ANSI-C program: SLC_ovr.c
NAME
SLC_ovr - oversample or subsample SLC data in range
SYNOPSIS
SLC_ovr <SLC> <SLC_par> <SLC_ovr>
<SLC_ovr_par> <r_ovr>
| <SLC> | (input) SLC file (fcomplex or scomplex) |
| <SLC_par> | (input) SLC parameter file of SLC file and point list
coordinates |
| <SLC_ovr> | (output) SLC file (fcomplex or scomplex) |
| <SLC_ovr_par> | (output) SLC parameter file of SLC file and point list
coordinates |
| <r_ovr> |
integer range oversampling factor (2 --> 16) if r_ovr < 0, the SLC will be subsampled integer range subsampling factor (-2 --> -16) |
EXAMPLE
SLC_ovr 09042.slc 09042.slc.par 09042_2.slc 09042_2.slc.par
2
Obtain a range oversampled version of 09042.slc with an
oversampling factor of 2. The output is stored in 09042_2.slc and
the associated parameter file in 09042_2.slc.par
INSTALLATION
Source code SLC_ovr.c in $ISP_HOME/src, executable version
SLC_ovr in $ISP_HOME/bin
DESCRIPTION
Range oversampling has several advantages for interferometric
processing. In situations where a range spectrum shift has
occurred due to high deskew, oversampling is required to ensure
that the baseband SINC interpolation used in the ISP programs
SLC_interp, SLC_interp_map,interf_SLC.c functions optimally. In any
case, range oversampling prior to resampling the images for
interferogram generation is expected to improve the performance
of the SINC interpolation. The valid range of oversampling
factors is integer values between 2 and 16.
Range oversampling is performed using an FFT combined with a
bandpass filter centered on the range frequency centroid.
Nominally this is a DC (f =0), but when the image has been
deskewed, the image is no longer at baseband and requires a
bandpass interpolation rather than a lowpass response.
Output SLC image parameters are also adjusted including the
effective range pixel spacing, number range samples, and
effective ADC rate. The range pixel spacing and the number of
range pixels in output SLC image parameter file are adjusted for
the range oversampling factor entered on the command
line.
For most applications range oversampling of 2 is recommended.
For IPTA, range oversampling helps in obtaining improved
localization of the point targets within the resolution
element.
If the range oversampling factor is set to a negative integer
the data are subsampled by that factor.
OPTIONS
none.
SEE ALSO
SLC_interp, SLC_interp_map, interf_SLC.c
© Copyrights for Documentation, Users Guide and Reference Manual by Gamma Remote Sensing, 2004.
UW, CW,TS,
last change 10-Aug-2004.