GPSBabel

You won’t find any standards when it comes to GPS receiver waypoint, route, and track formats. Each GPS receiver manufacturer seems to have its own data format. To further complicate things, software companies that make mapping programs also use their own data formats. This can make exchanging GPS data between different receivers and software a very big challenge.
In order to help address this, the folks at topoGraphix (www.topographix.com), a GPS and map software company, developed GPX. GPX stands for GPS Exchange, which is a lightweight, XML (eXtensible Markup Language) data format for exchanging waypoints, routes, and tracks between applications and Web services on the Internet. GPX is slowly building up momentum and is being adopted by both software vendors and Web service providers. However, until a standard is widely adopted (and I’m personally not holding my breath), your best bet to exchange GPS data is the free GPSBabel utility. This versatile program converts information created by one type of GPS receiver or software program into formats that can be read by others. GPSBabel is available for a number of different operating systems as a command line utility, and you can find easy-touse Windows front-ends if you prefer a mouse and menus.
To get more information about GPSBabel and download the utility, visit http://gpsbabel.sourceforge.net

Making Tracks in GPS System

Remember the story of Hansel and Gretel, the kids who dropped breadcrumbs in the forest to try to find their way back home? Their story would’ve had a different ending if they had a GPS receiver because all newer GPS receivers leave electronic breadcrumbs (called tracks or trails depending on the manufacturer) while you travel. Every so often, the GPS receiver saves the coordinates of the current position to memory. This series of tracks is a track log or track history. (Because various GPS models handle tracks differently, check your user manual for specific details.)
Note these differences between tracks and waypoints:

• Names and symbols: Although tracks and waypoints are both location data points, tracks don’t have names or symbols associated with them and can’t be edited in the GPS receiver.
• Autocreation: Unlike waypoints — that you need to manually enter —tracks are automatically created whenever a GPS receiver is turned on (that is, if you have the track feature enabled).

If track logging is enabled, tracks are shown on the GPS receiver’s map page while you move, like a trail of breadcrumbs. The GPS receiver constantly collects tracks while it’s powered on, so you need to clear the current track log before you start a new trip. If you want, you can save a current track log.

To route or not to route in GPS

A fair number of GPS receiver owners don’t use routes and find them to be an overrated feature. After all, after you reach your first destination, you can easily select the next location from the waypoint list and be on your way. In addition, if you want to record where you’ve been, just using tracks is much easier. I discuss this in the section, “Making Tracks.” However, here are a couple of situations when you should consider using routes:

• If you’re traveling to the same location on a regular basis (such as a guide leading clients on established trips).
• If you’re planning on sharing a route with other GPS receiver owners. Think of this as being a virtual tour guide. Routes can be downloaded and then uploaded to other GPS receivers.
• If you have a mapping program, you can plan a trip ahead of time and create routes on your computer by simply clicking your mouse where you want to go. When you’re finished, you can upload the route to your GPS receiver.

Using routes is a personal preference. Try creating and using routes to see whether they meet your needs. If they don’t, you can get by with waypoints and tracks.

Following Routes in GPS

A route is a course that you’re currently traveling or plan to take. In GPS terms, a route is the course between one or more waypoints. If multiple waypoints are in a route, the course between two waypoints is a leg. A single route can be made up of a number of legs.
Suppose it was a beautiful day, and you went hiking, deciding to make a loop: hike from a parking lot trailhead to a scenic waterfall, go over to a lake for some lunch on a sandy beach, and finally head cross-country until you reach a trail intersection that would take you back to your starting point at the parking lot. You’ve hiked in the area before; in fact, you’ve visited each of your planned destinations and marked them as waypoints in your GPS

receiver. However, you’ve never hiked this particular loop before, so you decide to make a route called LOOP with the following legs that you’ve already previously entered as waypoints:
PRKLOT to WTRFALL
WTRFALL to LAKE
LAKE to TRAILX
TRAILX to PRKLOT
After you create your route, the GPS receiver tells you how long each leg will be and also the total distance of the route. When you activate the route (tell the GPS receiver you’re ready to use it), this information is displayed:

• Direction: The direction you need to travel in order to reach the next waypoint in the route
  
• Distance: How far away the next waypoint is
  
• Duration: How much time it’s going to take to get there After you reach a waypoint in the route, the GPS receiver automatically starts calculating the information for the next leg. This continues until you reach your final destination.

Don’t confuse a route with an autoroute, which applies to GPS receivers that can provide you with turn-by-turn street directions to a destination you’re driving to. AutoRoute is also the name of a Microsoft European street mapping program.
Routes can be created ahead of time or entered while you’re traveling. Like with waypoints, after you create a route, you can delete or edit it, including removing or adding waypoints within legs.
Whenever you’re using a route or navigating to a waypoint, you don’t need to leave your GPS receiver on all the time. You can shut it off every now and then to conserve batteries. When you turn the GPS receiver back on, just select the waypoint or route that you were using, and the GPS receiver recalculates your present position and gives you updated information about how to reach your destination.
The number of routes and the number of waypoints that a route can consist of vary from one GPS receiver to another. Some inexpensive GPS receivers don’t support routes, but a high-end consumer GPS unit might have up to 50 routes with up to 125 waypoints in each route.

Using the waypoint list

GPS receivers have an information page that lists all the waypoints that you’ve created and stored. (Again, check your user manual for information on how to access and use this list.) The waypoints can be listed by name or those closest to your current location. By selecting a waypoint, no matter where you are, you can find your way to it.

• The distance to the waypoint, such as a parking lot or trailhead.
• The compass direction in degrees that you’ll need to head to get to the waypoint.

Any of the waypoints in the list can be deleted or edited. See your user manual for specific instructions.
If you roam around the Internet searching for information about GPS, you’ll come across handy collections of waypoints that you can enter into your GPS receiver. There are all manner of waypoint lists, from fishing spots to pubs in England. If you’re planning a vacation, consider doing a Web search ahead of time to see whether there are any waypoints associated with your destination. Then bring your GPS receiver along with you as a personal tour guide. GPS receivers designed for outdoor use always assume a straight line as the route between two points. That might be convenient for airplanes and boats, but it doesn’t take into account cliffs, rivers, streams, fences, and other obstacles on land. GPS receivers designed for automobile navigation are a bit smarter, having built-in databases of road information that’s used in suggesting and measuring appropriate routes from Point A to Point B. Depending on the GPS receiver model, other waypoint-related information that you may be able to display includes

• Travel time: The amount of time it will take you to reach the waypoint based on your current speed.
• Compass: A picture of a compass that displays the waypoint direction heading.
• Directional arrow: An arrow that points in the correct direction that you should be heading.
• Navigational hints: A picture of a road that moves as you travel. If the road is centered onscreen, your destination is straight ahead. If the road veers to the right or the left, you need to correct your course so that the road is centered. A symbol associated with the waypoint will grow larger as you get closer to it.

Some GPS receivers come with databases of cities, highways, airports, landmarks, and other geographic features. These are just waypoints stored in memory that you can’t edit or delete to free up memory for new waypoints.
Most GPS receivers support mapping. At the very least, a GPS receiver has a simple plot display, a map page that shows waypoints, tracks (see the upcoming section, “Making Tracks”), and your current position. More advanced (and expensive) GPS receivers support more sophisticated maps; your waypoints and tracks appear along with roads, rivers, bodies of water, and whatever built-in features the map has. When the map page is displayed, you can zoom in, zoom out, and move around the map with an onscreen cursor that you control with buttons on the GPS receiver.
A map page can be orientated two ways: so either the top of the screen always faces north or the top of the screen faces the direction you’re traveling. Orientating the screen to the north is probably the easiest if you’re used to working with maps, which usually are orientated with their tops to the north.

How to Save Waypoints?

The two types of waypoints you can enter and save to your GPS receiver are

• Current location: GPS receivers have a button on the case or an onscreen command for marking the current location as a waypoint. (Check your user manual for details.) After the waypoint is marked, the GPS receiver screen displays a waypoint information page where you can name the waypoint and associate an icon with it.
• Known location: If you know the coordinates of a location that you want to save as a waypoint, you can manually enter it in the GPS receiver. Most GPS receivers also allow you to mark wherever the cursor is on the map page as a waypoint. A known location could be a good fishing spot that a friend saved to his GPS receiver or perhaps a lake you want to visit that you got the coordinates from a digital map. Again, check your user manual for directions on how to manually enter a waypoint.

Always use meaningful names when you save a waypoint. GPS receivers typically assign a sequential number as the default waypoint name. Although numbers and cryptic codes might make sense when you enter them, I guarantee you that you probably won’t remember what they mean a couple of weeks down the road.
Some GPS units have a MOB function, which has nothing whatever to do with tommy guns or cement shoes. MOB stands for Man Overboard and was designed for boaters to use in case someone fell into the water. (Go figure.) After seeing or hearing the splash, the captain can press a button (that creates a waypoint appropriately named MOB) and then turn around and head back to the exact location of the unlucky sailor.
Although a GPS receiver is good for letting you know where you are, waypoints are important for helping you get somewhere you’d like to go. GPS receivers have a number of features that can help you navigate to a waypoint that you’ve entered.
Maybe you decide to go for a hike. Before you leave the trailhead, you save the location of the parking lot as a waypoint, naming it PRKLOT.
Note: Some GPS receivers support waypoint names only in uppercase characters; others allow you to use both uppercase and lowercase characters. As you hike down the trail, you hear the call of a rare ivory-billed woodpecker and head off into the brush, intent on getting a sighting of the very elusive bird. After an hour of tromping around in the dense woods, you discover two things. First, the bird was just a robin; second, you’re totally turned around and are somewhat lost. But fortunately, because you have a GPS receiver with you (and have read this book), you know that you’ll be able to easily find your way back to the car and be home in time for dinner. The following sections show you how.

Setting Waypoints

A waypoint is GPS lingo for a location or point that you store in your GPS receiver. Some manufacturers also call them marks or landmarks. A waypoint consists of the following information:

• Location: The location of the waypoint in whichever coordinate system the GPS receiver is currently using. Some receivers also store the elevation of the location.
• Name: The name of the waypoint. You get to choose your own name; the length varies between GPS receiver models from six characters on up.
  
• Date and time: The date and time the waypoint was created.
  
• Optional icon or symbol: An optional icon or symbol associated with the waypoint that appears on the GPS receiver’s map page when the area around the waypoint is displayed.

This could be a tent for a campground, a boat for a boat launch, or a fish for a favorite fishing spot. All GPS receivers can store waypoints, but the maximum number that you can save varies from model to model. As a general rule, as the price of a GPS receiver goes up, so does the number of waypoints that can be stored. Lower-end consumer GPS receivers store 100–250 waypoints, and top-of-theline models can store 1,000 or more.

Datum lessons learned

Here’s a quick story from my Forest Service firefighting days that illustrates the importance of being aware of datums. A fire was reported in a mountainous area of eastern Oregon, and my partner and I helicopter-rappelled in to put out the fire. Because the fire was bigger than expected, we requested some smokejumpers to assist. They were down from Alaska, helping out during the lower 48’s fire season, and they all had new handheld GPS receivers, which were pretty state of the art back then (1998). The fire continued to grow, and we called in a small air tanker to stop the fire’s spread. One of the Alaska jumpers pulled out his GPS unit, and we called in an exact set of coordinates for the pilot to hit. As the tanker approached, the pilot radioed us, asking whether we were sure that was where we wanted the retardant to go. Turns out that the jumper still had his GPS unit set with an Alaska map datum (that didn’t match the local datum on the pilot’s GPS receiver), and the coordinates that the Bureau of Land Management (BLM) jumper gave were on the other side of the ridge, nowhere near the fire. Fortunately, the pilot used his own initiative and dumped his load right where it needed to go.

How much latitude?

GPS units can display latitude and longitude in several different formats. Take the location at the top of Mt. Bachelor (some great skiing in Central Oregon if you’re ever in the neighborhood) and see how it can be expressed.

• Degrees, minutes, decimal seconds (D° M’ S”): 43° 58’ 46.94” N, 121° 41’ 14.73” W
• Degrees, decimal minutes (D° M.M’): 43° 58.7824’ N, 121° 41.2455’ W
• Decimal degrees (D.D°): 43.9797069° N, 121.6874253°W

And just for fun, here are the UTM coordinates for that same location: 10T 0605273E, 48 70240N. Ouch! Is this confusing or what? Although it doesn’t seem like it, all these coordinates refer to the exact same location. Remember, just like converting locations from one coordinate system to another, you can also use your GPS receiver as a calculator to convert from different latitude and longitude formats. Suppose you have some coordinates in decimal degrees and need them in degrees, minutes, and seconds:

1. Change the coordinate settings in your GPS receiver to decimal degrees.
2. Manually enter the coordinates as a waypoint.
3. Change the coordinate settings in your GPS receiver to degrees, minutes, and seconds.

When you look at the coordinates of the waypoint that you entered, they’re now displayed in degrees, minutes, and seconds. (Note: Because changing coordinate systems varies from model to model, check your user manual for specific instructions.)

Land navigation

Discovering how to effectively use paper maps and compasses for land navigation is both an art and a science, with complete books written on the subject. Here are two excellent, free online resources if you want to find out more.

• Map and Compass for Firefighters (NFES 2554) is a self-study course developed by the U.S. government for wildland firefighters. The course is available at www.nwcg.gov/pms/training/map_comp.pdf.
• Map Reading and Land Navigation (FM 3-25.26) is the U.S. Army field manual on the subject, available at www.army.mil/usapa/doctrine/DR_pubs/dr_a/pdf/fm3_25x26.pdf.

Another great way to become a pro land navigator is through the sport of orienteering. Orienteering involves using a map and compass to find control points (small flags) in the shortest amount of time as possible. Do a Web search for orienteering to find more about the sport and how you can participate in clubs and events in your local area.

Understanding GPS and Datums

A datum is a frame of reference for mapping. Because the earth isn’t flat, geographic coordinate systems use ellipsoids (think of a sphere that’s not perfectly spherical, much like the shape of the Earth) to calculate positions on our third planet from the sun. A datum is the position of the ellipsoid relative to the center of the earth.
Unless you’re a cartographer or geographer, that probably hurts just thinking about it. Sparing you a long and detailed technical description, here are the two important things that you need to know:

• All maps have a datum. Hundreds of different datums are in use. Most good maps used for navigation — and highway maps don’t count —usually state which datum was used in making the map.
• You can set what datum your GPS receiver uses. The default datum for GPS receivers is WGS 84, more formally known as the World Geodetic System 1984. WGS 84 was adopted as a world standard and is derived from a datum called the North American Datum of 1983. Most USGS topographic maps that you use for hiking are based on an earlier datum called the North American Datum of 1927, or NAD 27. This datum is divided into different geographic areas, so if you’re in the United States — at least in the lower 48 states — use a version of NAD 27 that mentions the continental U.S.

So why is all this datum stuff so important? In the United States, if a position is saved in a GPS receiver by using the WGS 84 datum and the same coordinates are plotted on a map that uses the NAD 27 datum, the location can be off as much as 200 meters. That’s more than a couple of football fields off. The latitude and longitude coordinates will be identical, but the location is going to end up in two different spots.
The moral of the story is to make sure that the datums on your GPS receiver and maps are the same. Or, if you’re with a group of people using GPS receivers, make sure that all your datums match.
Not having the map datum match the GPS receiver datum is one of the biggest errors that new users of GPS receivers make. I can’t emphasize this point strongly enough: Make sure that the two match!