The Nimbus F Random Access Measurement System (RAMS)

Abstract

In 1974, the Random Access Measurement System (RAMS) will be launched aboard the NIMBUS F satellite as part of the Tropical Wind, Energy Conversion, and Reference Level Experiment (TWERLE). This paper describes operation and performance of the RAMS instrument, which will provide a means of tracking and collecting data from a large number of instrumented platforms. In operation, the RAMS will perform satellite onboard processing of up to eight simultaneous platform transmissions, following search and detection of the randomly received platform transmissions in a compressed-time expanded-frequency domain. The processed data is stored aboard the satellite for readout every 108 minutes (orbital period), and platform locational coordinates and/or velocity components are determined in a central ground data processing facility. TWERLE system performance design goals are ±5 km position location, ±1 meter/second velocity determination, and 1000 platforms/orbit multiple access accommodation.