Gamma MSP: Reference Manual

SAR Sensor Parameter File

(ASCII file) such as <sensor>.par

NAME
<sensor>.par - contains parameter values describing the SAR sensor used to acquire the SAR raw data. This information is used throughout the SAR processing.

EXAMPLE
ERS1_ESA.par, an existing SAR sensor parameter file for the SAR on the ERS Satellites is used as an example:

title:	ERS-1 C-BAND radar 5.3000 GHZ 15.5500 MHz BW
sensor_name:	ERS-1
chirp_direction:	UP_CHIRP
receiver_adc_mode:	IQ
sample_type:	BYTE
receiver_spectrum_type:	NORMAL
SAR_center_frequency:	5.300000e+09 Hz
chirp_bandwidth:	1.555000e+07 Hz
chirp_duration:	3.712000e-05 s
ADC_sampling_frequency:	1.8962468e+07 Hz
file_header_size:	11644 bytes
record_length:	11644 bytes
record_header_size:	412 bytes
samples_per_record:	5616
antenna_azimuth_3dB_beamwidth:	0.2880 degrees
antenna_range_3dB_beamwidth:	5.4000 degrees
nominal_antenna_azimuth_angle:	90.0000 degrees
nominal_antenna_look_angle:	20.3500 degrees
nominal_platform_pitch_angle:	0.0000 degrees
antenna_pattern_filename:	ERS1_antenna.gain

FORMATS AND DEFINITIONS

The data types are defined in the MSP software include file typedef_MSP.h

title	ascii text description of parameter file
sensor_name	sensor name (ERS-1, JERS-1, ...)
chirp_direction	chirp direction flag values: (UP_CHIRP, DOWN_CHIRP)
receiver_adc_mode	Receiver ADC mode: (REAL, IQ), REAL denotes offset video sampling, while IQ is in-phase/quadrature ADC sampling, 2 samples/point
sample_type	sample type (FLOAT, BYTE), floats are 4 bytes/value and bytes are of type unsigned char, 1 byte/value
receiver_spectrum_type	SAR receiver spectrum: (NORMAL,INVERT), inverted spectrum caused by the receiver L.O. frequency above the chirp signal spectrum.
SAR_center_frequency	carrier frequency for radar (Hz)
chirp_bandwidth	chirp bandwidth (Hz)
chirp_duration	chirp duration (sec)
ADC_sampling_frequency	range analog-digital convertor (ADC) sampling frequency (Hz)
file_header_size	SAR raw data file header size (bytes)
record_length	length of record (echo) in bytes
record_header_size	record header size in bytes
samples_per_record	number of samples/echo (an I/Q pair counts as a single sample)
antenna_azimuth_3dB_beamwidth	azimuth antenna 3 dB (half-power) beamwidth (decimal deg.)
antenna_range_3dB_beamwidth	range antenna 3 dB (half-power) beamwidth (decimal deg.)
nominal_antenna_azimuth_angle	nominal azimuth antenna angle (including average. squint for simulation) (decimal degrees CW about N, right looking SAR 90.0, left looking: -90.0)
nominal_antenna_look_angle	nominal antenna look angle (decimal degrees CW (includes ave. roll for simulation) about the final T axis, rotation dependent on right or left looking
nominal_platform_pitch_angle	nominal platform pitch angle, CW rot. about the temp. C axis, nose up is +
antenna_pattern_filename	antenna pattern filename (relative to peak, one-way gain) (not in dB!)

COORDINATE SYSTEM FOR AZIMUTH, LOOK AND PITCH ANGLES:
N = DOWN
C = N x V /|N x V|
T = C x N
ROLL is measured about T axis CW + (right wing down)
PITCH is measured CW about the temp C axis (nose up +)
YAW is measured CW about +N axis (looking down).

DESCRIPTION
<sensor>.par - contains parameter values for SAR Sensor used throughout the interferometric data processing. This file does not change for JERS-1 and varies slightly for different processing and archive facilities for ERS. For Radarsat and SIR-C this file is created for each new processing run because of the large number of modes supported by each radar. <sensor>.par - is either taken from the existing SAR sensor parameter files or generated using create_sar_par. The formats used in <sensor>.par are defined in the in MSP type definition file typedef_MSP.h.

OPTIONS
The values of the SAR sensor parameter file <sensor>.par may be displayed together with the definitions using create_sar_par. This file can also be modified using a text editor.