Handheld GPS Buying Guide

Benefits of GPS (back to top)

The advantage of this technology is truly awesome and has proved to be helpful in varied fields, some of which are listed below:

• Navigation: GPS receivers are carried by wilderness explorers, mountaineers, and wildlife researchers. Competitors in such sports as Gliding even use these gadgets to determine their returning point. Computer controlled harvesters, mine trucks, and even ships and airplanes use GPS receivers.

 

• Military: Many fighter planes, infantry troops, and guided missiles such as cruise missiles, use the guidance of GPS receivers.

 

• Geological Experiments: Precise measurements of differences in the stress within the earth's crust can be achieved by comparing subtle changes in a topography compared to a standard reference. The cause of these changes can then be checked, into thus providing prior warning of any upcoming calamity.

 

• Mobile Phone Location: Sometimes in times of disasters or when a person is missing, GPS technology can be used to track the location of a mobile phone that may be carried by the person to be found.

 

• Time Synchronization: GPS satellites can be used for precise time measurements. GPS, being an unfailing atomic clock can be used as a time reference for various experiments requiring exact time calculations such as in the fields of seismology and high-end telecommunications.

 

• Airline Services: While passengers may be debarred from using their personal GPS receivers on airplanes, many airlines use their own GPS equipment to combine aircraft tracking with the television services provided to the passengers.

 

• Treasure Hunt Games: Geocaching involves use of handheld GPS receivers to reach a specific location marked by longitudinal and latitudinal values to find items hidden by other game players.

 

• Surveying: Land surveyors use GPS to locate property boundaries, survey markers, and other landmarks.

1. How GPS Receivers Function (back to top)

The main players in the GPS arena are the 27 satellites, each weighing 3,000 to 4,000 pounds orbiting the earth at a height of around 12,000 miles. The paths are designed to ensure that at any point of time any location on earth is 'covered' by at least 4 satellites. The GPS receiver on earth measures its distance from each of these satellites to arrive at an accurate location of where it happens to be. This feat is achieved through a process called 'trilateration'.

In reality, GPS systems use 3D trilateration. To understand this concept - consider a scenario where you are say, 5 miles from the Satellite A. Then you could be anywhere within an orbit of a 5 mile diameter. If you also know you are 7 miles away from satellite B, you can narrow your location to the area in which the two respective orbs overlap, which happens to be a perfect circle. If there is a third satellite, you now have access to another orb, which has only two points of intersection with the circle. The earth on which you stand can act as the forth orbit. Among the two points of intersection, one will be on earth and the other will be in space. Considering that you happen to be on earth, you can discard the other point in space. Thus, you have arrived at your exact location. The GPS receiver will now detect the latitude, longitude, and elevation of that point. Superimposing this data onto preinstalled topographical maps enables your exact location to be deduced. This entire process is a real-time application and is constantly recalculated as you move.

Since GPS receivers require a wide view of the sky to function, they may not always work on narrow streets lined with tall buildings or on tree covered forest paths. The speed at which a location is calculated determines the efficiency of the device. Normally, GPS receivers have an accuracy of around 10 meters.

2. Purchasing Criteria (back to top)

Since GPS technology is a very niche technology and not many people are in the know, it would be advisable to spend some time analyzing the various brands in the market. Also, during the time of purchase, talking to a technically savvy acquaintance or an owner of a GPS system would make more sense. Below are a few parameters you need to consider when making a purchase of a GPS receiver:

• Receiver Channels: The accuracy of a receiver is directly proportional to the number of channels it uses to collate data. One channel receives data from one satellite. Thus, more the number of channels, greater the information received. The maximum number of channels supported by a receiver is 16, which results in 95 per cent accuracy. In areas, where you may not have an unobstructed view of the sky, it is better to go in for a receiver having a minimum of 12 channels.

 

• Display: A large color screen enhances readability of the maps being displayed and thereby betters the chance of instant recognition of the area you happen to be in. Also, the screen should have a wide viewing angle, which is especially important in cases of dashboard receivers, which are mounted on car dashboards.

 

• WAAS: Wide Area Augmentation System (WAAS) is a network of satellites and ground stations that further enhance the receiver signal and perform corrective measures to improve the accuracy of location detection. WAAS enabled receivers have as much as 5 times the accuracy of other receivers, and boast of an accuracy of around 3 meters.

 

• Water Resistance: If you intend to use your GPS receiver in the outdoors or when camping, fishing, or rafting, it makes sense to invest in a device which offers some level of water resistance. This is an important consideration as even a miniscule entry of water can damage the unit.

 

• Level of Detail in Maps: The greater the detail offered by maps, the better the chance of the user accurately locating his position. While some GPS receivers have very general maps, it is better to go in for a device having street level maps. Since maps and locations keep changing, the device should enable you to update the maps in the receiver's firmware. Computer connectivity is another plus point as this enables one to download the latest maps or software onto the device. Inquire at the time of purchase if the manufacturer offers the facility to download maps from its website.

3. Making the Decision (back to top)

After deciding upon your requirements and preferences with regards to the various features mentioned above, you should compare various GPS receivers that match those requirements offered by leading brands at a site such as Smarter.com. A GPS receiver is a handy gadget for just about anyone. Man has always been curious by nature and the concept of getting to know where one is anywhere across the world is a facility to cherish. At the time of purchase of this device, keep in mind your requirements.

If you are a foot traveler or normally venture out into hilly terrain which does not permit the entry of any vehicles, a handheld receiver would be a better option for you. For a car aficionado, installing a car navigation system would be a good idea. This system provides a graphical representation of the route traversed by the car. Sometimes, the car navigation systems integrate with the DVD displays.

Some Personal Digital Assistants (PDA) are compatible with GPS receiver modules, which can be plugged into the extension port of the PDA. The PDA's memory too can be used to install detailed maps, making detection of the location that much easier.

Unlike car navigation systems, marine navigation systems, installed on boats, do not provide a graphical pathway for the navigator. They only serve to pinpoint the location on the sea.

With miniaturization reaching an all time record, GPS devices can now be attached to ones wrist. As with all electronic devices, the after sales service offered by the manufacturer as well as the warranty duration and coverage needs to be overly stressed upon. With proper care and maintenance, this gadget is designed to be sturdy and give years of trouble-free service.

Buying a good GPS receiver requires investment of a reasonable amount of time in researching and evaluating the various contenders and doing detailed research on a comparison shopping site like www.smarter.com. The trick is to strike the perfect balance between price and functionality; and the best way to begin is to find out exactly what your needs are. Hopefully, you now have more information to help make your purchasing decision more informed, now go find a great GPS system!