28 Day Extended Ephemeris Technology
Before a GPS receiver can calculate a position, it must know the location of minimum of four satellites.
A standard receiver does this by downloading satellite broadcast information that describes their orbital trajectory which is also known as the ephemeris.
The problem with this approach is that broadcast ephemeris messages are transmitted at a very slow speed (50bps) and they are only valid for a short period of time (2-4 hours). In poor signal environments such as indoors, urban canyons, and dense tree covered areas, downloading broadcast ephemeris information can take minutes or, often, fail altogether.
Our 28 Day Extended Ephemeris technology can by-pass the downloading process. In doing so, it allows the receiver to compute a position directly. This process saves the precious battery power of a receiver.