Some people think that after they have a GPS receiver, they really don’t need a map, especially if the receiver has built-in mapping capabilities. This isn’t necessarily true. GPS receivers are best used in conjunction with maps, whether those maps are paper or digital. Here are some of the reasons why:
- Detail: Most maps on handheld GPS receivers don’t offer the detail of full-size paper or digital maps, especially topographic maps and nautical charts.
- Size: A GPS receiver’s screen is pretty darn small, and it’s just about impossible to get the big picture that a full-size map can give you.
- Backup: If you have a paper map with you and know how to use it, the map becomes an important backup if your GPS receiver’s batteries fail or if you encounter poor satellite coverage. Gadget lovers might consider a paper map and magnetic compasses primitive, but they don’t require batteries — and both are lightweight and cheap, to boot.
- Complementary: After you get back home or to the office, you might want to see where you’ve been on a map, based on the locations that you’ve stored in the GPS receiver.
With a digital map, you can easily plot the exact route that you took or identify the places you visited. All maps and GPS receivers use coordinate systems, which are grids on maps that enable you to find locations on a map. Because GPS receivers are designed for use with maps, they support a number of coordinate systems that correspond to those commonly found on maps. Thus, you can take a location that you recorded on your GPS receiver and precisely locate it on a map. By default, your GPS receiver displays positions in latitude and longitude. But you can change the settings to display locations in exotic-sounding coordinate systems such as the Finnish KKJ27 grid, the Qatar grid, or the W Malaysian R grid. You probably won’t need to switch to some of these obscure coordinate systems, so you can stick with latitude and longitude or Universal Transverse Mercator (UTM), which are used pretty much everywhere.
If you’re fuzzy on what latitude and longitude or UTM are, which gives an overview of the two coordinate systems. Suppose you have your GPS receiver set to latitude and longitude, and you record some locations. When you get home, you find out that your paper map doesn’t have latitude and longitude marks but uses only the UTM coordinate system. Not a problem. Look in your GPS receiver user manual for information on changing the coordinate system from latitude and longitude to UTM. Location points that you store in latitude and longitude appear as UTM coordinates. This is a quick and easy way of converting data between coordinate systems. Or you can visit the Graphical Locator Home Page at Montana State University (www.esg.montana.edu/gl/index.html) to perform online conversions of latitude and longitude and Township and Range. Although Township and Range is a popular coordinate system used on many maps in the United States, don’t expect your GPS receiver to support this system.
Unlike the latitude and longitude and UTM grid systems, which were mathematically derived, grids in the Township and Range system may not always be the same size, thus making it difficult for a GPS receiver to determine coordinates in this system. Most maps that have Township and Range information also have latitude and longitude or UTM marks. If you have a location reported in Township and Range, you’ll need to spend a bit of time looking at a map, manually figuring out the position that the coordinates point to, and then plot that position by using a different coordinate system.
Modern technology rapidly evolves, and the same holds true for GPS. Since consumer GPS receivers first became available in the mid-1990s, the market has grown tremendously because of cheaper receiver prices and new ways to use GPS. A peek into a crystal ball shows what the future may hold for GPS.
- More accurate: The United States has started planning the next generation of GPS, dubbed GPS III. Driving factors are better accuracy and reliability, improved resistance to signal jamming, and the looming European Galileo system. Increasing the number of WAAS satellites in orbit is also planned. The first GPS III satellite is tentatively planned for launch in 2012. The U.S. government budget will have an impact on plans to improve the present GPS system; the Iraq invasion delayed the launch of several satellites.
- Smaller: GPS receivers will continue to shrink. GPS units already are integrated into wristwatches, and PC Card GPS receivers can plug into a laptop or PDA. The three limiting factors that prevent a consumer receiver from shrinking are antenna size, screen size, and power source size
- Cheaper: Prices will continue to decline as manufacturing costs decrease and production quantities increase.
- Easier to use: Simplified and less technical user interfaces will become more of a priority as GPS receivers become more appliancelike to meet the needs of specialized markets. An example is Garmin’s Forerunner product, which is targeted to runners and lacks a number of features typically found in traditional GPS receivers.
- Easier to view: Improved screen technology will make GPS receiver screens brighter and easier to read.
- More integrated: GPS receivers are being integrated into cars and trucks, cellphones, PDAs, Family Radio Service (FRS) radios, and other consumer electronic devices. Expect some new products and services that take advantage of location-aware data.
- Thriftier: User-replaceable AA and AAA batteries have long powered portable GPS receivers, but expect some changes in power sources.
- Built-in Lithium ion (Li-Ion) and nickel metal-hydride (NiMH) batteries, popular in cellphones and laptops, make sense for GPS receivers. Garmin started releasing rechargeable GPS receivers at the end of 2003.
- Further on the horizon, miniature fuel cell technology will keep GPS units going and going without frequent battery changes.
- Less wired: Most GPS receivers transfer data from personal computers through a cable. Wireless technologies such as Bluetooth (www.bluetooth.com) and wireless USB are well suited for fast and easy data transfers to GPS receivers without using cables.
The U.S. has had a monopoly on satellite-based location systems over the years (the Russian GLONASS, Global Orbiting Navigation Satellite System, has really never been a viable player), but that may soon change.
The European Union is moving toward deploying its own positioning system called Galileo. If everything goes as planned, Galileo will be operational by 2008 with a constellation of 30 stationary satellites. Position accuracy is touted as within a meter, which is ten times more precise than what GPS currently provides to civilians. The United States isn’t happy about this; as an alternative, GPS prevents the U.S. government and military from selectively degrading signals and blocking use elsewhere in the world. China, Israel, and India have expressed interest in becoming involved with Galileo. As of early 2004, after a number of negotiation sessions, the U.S. and European Union had reached a number of compromises that met both parties’ needs.
http://europa.eu.int/comm/dgs/energy_transport/galileo/index_en.htm
Some models of GPS receiver, designed primarily for automotive use, have a synthesized voice that provides you with route-finding information. Although this feature has been available as an option in some luxury cars for many years (for example, in the OnStar system), portable GPS units that talk to you are available. You don’t have to pay monthly subscription fees for them, and you can easily move them from car to car. (Ah, progress.)
If you’re using your GPS receiver primarily for navigation in your vehicle, mount it securely so that it doesn’t slide around the dashboard.
- GPS receiver manufacturers make mounting brackets for in-vehicle use.
- Do-it-yourself solutions can include Velcro, Silly Putty, small beanbags, or modeling clay (the nonhardening type).
Never mount your GPS unit where an airbag deploys during a crash.
Some GPS receivers aren’t limited to internal memory for storage, using support memory cards that can be plugged into the receiver to store data.
External memory can be either
- Manufacturer proprietary data cards
- Generic (and less expensive) storage, such as
- MultiMediaCard (MMC; www.mmca.org)
- Secure Digital (SD; www.sandisk.com)
A receiver’s internal memory holds such data as waypoints, track logs, routes, and uploadable digital maps (if the model supports them). The more memory the receiver has, the more data you can store in it. All the data that’s been stored in the GPS receiver is retained when the device is turned off. GPS receivers have different amounts of memory. Unlike personal computers, you can’t add memory chips to a GPS unit to expand its internal memory.
Well, yes, a GPS unit has to have an antenna to receive radio signals to do you any good. Several types are available, each with its advantages.
Internal antennas
All GPS receivers have one of two kinds of built-in antennas. One antenna design isn’t superior to the other; performance is related to the receiver’s antenna size. (Cough . . . bigger is better.)
Patch
An internal patch antenna is a square conductor mounted over a groundplane (another square piece of metal). Patch antenna models reacquire satellites faster after losing the signal.
For best performance with an internal patch antenna, hold the receiver face up and parallel with the ground.
Quad helix
An internal quadrifilar helix antenna (or quad helix) is a circular tube wrapped with wire. Quad helix antennas are more sensitive and work better under tree cover than the other types.
For best performance with an internal quad helix antenna, hold the receiver so that the top is pointing up to the sky.
External antennas
Some GPS receivers have connectors for attaching external antennas. An external antenna is useful if the GPS receiver’s view of the sky is otherwise blocked, like in a boat, a car, an airplane, or a backpack.
Reradiating antennas
If a GPS receiver doesn’t have a jack for connecting an external antenna, you can improve the reception with a reradiating antenna. These antennas work just as well as conventional external antennas that plug into a GPS receiver.
A reradiating antenna combines two GPS antennas:
- One antenna receives the GPS signal from the satellites.
- The other antenna is connected to the first and positioned next to the GPS unit’s internal antenna. Here are a couple of sources for reradiating antennas:
- Roll your own: If you’re handy with a soldering iron, search Google for reradiating antenna GPS for tips on how to make one yourself.
- Buy one: Purchase an assembled reradiating antenna from Pc-Mobile at www.pc-mobile.net/gpsant.htm.
