GPS repeaters are devices that are used to transmit signals to places where they normally cannot reach. They operate by receiving satellite signals with an antenna located outside of a building, and re-transmitting the signals to the indoor area or covered space, resulting in consistent and uninterrupted access to signals underground or in other hard-to-reach areas. The use of re-transmitted signals means that the GPS receiver is tracking the current GPS status, so that when the receiver is moved from indoors to outdoors, the receiver is instantly tracking the location, instead of taking several minutes on the acquisition of the current GPS state.
GPS repeaters consist of three components: an active outdoor GPS antenna, typically mounted on the roof of a building to pick up signals, a repeater unit with a built-in passive antenna used to re-transmit the GPS signal indoors, and a coaxial cable that connects the two. The antenna located in the repeater unit can typically cover a radius of up to 20 metres, but multiple repeaters can be used to provide coverage over a larger area. It should be noted that all the repeaters in a single network will transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself.
Wide or long range GPS coverage through a GPS repeater kit allows numerous GPS devices, whether inside or outside of a building, to access and lock on to the same signal at all times. This is a benefit that proves to be critically important for emergency service workers, first responders, and military personnel who need instant location accuracy. With the help of GPS repeaters, rescue vehicles no longer have to wait to acquire signals upon exiting a building, allowing a constant state of readiness. Repeaters are also useful in computer and electronic testing facilities, aircraft servicing hangars where on-board satellite navigation equipment is tested indoors and in all areas or locations where signal strength may be an issue.