Advanced Communications Technology Satellite (ACTS): Four-year system performance

The Advanced Communications Technology Satellite (ACTS) was conceived at th e National Aeronautics and Space Administration (NASA) in the late 1970's a s a follow-on program to ATS and CTS to continue NASA's long history of sat ellite communications projects. The ACTS project set the stage for the C-ba nd satellites that started the industry, and later the ACTS project establi shed the use of Ku-band for video distribution and direct-to-home broadcast ing. ACTS, launched in September 1993 from the space shuttle, created a rev olution in satellite system architecture by using digital communications te chniques employing key technologies such as a fast hopping multibeam antenn a, an on-board baseband processor, a wide-band microwave switch matrix, ada ptive rain fade compensation, and the use of 900 MHz transponders operating at Ka-band frequencies. This paper describes the lessons learned in each o f the key ACTS technology areas, as well as in the propagation investigatio ns.