There are basically three different types of electronic dog tracking collars.
Directional radio tracking collars, often referred to simply as radio frequency collars or RF. This technology uses a radio transmitter on the dog tracking collar which beacons out a radio signal.
The dog owner uses a directional antenna in order to pick up the beaconing signal from the dog collar. Depending upon the strength of the signal, a relative distance to the dog can be determined. More sophisticated radio collars will also vary the timing of the beacons to provide additional information such as if the dog is moving or standing still.
Popular brands for RF dog collars are Innotek, Tracker, and Marshall.
A less expensive type of radio tracking can be found using the Loc8tor device. This is handy item can be use for a variety of tracking purposes. The range is somewhat limited and is probably best suited for smaller dogs or dogs who would not wander farther than the 600 foot direct line of sight distance of the Lo8cator.
Still, it could be very useful for not-so-far wandering dogs.
GPS / RF dog collars use a combination of GPS technology and radio frequency.
The dog collar has a GPS device that can determine its exact position relative to a GPS satellite. This is the same technology that is used in many car navigational systems.
The owner also has a GPS device so he will know his exact position as well.
In addition to the GPS device, the tracking dog collar also has an RF transmitter that can transmit its GPS coordinates to a receiving device, which is held by the owner.
So based upon the two GPS coordinates -- one from the GPS dog collar and the other from the owner, the location of the dog relative to the owner can be determined.
The Garmin Astro uses this kind of GPS and RF technology in their dog tracking collar.
GPS / Cellular tracking systems use a method similar to the GPS / RF combination, except GPS / Cellular dog collars use the cellular phone networks rather than a radio frequency signal to transmit the dog's coordinates to the owner.
This type of system is most popular with pet locating services.
