatic data can match or better the SNR that is achievable with the monostatic data.