A market for Time To First Fix Booster in PNDs?

By Dr. Marco Cavadini, Globs Consulting

A market for Time To First Fix Booster in PNDs?
From a consumer perspective a user friendly experience with a Personal Navigation Device (PND) starts with a fast determination of the initial position, known as TTFF (Time To First Fix) in GPS jargon. This paper investigates under a technical and marketing standpoint how this TTFF can be improved and how this upgrade could be monetized.

Technical background
In order to produce a valid position, a GPS receiver must know (among other measurements) the position of its reference points: the GPS satellites. The GPS satellite position can be accurately reconstructed starting from a set of data called ephemeris that is periodically broadcasted by each GPS satellite. In good GPS signal conditions ephemeris are typically decoded by the receiver directly from the satellite signal and maintain their validity for about 4 hours.

To overcome the fact that in difficult signal conditions, such as urban environments, downloading the ephemeris can take a very long time, in recent years ephemeris ‘extensions’ techniques have been developed to extend the validity of the data beyond the 4 hours, thus eliminating the need of a new download after their expiration. The first generation of extensions techniques are based on a small file periodically made available by the GPS chipset manufacturer on a server, which once downloaded on the GPS receiver can lead to an extension of the ephemeris validity period up to 14 days. Such solution being unpractical for unconnected devices (first of all PNDs), a second generation of ephemeris extension has been developed, that is able to produce the extensions directly on the GPS receiver (eliminating the need to connect to a server) achieving a typical extension period of 3 days.

A market for Time To First Fix Booster in PNDs?
A market for Time To First Fix Booster in PNDs?
Client generated GPS ephemeris extensions is nowadays a widely applied technology in Tier 1 PND products, typically marketed with brand names such as Instant Fix II, HotFiX or other names. The end user benefit is that in typical usage scenarios the Time To First Fix (TTFF) of the PND carrying such technology is drastically accelerated from the minutes range down to a few seconds, leading to a much more satisfying navigation experience.

Such TTFF acceleration technology is nowadays available also from third party, GPS chipset independent providers. It is technically possible to develop a TTFF ‘booster’ technology that can be applied to almost any existing PND (independently from the underlying GPS chipset) and obtain the same level of acceleration effect and end user benefits available on PNDs that natively come with such feature.


Monday, May 11th 2009
Marco Cavadini

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