The Whale Telemetry Group (WTG) specializes in using radio tags (both conventional VHF and satellite-monitored UHF) to study the movements, critical habitats, and dive characteristics of free-ranging whales and dolphins around the world.
Our satellite (UHF) tags are monitored by the Argos Data Collection and Location Service, which has receivers on National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POES). When a tagged whale surfaces to breathe, its tag transmits a signal that is picked up by these receivers. Tag locations are calculated by Argos from the Doppler shift of received transmitter frequencies when multiple transmissions are received during a satellite's passage overhead. Details on how this system works can be found on the Argos website at https://www.argos-system.org/.
Since the deployment of our first satellite tag on a humpback whale in 1986, our satellite tag technology has undergone several iterations, from a large, surface-mounted cylinder (16.2 cm diameter, 15.8 cm tall) to a much smaller, implantable cylinder (1.9 cm diameter by 19 cm long housing). A description of the evolution of our tag technology can be found in the following publication:
Mate, B., R. Mesecar and B. Lagerquist. 2007. The evolution of satellite-monitored radio tags for large whales: One laboratory's experience. Deep-Sea Research II 54:224-247.