How the Argos System Works

N.O.A.A. satellites orbit every 108 minutes or about 14 times a day. The satellite scans a 5,000 kilometer wide area as it passes. The satellite is within transmitter range for about 10 minutes. If the transmitter is sending then the satellite will receive multiple messages from the swan's transmitter.

Because of the earth's rotation a transmitter at the equator would be scanned once a day while a transmitter at the pole could be scanned 14 times a day.

Argos
(click for bigger image)

When the satellite passes one of three main ground stations, it downloads the information to computers. The computers then calculate the location of the swan and send the owner of the transmitter an E-mail message.

The Shadow-A-Swan website then updates the archive for each swan, maps the longitude and latitude and calculates the distance traveled since the last reported location.