The Garmin Astro system consists of two components: a Handheld GPS unit (Astro 320) which looks like a walkie-talkie and a Dog GPS unit (Astro-DC-40). These two GPS units communicate via radio signals. The Dog GPS computes its location from the GPS satellites, detects whether your dog is moving or on point, and sends that info to your Handheld GPS every 5 seconds. The Handheld GPS then plots the exact location of your dog on a map screen, shows distance, and whether your dog is moving or on point.
On your Handheld GPS, the Map Screen shows your location, your dog's location, and the path that your dog has hunted. Alternately, view your dog(s) on the Compass Screen which shows your location, your dog's distance, and direction -- perfect for running multiple dogs. Track up to 10 dogs on one Handheld GPS system! Just add however many extra DC 40 dog GPS collars you need.