Monday, January 31, 2011

Harley End of January

After a 1 month hiatus, Harley’s GPS started functioning again on Jan 25. The GPS data confirmed the readings taken by the satellite that Harley has not moved from his winter quarters between Parthenon and Jasper, Arkansas. He has been in this area since late October, roosting in trees along the creek in the evening and venturing not too far from this valley during the day. Hopefully the last 2 days of GPS data is the start of a period of normal functioning by the radio. The attached map shows the bird’s locations this month, the red hexagons are GPS locations and the blue teardrops are satellite calculated locations.

* For those not familiar with the way this transmitter works, Mark Martell kindly wrote a quick explanation: We are using a satellite linked radio with a GPS unit. The GPS unit is supposed to turn itself on hourly between 7am – 6pm (varies a bit with season) and calculates its position (within 150 m). That information is stored in the radio and then transmitted to an earth-orbiting satellite every 3 – 7 days (again depending on season). While the satellite is in communication with the radio, the satellite estimates the location of the radio. Both the GPS data and the satellite estimates are sent to me. Since the GPS data is more accurate, and we get more locations, I typically do not use the satellite estimate and rely exclusively on the GPS data.

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