A number of GPS receivers are on the market. Usually a GPS receiver with more features costs more.
GPS manufacturers have done a pretty good job making user interfaces easy to use. After you know the basic concepts of GPS receivers and are familiar with a manufacturer’s user interface, a GPS tracker device is usually as easy to use as a cellphone and easier to use than a personal computer.
Display and output
GPS receivers have three choices for information display or data output:
(1) Monochrome LCD screen: Most GPS receivers have a monochrome liquid crystal display (LCD) screen.
(2)Color screen: These are especially useful for displaying maps.
Color screens usually have shorter battery lives than monochrome ones. (3) No screen: Some GPS receivers only transmit data through an expansion slot or a cable; a receiver with a cable is often called a mouse GPS receiver because it resembles a computer mouse. Such receivers are designed to interface with a laptop computer or PDA running special software. All GPS data is sent to the laptop and processed there with mapping soft-ware. A Magellan SporTrak GPS receiver is shown on top of the laptop for comparison. Most GPS receivers that have screens can output data to a PC or PDA.
A GPS receiver alarm can transmit a tone or display a message when you approach a location that you specify. This feature can be especially useful when you’re trying to find a place and visibility is limited by darkness or inclement weather — or you’re busy doing something else and aren’t looking at the GPS receiver screen.
Built-in mapsEvery GPS receiver has an information page that shows waypoints and tracks. The page is a simple map that plots travel and locations. It doesn’t show roads, geographic features, or man-made structures.
Some GPS receivers have maps that show roads, rivers, cities, and other fea-tures on their screens. You can zoom in and out to show different levels of detail. The two types of map receivers are
Basemap: These vehicle GPS tracking devices have a basemap loaded into read-only memory that contains roads, highways, water bodies, cities, airports,
railroads, and interstate exits.
Uploadable map: More detailed maps can be added to this type of unit (in either internal memory or an external memory card). You can install road maps, topographic maps, and nautical charts. Many of these maps also have built-in databases, so your GPS receiver can display restau-rants, gas stations, or attractions near a certain location.
Electronic compassAll GPS receivers can tell you which direction you’re heading — that is, as long as you’re moving. The minute you stop, the receiver stops acting as a compass. To address this limitation, some GPS receivers incorporate an elec-tronic compass that doesn’t rely on the GPS satellites.
Like with an old-fashioned compass, you can stand still and see which direc-tion your GPS receiver is pointing toward. The only difference is that you see a digital display onscreen instead of a floating needle.
Electronic compasses need to be calibrated whenever you change batteries. If your GPS unit has an electronic compass, follow your user guide’s instruc-tions to calibrate it. Usually, this requires being outside, holding the GPS unit flat and level, and slowly turning in a circle twice.
The elevation or altitude calculated by a GPS receiver from satellite data isn’t very accurate. Because of this, some GPS units have altimeters, which provide the elevation, ascent/descent rates, change in elevation over distance or time, and the change of barometric pressure over time. On GPS units with an electronic altimeter/barometer, calibrating the altimeter to ensure accuracy is important. To do so, visit a physical location with a known elevation and enter the elevation according to the directions in your user’s guide. Airports are good places to calibrate your altimeter or get an initial base reading; their elevation is posted for pilots to calibrate their air-planes’ altimeters. If you’re relying on the altimeter/barometer for recre-ational use, I recommend calibrating it before you head out on a trip.
Some GPS receivers have features that allow you to increase the accuracy of your location by using radio signals not associated with the GPS satellites. If you see that a GPS receiver supports WAAS or Differential GPS, it has the potential to provide you with more accurate location data.
Wide Area Augmentation System (WAAS) combines satellites and ground sta-tions for position accuracy of better than three meters. Vertical accuracy is also improved to three to seven meters.
Coast Guard DGPSDGPS signals are freely broadcast by a series of U.S. Coast Guard stations in the United States. Whether you can receive these Coast Guard broadcasts depends on your location.
DGPS services are offered commercially for the surveying market. You can rent or purchase electronic and radio equipment for gathering precise loca-tion information in a relatively small area.
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.
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.)
An internal patch antenna is a square conductor mounted over a groundplane. 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.
An internal quadrifilar helix antenna 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.
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.
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:
(1)One antenna receives the GPS signal from the satellites.
(2)The other antenna is connected to the first and positioned next to the GPS vehicle tracker device internal antenna.
Internal memoryA 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.
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
(1)Manufacturer proprietary data cards
(2)Generic (and less expensive) storage, such as
• Secure Digital
Many GPS receivers have built-in accessory programs that display various handy features such as
(1)Calendars with the best time to hunt and fish
(2)Sunrise, moonrise, sunset, and moonset tables
User interface modes
Some GPS receivers have simple and advanced user interface modes.
(1)Simple mode: This displays only often used commands and features.This is an excellent option for the novice user who wants to use basic GPS receiver functions without being distracted or confused by the many other features. (2)Advanced mode: This shows all commands and features.
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.