Gamma ISP: Reference Manual

az_spec_SLC

ANSI-C program: az_spec_SL

NAME
az_spec_SLC - computes azimuth doppler spectrum and Doppler centroid from SLC data.

SYNOPSIS
az_spec_SLC <SLC> <SLC_par> <spectrum> [roff] [namb]

<SLC>	single-look complex (SLC) SAR data file (fcomplex or scomplex SLC format)
<SLC_par>	SLC parameter file
<spectrum>	output Doppler spectrum (text format)
[roff];	range sample offset to center of estimation window (enter - for default=center_swath)
[namb];	number of multiples of the PRF to add to the estimated centroid (default=0)

EXAMPLES
az_spec_SLC 19990915.slc 19990915.slc.par 19990915.az_spec

DESCRIPTION
az_spec_SLC reads SLC data (both fcomplex and scomplex format) and the ISP SLC image parameter file. and computes the azimuth Doppler spectrum and the Doppler centroid from SLC data. The azimuth Doppler spectrum is written to a text file for plotting using gnuplot. During execution the user is queried if the Doppler centroid currently in the SLC parameter file (should be replaced by the estimate derived from the SLC data.

To plot the azimuth spectrum in PNG format:

echo "set term png; set output '19990915.az_spec.png';set grid; set xlabel 'Hz'; set ylabel 'Relative Power'; set title 'Azimuth Spectrum'; plot '19990915.az_spec' with lines lw .5 "|gnuplot

This program estimates the constant component of the Doppler centroid. The Doppler centroid of data produced by Radarsat-1 or JERS-1 vary from near to far range. The user can vary the position of the estimate from near to far range using the roff command line parameter. Estimating the centroid in the near and far range can be used to confirm the slope and centroid values contained in the SLC metadata. The namb option can be used to add a number of multiples of the PRF to centroid estimate.

SEE ALSO
typedef_ISP.h, SLC_par.