Types of GPS
With GPS receiver chips as small as 15x17 millimeters and thinner than a match-head (not including antennae), these tiny bundles of navigational joy can be secreted into just about anything, including cars, boats, PDAs, cell phones, watches and those mysterious little strips in the new $20 bills (just kidding). That said, for the purposes of this article, we will only focus on the portable, stand-alone GPS units.
Key Features
Standard Features. These devices come with a host of standard features, including driving instructions, point-of-interest databases containing airports, hospitals, hotels, dining options, shopping, gas stations and ATMs - which can be priceless when you're traveling - and an address book. Most units can calculate routes based on fastest time, shortest distance, least or most use of freeways and toll-free roads. Multi-stop trip planners are less common, but a nice touch. Some GPS units will also have settings for pedestrian, bicycle and bus modes.
Voice-Guided Driving Directions. While this is also invariably a standard feature, the newer text-to-speech technology is not. This feature announces actual street names rather than generic instructions, like "turn right in 0.5 miles." These audible directions even recalculate and correct when you miss a turn.
Maps. Virtually all GPS units come pre-loaded with detailed 2D (and sometimes 3D) maps of North America. Maps from other countries can be easily downloaded and installed.
Where Am I/Help Me. Keep an eye out for units with one-touch "Where Am I?" and "Help Me" buttons. "Where Am I?" gives you the street you're on and the nearest cross streets, which can be really handy if you're giving directions to a tow truck or trying to rendezvous with someone. "Help Me" will tell you where to find the nearest police station, hospital or car service station.
Currency/Measurement Converter/Calculator. International travelers will find these features handy when you're visiting several countries in a short period of time.
Language Translator. This feature allows you to translate words and entire phrases in Spanish, French, Portuguese, German and more. With an extra accessory (usually sold separately) you can choose from a list of categories like recreation, food and drink, accommodations and transportation and have the translation displayed in text form or even spoken using a text-to-speech interface.
Bluetooth. The top-end GPS units are integrated with Bluetooth which, when paired with a Bluetooth-compatible phone, allows you to make and answer calls from the GPS device. This is especially cool when used in tandem with a point-of-interest feature, allowing a one touch phone call for whatever destination you're looking up.
Multimedia Player. Many GPS units now come with a small multimedia suite, including an MP3 player, audio book player and picture viewer. Some come with as much as one gigabyte of memory set aside for these features.
Traffic and Weather Alerts. The high-end models will have extra bells and whistles like real-time traffic and weather alerts (with subscription fee).
Vehicle Mount/Cigarette Lighter Power Adapter. These accessories should be a given at this stage, but it's best to check that your model has them included. Avoid the permanent mounts (i.e., glue-like adhesive) in favor of a window suction base so you can use the unit in multiple vehicles and/or rental cars.
External Volume Control. After all the other tech crammed onto these units, external volume control, or any volume control come to that, should be a no-brainer. Not so. This can be especially perturbing when you're trying to hear voice-guided driving directions in noisy environments.
How to Choose
Depending on where you aim on the tech scale, some GPS units come packing less-than-stout receiver chips that will falter or completely fail when you find yourself in obscured locations like tunnels, parking ramps, in deep jungle foliage or an in an urban jungle of skyscrapers.
Display quality also varies. Ideally, aim for a large, color screen that's readable from indirect angles and in bright sunlight.
Onboard map quality varies between manufacturers. Some come with excellent street-level maps included; others require you to download these at an additional price.
Battery life is pretty static in these units with a few rare exceptions on the high-end models. They should all have rechargeable lithium-ion batteries and perform similarly, with a dramatic drop in performance when the multimedia features are in regular use or the screen brightness is set to maximum.
