A few drawbacks to GPS receivers that support memory cards

Here are a few drawbacks to GPS receivers that support memory cards:

• Added cost: They add a bit more cost to the receiver price because of the built-in card reader and associated technology.
• Reader: You need a memory card reader connected to your computer to transfer data back and forth between the GPS receiver. However, some computers (notably laptops) have built-in card readers. If your GPS receiver didn’t come with a card reader, any third-party reader will work. These devices are inexpensive and easy to use. Just plug the reader into a USB port, and Windows treats the memory card like a hard drive or floppy disk. You can then copy data back and forth between your hard drive and the memory card. Card readers are inexpensive, and you can purchase a basic model for under $20.
• Removal: Memory cards can be a little tedious to swap because you need to remove the GPS receiver batteries to access the card slot. Just like digitals cameras, GPS receivers that support memory cards usually come with a card that has a relatively small amount of storage space (8–16MB). In fact, if they both use the same type of memory card, you can swap a card between your digital camera and GPS receiver. You’ll probably want to upgrade to a larger capacity card. Blank memory cards with the GPS receiver manufacturer’s brand name tend to be more expensive than standard MMC and SD cards. I don’t find any difference between the two, and you can save money with third-party memory cards in your GPS receiver.

Managing GPS Receiver Memory

If you own a GPS receiver that uses a memory card, congratulations! I personally like the versatility these receivers offer (such as stuffing a bunch of maps onto a single, large-capacity memory card). This section talks about how to get the most out of your memory card GPS receiver. If your GPS receiver uses only a cable to connect to a computer, you can skip this section. Better yet, read along to see how memory cards work for transferring data.
If your GPS receiver supports using a memory card, you have some significant advantages when exchanging data with a computer, including

• Upload speed: Uploading maps from your computer to a GPS receiver is considerably faster with a memory card than via a serial port cable. Because GPS receivers communicate at a fairly low baud rate, transferring 10–20MB of map data can take a long time (up to hours depending on how the serial port is configured).
• Affordable and practical: Memory cards have gotten inexpensive over the years. You can load frequently used maps on several cards and not bother with repeatedly uploading data from map program CDs. You can easily pick up a 128MB memory card, which I’d recommend as a minimum size, for under $40. I like to use Froogle (http://froogle.google.com) to find the best prices online.
• More storage: Memory cards give you considerably more storage than GPS receivers with fixed amounts of internal memory. You can currently purchase memory cards that provide between 8–512MB of data storage. Handheld GPS receivers that don’t support memory cards might have only 1–115MB of internal storage.
• Versatility: You can use the memory card in your PDA, digital camera, and cellphone (if all the devices support the same type of card).
• Minimal settings: When using a memory card, you don’t need to worry about COM ports, baud rates, and protocols when transferring data. (However, if you’re using your GPS receiver with a laptop and cable connected to a moving map program, you still have to contend with getting all the settings just right.)

Virtual GPS

Lowrance (www.lowrance.com) has a unique series of simulators for its sonar and GPS products that run on your computer. Just download and run a program from the Internet, and a lifelike replica of the product appears onscreen. The GPS receiver simulators don’t actually track satellites, but other than that, work just like the real thing. Use your mouse to click buttons, and the keyboard arrow and Enter keys to select menu items and change settings.

Although Lowrance designed the simulators as a way for potential customers to become familiar with their products (and for owners to practice with them), GPS receiver simulators are an excellent way to find out about concepts and functions that are common to all GPS receivers, no matter what the brand or model. The user interface and features vary between brands and models, but key GPS receiver concepts such as datums, coordinate systems, waypoints, routes, and tracks remain the same. The Lowrance simulator, shown in the figure here, lets you come up to speed on basic GPS receiver operations without even owning a receiver; plus it’s fun to play with. (If you download a simulator, get a copy of the real product’s user manual so you can understand and try all the features. These can be downloaded from the Lowrance site as well.)

To download Lowrance simulators, go to
www.lowrance.com/software/pcsoftware/demos.asp.

How to simulate navigation

Some GPS receivers have a simulator or demonstration mode. This is probably one of the most overlooked (but coolest) features on a GPS receiver. The simulator mode acts as if the receiver is actually acquiring GPS satellite information. You select a speed and a direction, and the GPS receiver pretends you’re moving. Because the receiver isn’t relying on acquiring satellite data, you can comfortably sit inside the house in your favorite chair, getting familiar with your new purchase.
Depending on where you live or work, how many windows you have, and your view of the sky, your GPS receiver might (might) work indoors (or at least close to windows). Although you’re limited to what you can do with a GPS receiver indoors, it’s fun to see just how much GPS coverage you can get walking around inside a building.
There are lots more things you can do with a GPS receiver besides using it for basic navigation. Think outside the box. Some examples include

• Take digital pictures of cool places and record their coordinates with your GPS receiver. You can post them on a Web site or e-mail them to friends.
• If you have a small GPS receiver (like a Garmin Geko), securely attach it to your dog’s collar and track where Fido goes for the day. (You can also find commercial GPS pet locator products on the market.)
• Use your track log to create art. Some GPS users express themselves as artists by using their GPS receiver to record their movements as they walk around trying to create shapes or pictures. (Don’t believe me? Check out www.gpsdrawing.com.)

Your goal should be to become confident using your GPS receiver and to have fun in the process.

Finding your ancestors

A lot of people are into genealogy these days, and your GPS receiver can be a helpful tool in tracking your ancestors, whether they are Aztec people or Visigoths. When you visit a cemetery looking for long-lost kin, bring your GPS receiver with you to record the exact locations of tombstones and grave plots. You can pass the latitude and longitude on to other relatives doing their own genealogical research. The coordinates can be extremely useful for someone locating a small out-of-the-way cemetery in the countryside, or a relative buried in a cemetery with thousands of plots.

How far, how fast?

Your GPS receiver also contains a very accurate trip computer that displays information about distance, speed, and time. After you read your user manual on how to reset and start the trip computer, here are some ideas for getting familiar with how it works:

• When exercising: When you run, jog, bike, or whatever, take your GPS receiver with you on your favorite course to see just how far you go. At the end, check your average and maximum speed.
• When on walks: If you have children and they walk to school, go with them on their route to see exactly how far it is. (And then tell them you used to have to walk at least ten times that distance . . . in the snow . . . uphill both ways . . . when you were young.)
• When doing lawn work: The next time you cut the grass, take your GPS receiver with you and see just how far you push your lawn mower. Don't drop and chew the receiver with the mower, if that happen then all my condolence is for you.
  

Coming home

Everyone has opinions and like to know where people stand on different things, so here’s an exercise to let you know exactly where you stand —when you’re outside your backdoor.

1. Take your GPS receiver outside where you live and create a waypoint for the spot where you’re standing.
2. Name the waypoint HOME.
3. Turn the GPS receiver off and go for a walk. How far is up to you, but at least travel far enough that you can see your starting point.
4. When you’re ready to head back home, turn the GPS receiver back on and use it to navigate back to the HOME waypoint.

Be sure to move through the different onscreen pages to watch the direction and distance change as you head back home. After you enter the HOME waypoint, no matter where you are, if you have your GPS receiver with you, you can always tell exactly how far away home is. Remember, this is in a straight line as the crow flies unless you’ve got a GPS receiver that supports autorouting.

How to Use Your GPS Receiver?

Finally! After you initialize your GPS receiver and change some of the system settings, it’s time to use it. Start with _ Going through the GPS receiver’s different onscreen pages and see what information is displayed.

• Walking around and watching what happens to the numbers and your position on the GPS receiver’s mapping and trip pages. (Do this outside, of course.)
• Pressing buttons and seeing what happens. You may want to have your user manual nearby in case you get lost between information screens.

GPS receivers are pretty robust, and you’re not going to hurt your new purchase by being curious.
GPS receiver screens can be scratched relatively easily. Investing in a carrying case will keep the screen scratch-free; many cases have a clear plastic face that allows you to use and view the GPS without taking it out of the case. Another way to keep the screen from being scratched is to buy thin, clear plastic sheets used to protect PDA screens, cut them to shape, and place the sheet on top of the GPS receiver screen.
The following are some simple exercises you can try that will help you become familiar with your GPS receiver. When you first start using your GPS receiver, take the user manual with you. If you forget how to do something or have a question, the manual will be right there for reference.

How to Change GPS Receiver Settings?

After you initialize your GPS receiver for the first time, you need to change a few of the receiver’s default system settings. You only need to do this once, and a few GPS receivers will prompt you to make some of these changes as part of the initialization process. These changes are mostly to customize settings based on your location and needs. Check your user manual for specific information on how to change the system settings described below. Although GPS receivers have a number of system settings that you can change, here are some of the important settings you’ll want to initially adjust:

• Time: Your GPS receiver gets very precise time data from atomic clocks aboard the satellites, but it’s up to you how the time will be displayed. You need to specify
• Whether to use 24-hour (military time) or 12-hour (AM and PM) time
• Whether Daylight Savings Time is automatically turned on and off
• What your time zone is (or your offset from UTC)
• Your GPS receiver gets time data from the satellites in the UTC format. UTC stands for Coordinated Universal Time (no, the acronym doesn’t match the meaning), an international time standard. UTC is a time scale kept by laboratories around the world, using highly precise atomic clocks. The International Bureau of Weights and Measures uses time data collected from the labs to establish UTC, which is accurate to approximately one nanosecond (about a billionth of a second) per day. In 1986, UTC replaced Greenwich Mean Time (GMT) as the world time standard. The Greenwich meridian (prime meridian, or zero degrees longitude) is the starting point of every time zone in the world. GMT is the mean time that the earth takes to rotate from noon to the following noon. These observations have been kept since 1884 at the Royal Observatory in Greenwich, England. In hours, minutes, and seconds, UTC and GMT always have the same values.
• Units of measure: Your GPS receiver can display distance information in statute (such as feet and miles), nautical (knots), or metric (meters and kilometers) formats. The default setting for GPS units sold in the United States is statute, so unless you’re boating or want to use the more logical metric system, leave the setting as-is.
• Coordinate system: By default, your GPS receiver displays positions in latitude and longitude. If you want to use location coordinates in a different format, now’s the time to change the setting.
• Datum: The default datum for all GPS receivers is WGS 84. Unless you’re planning on using your receiver with maps that have a different datum, leave the default setting.
• Battery type: The default battery setting on most GPS receivers is alkaline. If you’re using another type of battery, select the correct type. The battery type setting doesn’t affect the GPS receiver’s operation; it only ensures that the battery life is correctly displayed on the screen because different types of batteries have different power characteristics.
• Language: Most GPS receivers are multilingual, so if you’d rather view the user interface in a language other than English, it’s as simple as selecting a different language from a menu.

The trimble software

During certain times of the day, you might have better satellite coverage than at other times because of the number of satellites that are in view and the position of a single satellite relative to the GPS receiver and other satellites in the constellation.
Trimble Navigation (www.trimble.com), one of the largest manufacturers of commercial and professional GPS receivers, has a free Windows program called Planning, shown in the figure here. Planning is designed for surveyors who need to know when the best time is to use GPS surveying instruments. Just enter the latitude and longitude coordinates of a location and the date, and Planning gives you information on

• DOP: Dilution of Precision describes how accurate a reported GPS position is. The smaller the DOP number, the higher the accuracy.
• Satellites: You can see how many satellites are in view if the sky is unobstructed, the optimumtimes of satellite visibility, and the satellite orbit paths. You don’t need to be a surveyor to use this information. Knowing optimal GPS times is useful for all sorts of outdoor activities. For example, if you’re serious about geocaching, you can select the best time of day to look for caches when your GPS receiver gives you the most accuracy. Planning is easy to use and works for any location in the world with all the GPS satellite information presented in graphs or lists.

To download Planning, go to www.trimble.com/planningsoftware_ts.asp?Nav= Collection-8425.

Preparation for GPS receiver initialization

You really don’t need to know this technical information to operate your GPS receiver, but to start acquiring satellites to get an accurate location fix, a GPS receiver needs the following satellite data:

• A current almanac (rough positions of all the satellites in orbit)
• The GPS receiver’s current location
• The current date and time
• Ephemeris data (precise position of individual satellites)

If some or all the data is missing or out-of-date, the GPS receiver needs to get updated information from the satellites before it can accurately fix a current position. The types of data that are outof-date or missing determine how long the GPS receiver takes to initialize. If the GPS receiver is brand new, out of the box, several hundred miles away from where it was last used, or has been stored for a prolonged period of time, initialization will take longer.

How to Initialize Your GPS Receiver?

Your GPS now has power, so it’s ready to go, right? Well, almost. After you put batteries in your GPS receiver and turn it on for the first time, don’t expect it to instantly display your location. A GPS receiver first needs to go through an initialization process before it can tell you where you are. The type of initialization and the amount of time it takes depends on what information the GPS receiver has previously received from the satellites and when. The process is mostly all automatic, and you don’t need to do much as your GPS receiver starts up and begins to acquire satellites. Your GPS user manual may contain model-specific initialization information. To initialize a new GPS receiver, take it outside to someplace that has an unobstructed view of the sky (such as a large field or a park) and turn on the power. (You did install the batteries first, right?). After the start-up screen displays, the receiver will begin trying to acquire satellites.
It can take anywhere from 5–30 minutes for the GPS receiver to gather enough satellite data to get a position fix for the first time (usually more toward the 5 minutes end of the scale). Don’t worry; your GPS receiver isn’t going to be this slow all the time. After the GPS receiver is first initialized, it usually only takes 15–45 seconds to lock on to the satellites when you turn it on in the future. In order to speed up the location fix for the first time or when the GPS receiver has been moved hundreds of miles since it was last turned on, many GPS receivers have an option where you move a cursor on an onscreen map of the United States or world to show your general location. Providing a general location helps the GPS receiver narrow its search for satellites that are visible from your present location, speeding up the initialization process. Manufacturers often use the terms cold start and warm start to describe different GPS receiver start-up states and times. Unfortunately, their definitions of these terms can be different, which makes comparative information about start times not very useful. Just remember that under the same conditions, with a similar view of the sky and with their antennas optimally orientated, most modern GPS receivers generally take the same amount of time to acquire satellites and fix a location.
Most GPS receivers have a satellite status page that’s displayed while the receiver is acquiring satellites; see an example status page in Figure 5-1. This page typically consists of two circles that represent a dome of sky above your head. The outer circle is the horizon, the inner circle is 45 degrees above the horizon, and the center of the inner circle is directly overhead. The N on the page represents north.
Based on the almanac information, the GPS receiver shows the position of satellites within the circles, representing them with numbers. As a signal from a satellite is acquired, the number is highlighted or bolded. Underneath the circles are a series of bar graphs with numbers underneath them that represent signal strength. The numbers correspond to the satellites that the GPS receiver has located. The more a bar is filled in, the better the GPS receiver is receiving signals from that particular satellite. Try moving your GPS receiver to watch the satellite signal strength change. If signals are weak or you get a message about poor satellite coverage, move to another location and change the position of the receiver to better align it with the satellites that are shown onscreen. If you’re successful, you’ll see new satellites acquired, the signal strength increase, or both. The more satellites you acquire and the stronger the signals, the more accurate your receiver is. Holding the GPS receiver properly will optimize signal reception. If your GPS receiver has a patch antenna, hold it face up, parallel to the ground. If your GPS receiver has a quad helix antenna, hold it straight up so that the top of the receiver is pointing toward the sky.
After the GPS receiver gets enough information from the satellites to fix your location, the screen typically displays an Estimated Position Error (EPE) number. Based on the satellite data received, this is the estimated error for the current position. The smaller the number displayed, which will be in feet or meters, the more accurate your position.
Estimated Position Error (EPE) is a bit confusing. If you see an EPE of 20 feet, it doesn’t mean that you’re within 20 feet of the actual coordinates. You’re actually within up to two times the distance of the EPE (or even more) from the actual location. For example, if you have an EPE of 50, your location could be 1–100 feet of the actual coordinates. EPE is not a maximum distance away from the actual location; it’s only a measurement estimate based on available satellite data. To complicate things even further, different GPS receiver manufacturers use different formulas for determining EPE, so if you set three different GPS receiver brands next to each other, they all display different EPE numbers. Some manufacturers are conservative with their numbers, and others are optimistic. Don’t get too caught up with EPE numbers; just treat them as ballpark estimates — and remember, the smaller the number, the better.

More about GPS battery

After you select the type of batteries you’re going to use, you should be aware of some other issues when it comes to powering GPS receivers:

• Battery life gauges: In the GPS receiver’s setup information page, you can specify what type of battery you’re using, such as alkaline or NiMH. The battery type setting helps the GPS receiver make an accurate guess how long the battery will last. Remember that different battery types have different discharge rates. All GPS receivers also have an onscreen battery gauge that shows you how fully charged the batteries are. If you set the wrong type, the worst that will happen is that the gauge won’t be accurate. See how to extend battery life with some GPS receiver models in the sidebar, “Battery saver mode.” Always check the battery level of your GPS receiver before you head out on a trip and also remember to carry spare batteries. One way to tell which batteries are new or charged is to put a rubber band around the good ones. By feeling around in your pack or pocket, you can instantly tell which ones are fresh. Note: Rechargeable batteries discharge faster than alkaline batteries when they’re not in use, so if you haven’t used your GPS unit in a couple of months, don’t be surprised if those rechargeable batteries are dead or don’t have much life left in them.
• Cigarette lighter adapters: If you’re primarily using your GPS receiver in a car or truck, you can save on battery costs by powering the GPS receiver with a cigarette lighter adapter. These handy devices run a GPS receiver from your car’s electrical system. You can buy a generic version or one made for your model (sold by that GPS receiver manufacturer). Depending on the model, adapters cost between $20–$40, with the generic versions a bit cheaper than the manufacturer models. Cigarette lighter power adapters have straight or coiled cables. Although coiled cables are tidier, if your cigarette lighter isn’t close to the dashboard, a coiled cable can pull your GPS receiver off the dashboard if it’s not securely mounted. Adapters with straight cables don’t have this problem; you can tidy up any slack in the cable with a plastic zip tie.

Battery saver mode

Some GPS receivers have a battery saver mode that can greatly extend the life of your batteries. (Check your user manual to see whether your model has this feature and how to turn it on.) Normally, a GPS receiver processes satellite data every second and determines your speed and location. Based on this information, the GPS receiver predicts where you should be the next time it gets satellite data. If the prediction is close to your actual position and battery saver mode is turned on, the GPS receiver will start receiving satellite signals every five seconds or so instead of every second. In addition, some of the internal electronics are turned off during this wait period. Because a reduced amount of power is needed, the battery life is extended. The GPS receiver continues to access satellite data every five seconds until the predicted location isn’t accurate anymore, at which time it switches back to receiving data every second, starting the process over again. (Some GPS receivers provide you with a number of choices of how often satellite data is received. The more seconds, the more battery efficient the receiver is.)

GPS Battery Resources

You can really get geeky with batteries and powering your GPS unit. If you get a charge out of electricity, here are some links to nitty-gritty information sources that cover voltage, milliamperes, and GPS drainage rates:

• Battery drain for selected GPS receivers:www.gpsinformation.net/main/bat-5.txt. This site offers the lowdown on just how much juice different GPS receiver models consume.
• The Great Battery Shootout!: www.imaging-resource.com/ACCS/BATTS/BATTS.HTM. This site is more orientated to digital cameras (not GPS receiver-specific), but you’ll find some good data on how different types of batteries perform.
• Newsgroups: sci.geo.satellite-nav. Do a Google Groups search in this USENET newsgroup for batteries and be prepared to spend a couple of hours reading through educational (and sometimes controversial) posts.

When you check these sources, you’ll run into mAh, which means milliampere-hours. Most rechargeable batteries like NiMH have the mAh rating printed on their label. This rating is the battery capacity. Typically, the higher the mAh number, the longer the battery will last.

Becoming Familiar with Your New GPS Receiver

After considering all the options, making your list, checking it twice, and finding out which GPS receivers are naughty and nice, you’ve finally come to that blessed event where you’re the proud owner of a GPS receiver. But before you step out the door for a 100-mile wilderness trek or cross-country road trip, intent on relying on your new electronic gadget as a guide, be sure spend some time getting to know your GPS receiver.
A good place to start your GPS familiarization process is with the user manual. Many GPS receivers have a quick-start guide that gets you up and running in a matter of minutes. These guides are perfect for those impatient, got-to-haveit-now people; however, I suggest that you also take the time to read the full user manual. Otherwise, you could miss out on some important information contained in the full user manual.
In addition to the user manual, this section will also help you become familiar with your GPS receiver so you can get the most out of it. Obviously, because so many GPS receiver models are on the market, don’t expect to find detailed operating procedures for your specific model here: You need your user manual for that. What you can expect is basic information that applies to most GPS receivers, including some things most user manuals don’t mention. Based on a number of years of search and rescue experience, I can list numerous occasions when hunters and hikers thought that their GPS receiver was some kind of magic talisman that would prevent them from getting lost. And quite often when the search teams finally found them, they had no clue whatsoever how to properly use their GPS receiver. If you’re going to rely on a GPS receiver for navigating outside of urban areas, take the time to find out how to use it so the friendly, local search-and-rescue people don’t have to come looking for you. I’ll step off my soapbox now, thank you.

Road warriors

If you’ll use your GPS receiver primarily in a car or truck for road navigation, your feature criteria is a bit different than a GPS receiver designed primarily for outdoor recreational use. Although any GPS receiver with a base map or uploadable street maps can help you stay found on the road, some models are more suited to automobile navigation. And although some GPS receivers are designed primarily for automotive use, I prefer handheld GPS receivers that offer versatility because they can be used in a car or for outdoor recreation. Some important features to look for in a GPS receiver that you’re going to use for road navigation include

• Automatic route selection: A GPS receiver designed for street navigation allows you to find addresses, street intersections, and highway exits. Just enter where you want to go, and the receiver calculates the shortest or fastest way to get there. Pretty slick, isn’t it? The selected route is highlighted on the map screen, and your progress is displayed as you travel. If you encounter a traffic jam or other road problem, you can instruct the receiver to recalculate a new route from your present position and avoid the problem.
• Turn here directions: The GPS receiver lists all the streets and roads in your route at which you’ll need to make turns, including the street name, an arrow that points to the correct turning direction, how far ahead the turn is, and how long it’s going to take to arrive at the turn. The GPS receiver gives an audible or visual signal prior to when you need to turn.
• Points of interest: Maps that are used with road navigation GPS receivers have databases of information about gas stations, restaurants, freeway exits, hotels, attractions, entertainment, shopping, and emergency services along your route. These are dubbed Points of Interest (POIs); the GPS receiver can display information about specific POIs.
• External antenna support: Because the metal body of a car or truck might interfere with satellite signals, an external antenna might be required to connect to the GPS receiver. An external antenna also provides you with more mounting location options because only the antenna (and not the GPS receiver) needs to be mounted someplace with a clear view of the sky. Note: Some heated windshields can block satellite signals. In cases like that, you’ll probably need to use an external antenna with a magnetic roof mount.

If you’re a GPS road warrior, you’ll definitely want a 12-volt cigarette lighter adapter so you don’t go through a lot of batteries during a trip. And finally, if you’re more of an urbanite (versus an outdoors) adventurer, another option is to use a PDA, such as a Pocket PC or Palm with GPS hardware and street navigation software. Chapter 6 discusses the ins and outs of using PDAs with GPS.

To map or not to map

In terms of features, probably the biggest decision you’ll need to make is whether to get a GPS receiver that displays maps. If you plan to use your GPS receiver for on-the-road navigation, you need a mapping model. If you’re primarily using your GPS receiver for outdoor activities, you need to decide whether to spend the extra money and get a model that displays maps. Quite honestly, no matter what a salesperson might tell you, a GPS receiver with built-in maps isn’t required for activities such as hiking, geocaching, fishing, bird watching, kayaking, or other outdoor pursuits.

Using waypoints and tracks are all you need to navigate and successfully stay found. (Of course, you have a paper map and compass with you, and know how to use them, right?) Even though your GPS receiver doesn’t display maps, if it can interface with a PC, you can still download information on where you’ve been and have it show up in a digital mapping program. That said, mapping GPS receivers are pretty handy because they give you a quick, big-picture view of where you’re located in relation to other features. And just the sight of a map, even though it’s tiny and lacks a lot of detail, can be pretty reassuring at times; even for a seasoned outdoors-person. Although I’m a firm believer that a mapping GPS receiver should never take the place of a paper map and compass, if your budget allows a mapping GPS receiver along with the digital maps to load with it, I’d say buy it. I personally use a mapping model for outdoor navigation and treat the map feature as just another tool in my bag of navigation tricks.

How to Select a GPS Receiver?

Before you purchase a GPS receiver, you should spend some time kicking the proverbial tires. Don’t rush out and buy a receiver based on one or two good Internet reviews without having a chance to hold that very GPS receiver in your hands to see how it works. Spend some time comparing different brands and models to determine which one works best for you. Because GPS units are sold in most sporting goods stores and many large retail chains, you shouldn’t have to buy a receiver sight unseen.
The three largest manufacturers of consumer GPS receivers in the United States are Garmin, Magellan (a part of Thales Navigation), and Lowrance. All these manufacturers have extensive Web sites that provide detailed information about their products. If you’re in the market for a GPS receiver, definitely spend some time browsing through product literature. The Web site addresses for these manufacturers are

• Garmin: www.garmin.com
• Magellan: www.magellangps.com
• Lowrance: www.lowrance.com

And don’t just look at the marketing literature. Download the user manuals for the models you’re interested in to better understand their features. All GPS receiver manufacturers offer free Adobe Acrobat PDF versions of their product user manuals on their respective Web sites. If you’re in the market for a GPS receiver, these are excellent resources for comparing features and seeing what the user interface is like because the manuals have instructions as well as screenshots.
Friends with GPS receivers are also a good source of information; ask to take their different brands and models out for a test drive. Here are the two big questions that you should ask yourself before you begin your GPS receiver search:

• What am I going to use it for? Think about what activities you’ll be doing with your GPS receiver: hiking, biking, fishing, sales trips on the road, and so on. What will you expect your GPS receiver to do? Navigate streets or the wilderness, store favorite fishing spots, or find geocaches (hidden goodies from the popular electronic treasure hunting sport of geocaching)? When you get specific with your answers, you start to identify features that your GPS receiver should have to meet your needs.
  
• How much do I want to spend? How much money you’ve got in your wallet or purse is obviously going to influence which models you end up considering. The more features a GPS receiver has, the more it’s going to cost. So if you can figure out exactly what you’re going to use the receiver for (see the preceding bullet) as well as which features you really need (versus those that are nice to have), you’ll end up saving some money. Generally, figure on spending anywhere from a little under $100 to $500 for a handheld GPS receiver, although note that a few specialized automotive and aviation models can cost up to $1,000.

For the most part, the cost of a GPS receiver really has nothing to do with accuracy. An expensive GPS receiver isn’t more accurate than a cheaper model. The only exceptions to this rule are GPS receivers that support Wide Area Augmentation System (WAAS), which can be more accurate than GPS receivers that don’t have these enhanced location features. Figuring out how much you want to spend and what you want your GPS receiver to do narrows your options considerably, but you’re likely still going to be faced with a number of choices. The next step is to narrow down the list of candidates with some more questions and things to consider, including _ Map display: Do you want to view maps on your GPS receiver? If so, you definitely need a mapping model — a GPS receiver that displays maps. See the later section, “To map or not to map.”

• Function: Will you use your GSP receiver primarily for road navigation or outdoor recreation? Models are better suited for one or the other. See the upcoming section, “Road warriors.”
• Accessories: Does your budget include accessories such as cases, cables, vehicle mounting brackets, a case, and uploadable maps?
• Battery needs: Consider the following questions:
• • How many hours does the GPS receiver run on a set of batteries?
• Remember two things: Different models (and their features) have different battery diets, and different battery types have varying life spans. (See the upcoming section, “Battery basics,” for the skinny on the different types of batteries and their life expectancy.)
• Will you need to carry spare batteries (always a good idea), and if so, how many? I recommend always carrying at least one fresh set of spare batteries.
• Will you be using a cigarette lighter power adapter as an alternative to using batteries?
• Memory: How much memory does the GPS receiver have and is it expandable? This is a critical question if you’re interested in a GPS receiver that supports uploadable maps. Visit the GPS receiver manufacturer Web site to get an idea of how much memory maps can take up.
  
• Display screen: Find out the following:
• How big is the screen and how well can you read it? Make sure to consider visibility at night, in bright sunlight, and in poor weather conditions. The size of the screen is directly related to the overall size of the GPS receiver, so if you want a larger, more readable screen, expect a larger GPS receiver to go with it.
• Do you really need a color screen? A color screen makes reading maps easier because different colors are associated with map features. Note: Color is more of a preference than a requirement.
  
• User interface: Does operating the GPS receiver make sense to you? Sure, some learning is required to come up to speed, but using a GPS receiver should mostly be intuitive. Be sure to compare different brands and models because user interfaces are far from standardized.
  
• External controls: Look at different designs:
• Are the buttons and controls on the GPS receiver easy to use?
• Are the controls hard to operate while wearing gloves or mittens?
• Weight and size: Do you want absolutely the smallest package you can get? Note that there’s only about a 7-ounce weight difference between the lightest and heaviest handheld GPS receivers.
  
• Computer interface: Do you plan to connect your GPS receiver to a computer to download and upload data? If so, make sure that the receiver can interface with a computer to exchange data; I think this feature is a must so you can upgrade the GPS receiver’s firmware.