SARTREK Newsletter: June 2001

In This Issue:

1. SAR-based Technical Solutions for Agriculture Markets
2. Operations Update
3. Did You Know

SAR-based Technical Solutions for Agriculture Markets

One of RADARSAT International's key strategies moving forward is the creation and introduction of SAR-based information services to new worldwide markets. Based on our experience, Agriculture appears to hold strong potential for these services and for RADARSAT-2.

When referring to the agricultural sector, we are including both private and government organizations in the following areas:

• Seed/fertilizer companies
• Food processors
• Agricultural consultants
• On-line agricultural services (including the IT and web companies)
• Crop insurance companies
• Grower organizations
• Governments (compliance monitoring and policy development)

Our business development research has revealed that the information these organizations require is broad and includes

• Crop acreage and crop type
• Soil moisture (irrigation scheduling, crop forecast models)
• Weather information (e.g. hail alerts and warnings)
• Pest -watch information, alerts, and reports
• Crop health, vigour, and damage reports
• Compliance monitoring

To date, RADARSAT International's efforts to penetrate the Agriculture markets with SAR data have been with RADARSAT-1. RADARSAT-1 has been used effectively for crop acreage in such places as India, China, Japan, and Europe as well as for compliance monitoring. In most cases, multi-temporal images are necessary to increase the accuracy of discrimination between crop types and thus crop acreage.

We anticipate that the addition of RADARSAT-2 benefits will propel us further into the agricultural business. These benefits include

• Multi-pol (or selective polarization), in particular quad-pol, to increase the information content of a single image acquisition. Studies have shown crop identification, acreage estimates, and crop condition is viable information from multi-pol data.
• Improved spatial accuracy to enhance field size estimation and field boundary location.

Select from the following for write-ups on SAR-based information for compliance and crop monitoring:

• Defining the Sensitivity of Multi-frequency and Multi-polarized Radar Backscatter to Post-Harvest Crop Residue
• The Potential of RADARSAT-2 for Crop Mapping and Assessing Crop Condition

Operations Update: Reception and Archiving Subsystem (RAS)

MDA has prime responsibility for the RADARSAT-2 RAS. RADARSAT International does not have a direct role but does have a strong interest in the successful functionality of the RAS because of its contribution to the responsiveness of the entire ground segment (e.g. product turnaround time).

The RAS functions include reception and archiving of Signal Data received on the X- band downlink from the RADARSAT-2 satellite at the Gatineau (GSS) and Prince Albert (PASS) Satellite Stations. In summary the RAS functions are

The RAS Faciligy

• Receiving the RADARSAT-2 Signal Data and converting it into archive segments in FRED (Framed Raw Expanded Data) format
• Decrypting the Signal Data
• Providing long-term storage of the archive segments
• Sending data to the Processing and Distribution Subsystem on request
• Generating RADARSAT-2 Catalogue information for entry into CEOCat.

Overview of RAS Design

The RAS functions will be provided as upgrades at GSS, PASS, and CCRS Headquarters (Booth Street, Ottawa), which currently support RADARSAT-1 and other missions. The upgrade will be split between CCRS and MDA where CCRS will provide

• Upgrade to the tracking and reception capabilities at GSS and PASS
• High-speed data link between PASS and GSS
• Upgrade to CEOSAM (Canadian Earth Observation Satellite Acquisition Management) at CCRS Headquarters to provide high-level control of PASS and GSS

and MDA will provide

• Overall system engineering including integration of CCRS and MDA components
• Function to record and archive the RADARSAT-2 data at both PASS and GSS

The MDA solution will be built from upgraded versions of MDA's "off-the-shelf" EO components, which include

• Direct Archive System (DAS) for recording of the downlink data and conversion into archive segments
• Archive Management System (AMS) for decryption of archive segments and management of the long-term RADARSAT-2 archive. The AMS will be customized to use existing data storage system services at PASS and GSS, and sized to accommodate up to 130 GB of archival data at each site every day
• Acquisition Cataloguing System (ACS) for the generation of metadata and browse imagery to populate CEOCat
• Reception, Archiving, and Cataloguing System (RACS) for coordination of other MDA components and interfacing with CEOSAM

The RAS plays a significant role in the timeline for fast turnaround delivery of products to the end-user. Early bench marking has indicated that we are meeting or exceeding initial estimates for the performance of the rate of conversion of raw recorded data into archive segments by the DAS, and the rate of decryption of Signal Data by the AMS. The one area in which improvements prove to be a technical challenge is the data transfer rate between PASS and GSS. This challenge will keep us busy as the team investigates various solutions.

Did You Know

• ARCHIVE SEGMENT: An archive segment is similar to a "swath," but may include one or more scenes. Each archive segment corresponds 1:1 with a single RADARSAT-2 imaging activity (i.e. single SAR-on interval with no change of beam/mode). For example, if RADARSAT-2 were to obtain a long unbroken swath of ScanSAR data (e.g. for ice monitoring) it would be stored in RAS as a single archive segment and could represent many "scenes" worth of data.
• CEOCAT: CEOCat, the Canadian Earth Observation Catalogue hosted at CCRS, houses the metadata for all Canadian Earth-observation data, which is part of the Canadian Government's holdings.
• PROCESSING AND DISTRIBUTION SUBSYSTEM: Although only one Processing and Distribution Subsystem currently is being planned, the design of RAS will support the addition of more processing systems to the Ground Segment. This initial processing system will be located at GSS and is better known in the RADARSAT-1 program as the CDPF, or Canadian Data Processing Facility.
• POLARIZATION: Polarization is defined as the shape and locus of the tip of an electromagnetic wave's electric field vector in the plane orthogonal to its direction of propagation.
• QUAD-POL RADAR: A system designed to simultaneously collect SAR data over an area in two orthogonal polarization states on transmit and the same two polarization states on receive (in the case of RADARSAT-2-H and V transmit; H and V receive), and retains the phase information during the data processing.The interesting information from an application perspective is the difference in phase between the various channels (HH vs. HV for example). Retaining the phase information provides the full scattering matrix of the scene from which the signature for any receive and transmit polarization may be synthesized.
• LINEAR POLARIZATION: Represented by HH, HV, and VV, this polarization is described by a straight line. This can lie in any direction in addition to the horizontal and vertical planes.
• CIRCULAR POLARIZATION: A polarization for which the H and V components have equal amplitude but are 90&#deg; out of phase. The polarization direction is either right handed (clockwise) or left handed (anti-clockwise) looking in the direction of travel. With a single bounce (smooth surface) the received wave is moving in the opposite direction of the transmitted (i.e. RL). For volume or multiple scattering mechanisms the received wave is rotating in the same direction as that of the transmitted wave (RR).
• CROSS POLARIZATION: The observed signature when the transmit and receive polarizations are orthogonal (e.g. HV or RL).

More information