No Math: Bistatic SAR Processing Using Numerically Computed Transfer Functions

Standard SAR processing algorithms use analytically derived transfer functions in the 2-D frequency and the range- Doppler domains. These rely on the assumption of hyperbolic range histories of monostatic SARs on straight flight paths. A moderate deviation from these conditions can often be handled satisfactorily by a range-variant velocity parameter. However, bistatic SARs with considerable separation between transmitter and receiver can no longer be approximated accurately enough by hyperbolic range histories. In [1] we have presented an alternative approach, NuSAR. We suggested using numerically computed transfer functions for bistatic SAR processing. We presented the idea and gave hints on how to compute the three transfer functions required for SAR processing. In this paper we present bistatic simulation results with the NuSAR algorithm. It is shown, that NuSAR works well even in extreme bistatic configurations, as long as we restricted ourselves to quasi-stationarity, i.e. where the velocity vectors of receiver and transmitter are similar enough that we may assume the point response function to be sufficiently azimuth-invariant within a single azimuth processing block.