GPS Coverage
The Global Positioning System (GPS) is a navigation satellite system that works worldwide through the signals of more than two dozen of satellites. These signals allow GPS receivers to determine the current location, speed and direction. The system was designed and developed by the United States Department of Defence and was launched in 1978. Nowadays, GPS is totally free for civilian use as a public good and it is available 24 hours per day each day of the year.
A GPS receiver, as the one adopted by EASY WALK, calculates its position by a trilateration of the measured distance between itself and some GPS satellites with known positions. GPS provides accurate location and time for an unlimited number of people in all weather, day and night, anywhere in the world.
GPS has become a mainstay of transportation systems worldwide, providing navigation for aviation, ground, and maritime operations. Disaster relief and emergency services depend upon GPS for location and timing capabilities in their life-saving missions. Everyday activities such as banking, mobile phone operations, and even the control of power grids, are facilitated by the accurate timing provided by GPS. Farmers, surveyors, geologists and countless others perform their work more efficiently, safely, economically, and accurately using the free and open GPS signals.
And now with EASY WALK, even blind and visually impaired people can exploit GPS thanks to a new service, which is active and warranted 24 hour per day and 365 days per year and perfectly functioning under the coverage of the GPS satellites signals.
Notes
A GPS terminal can calculate its location to an accuracy of 15 meters. In optimal conditions, the accuracy may be within a few meters. The accuracy depends on the number of satellites, the signals of which the GPS module receives, and it can also be affected by poor satellite geometry. Availability and quality of GPS signals may be affected by buildings and natural obstacles, as well as weather conditions. The GPS receiver should only be used outdoors to allow reception of GPS signals.
The GPS receiver antenna shoud be positioned as described in the module instructions to enhance reception and signal accuracy. Some car windshields and windows may contain metal, which may block or weaken the satellite signals. If you stand still, GPS cannot detect which way you are facing, because it determines your direction on the basis of your movement.
In addition, the GPS is operated by the United States government, which is solely responsible for accuracy and maintenance of the system. The accuracy of location data can be affected by adjustments to GPS satellites made by the United States government and is subject to change with the United States Department of Defense civil GPS policy and the Federal Radionavigation Plan.
For these reasons, GPS should not be used for precise location measurement, and you should never rely solely on location data from the GPS receiver.