Stanford's 46-meter breaking old Weaksignal Distance record.

Date:         Mon, 15 Nov 1999 07:19:08 -0800
Reply-To:      John L. Callas 
Sender:       MARS-NET 
From:         "John L. Callas" 
Subject:      SUCCESS!  Stanford Successfully Detects Mars Relay Beacon
Comments: To:,,

The Stanford 46-meter Antenna successfully detected the 1-watt MGS Mars Relay Beacon from Mars during at test of the system on 1999-11-03 and 1999-11-04. Initially, the results of the experiment failed to indicate a signal detection above background, although telemetry from on board the MGS spacecraft indicated the Mars Relay was operating nominally. A small timing error, discovered after the test in the Doppler compensation data used by Stanford to track the expected received frequency of the signal returning from Mars, prevented the signal from being resolved in the collected data. However, the effects from the Doppler timing error were exactly characterized and the data were reprocessed to remove the effects of the small timing error. When that reprocessing was perform the Mars Relay signal became clearly and unambiguously resolved in the Stanford data at the expected signal strength. Furthermore, the Stanford Antenna with its sensitivity observed the Mars Relay mode transition from the continuous wave (CW) mode to the FM modulated subcarrier mode during the test.

Additionally, Stanford was able to discern the effects of the obscuration of the Mars Relay signal in line of sight to the Earth by the motion of the MGS solar panels during each orbit. These successful detection results by Stanford independently confirm the fully functioning operation of the Mars Relay and its ready status to support Mars landed operations beginning on 1999-12-03. The Stanford tests were conducted by Dr. Ivan Linscott of Stanford, Dr. John Callas of JPL, and Dr. Michael Cousins of SRI International.

As an additional note, this detection by Stanford sets a new World record (Solar System record) for the distance an UHF signal has been transmitted and received, 230 million kilometers, and the first ever detection of an UHF signal from Mars. The previous record of 50 million kilometers was also held by the Stanford 46-meter Antenna.


John Callas

 John L. Callas                        Jet Propulsion Laboratory

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