Gamma MSP: Reference Manual

azsp_SLC

(ANSI-C program) azsp_SLC.c

NAME
azsp_SLC - Doppler centroid estimation from SAR range compressed or SLC (single look complex) data.

SYNOPSIS
azsp_SLC <SAR_param> <PROC_param> <SLC_data> <spectrum> [loff] [roff] [nsub] [slc_format]

<SAR_param>	SAR sensor parameter file
<PROC_param>	MSP Processing Parameter File
<SLC_data>	range compressed or SLC input data
<spectrum>	output azimuth spectrum
[loff]	lines offset to start of estimation window (default=0)
[roff]	range samples offset to center of estimation window (enter - for default=center_swath)
[nsub]	number of sub-apertures (default = 8)
[slc_format]	input SLC image format flag (default=0) 0: FCOMPLEX (pairs of 4-byte-float) 1: SCOMPLEX (pairs of 2-byte-short-integer)

EXAMPLE
azsp_SLC ERS1_ESA.par p8560.slc.par 8560.rc 8560.azslc

DESCRIPTION
The azimuth spectrum and Doppler centroid are calculated from the SAR range compressed or SAR SLC data. Summation of spectra obtained with the FFT of azimuth data segments are used to derive estimates of the azimuth power spectrum. The normalized Doppler spectrum energy as a function of the azimuth frequency. This program can be used with range compressed data prior to azimuth compression which is useful for processing of offset video SAR data to determine the shape of the azimuth spectrum.

The number of sub-apertures nsub is the number of blocks of data used to estimate the spectrum. Each block has 512 range lines. The estimate of the shape of the Doppler spectrum improves significantly as the number of blocks is increased up to the length of the synthetic aperture.

The number of spectra averaged in each block is set to 1024 and is taken from the center of the available swath. The user can specify on the command line if the SLC data are FCOMPLEX or SCOMPLEX format data.