REVIEWS - What Makes Up the Best GPS?

By. Aristalina

Handheld GPS Reviews

What exactly makes a gps unit the best? If you base the answer only on the opinion of users, you will never arrive at one common general answer.

The first real step to find the best gps unit is to research. Although gps devices are primarily meant to assist in navigation, different models now also carry an outstanding array of features. Yo can have a gps device with voice navigation, international maps, media players, waterproof shield, heavy duty batteries and locators.

Full featured gps devices can cost as much as $2000. A gps unit that will bleed your pockets dry is definitely not the best for you. If you can afford expensive devices, then the best gps for you might be the one that carries every feature you can ever imagine. Those who have a little extra to spare would typically opt for units that have entertainment features.

Users will always disagree when it comes to gps features. A gps device should be user friendly regardless of its price or number of features.

Forums, message boards and review sites have all the advice you will need to pick the best gps device.

How Does GPS  Work?

GPS (Global positioning system) GPS (Global positioning system) is a satellite sourced navigation system developed by the Unites States Department of Defense and is administered by United States Air Force 50th Space Wing. It uses a constellation linking 24 to 32 satellites orbiting earth that transmit well defined radio wave signals, which allow GPS receivers to establish their existing location, the timings, and their speed.

GPS satellites GP system makes use of the information provided by the GPS satellites orbiting around earth twice in every 24 hours at around 7000 miles per hour.All GPS satellites are equipped with solar panels and thus make use of solar energy to power the resources. Satellite signals Each of these satellites recurrently sends signals to the receivers on the earth which work out all the information. The signal comprises of three basic parts - a pseudorandom code, ephemeris data and almanac data .Satellites transmit 2 low powered radio signals L1 and L2, civilian GPS makes use of L1 signal which has a frequency of 1575.42 MHz in UHF band. Ephemeris data gives an account of the satellite position and other related orbital information. Magellan and Garmin offer superior GPS receivers which are exceedingly accurate due to their parallel channel design. A GPS receiver locked in to 4 different satellites can accurately determine the three dimensions that is, the latitude, the longitude and the altitude. The GPS needs an highly accurate clock. GPS makes use of this same clock in its satellites. MAGELLAN AND GARMIN Leading brands with GPS solutions, Garmin and Magellan have a variety of products on offer.

Blackberry and PDA’s for Mobile and laptop integration with the GPS receivers is another range of products. Customized software solutions from Magellan and Garmin GPS’ handheld for topographic, marine and street navigation. Recent Garmin GPS receivers are equipped with WAAS (Wide Area Augmentation System) which corrects to the average of 3 meters by improving and transmitting GPS signals through beacon transmitters.

Limitations and error introduction in the GPS receivers

Improper synchronization and correction of atomic clock time in satellite and receiver.

Ephemeris errors- errors due to incorrect location co ordinates of the satellite.

• Needs clear Line of sight from the satellite to the receiver.
• Delays in the atmosphere while passing through Ionosphere and troposphere introduces delay time errors in the signals.
• Improper synchronization and correction of atomic clock time in satellite and receiver.
• Ephemeris errors- errors due to incorrect location co ordinates of the satellite.
• GPS does not work under water, under ground or inside the buildings.

Check out the outher guide on Triton GPS