and -m options. If the user desires, the raw data can then be deleted (-x option) in order to save disk
space. The SLC images are typically about 10% the size of the raw data due to data decimation
performed by the processor.
The raw data files include the UTC time in the file name in the format YYYYMMDD_HHMMSS.raw
For each RAW data file there is also a RAW_PAR file with the same root name and the extension
“raw_par”.
The time-stamp for data acquisition in the command line must be provided in ISO 8601 format as
THH:MM:SS (example T10:11:58) or type now to start the first scan right away.
Important to note is the -a option. Nominally the processor performs a frequency dependent azimuth
interpolation to compensate for the the antenna frequency dependent squint angle. This option turns off
this interpolation step for data acquired with a constant azimuth angle.
6.1.2 gpri2_capture.py
This program acquires a single GPRI2 raw data set. Input used to specify the operating parameters of
the acquisition are stored in a parameter file called a “profile”. This profile is organized as keyword
value pairs and described in Section 6.6.1 . There are template profiles (*.prf) for different duration
chirps (250us, 500us, 1ms, 2ms, 4ms, and 8ms).
*** GPRIII data capture program v2.0 12Jul2011
Usage: gpri2_capture.py: [options] p profile o output_filename
Options:
h, help show this help message and exit
e INTERFACE, interface=INTERFACE
use specified Ethernet interface [default=eth0]
m MAC_ADDR, macaddr=MAC_ADDR
use USRP2 at specified MAC address [default=None]
f FREQ, freq=FREQ set frequency to FREQ
d DECIM, decim=DECIM
set fgpa decimation rate to DECIM [default=16]
g GAIN, gain=GAIN set USRP2 gain in dB (default is midpoint)
K SCALE, scale=SCALE
set rx input scaling of usrp2, scale_iq (default is
1024)
S SHIFT, shift=SHIFT
set rx output shifting of usrp2, shift_iq (default is
0). Allowed values 0, 1, 2 and 3
looffset=LO_OFFSET
set daughterboard LO offset to OFFSET [default=hw
default]
rxbufsize=RX_BUFSIZE
set rx buffer size to RX_BUFSIZE [default=0]
N NSAMPLES, nsamples=NSAMPLES
number of samples to capture [dinf]
T CAPTURE_DURATION, captureduration=CAPTURE_DURATION
number of seconds to capture [dinf]
o OUTPUT_FILENAME, outputfilename=OUTPUT_FILENAME
output filename for captured samples [default=None]
