GPS Niche.com

How to Buy a GPS Device

They are among the hottest products in technology, but it's easy to spend a lot on a GPS device and be disappointed. We explain the benefits and pitfalls.

Tracey Capen, PC World
PC World
Monday, April 7, 2008; 12:19 AM

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Paper maps were fine in their day--but like the wind-up watch, the tube TV, and crank windows in cars, they're becoming as undesirable as last year's cell phones as new technologies continue to emerge.

Today's navigation tool, the portable GPS device, can do things that paper maps are incapable of, such as automatically showing your precise location anywhere on the globe, providing precise turn-by-turn instructions on how to drive from any Point A to any Point B, identifying where the nearest gas and coffee outlets are, and warning you when traffic problems make a detour highly advisable. It's like having a localized MapQuest right on your dashboard or in your pocket. When you're venturing into alien territory, a GPS device can give you greater security and confidence than you'll ever get from paper.

There are many handheld GPS products designed for hiking and outdoor activities, but here we'll focus our attention on aftermarket products designed for vehicles.

We strongly advise you to read the entire guide to help you figure out which type is most suitable for your purposes; but if you want to jump right in, you can find an array of excellent products here.

The prices of GPS devices vary widely, depending mostly on the units' screen size and features. Some automobile-centric models with small screens and basic mapping features cost around $150, while top-of-the-line models with big screens, XM Radio functionality, and multimedia capabilities can reach $700. Simple handheld GPS models with tiny screens and no built-in maps start at about $100; high-end models with more-sensitive receivers, color screens, extensive mapping capabilities, and rugged cases can cost as much as $600. And you can easily spend another $200 to $300 for topographical and street maps.

So, before buying a GPS model, ask yourself the following questions:

If you tend to take short trips, repeat the same commute, and only occasionally need directions, buy a GPS device in the $200-to-$300 price range. As exciting as GPS may seem in theory, you need to figure out whether you'll actually use it enough to justify the cost.

If you expect to use it daily (for sales calls, for example) and you have complicated travel itineraries, you'll find that a GPS unit quickly becomes indispensable. In that case, buy the best one you can afford.

Though car-centric GPS devices are meant for mounting in your vehicle, actually doing this may not be easy.

Most automobile-centric GPS kits include a mounting bracket with a suction cup designed to stick to your windshield or a flat surface on your dash. The catch is that in some states(including California) windshield mounts are illegal. Another problem: Not all dashboards are flat and many have pebbly surfaces that prevent suction cup mounts from adhering to them.

Some optional mounts fit into the air-vent grille in your dashboard. But these, too, can be problematic because the mount and the unit will block at least some of the airflow from the vent. Furthermore, light though most units are, they may be too heavy for a vent mount to support steadily.

Another approach is to hold the mount with weighted beanbags, but you'll need a flat, horizontal surface to place them on. Even so, beanbags and air-vent mounts may be your best options in states that prohibit windshield mounting.

If you expect to use your GPS device primarily to find convenient java shops during occasional travels--or retail outlets that you've never visited before--working with less-than-up-to-the-minute mapping data is probably okay. And you can always turn to MapQuest for more-recent information. On the other hand, if getting from one place to another on time is essential, you'll want to update your mapping data as often as possible, even if you have to pay for it.

How GPS Works

The Global Positioning System--the technological underpinning of all GPS devices--is composed of orbiting satellites (which transmit time and position signals) and GPS receivers (land-, sea-, or air-based devices such as the handheld or car-mounted GPS units that consumers use)--that mathematically calculate their current location based on data from the satellites. The system works nonstop, anywhere on the globe.

To provide an accurate fix of your current location, the GPS device must have direct lines of sight to at least three satellites in the sky. So if you're hiking in a deep canyon of rock or concrete, your GPS device may display inaccurate location information, or fail to identify your location at all. The more satellites a GPS unit sees, the more accurate its reckoning becomes--to within 20 feet of your true position in some instances. Under those conditions, a GPS device can give you a fairly accurate reading of your current altitude, too-not terribly important information if you're in a car or on board a ship, but potentially critical if you're out in the wilds.

Like many technologies we take for granted, GPS began as advanced technology for the U.S. military. The system's precise positioning capabilities gave the armed forces a technological edge over their adversaries (and allies). When released for private and commercial use in the 1980s, GPS proved an immediate boon to ships at sea, which until then relied on a 300-year-old technology, the sextant.

Personal and portable GPS units appeared about a decade ago when designers reduced GPS electronics to one or two chips; miniaturized memory meant that the receiver and map data could be placed in a box that would fit in your hand.

The two most common types of portable GPS units are small handhelds (typically used in the field) and on-dashboard models for your car. Since most on-dash models have internal batteries, they can double as handhelds when you're walking city streets.) But there are many variations on the theme: Models for boats are the next most common, but units designed for motorcycles, bicycles, and runners, as well as GPS/PDAs, GPS sport watches, GPS/walky-talkies, and even units for tracking the movement of a hunting dog in the field, have emerged.

Key Features

: Car-centric GPS models sold in the United States typically include detailed street maps for the entire country. It's like having an entire set of Thomas Guides for the U.S. localities packed into a box the size of an iPod. Some GPS vendors may include maps for Canada and Puerto Rico as well. And you can buy additional digital maps for various foreign lands. Nearly all of this electronic map data comes from two or three primary sources, so the information is quite similar, regardless of which model you purchase.

Handheld models are less homogeneous: Some can't display maps at all (instead they report your longitude and latitude, with a trail (or "track") of such coordinates to indicate where you've been; others let you load street maps and topographic maps, and a few can display downloaded satellite images. Maps are harder to read on the smaller screens that most handheld models have.

: Most car-centric models can display map data in 3D map view, also called bird's-eye view. As you travel along, the GPS map continually updates to show your current position and the surrounding terrain. Using a device that offers only a 2D view is like looking straight down at a 3-square-inch section of a typical paper map.

A 3D view gives you a graphical representation of the view out of your windshield, but from an elevation of a couple hundred feet--something like a low-altitude Flight Simulator. The resulting map is easier and faster to interpret while you are driving.

: The raison d' ê tre for any automobile-centric GPS units, turn-by-turn directions prompt you visually and with spoken instructions regarding when to turn right, when to turn left, and when to get on or off a freeway, from starting point to final destination. You simply use an on-screen keyboard to enter an address (usually with text that automatically fills as you enter the letters) and press the Go button. Do not attempt to do this while you're driving! Set up your trip before turning your key in the ignition.

The GPS device will take some seconds to calculate the route and point you in the right direction on its digital map. When driving, you must get these directions clearly and in timely fashion--not too early or too late, but at the right moment so you can safely prepare and execute your change in direction. Almost all car-centric models handle this task beautifully.

Most units deliver spoken directions through their built-in speaker, which needs to have sufficient volume and clear sound to overcome vehicle noise. A few models include a short-range FM transmitter for sending voice prompts though your car's audio system.

: The Points of Interest feature consists of a database of locations and services--gas stations, hotels, parks, coffee shops, and so on--that you may want to consult during your travels. Most automobile-centric GPS units have millions of POIs in their database. But because businesses change even faster than roads do, POI lists tend to be less accurate than GPS street maps. Better POI lists provide phone numbers along with the names and locations of services.

Recently car-centric GPS units have begun doing away with hard control buttons in favour of touch screens, which are faster and easier to use than mechanical buttons. By tapping on the screen, you can enter addresses, search for POIs, change screens, and alter various GPS settings. Touch screens also let you use virtual, intelligent keyboards, the most advanced of which make data entry extremely fast.

Need to add an address? Start typing the street name for a given city and the keyboard displays only the letters that make up a valid street name in that city. In most instances, the keyboard will disappear after you've entered three or four letters, and you're left with a short list of legitimate names. Entering a complete address in this way takes very little time.

You won't find touch screens on many handheld GPS devices because their (typically) smaller screens make tapping less efficient; as a result, handhelds often have far more complex controls.

: Screens on automobile-centric GPS models generally range from about 3.5 inches to 7 inches diagonally. Don't be too quick to dismiss a smallish display: A device with a well-designed screen and clear audio directions can work just fine. And models with smaller screens usually cost far less than their big-screen counterparts. Large screens do have obvious advantages, however: Bigger maps, more room for travel data (such as speed, direction, street labels), and roomier virtual keyboards may justify the extra cost for you.

Using a built-in or added-on FM receiver, a GPS with traffic report capability can receive signals from theTraffic Message Channel (TMC), a subscription service broadcast in selected cities. Traffic tie-ups and construction information appear on your GPS map, enabling you to avoid delays by choosing an alternate route. Some GPS models will automatically reroute you, based on the TMC reports.

GPS devices store all of their mapping and POI data in one of two ways: on a built-in hard drive, or on flash memory cards, typically Micro SD Cards. Hard-drive models tend to be faster at calculating routes and searching for POIs, but media cards are more durable. Though hard-drive-based models don't require a media card slot, such a slot is useful for updating maps and backing up addresses and favorites.

: Channels determine the number of satellite signals the GPS can receive simultaneously. Low-costs models typically have 12 channels, while high-end models may accommodate up to 24. Roughly speaking, the greater the number of channels, the better the device's accuracy.

: Waypoints are specific geographic locations, described by longitude and latitude, that you have recorded in your GPS unit. Press the waypoint record button on your GPS at a trailhead, and you can always find your way back to your car. Waypoints are rarely used with automobile-centric GPS devices, but they're essential for handheld models. Low-cost units will store relatively few waypoints; high-end models will store hundreds, permit you to manage them within the GPS, and enable you to label them as you wish.

Another centrepiece of handheld navigation is the Tracks feature. As you walk or drive though the countryside, your GPS device records and displays a breadcrumb trail of where you've been. This process lets you easily backtrack to your starting point; some models also let you download your track to your personal computer and view your travels on a topographic map. Print out the map and the track for a permanent record of your journey. As in the case of waypoints, low-end models offer limited track storage, while high-end models store many and allow you to identify them by adding custom names.

Other Important Features to Look For

Almost any GPS model sold today can display your location with astounding accuracy. But streets and businesses change, so the accuracy of that information depends on how up-to-date it is. A less-reputable GPS vendor could cut the cost of its low-end products by providing outdated mapping data. Check whether the vendor provides regular map and POI updates, and how much they cost. Some vendors offer free updates for a fixed time; others charge up to $100 or so for each update.

Car-centric GPS devices can be more distracting than a cell phone to a driver. The maps must be readable at a quick glance, so they must have high-quality graphics and avoid the clutter of nonessential information. For the same reason, the device's touch-screen controls must be well organized and clearly labeled. Some vendors make it easy to add an impromptu pit stop along the programmed route, but too many do not.

: Bright, direct sunlight can overwhelm a GPS unit's built-in screen backlighting, rendering your maps unreadable. On better units, a reflective coating behind the screen uses sunlight to brighten the display, enabling you to read your maps quickly in any lighting.

: If you plan to use your GPS unit mostly in the car, look for a kit that includes a sturdy mounting bracket and both AC and 12-volt power adapters.

Because some states ban the use of windshield-mounted GPS devices, it's important to know your state's applicable rules before you buy. The merchant selling you the device may be able to provide you with an alternative mount as necessary--perhaps an air-vent mount or beanbag mount.

: GPS devices designed primarily for in-car use don't have batteries. Instead, they plug into the car's 12-volt power port. This arrangement means that you can take the GPS into your home or hotel room and add destinations, or check routes before you head out on the road. It also means that you can use the GPS as a handheld device on occasion.

Out on the trail, a handheld GPS device with batteries is mandatory. For short trips, a model with built-in rechargeable batteries will do. But if you take to the hills for hours or days at a time, you should pick a unit that runs on replaceable AA or AAA batteries--preferably rechargeables. Small GPS units typically save weight and space by using two AAA cells, but these may last for only 4 or 5 hours on one set of batteries. Larger handhelds use up to four AA cells (which means more weight) but run for as long as 12 hours per set.

: If you expect never to use your GPS unit outside your car, weight isn't an issue. But the situation is quite different if you're the one carrying the device. Handheld models range in weight from a couple of ounces to nearly a pound--not counting the weight of extra batteries.

If you often drive in cities filled with tall buildings, GPS signals can be spotty, and your location accuracy may plummet. And of course, missing a turn because the GPS doesn't know exactly where you are can be bad news. Some higher-end GPS models include a feature called dead reckoning, which uses interpolation to fill in brief gaps caused by lapses in the GPS signals. IThe procedure involves estimating your speed and direction, and updating the map accordingly. But don't be surprised if its accuracy is poor.

One potentially useful feature if you're a regular commuter in a metropolitan area that has the TMC FM signals is traffic reports, as discussed earlier.

: Support for XM Radio isn't essential for navigation, but it's nice to have when you're on the road for hours or days. Like TMC traffic reports, XM Radio is a subscription service and is found mostly in more expensive GPS models.

Increasingly, GPS vendors are adding extras that have nothing to do with navigation to their GPS models. They have to do this because, for most people, GPS devices aren't must-have products. Again, if your car travel consists largely of an unvarying daily commute along the same route, you won't take much advantage of their strongest capability, which is for trip planning.

To entice a broader group of potential buyers, many GPS vendors now include media player capabilities in their devices, so you can listen to MP3 music and audio books, play video clips, and view JPEG images. One model we recently reviewed includes a built-in calculator. Portable gaming is sure to follow.

© 2008 PC World Communications, Inc. All rights reserved

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