GPS's and Digital Mapping Software

GPS's and Digital Mapping Software (Revisited)

There is a hiking buddy of mine, who often signs his email messages as "Chief War Fugawi" (think about it) used to have a T-shirt that said "You're not lost if you don't care where you are!" This seems to be sort of the "What!? Me worry?" approach to route findings on long backpacks. Of course, that is not really his style, nor is it really mine. It is important to know where you are , if for no other reason that to have a sense as to how far it will be to get out, and get a real shower. I have discussed global positioning systems (GPS) and software for hikers over the past couple of years in the Tennes-Sierran. But like any emerging technology area, a couple of years back can be nearly ancient history, because changes come so quickly. What was absolutely the latest greatest gismo 9 months ago is practically a technological dinosaur today. There have been some major improvements, and the technology is maturing, so I thought it would be worth another look.

First, hand-held GPS devices. Unless you have been living under a rock for the past few years, you have probably heard about these things. GPS units are basically small satellite receivers, with a built-in computer. They can be used to figure out where you are on the planet. Without going into a lot of detail, basically, there about 24 GPS satellite transmitters orbiting the earth, a little over 12,000 miles up. (Note that such is not high enough to be in geo-synchronous orbits, so the satellites do cross the sky overhead.) They send out signals, which essentially say 1) my name is such and such 2) my location in the sky is this, and 3) this is the exact time that I sent out this signal. The hand held GPS receiver, which stores all these orbits in its memory, gets the signal about 65 milliseconds later. And now the calculator in the GPS goes to work and figures: let's see. If that signal was sent at exactly 4:08pm Greenwich Mean Time, and I received the signal from satellite # 22 exactly 72.6298453 milliseconds after it was sent, and electrical waves travel at the speed of light, which is 186,000 miles per second, then satellite #2 is exactly 13,509 miles, 798.47 feet from me. And Satellite #14 just sent out a signal, etc, etc. Once the GPS receiver gets signals from 3 or 4 satellites, it knows to within a few inches of where it is on the face of the planet. (What is really amazing is that the clock on these GPS's is so accurate. It is the most accurate clock you will likely ever own, because it gets updated from the satellite clocks all the time.) If you want to learn a bit more about how GPS works and how you might use it, go to our GPS Tutorial

So that is how they work. What is the news about these devices? In a nutshell, there are five major improvements that may make you want to reconsider if you do not already own one.

Much lighter weight. Most of the hand held devices a few years ago (like 3 or 4) weighed well over a pound. Now, especially if you load them with lithium batteries, rather than normal alkaline batteries, you are talking about 8 or 9 oz. Big improvement. They are also smaller, and easier to manipulate in the field.
Vastly more sensitive. Most devices are now 12-channel receivers, which means they can monitor the signals of 12 satellites simultaneously. Most important for those of us living in the Southeast, they now work under heavy tree canopies. The older devices simply would not compute a position unless you were out in the clear. Fine for out west, but not very useful in the Smokies.
Faster response. It used to be that you could figure 5 minutes under ideal circumstances to get a fix. Just for fun, I took my new unit out under the worst possible (for a GPS) conditions: it had been more than 1500 miles since I last turned it on, and when I did turn it on, I was in a climax forest, which passes for my back yard. I had a fix in about 3 minutes. Then, a couple of hours later, I turned it on under open skies: 30 seconds to get a fix.
Cheaper. Like any new technology, the prices have come down. You can buy the less expensive ones for about 100 bucks at K-Mart. You can get lots of bells and whistles for $250, and for a bit more, well, you can have built-in maps displayed, and color screens. (I settled for mid-range. You have to draw the line somewhere.)
Easily configured and integrated with computer mapping software. I will talk about mapping software below, but with a $40 cable, you can upload pre-planned waypoints to your GPS at home, or you can mark your route in the field, and find out where you REALLY went when you get home.

All this said, these units are still no substitute for map reading skills. But then in my opinion, if you don't know how to read a topo map, you shouldn't be out in the backcountry anyway. But the GPS is a great adjunct to good map reading skills, and I think that using a GPS along with topographic maps can help you learn more about the landscape. For those of you that are still not convinced, I figure there are at least three situations that come to mind where GPS units can be especially helpful: a) in high elevations, in the fog, if you can not see surrounding peaks to get a compass fix; 2) looking down into a sea of canyons from a plateau, and trying to figure out which one you need to get into. Believe me, I have tried this many times, and it ain't as easy as it sounds; 3) trying to get a simple fix under heavy vegetation, in complex terrain, like the Smokies.

Someone who is slightly familiar with maps and GPS units, but has not used them extensively might ask: "Why go to the bother of uploading waypoints from your computerized map to your GPS, when you can just enter directly from the GPS unit as it is held in your hand?" That is a legitimate question and one that I used to ask, until I started entering lots of waypoints by hand. If you think about the process you have to go through for a bit, the benefits of direct uploading become obvious. For example, suppose I am going to do an off trail hike in the Sierras, one which will take me out for 5 or 6 days. Because the guidebook has indicated that it is important to be careful to pick the correct pass to hike through on day 3, because the alternatives are dangerous, I would really like to program in the waypoint for Carol Col into my GPS to make sure I get to the correct pass. Without the GPS capability of the mapping software, before I leave on my trip, I get out the topo map, and get out my yardstick to grid the map with coordinates in the area of the pass. Of course, I will have to do some estimating, because there is some error in my lines as I have drawn them on the map. Then I do a bit of extrapolating with a ruler to get the exact position of the pass. Let's suppose it is in Zone 11, 347,256 m Easting, 4,126,997 m Northing. (For those of you unfamiliar with Universal Transverse Mercator (UTM) coordinates, they are much easier to use that latitude and longitude.) So with that information, I turn on my GPS, page to the waypoint screen, and start manually entering the waypoint name as CRLCOL for Carol Col. Since data entry is by scrolling through the entire alphabet and a list of numbers from 0 to 9, each letter or number entry may require 10 - 20 clicks of the scrolling button. So to enter a 6 letter name, you need to perform maybe 40 - 90 clicks. Then it is time to enter the coordinates, which requires scrolling through the number list too, and each UTM coordinate has 2 zone digits and 13 actual coordinate digits to scroll through, so you may have another 50 or 75 clicks. Is your thumb tired yet? Actually, it is not as bad as it may sound, but it does get a bit tedious if you want to enter and name 5 or 10 waypoints.

OK, let's see what the process is like with the mapping software and interface cable. First, you click on your waypoint tool in the software, then move your mouse to the point on the map you want to make as a waypoint. You click on it, and type in the name that is compatible with the naming conventions of your GPS. (If it takes you longer than 3 seconds to type in "CRLCOL," maybe you need to be buying typing instruction software, as opposed to mapping software.) When you have mouse-clicked on and named all the waypoints you want, you turn on your GPS and plug in the cable, click on the download wizard, and in about 1 or seconds, all that waypoint data is now stored in your GPS. Nifty, huh? The bottom line is that it is a lot quicker to do the waypoint entry on the computer at home than on the trail. On the other hand, I would still rather be sitting around a campfire in the mountains, trying to enter waypoint data by flashlight and taking forever to do it, than sitting in front of a computer at home, doing it quickly. Of course, doing it at home helps me anticipate or savor the hike even more, and that can't be bad. And maybe that is a large portion of what this is all about anyway.