GPS Technology Keeps You Right on Course

Navigating has challenged explorers and adventurers of land and sea for centuries; early techniques generally relied on good fortune and visibility. Some methods involved line of sight, such as celestial navigation (finding your way by sun, moon, stars and planets) or simply leaving a trail of stones for a safe return. Sometime in 13th-century Europe, a magnetic needle was placed on a pin, which is the basis of the modern compass. Unfortunately, early navigators did not have an understanding of magnetic variations so it wasn’t used to its full potential.

Over the years navigating evolved with the use of detailed topographical maps in conjunction with a compass where you could manually compensate for the variation in true north and magnetic north. This is an accurate method, but in poor visibility even experienced navigators have difficulty.

In the early 1980s, the United States Department of Defense Global Positioning System became available for free to civilians anywhere in the world regardless of borders, weather or time of day. The system is made up of a network of 24 satellites that each circle the Earth twice daily in a precise path and transmit information back to Earth, 17,000 kilometres away. At any given time six satellites will be overhead.

To make use of this system one must have a GPS receiver that locates a signal and locks onto at least three or more of the orbiting satellites. The unit then calculates a 2D position (latitude/longitude) based on the time a signal was transmitted from the satellite with the time it was received. With this information and a few more satellites, the unit can determine a 3D position, which includes elevation in addition to latitude/longitude. Once the position is known, other useful information can be calculated, such as speed of travel, trip distance, bearing, distance to destination, and the unit can also record point-of-interest data or waypoints for future reference. Horizontal accuracy (distance) is within 15 metres, but vertical accuracy (elevation) can be approximately 30 metres. Altimeters can be used in conjunction with GPS for more precise calculations.

There is also a Wide Area Augmentation System (WAAS) that broadcasts additional signals from the basic GPS satellites. At this time, it’s only available in Canada and the United States. Remarkably, positions can be pinpointed to within three metres with the WAAS capable GPS units.

My most memorable experience with accuracy occurred in a five-day backcountry expedition race in the Purcell Mountain Range of British Columbia. Our team had lost the topographical maps in a river one night, so we were forced to withdraw from the race and use the emergency GPS to notify race officials of our location.

With our coordinates, we were able to pinpoint a deactivated logging road six kilometres away from our known position. Two hours of bushwhacking on the given bearing brought us to the road and waiting officials. This safe and speedy evacuation gave me complete confidence in the GPS technology.

By the time this edition of Outpost goes to press, I will be part of a group retracing the steps of the 1845 Franklin Expedition to King William Island in the Canadian Arctic. The ill-fated search for the North West Passage ended in tragedy when their two ships became trapped in ice off the coast of the island. All 120 men perished with little trace. Our objective is to find clues to piece together the mystery of their doomed voyage. The area has not been fully explored, so our group anticipates the use of GPS for navigating in the notorious foggy conditions and to log any findings of interest for archeological and historical reasons.

But the use of GPS is not reserved for the exclusive use of the hardcore adventurer. GPS units have found their way into mainstream use and with its ability to transfer data or load programs, information for just about anything relevant to navigating is at your fingertips. The automobile industry has been installing GPS receivers into late-model vehicles as a standard option for a number of years, and the units are also used as anti-theft devices on machinery and equipment for tracking purposes.

There are some limitations of GPS but as the technology improves these points are less of a consideration. Some models of GPS are even drop resistant and waterproof. However, dense forest or tall buildings can affect the strength of the signal and may give unreliable positioning, batteries can also run out or there could be other malfunctions, so it’s wise to bring along a map and compass just in case.

This decade has seen many advances in electronic technology and GPS is no exception. With a little practice anyone can learn to use this high-tech piece of equipment and enjoy exploring off the beaten path with confidence.

Chris Christie lives in Squamish, B.C., near the towering granite walls of the Chief. Here he has found a balance between living in the big mountains of the Whistler region and being on the fringe of city life in Vancouver.

This entry was posted on Saturday, September 22nd, 2007 at 9:05 pm and is filed under Technology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a comment, or trackback from your own site. Add to del.icio.us.