PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2015-09-17, Version 1.1" RECORD_TYPE = STREAM OBJECT = DATA_SET DATA_SET_ID = "CO-SSA-RADAR-5-STDR-V1.0" OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = CO INSTRUMENT_ID = RADAR END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_INFORMATION ABSTRACT_DESC = "N/A" ARCHIVE_STATUS = "ARCHIVED - ACCUMULATING" CITATION_DESC = "N/A" DATA_OBJECT_TYPE = TABLE DATA_SET_COLLECTION_MEMBER_FLG = "N" DATA_SET_NAME = " CASSINI ORBITER SSA RADAR 5 STDR V1.0" DATA_SET_RELEASE_DATE = 2015-12-17 DATA_SET_TERSE_DESC = " The Cassini SARTopo product contains surface heights estimates (and related measurements) of Titan in profiles between two SAR beams within a single SAR image. " DETAILED_CATALOG_FLAG = "N" PRODUCER_FULL_NAME = "Bryan W. Stiles" START_TIME = 2015-260T16:19:10.828 STOP_TIME = "NULL" CONFIDENCE_LEVEL_NOTE = " * Confidence Level Overview The SARTopo data product has been produced using BIDR data sets that have been calibrated. Empirical range and doppler corrections have been applied to BIDR product being used in order to minimize image artifacts due to errors in pointing and emphemeris knowledge. * Review SARTopo data will be validated internally by the Cassini Radar Team prior to each release of data to the PDS. The overall data set organization will also be peer reviewed once by the PDS prior to the release of the first volume. * Data Coverage and Quality Currently 20 SAR observations comprising roughly 20% of the surface of Titan are planned for the nominal Cassini mission. BIDR data will be obtained for each such observation. SAR observations of Titan occur at irregular intervals throughout the mission. Each observation is nominally 40 minutes long. Shorter-duration cases occur whenever RADAR shares a Titan observation with another Cassini instrument. SARtopo data will be available for observations that have BIDR data. The SARtopo file contains estimated surface heights (and related measurements) of Titan in profiles between two SAR beams within a single SAR image. SARTopo files will only be produced for Titan flybys that have SAR imaging. * Limitations Ephemeris error is expected to improve throughout the mission. Since there is no plan to recompute the ephemeris of previous observations as new measurements are obtained, however, earlier observations may have poorer location accuracy. The dominant calibration error term is error in our knowledge of the gain of the attenuators in the receiver. Engineering tests are currently planned to improve our knowledge of the attenuator gains. SAR images are prone to artifacts such as: 1) poor calibrations at the edge of the beams 2) extreme noisiness in regions with a small number of overlapping measurements (looks) 3) scalloping and antenna calibration misalignment due to errors in ephemeris and pointing knowledge 4) distorted imagery near the ends of the swath due to non-optimal pointing while turning to make altimeter measurements. Artifacts of type 2 and 4 are unavoidable. Types 1 and 3 can be minimized by empirically correcting range and doppler biases in the data. We have sought to minimize the occurrence of these artifacts in the BIDR images, but there are still noticeable seams between beams and poor calibration near the edges of the swath. The artifact minimization algorithm does not attempt to use the estimated range and doppler biases to correct ephemeris or pointing. For this reason location errors of a few kilometers are possible. The TA Titan Observation on October 25, 2004, was the first SAR observation. It has some special features. The first (earliest) third of the swath has noticeable scalloping in the along track dimension and is noisier than the rest of the image. This portion of the swath has non-optimal viewing geometry and a small number of looks due to pointing constraints for other Cassini instruments. A substantial portion of the last (latest) third of the swath is in low resolution SAR mode. This mode coarsens the cross track resolution of the image by a factor of 2. It was used on TA in order to accommodate conservative SNR expectations. In the same region of the image, an experiment was performed in which the data compression technique typically used by SAR was turned off. Due to data volume and data rate constraints this resulted in fewer looks and noisier data. " DATA_SET_DESC = " * Data Set Overview The SARTopo file contains surface height estimates in profiles between two SAR beams. Each row in the file contains height estimates and ancillary data that correspond to a set of pixels in the BIDR image. For more information about the format and content of the SARTopo files, see the Cassini Radar Burst Ordered Data Product (BIDR) Software Interface Specification, JPL D-27899. A copy of the document is located on this volume as file BIDRSIS.PDF in the DOCUMENT directory. * Parameters A complete listing of the parameters can be found in the SIS. * Processing The encoded raw active mode data in the Burst Ordered Data Product (LBDR) files is decoded and processed into SAR images by the Cassini RADAR Instrument Team. Each of the five beams is treated separately by typical SAR processing (azimuth and range compression). The image strip is then produced by selecting the best beam for each pixel. The selection is performed by choosing the beam with the most looks. In the event of a tie the highest SNR beam is chosen. The pixel values in the primary BIDR images will be normalized backscatter cross-section values corrected for incidence angle effects. The incidence angle correction algorithm is TBD and will be determined jointly by the Cassini RADAR Instrument and Science Teams after enough data is acquired to estimate the variation of sigma0 due to incidence angle over the surface of Titan. Until the final correction algorithm is determined, the primary BIDR image will be computed with a preliminary incidence angle correction. The exact form of this correction can be found in the PDS label for the primary BIDR image file. These BIDR files are used to generate SARTopo files (CSV format) that contain height estimates of Titan in profiles between two SAR beams within a single SAR image. Each row in the file contains height estimates and ancillary data that correspond to a set of pixels in the BIDR image. A seperate SARTopo file is produced for each SAR beam overlap profile. The SARTopo implementation yields 1-5 profiles in each SAR pass that are 10 km by 1000s of km long. * Data See Parameters. * Ancillary Data There are no ancillary data needed to use the SARTopo files. * Coordinate System The oblique cylindrical coordinate system is fully described in the data set map projection catalog DSMAP.CAT, which is located in the CATALOG directory on this volume. * Software No software is provided within this volume. * Media/Format The data are provided on media as determined by PDS. The BIDR data files are ZIPPED as described in the PDS standard. Detached labels are provided for the ZIPPED files; the ZIPPED files also include their attached labels. Detailed formats are defined within the attached labels of the files and in the Cassini Radar Basic Image Data Record Software Interface Specification. " END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_MISSION MISSION_NAME = "CASSINI-HUYGENS" END_OBJECT = DATA_SET_MISSION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ELACHIETAL2005" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "ELACHIETAL2004" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "STILESETAL2009" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LUCIANOETAL2010" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "LORENZETAL2013" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = TITAN END_OBJECT = DATA_SET_TARGET END_OBJECT = DATA_SET END