The first consumer global positioning system receivers (GPS) were primitive compared to what is available now. They also carried higher price tags. And to use them, a person had to have better-than-average map skills, along with the ability to decipher coordinates and relate them to a position on the ground. On top of all this, their accuracy was fair, and some models ate batteries like a kid consumes candy.

That's all changed now. Rent a car and it likely has an easy-to-use GPS that only requires the user to enter a street address, intersection, or point of interest, all selected from a menu. Consumer models are also much easier to use, as well as being small enough to fit in a shirt or jacket pocket. Buyers no longer need to take out a second mortgage to afford it, either. Models that are well ahead of those on the market only five years ago now carry price tags around $100.

Upscale consumer models made by Garmin and Magellan also offer the choice of moving map display in color in a compact unit. Most of these will also connect to a laptop PC, enabling the user to see an exact location that's continually updated.  

In the spring of 2000, Selective Availability, a feature that degraded accuracy of GPS for non-military use was eliminated. What this means is that coordinates now are accurate within 15 meters, or about 50 feet.

Current models also acquire positions quickly. Units other than the least expensive use 12 channels, a separate channel for each satellite that may be usable at any time. Software is also faster, allowing a GPS new out of the box to initialize in only two or three minutes.

What does all this mean to anglers, backpackers, and backcountry adventurers? Confidence. Regardless of time of day or weather, a person can know their location. Planning a trip to unfamiliar country is also made easier. All but the least expensive models will interface with map software on a PC, usually through a serial port. By clicking on a map point on the monitor, a position can be uploaded and stored in the GPS. These positions will then be used to navigate to a remote fishing hole or camp site.

Anyone who travels in the Rockies knows how quickly the weather can change. A storm can bring clouds, rain, and fog, obscuring landmarks. Since a GPS works in any weather, a hiker can find the way back to the trailhead, even in dense fog.

With the growing popularity of GPS map makers are producing GPS-ready charts. Anyone who tried using satellite navigation with USGS topos and other maps will appreciate the ease of using map software. National Geographic/TOPO! and others offer topographic maps on CD for PCs.

Once a route is planned and waypoints stored in the GPS, the software will print a map of the area, including a grid to make it simple to pinpoint a location. Most GPS units give the user a choice of grids, among them Lat/Lon and UTM. Lat/Lon is the oldest system and also the most complicated to plot due to its irregular grid. It does have the advantage of providing a quick approximate location. For navigation on foot, it's more complex than necessary.

Consisting of 1,000-meter rectangles, the UTM grid is probably the simplest system. A GPS will give a pair of numbers that make it easy to plot a map position. The pair tells the starting point - which is always the lower left corner of a rectangle. The last three digits of each pair are the number of meters from the lower left corner to the right, then up, in that rectangle. Even on a 1:24,000 USGS quad, the grid size is small enough that the coordinates can be estimated with reasonable accuracy.

All of this high-tech satellite gear surely has a down-side. That's true. A GPS depends on battery power. In the energy saving mode, some units will give 20 or more hours of operation. It's wise to carry extra batteries, and a map and compass. Other than this, there's no disadvantage in using GPS for backcountry travel. It's the surest way to know where you are at any time in any weather.

Copyright © 2000 by Al Marlowe. No reproduction, linking, or copying without permission

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