| If your GPS device told you do drive off a cliff or | | | | sometimes even dense foliage can block the signal |
| ford a raging river, would you do it? You may | | | | reception and cause positioning errors or prevent |
| respond, of course not, that's stupid. | | | | a position reading at all. |
| Unfortunately, many people substitute technology | | | | Anomalies like high static discharge during lightning |
| for common sense, often with tragic results. | | | | storms, humidity, ionized air and barometric |
| Satellite navigation systems are changing the way | | | | pressure can definitely cause false information, |
| in which we navigate from place to place by land, | | | | data error or miscalculations. A satellite signal |
| sea or air; in remote wilderness areas or through | | | | slows as it passes through the atmosphere. |
| congested urban streets. The GPS system has | | | | Ionosphere and troposphere delays may cause |
| been called the greatest advance in outdoor | | | | distortion. GPS units normally will not work indoors, |
| navigation since the invention of the compass and | | | | underground or underwater. |
| has become a widely used aid to navigation | | | | In automotive GPS receivers, metallic features in |
| worldwide, a useful tool for map-making, land | | | | windshields, such as window tinting films or |
| surveying and recreational navigation. An | | | | defrosters elements can degrade reception inside |
| estimated 50 million navigation devices, including | | | | the vehicle. Receiver clock errors are also |
| in-car systems, handheld or portable units and | | | | common. This type of error occurs because a |
| smart phones, will be in use in the United States | | | | receiver's built in clock is not as accurate as the |
| this year. | | | | atomic clocks onboard the GPS satellites and will |
| Whether you're prospecting, hunting, fishing, | | | | reflect varying timing errors. These distortions can |
| cross-country skiing, or taking a hike in the back | | | | result in positioning errors of hundreds of miles. |
| country, a GPS receiver can help you reach your | | | | Unreliable data is also a major contributor to GPS |
| destination and return safely - but only if you | | | | errors. With an incalculable number of roads and |
| know how to accurately use it and recognize its | | | | millions of miles of ground to cover, it is impossible |
| limitations. | | | | for any data system to be 100% accurate. A |
| The Global Positioning System (GPS) is a | | | | road network is a constantly changing entity; |
| satellite-based navigation system made up of a | | | | roads are diverted or closed, construction |
| complex network of more than 30 satellites | | | | reroutes traffic while weather affects road |
| placed into orbit by the U.S. Department of | | | | conditions. The data feed used in GPS units is |
| Defense. The GPS network, also called | | | | dated. Fresh updated content may not be |
| NAVSTAR, was originally intended for military | | | | available for several months. It is important to |
| applications, however when Korean Air Lines Flight | | | | remember that this data is updated quarterly at |
| 007 was shot down in 1983 after straying into | | | | best and in some cases only released twice a |
| the USSR's prohibited airspace, President Ronald | | | | year. |
| Reagan issued a directive making GPS freely | | | | Although GPS Navigation is becoming increasingly |
| available for civilian use as a common good. The | | | | popular, these units have the ability to highlight |
| GPS works all the time, in any weather condition, | | | | human error. A GPS devise will attempt to advise |
| anywhere in the world, 24 hours a day. | | | | you depending on the destination your have |
| Powered by solar energy, the numerous satellites | | | | entered. An incorrect address or a mistake in |
| that make up the GPS space segment orbit at | | | | spelling are common errors. Instead of making our |
| approximately 12,000 miles above the earth. | | | | lives easier, some of these devices are so |
| Moving constantly at speeds in excess of 7,000 | | | | technologically enhanced they are very difficult to |
| mph, the satellites each make two complete | | | | use. User mistakes account for the majority of |
| orbits of the earth in less than twenty-four hours. | | | | GPS errors, however a GPS receiver has no way |
| The GPS satellites are kept on track by small | | | | to identify and correct these mistakes. |
| rocket boosters. Primarily operated on solar | | | | GPS technology isn't perfect! It's imperative to |
| power, the satellites also employ backup batteries | | | | pair its directions with a healthy dose of common |
| in anticipation of power loss during a solar eclipse. | | | | sense. Many drivers exhibit a surprising willingness |
| The first GPS satellite was sent into orbit in 1978, | | | | to rely on gadgets instead of experience. They |
| with a full constellation of satellites achieved in | | | | are finding that satellite navigation may replace |
| 1994. Weighing approximately 2,000 pounds, each | | | | paper maps, however following the GPS's not |
| satellite is about 17 feet across with the solar | | | | always reliable directions, many users are getting |
| panels extended and is built to last about ten | | | | hopelessly lost, hitting dead ends or road closures |
| years. Replacement satellites are constantly being | | | | and even swerving into oncoming traffic. |
| built and then launched into orbit. | | | | Even if you are not blindly following erroneous, |
| GPS signals can be affected by multi-path issues, | | | | computer-generated instructions, research studies |
| where the radio signals reflect off surrounding | | | | tell us that "using GPS while behind the wheel is |
| terrain such as tall buildings, mountains or large | | | | actually more distracting and less safe than |
| obstructions. This increases the travel time of the | | | | unfolding a paper map and using it to find your |
| signal and can cause inaccuracy. The number of | | | | way". A large portion of drivers, according to the |
| satellites visible, or the more satellites a GPS | | | | study, relied exclusively on their GPS unit for |
| receiver can "see" will also affect accuracy. | | | | directions, "rendering them completely oblivious to |
| Electronic interference, buildings, terrain or | | | | the world around them. |