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