GPS navigation device manufacturers know that a quick time to first fix is a selling point with consumers. Running predictive calculations of satellite positions while the GPS navigator is off is one way to speed up the time taken to establish a lock on a few GPS satellites so that navigation can begin is to. It works by giving the restarted GPS device a head start by knowing where to start looking for GPS satellites. Time saved with this technique makes possible warm start ups taking as little as 3.5 seconds.

Starting with the Nuvi 205 of the Nuvi 2×5 models, Garmin has based their product on STMicroelectronics’ Teseo GPS engine. As the result of collaboration with Rx Networks, their GPStream PGPS product is included. It enables the behaviour of GPS satellites to be modelled based on broadcast ephemeris readings for accurate prediction of satellite positions up to 5 days ahead. A single broadcast ephemeris reading allows the accurate prediction of satellite orbits which are developed and refined every time new broadcast ephemeris is obtained.

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