The SETI League, Inc., a membership-supported, non-profit {501(c)(3)}, educational and scientific organization Searching for Extra-Terrestrial Intelligence

SETI League EME (Moonbounce) Station


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The moonbounce beacon operates on a carefully maintained schedule so that one can look for a signal and expect to find it. The transmission is synchronized by NIST using the internet and software called "ntp" or network time protocol. Theoretically this protocol can keep computers synchronized within microseconds. For this application, synchronization to the nearest second is sufficient. Additional time-related functions involve antenna tracking of the Moon and relaying data to and from the three computers that run the beacon and provide the web data. These functions require less precision - minutes - although they, too, are accurate to the second. (Why not?)

In addition to the xntpd program running on the Unix computer that controls the beacon, a donated Trimble Thunderbolt GPS frequency standard provides both reference time and a standard frequency. Finally, an Eventide ECW-40 GPS synchronized clock with digital display is used as the station clock and a readily visible reminder of how late it's getting.

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this page last updated 4 January 2003
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