How Does a Tracking Device Work?by Michael Hinckley
A tracking device requires at least two pieces--a transmitter and a receiver. The transmitter is placed on the object to be tracked and is turned on which causes the transmitter to emit radio signals. In some cases, these are GPS radio signals and in other cases, it is simple high-frequency radio waves.
The receiver is tuned to the radio frequency of the transmitter, or in the case of a GPS tracking, the receiver collects data transmitted by a certain set of GPS satellites. Either signal type provides the receiver with the direction of and distance to the transmitter, which is then displayed.
In the case of a GPS tracker, the signal is relatively constant since the transmitter is in constant contact with the receiver and the transmitter, adjusting the distance between the two as either or both move. GPS transmitter signals can be disrupted by large quantities of metal and concrete, such as tunnels, underground parking structures, and even some buildings. In the case of high-frequency radio transmissions, the strength of the signal is determined by the distance between the receiver and the transmitter and the signal can be lost if there is too much distance or interference between the two. Additionally, the signal can be interfered with by other radio transmissions, the presence of electro-magnetic waves (such as in an electrical generation plant), and by dense objects, such as concrete, steel and mountains.