RISAT-1

Long name	Radar Imaging Satellite 1 (RISAT-1)
Short name	RI1
Sensor type	Synthetic-aperture radar (SAR)
Platform	RISAT-1
Frequency	5.35 GHz
Band (wavelength)	C (5.3 cm)
Polarization	HH, HV, VH, VV, RH, RV (Fully polarimetric and compact polarimetric)
Key file name (use to open data set)	BAND_META.txt
Supported file extensions	.txt, .tif, *.dat
Data distributor	Indian Space Research Organization (ISRO)
Sections	Data product name and description Distribution disk files Returned data for supported format References

Data product name and description

RISAT-1 has five acquisition modes. Each is described in the proceeding tables.

Note: The information provided herein is based on the RISAT-1 reference documentation cited under References.

Mode	Swath width (km)	Resolution (range x azimuth, m)*	Polarization	Description/notes
High Resolution Spotlight [HRS]	10	0.67 x 1.0	Single (HH or HV or VV or VH) Dual (HH+HV or VV+VH) Circular (RV + RH)	In the sliding-spotlight mode, the antenna beam is oriented continuously to illuminate a particular 10-by-100 kilometer sliding spot on the ground, which can be imaged at a resolution of 1 meter.
Fine Resolution Stripmap [FRS-1]	25	2.2 x 3.3	Single (HH or HV or VV or VH) Dual (HH+HV or VV+VH) Circular (RV + RH)	Based on conventional mode of SAR Stripmap imaging.
Fine Resolution Alternate Polarization Stripmap [FRS-2]	25	4.0 x 3.0 (circular) 4.7 x 10.0 (quad)	Circular (RV + RH) Quad (HH+HV+VH+VV)	This mode is a hybrid of Stripmap and ScanSAR.
Medium Resolution ScanSAR [MRS]	115	8.8 x 24.0	Circular (RV + RH) Quad (HH+HV+VH+VV)	Six-beam ScanSAR mode.
Coarse Resolution ScanSAR [CRS]	220	8.8 x 48.0	Single (HH or HV or VV or VH) Dual (HH+HV or VV+VH) Circular (RV + RH)	Twelve-beam ScanSAR mode.

* Resolution is always single-look complex (SLC) unless noted otherwise.

Processing level	Acquisition mode	Description/notes
Raw	Not supported	N/A
1 Single-look complex (SLC)	[FRS-1] [FRS-2] [MRS]	CEOS format. Geometry: Slant range
1 Ground-range detected (GRD)	[FRS-1] [MRS] [CRS]	CEOS format. Geometry: Ground range
2 Terrain georeferenced	[FRS-1] [MRS] [CRS]	CEOS and GeoTIff formats. Geometry: Ground range
2 Enhanced terrain georeferenced	[FRS-1] [MRS] [CRS]	CEOS and GeoTIff formats. Geometry: Ground range

Distribution disk files

RISAT-1 data products are distributed in CEOS and GeoTIFF formats, both of which are supported in CATALYST Professional.

Warning: Data sets for this sensor are organized in a specific folder structure on disk. GDB uses this structure and the file names to identify the data product type. Do not alter the folder structure or any file names prior to data ingestion to ensure the image data and auxiliary information are imported correctly.

Table 1. CEOS
File name	Format	Required	Contents/details
BAND_META.txt	ASCII	Yes	Key file name. Contains metadata that applies to the data set.
*_grid.txt	ASCII	Yes	Table of ground control points (GCP), slant-range distance, and incidence angles. One grid file per polarization.
dat_01.001	Product-specific binary	Yes	SAR image data. One file per polarization.

Table 2. GeoTIFF
File name	Format	Required	Contents/details
BAND_META.txt	ASCII	Yes	Key file name. Contains metadata that applies to the data set.
*_grid.txt	ASCII	Yes	Table of ground control points (GCP), slant-range distance, and incidence angles. One grid file per polarization.
*.tif	GeoTIFF	Yes	Image data. One GeoTIFF file per polarization.

Returned data for supported format

RISAT-1 data can be opened directly in its raw vendor format or imported into a PCIDSK (*.pix) file using the key file (BAND_META.txt). For optimal processing, use the PCIDSK format.

In the following table, the data structure after it is imported into a PCIDSK file is described.

Data product	Data returned	Details
Level 1 Single-look complex (SLC), single polarization [FRS-1]	1 x [C32R] Raster channel 1x [GCP] GCPs from grid file 1 x [ORB] Orbit segment 1 x [ARR] Incidence angle array	Data calibrated in sigma nought.
Level 1 Single-look complex (SLC), dual and circular polarization [FRS-1] [FRS-2]	2 x [C32R] Raster channels 1x [GCP] GCPs from grid file 1 x [ORB] Orbit segment 1 x [ARR] Incidence angle array	Data calibrated in sigma nought.
Level 1 Single-look complex (SLC), quad polarization [FRS-2]	4 x [C32R] Raster channels 1x [GCP] GCPs from grid file 1 x [ORB] Orbit segment 1 x [ARR] Incidence angle array	Data calibrated in sigma nought.
Level 1 Ground-range detected (GRD), single polarization [FRS-1] [MRS] [CRS]	1 x [32R] Raster channels 1x [GCP] GCPs from grid file 1 x [ORB] Orbit segment 1 x [ARR] Incidence angle array	Data calibrated in sigma nought.
Level 1 Ground-range detected (GRD), dual and circular polarization [FRS-1] [MRS] [CRS]	1 x [32R] Raster channels 1x [GCP] GCPs from grid file 1 x [ORB] Orbit segment 1 x [ARR] Incidence angle array	Data calibrated in sigma nought.
Level 2 Terrain georeferenced	1 x [32R] Raster channels 1x [GCP] GCPs from grid file	Data calibrated in sigma nought.
Level 2A Enhanced terrain georeferenced, single polarization [FRS-1] [MRS] [CRS]	1 x [32R] Raster channels 1x [GCP] GCPs from grid file	Data calibrated in sigma nought.
Level 2 Terrain georeferenced, dual and circular polarization	2 x [32R] Raster channels 1x [GCP] GCPs from grid file	Data calibrated in sigma nought.
Level 2A Enhanced terrain georeferenced, dual and circular polarization	2 x [32R] Raster channels 1x [GCP] GCPs from grid file	Data calibrated in sigma nought.

References

RISAT-1 Data Products Format V1.4 (September 2015). SAC/ISRO. 66 pages.

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