GPS was developed in the 1970’s by the US Defence Department in order to coordinate submarine missiles. They started launching satellites in 1972 and currently there are 24 GPS satellites in orbit. Watches with GPS receivers use this constellation of 24 GPS satellites to communicate with.
Wherever you are in the world the GPS system is capable of receiving information from up to 12 satellites positioned on the same side of the earth as you. So you are not limited by signal strength or location, you are able to go anywhere in the world and obtain the information you need for your purpose.
GPS signals are unaffected by weather but can sometimes be interferered with by dense tree cover, tall buildings or mountains.
Development
Casio states that the watch “was acclaimed for its advanced feature allowing the wearer to easily determine directions and distances in relation to his or her location or destination,
which is especially useful for outdoor activities such as mountain climbing and fishing, where lightweight compact devices are needed.”
In 2003 Garmin teamed up with Timex to create a watch for Timex’s Ironman series of watches, using GPS to provide speed and distance data for runners. In the winter of that year Garmin brought out its own GPS tracking watch the Forerunner 201 which retailed for approximately $160.
It made sense for Suunto a company well known for its magnetic compasses to become involved in making watches with GPS capabilities which they have in their Vector, X-Lander and X10 watch ranges.
Since Casio decided not to continue in this market, Garmin, Suunto and Polar have become the main manufacturers in the GPS area.