6.2.3 gpri2_proc.py
Takes a GPRI2 echo data and process to SLCs for channel-1 and channel-2.
In the case that the data are acquired with alternating transmit polarization (C-
Band only) then the user can specify the transmit polarization. The two SLCs are
then obtained with from the data where the specified transmit polarization was
used. The names of the SLC will include either H or V prior to the extension
eg. 20110707_115716Hu.slc was acquired with H transmit polarization from the upper
receiver channel. Upper and lower refer to the RX channels on the side of the RFA.
Usage: gpri2_proc.py: [raw_data] [raw_par] [slc1] [slc2] options
Process GPRI-2 raw data to SLCs v2.1 27-July-2011 clw
Options:
--help show this help message and exit
-F DATA_TYPE, --data-type=DATA_TYPE
Specify the data type (float32, int16)
[default=int16]
-z ZERO, --zero=ZERO Number of samples to weight at the start of the echo
[default=300]
-d DEC, --decim=DEC Raw data decimation factor to apply [default=1]
-R RMAX, --rmax=RMAX Maximum SLC slant range (meters), default is 0.9 of
the aliasing slant range for the chirp
-r RMIN, --rmin=RMIN Minimum SLC slant range (meters) [default=50.0]
-a, --ati Turn off azimuth interpolation, required for Along-
Track Interferometry [default=False]
-e, --little_endian Generate little-endian SLCs, Gamma Software default is
big-endian [default=False]
-h HEADING Heading of radar boresight clockwise from North (deg.)
[default=0.0]
-k KBETA Kaiser Window beta parameter [default=3.0]
-t TX_ANTENNA Specify TX antenna for C-band data acquired in HV mode
(H,V): [default=V]
Input to the program are the raw data and raw_par parameter files. Output are the
SLC images slc1 and slc2 from each of the two channels. The user enters the names
of the SLCs as the parameters slc1 and slc2. Two SLC meta data files are also
created with extension .par.
20110715_105720u.slc 20110715_105720u.slc.par
20110715_105720l.slc 20110715_105720l.slc.par
The starting slant range RMIN for the SLC images is by default 50 meters. The
r
parameter command
line parameter can be set to about 5 meters,
r 5
The maximum slant range in the SLC is given by the
-R
RMAX
command line parameter. The
maximum slant range possible for a particular chirp is determined by the chirp length, the ADC
sampling rate and the chirp bandwidth. Since we are using the full 200 MHz bandwidth for each chirp,
the pixel spacing is fixed at
delta_r = 0.75m
. The maximum possible range
R_MAX
for a particular
chirp duration
t_c
is given by:
R_MAX = 0.9 * t_c * 3.125e6 * delta_r
Hence for a 2ms chirp the maximum possible slant range is 4.218 km.
