Differences Between The GPS Enabled Altimeter Watch And The Barometer Driven Altimeter Watch
Sunday, March 21st, 2010GPS or barometric pressure are the two ways most altimeter watch software calculates altitude.
The original altimeters (discovered by French physicist Louis Paul Cailletet) used barometric pressure to calculate altitude. While the methods for gathering barometric pressure have changed with technological advances, the calculation itself has remained constant. Most altimeter watches apply a simple formula to the barometric pressure to determine elevation above sea level. In the last few years, the invention of GPS watches has introduced a new alternative to the traditional altimeter watch. As the name implies, GPS altimeter watches us longitude and latitude to communicate position to a satellite, which in turn returns various map datum, including altitude.
If your altimeter watch is GPS enabled, the way it calculates altitude is by sending your latitude and longitude to a satellite, which likely communicates with the manufacturer and returns your altitude, among a number of other data points. Because of this GPS altimeter watches are considered to be more accurate that their barometric watch counterparts. Not having to recalibrate is one of the obvious benefits to owning a GPS enabled altimeter watch. However, one of the downsides is your position and altitude is often subject to terrain - on flat, open terrain you will have near perfect communication with the satellite. However, in mountainous terrain, particularly in a canyon or gorge, you will often have poor satellite signal, resulting in inaccurate latitude and longitude positioning. Obviously, this results in somewhat questionable accuracy of your elevation. Examples of GPS enable altimeter watches are the Forerunner 305 or the Suunto X10.
Most altimeter watches using barometric pressure have a built in software component that uses the watch barometer to calculate altitude. While the exact function that the watch uses to determine altitude is beyond the scope of this article, it is important to remember that barometric pressure changes rapidly as weather changes. Because of this, during outdoor activity it is important to use known positions to calculate altitude and recalibrate your watch if necessary. While there are literally hundreds of watches out there using barometric pressure to calculate altitude, some of the more popular brands are HighGear, St.Moritz, and Suunto.
The entry price point for GPS enabled altimeter watches is around $250. While a bit more expensive than the barometric pressure altimeter watch (lowest price of around $100) often GPS altimeter watches come with many features, such as trip distance, not in their barometric counterparts. When looking for a watch compare carefully the individual watch feature set that best matches your needs.
Learn more about the types of Altimeter Watches. Stop by Anthony Edward’s site where you can find out all about the best altimeter watch for your needs.