Ultra high resolution spaceborne SAR processing with EETF4

The performance of the EETF4 (extended exact transfer function 4th order) SAR processing algorithm is investigated. 1-D ETF analysis is used to show that the spaceborne SAR processing approach has to be used when the resolution is less than 1 m, especially with increasing squint angles. Phase differences for a spaceborne INSAR are estimated and used as input to the inverse-EETF4 and then the simulated raw data are processed with EETF4 using 1 block with squint 20 degrees and 0.3 m resolution. Point targets are processed with 40 degrees squint for one block of size 1100 range pixels. It is indicated that multi-block processing with block size 565 range pixels at extreme Doppler centroid variation works properly up to 10 degrees squint. Point targets with resolution 0.3 m were also processed with an erroneous satellite speed of 0.07 m/s, which causes visible degradation.