At 11:36 22/05/99 , Phil Rogers wrote: >Someone please correct me if I am wrong, but as a radio telescope, Aricebo >should be passive and transmit no signal at all. It is more akin to a telemetry >receiver for non-manmade signals rather than a radar which does transmit > peak power signals of very limited duty cycle. Aricebo is also used as an ionospheric radar system, using megawatt peak pulse transmissions of small duty cycle. Tony Beresford