AWiFS Camera For Resourcesat

摘要

Remote sensors were developed and used extensively world over using aircraft and space platforms. India has developed and launched many sensors into space to survey natural resources. The AWiFS is one such Camera, launched onboard Resourcesat-1 satellite by ISRO in 2003. It is a medium resolution camera with 5-day revisit designed for studies related to forestry, vegetation, soil, snow and disaster warning. The camera provides 56m (nadir) resolution from 817 km altitude in three visible bands and one SWIR band. This paper deals with configuration features of AWiFS Camera of Resourcesat-1, its onboard performance and also the highlights of Camera being developed for Resourcesat-2. The AWiFS is realized with two identical cameras viz. AWiFS-A and AWiFS-B, which cover the large field of view of 48°. Each camera consists of independent collecting optics and associated 6000 element detectors and electronics catering to 4 bands. The visible bands use linear Silicon CCDs, with 10μ x 7μ element while SWIR band uses 13μ staggered InGaAs linear active pixels. Camera Electronics are custom designed for each detector based on detector and system requirements. The camera covers the total dynamic range up to 100% albedo with a single gain setting and 12-bit digitization of which 10 MSBs are transmitted. The Camera saturation radiance of each band can also be selected through telecommand. The Camera provides very high SNR of about 700 near saturation. The camera components are housed in specially designed Invar structures. The AWiFS Camera onboard Resourcesat-1 is providing excellent imageries and the data is routinely used world over. AWiFS for Resourcesat-2 is being developed with overall performance specifications remaining same. The Camera electronics is miniaturized with reductions in hardware packages, size and weight to one third.