ENVISAT ASAR data reduction: impact on SAR interferometry

An onboard synthetic aperture radar (SAR) signal-data reduction algorithm called Flexible Block Adaptive Quantization (FBAQ) was developed in 1994 for the Advanced SAR (ASAR) on the ENVISAT satellite. This paper presents work done in a follow-on study that examined the impact of the data-reduction algorithm on the accuracy of two digital elevation models (DEM) produced by using the technique of repeat-pass SAR interferometry. All three allowable data compression ratios were investigated to determine the maximum compression ratio appropriate for SAR interferometry. Based on the scenes studied it was concluded that a reduction from 8 to 4-bits/sample was the maximum data reduction ratio appropriate for precision SAR interferometry, while 8 to 3-bits/sample and 8 to 2-bits/sample encoding were only appropriate for less-demanding wide-swath applications.