Global Positioning Systems|
Go 12 channels and forget the rest.
In the early years when
prices were above $400 and technology was still new, GPS units were best suited for the technoweenie who simply wanted the latest electronic toy for use outdoors. As prices dropped toward the $200 range, more and more consumers began snapping them up, and getting disillusioned. While consumers expected reliable route-finding, what they got was a reality of waiting for satellite lock-on and difficulty in clearing trees and other natural obstacles in order to achieve an accurate read.
Although having the time
to lay out a picnic while establishing a position fix sounds like fun, it's not exactly what consumers had in mind when they plunked down the green for a GPS. Most expected immediate and reliable navigational information. Part of the problem stemmed from the fact that the early and cheaper GPS units relied on multiplexing receivers. These receivers used one or two channels to track satellites, find a satellite, lock onto it, read it, then release that satellite to find the next. Since a GPS needs a minimum of three satellites to achieve a two dimensional position fix and at least four to achieve location and elevation (three dimensional fix), a GPS relying on this method had to piece together and then average the navigational information and typically experienced more problems maintaining satellite contact, especially in marginal conditions.
Enter the 12-channel or
parallel channel receiver, now offered by Lowrance, Garmin and, most recently, Magellan. Still priced at $250 or under, these receivers use each channel to individually lock onto and hold a satellite and the best four signals get used to provide accurate, reliable and as close to instantaneous information as possible. As for the older versions utilizing multiplexing receivers, I wouldn't give 'em the time of day and have to wonder why the manufacturers still offer them. 12-channel or bust is my motto and recommendation to you. Contributed By: Michael Hodgson
Michael Hodgson is a an award-winning journalist and author of numerous books including Camping for Dummies, Compass and Map Navigator, and Facing the Extreme. He is a volunteer instructor for the American Red Cross, Nevada County Sheriff's Search & Rescue team and was a former mountain guide. Michael is well-known for his sense of humor and eagerness to try anything once in the pursuit of a really good story. His friends remain amazed that he can still walk. He has partnered with his journalist-wife, Therese Iknoian, on four web sites: his own www.AdventureNetwork.com, plus www.GearTrends.com, www.TotalFitnessNetwork.com, and www.SNEWSnet.com