The Global Positioning System (GPS) is a Global Navigation Satellite System (GNSS) developed by the United States Department of Defense. It uses a constellation of between 24 and 32 satellites that transmit precise microwave signals, that enable GPS receivers to determine their current location, the time, and their velocity. Basic ConceptA GPS receiver calculates its position by carefully timing the signals sent by the GPS satellites high above the Earth. Each satellite continually transmits messages containing the time the message was sent, precise orbital information, and the general system health and rough orbits of all GPS satellites. The receiver measures the transit time of each message and computes the distance to each satellite. How it Helps in MountaineeringGPS is now being exploited in many aspects of day to day life. In mountaineering activities, a system that can pin-point a user’s position within seconds has tremendous potential; a commercial GPS receiver is able to do this. Not only does the system work 24 hours a day, but it is also not weather or ability dependent. Technology is advancing, receivers of GPS signals are becoming cheaper, smaller and more readily available to everyday users. The implications for outdoor safety are significant; both in perception and usage.Navigation: “Where am I going?”GPS helps you determine exactly where you are, but it is sometimes important to know how to get somewhere else. GPS was originally designed to provide navigation information for ships and planes. So it’s no surprise that while this technology is appropriate for navigating on water, it’s also very useful in the air and on the land. Finding your way across the land is an ancient art and science. The stars, the compass, and good memory for landmarks helped you get from here to there. But, landmarks change, stars shift position, and compasses are affected by magnets and weather. The situation has never been perfect. Today hikers, bikers, skiers, and drivers apply GPS to the age-old challenge of finding their way. Borge Ousland used Trimble GPS to navigate the snow and ice to ski his way to the top of the world and into the record books. And two wilderness rangers employed GPS to establish a route across the Continental Divide for horse riders and packers.Benefits:* A grid reference to your actual position.* The facility to return to a position you have visited earlier.* Whilst on the mountain, entering a position of the centric grid reference you would like to visit, to which the GPS compass will indicate the direction.* You can enter waypoints prior to a journey to use a navigation aid during your trip.What are the main concerns?* An exposed mountain side is not the place to start programming in your intended room. This should be done at home as part of your preparation.* You need to be completely au fait with the functions of your GPS before you rely on it.* Signal reflection: large areas of rock can reflect the signal, causing it to travel further and cause an error in calculating your position.* User error is always a possibility, particularly fatigued or stressed. Perhaps most significant and common errors occurs when taking grid references from the map input to the GPS. * Loss of battery power is unlikely in cold conditions.* Where do you get your detail about the surrounding terrain?* Your position may not be clear line of sight with overhead satellites, if you are in a deep valley for example.Which one to buy?There are various GPS receivers available in the market like Garmin, Tom Tom, Magellon Maestro, Golflogix. In India, Garmin has the sale and service center, and for the rest, you have to buy them from another part of world. Here are some of the Garmin GPS receivers:Basic Handhelds: eTrex, GPS 72, GPS 76Mapping Handhelds: Oregon series- 200, 300, 400c, 400i, 400tAdvanced: GPSMAP 76CSx, GPSMAP 76CS, GPSMAP 76S. Garmin Dealers in India:ASPL India Ltd: New Delhi: 011-25674449, 41740346, 51513601, 51513606Apexcomnet: Dehra Dun: 0135- 2724698, 2725291.ASIM India: New Delhi: 011- 65188627/ 9899676507AUTSUN: New Delhi: 011-41639928GPS India: New Delhi: 011-24651445, 41740346, 9810972144.GPS is an excellent navigation aid, but whether it is an essential piece of equipment is largely a matter of personal judgment. So, in your next expedition, you won’t feel lost. Keep Trekking.Next Week: Porsche World Roadshow at Aamby Valley City.The writer is a city based gemologist and owns an adventure club, clubfootloose.com, mail him at solisethi@gmail.com
