| Global Positioning System (GPS) is a navigational | | | | possible campsites, and other items of interest on |
| aid originally developed for the military. The | | | | their trail. However, the portability demanded by |
| system simply receives signals. It is the applied | | | | hikers will also limit the functionality of the system |
| technology that gives the GPS its versatility. | | | | as small screens mean that some detail will be |
| If you have ever used map and compass, you will | | | | lost. |
| understand a little about how the GPS works. In | | | | It is GPS technology that is used to track |
| order to find your position on a map, you need to | | | | individuals on home arrest, to trace missing pets, |
| have three points of reference. The intersecting | | | | stolen vehicles, and missing people. Small systems |
| line from the reference points is where you are. | | | | can be incorporated into pet collars and |
| Map and compass work uses triangulation | | | | wristwatches. As long as the receiver is active, it |
| (bearings), GPS uses trilateration (distances) to | | | | can be found. |
| calculate location. Satellites orbiting the earth emit | | | | Marine and aviation GPS units are sophisticated |
| unique signals that can be received by a GPS. The | | | | and specialized. The principles involved are the |
| GPS software interprets the signal, identifying the | | | | same as any standard system the software is |
| satellite that it came from, where it was located, | | | | much more highly developed. |
| and the time that it took for the signal to reach | | | | Any fisherman, who is using a fish finder on his |
| the system. Once the receiver has both time and | | | | boat, is using a GPS that is enhanced by sonar |
| distance it begins to determine position. | | | | and tracking devices. Units have been developed |
| Three satellites provide the intersection point and | | | | for use on float tubes also -- as GPS technology |
| the fourth is used to check that the positioning is | | | | advances, the systems become more and more |
| accurate. Accuracy depends upon the | | | | compact and their uses more and more |
| synchronization of atomic clocks in the satellites | | | | extensive. |
| with the clock in the GPS system. Although the | | | | If you are considering purchasing a GPS, make |
| clock in the GPS is not atomic, utilizing the fourth | | | | sure that it can be updated easily. This is |
| satellite gives it that functionality as the internal | | | | especially true if you buy a multi--function GPS or |
| clock adjusts itself to correct any discrepancy | | | | one that is used where conditions change |
| discovered. | | | | regularly. An in--vehicle GPS soon loses its |
| GPS has gone far beyond its initial military | | | | usefulness if it is not updated as road systems |
| application. Drivers can find their way through city | | | | change. |
| streets, long distance trekkers use the technology | | | | Updates vary according to the device being used. |
| to cross unfamiliar terrain, mariners and pilots use | | | | They can come in CD/DVD packages or as |
| GPS enhanced data to cross the seas and skies. | | | | computer downloads. The user can purchase |
| In--vehicle GPS can be integrated into the car | | | | maps specific to the area in which the GPS will be |
| entertainment system or can be installed as a | | | | used or a range of maps and routes. These are |
| removable device. These systems need to tell the | | | | available from GPS software companies who will |
| driver where he/she is and how to reach their | | | | charge proportionally to the sophistication of the |
| destination. The information includes road | | | | software. |
| directions plus relevant features along the way | | | | GPS units vary in price according to their |
| such as rest stops, gas stations, points of | | | | usefulness. It is possible to buy units for less than |
| interest, etc. Auto GPS uses voice commands so | | | | one hundred dollars to units costing more than |
| that the driver can concentrate on the road. | | | | one thousand dollars. What your needs are will be |
| Hikers and trekkers use similar technology, but | | | | a factor in the cost of your unit. If you are a |
| normally without the inclusion of road systems on | | | | backpacker then portability is a major |
| their devices. Mapping software defines the | | | | consideration. If you are a trucker, you need to |
| territory that the hiker will encounter. The user | | | | be able to find a delivery point as quickly and |
| can enter waypoints (points of reference) so | | | | conveniently as possible. Whatever device you go |
| they can return using the same route. They can | | | | for, cost is generally related to quality. Buy the |
| add points of interest such as water sources, | | | | best you can afford. |