FIND YOUR WAY WITH A
GPS By Allen Macartney
T
WO FRANTIC paddlers beached their canoe at my wilderness camping site in Algonquin Park. Distraught, they waved from waters’ edge and shouted, “Can you tell us where we are?” “Sure,” I said, putting down the frying pan and approaching the pebbly, little beach. “Where’s your map?” “We’ve got a GPS,” one of them said, proudly presenting it skyward. “Great,” I replied. “But where’s your map?” Since prehistoric times, travelers have been getting lost and seeking a reliable means to find their way. Cavemen used twigs and stones to mark their route to distant hunting grounds. Ancient mariners hugged the coastline to avoid getting lost and falling off the edge of the earth. Phoenician traders depended on the North Star to navigate around the Mediterranean Sea. Vikings used a magnetic, fish-shaped piece of metal to wend their way to the next Atlantic coastal village ripe for plunder. Today, global positioning systems (GPS) have removed much of the uncertainty of wilderness and urban travel. With the push of a button, a GPS can tell you exactly where you are almost anywhere on the face of the Earth—from the market in Ottawa to its counterpart in Patagonia, Argentina. Have you ever found a perfect fishing spot where the fish practically jumped into the canoe? With a GPS, you can hit a couple of buttons and lock in that exact location forever. My own GPS
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O T TAWA O U T D O O R S W I N T E R
can save almost 1,000 locations, called “waypoints.” The saved data helps you to return to the exact spot whenever you wish. By following the GPS compass heading, you can determine the distance from your destination, your current speed, and how long it will take you to get there at that speed. How does it work? A constellation of 24 satellites (21 active with three operating spares) circles the Earth in synchronized orbits at an altitude of about 17,000 kilometres. Travelling at 11,000 kilometres an hour, and equipped with precisely calibrated clocks, the satellites transmit the exact time and position at the speed of light. On the ground, a GPS receives the satellite signals, measures the time it took for the signals to reach it, and calculates its position using triangulation. At any one time, up to six satellites are “visible” in the sky to your GPS. It must be able to lock onto at least three satellites to calculate a position accurately. The more satellites the GPS can contact, the more precise the calculation. My own GPS, a Magellan SporTrak Colour, provides accuracies to three metres almost anywhere on Earth. Less expensive models can usually provide accuracy between 10 and 100 metres. GPS is widely used by soldiers, mariners, aircraft pilots, backpackers, canoeists, surveyors and others. Small wonder that French and English digging crews starting on opposite sides of the English Channel were able to meet in exactly the right place when they built the Chunnel. GPS is a boon to mapping
and surveying companies whose reputations depend on pinpoint accuracy. Wildlife biologists have fixed GPS systems with micro-transmitters to track threatened species, like the Mojave Desert tortoise. GPS-equipped balloons are monitoring holes in the ozone layer in Antarctica, while marine buoys track major oil spills by transmitting GPS data. Should we rely solely on technology to keep us informed? Just like our bewildered friends on the beach in Algonquin Park, having a GPS doesn’t mean your old compass and map should languish in the closet. GPS has not made maps obsolete. On the contrary, maps will enhance GPS capability and should not be considered mutually exclusive. Paper maps provide the “big picture” for planning your route around pesky obstacles and leading you to those beautiful “must-see” locations. Consider the time my son and I were planning a weekend cycling trip over a rough trail we’d never seen. Our maps identified a two-kilometre section early in the trip as difficult for cycling. We had some questions: How bad is the trail? Is the distance accurate? Will we have to carry our bikes and camping gear? The GPS helped clarify the situation and proved the map wrong. The rough section was actually 1,157 metres long and very “do-able.” Our high-tech gadget gave us an edge by removing doubt and boosting our confidence.
Lost and found
The main reason people buy GPS units is to help them navigate easily from point to point. GPS units with midrange to advanced capabilities contain pre-loaded city and topographical maps. Some don’t provide many details and are limited to showing major roads, railways, rivers, lakes and airports. More expensive models like my Magellan have detailed maps that even show contour lines—great for snowshoeing, backpacking, rockclimbing and cycling trips. They have 8, 16 or 32 megabytes of RAM memory to accommodate downloading detailed maps from the Internet. Some bare-bones, inexpensive GPS units don’t have built-in maps. They provide little more than your coordinates, so www.OttawaOutdoors.ca
