S4 (Version 2)

Abstract

SAR — Synthetic Aperture Radar — is a technology that creates images from space or airborne vehicles via illuminating the ground with radar and recording the echoes. The recording made by a SAR instrument requires extensive computer processing to produce a focused image; this is called "SAR processing." The SIR-C mission took SAR image data during two space shuttle flights. The SIR-C instrument can simultaneously image a strip of the Earth in different radio frequency bands and different polarizations. The raw data was recorded on board the shuttle and returned to ground with the astronauts. A SAR processing system was built around a 32-node CM-5 computer for SAR processing and a tape handling system to convert the raw data to disk. The SAR processing part was estimated to perform at 2 gigaFLOPS. In this Grand Challenge component, we have parallelized the SIR-C SAR processing to run on the CRAY T3D and T3E machines. To demonstrate 10 and 50 gigaFLOPS performance, we processed a fixed set of raw SIR-C data on the CM-5 production system and the 512-node T3D (for 10 gigaFLOPS) and the 512-node T3E (for the 50 gigaFLOPS) systems at Goddard Space Flight Center. The criterion for meeting the (nn) gigaFLOPS benchmark is: (time/scene on CM-5) / (time/scene on T3?) = nn/2. For the 10 gigaFLOPS milestone, 5-times speedup is required. The 50 gigaFLOPS milestone requires 25-times speedup.

DateOfInformation

Thr Jul 9 15:13:55 1998

Domain

Scientific and Engineering Applications

Keyword

Solid Earth Science, fast transform methods

Language

Fortran 90, C

Name

S4 (Version 2)

TargetEnvironment

Systems using Cray shmem library or Intel Paragon Nx Message Passing Library

Webpage

http://alphabits.jpl.nasa.gov/SAR/

ContactIs

Craig Miller

Files

S4 (Version 2)