Also see
Transmitter Hunting: Radio Direction Finding Simplified By Joseph D. Modell http://books.google.com/books?id=RfzF2-fHJ6MC&pg=PA308&lpg=PA308&...
73 Trevor M5AKA
--- Trevor m5aka@yahoo.co.uk wrote:
First demonstrated on OSCAR-6 see
(WO/1999/041723) APPARATUS AND METHOD FOR LOCATING MISSING PERSONS, ANIMALS, AND OBJECTS http://www.wipo.int/pctdb/en/wo.jsp?IA=WO1999041723&DISPLAY=DESC
"Animal tracking tags using Ultra High Frequency (UHF) Transmitters provide long-range tracking through orbiting satellite receivers by using very low data rates. The low data rates allow the use of very narrow bandwidths to communicate the animal's identification and to determine the animal's position by measuring the Doppler shift of the transmitter's carrier. This technique was first demonstrated using the OSCAR 6 amateur radio satellite and has been used to locate Emergency Locator Transmitters (ELT) from downed aircraft and hikers. Unfortunately, narrow band systems can only service a limited number of tags."
73 Trevor M5AKA
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