2. The State Of Technology

A GPS satellite (courtesy of NASA)

The underlying principles of GPS have remained largely unchanged since the technology first became available for civilian use a few years ago. A GPS sensor receives radio signals from a network of satellites operated by the U.S. Department of Defense. The GPS receiver's position is determined with a complex formula based on the radio signals' speeds and distances from the receiver. Calculations that serve to reduce the satellites' margins of errors are also a part of the equation. Among the factors that can offset signals are atmospheric conditions such as ion-charged stormy weather or terrestrial objects, like trees or large buildings.

A system of satellites supports military, commercial and consumer GPSes (copyright Garmin Ltd.)

GPS devices also take advantage of terrestrial bases equipped with sensors and linked to satellites, which is why their accuracy is now within a 16.4-ft. radius. Ground stations process and correct the satellite signal data and work in tandem with a separate network of satellites in geo-synchronous orbit. The terrestrial systems are called WAAS (Wide Area Augmentation System) in the United Sates, EGNOS (European Geostationary Navigation Overlay Service) in Europe and MSAS (Multi-Functional Satellite Augmentation System) in Japan and Asia.

GPS accuracy is set to get an additional boost following the European Commission (EC)- and European Space Agency-sponsored launch last year of what will be the first of a 30-satellite GPS network. Besides helping Europe to become GPS-independent from the United Sates, the EC claims its GPS system will enable consumers to purchase devices that offer an accuracy of within 3.3 ft. The EC satellite network is slated to become fully operational by the end of 2010.

Multipath signals reduce the quality and utility of GPS satellite transmissions. (copyright Garmin Ltd.)

Prices will also continue to drop. GPS sensor components that OEMs buy to design into their consumer devices - most of which are made by SiRF - now sell for less than $5. The current price point represents over a five-fold discount compared to just a few years ago.

According to analysis firm, Forward Concepts, non-cellular GPS digital signal processors, which are the equivalent of a CPU in a PC, have a 2006 average selling price of $3.02. GPS DSP prices should continue to fall 8.8% per year, Forward Concepts says. While OEMs balked at offering pricing forecasts for their devices, you can reasonably assume that their prices will drop commensurate with those of GPS DSPs. Already, not more than one year ago, you could easily pay well over $1,000 for a consumer-grade GPS unit. That price point is a lot more than what the Garmin Nüvi 350, HP rx1950 Navigator and Navman ICN 550 reviewed here cost, while prices have already decreased further since this article was written.