Best GPS Unit
August 25th 2009
Understanding what GPS is:
GPS stands for Global Positioning System and was initially developed by the United States for military purposes. It is still operated by the US Defense Department, but is now free for civilian use.
The GPS navigation system is made up of 24 satellites that are situated at a distance of 12000 miles above the Earth. They circle the Earth twice a day in precisely determined orbits, each satellite providing a continuous coverage of its position. The satellites are solar-powered, with a battery back-up in the event of a solar eclipse, are equipped with atomic clocks for accurate time measurement and a rocket booster to help stay in exact orbit.
The continuous signals received from these satellites are used by GPS units in the operation of their navigation and tracking systems. The GPS devices note the transmission time of the signal by the satellite and the time it was received by the receiver and compare the difference to calculate how far the satellite is. Based on how long it took to receive the signal after the transmission, you can determine the distance of the receiver from the satellite.
Using signals from three satellites, a GPS unit can calculate latitude and longitude. To determine altitude, you need signals from four satellites. By knowing latitude, longitude and altitude, you can get precise position and directions - you can get an accurate position in the range of fifteen feet or nearer - and this knowledge is certainly vital in various personal and professional spheres.
With technological advances and innovations, GPS devices are now available in handy, portable forms that can be easily conveyed around. The use of portable GPS tracking and GPS navigation systems has certainly made life a lot easier and convenient for professionals from fields like geology, surveying, archeology, mapping, forestry, transport, avionics, and search and rescue, to give just a few examples. Portable GPS units are also used widely for regular civilian activities like navigating your car through traffic, for finding road directions in a new area, for finding your route when hiking, biking or walking. You can also use a GPS tracking system to keep an eye on your children or your pets.
Getting a portable GPS unit:
If you want to get a portable GPS device, first decide what you are going to use it for. Is it for personal or professional use or both? Are you going to use it to plot the quickest route to your destination or is to get traffic flow information or both? Do you plan to use it exclusively in your car or do you want a hand-held one that you can walk around with or both? Do you want a sturdy one that will withstand a somewhat rough usage? Once you have a general idea of what you need, you can check out the various portable GPS units available in the market and see which one fits your requirements.
Some of the leading makers for portable GPS devices are -
- Garmin
- Magellan
- TomTom
- Delphi
- Harmon-Kardon
- Rand McNally
- Alphine
- Audiovox
- Cobra
- Lowrance
- Navman
Here are some features to look for when buying a portable GPS:
The GPS unit should contain a road map database. This is essential for the GPS navigation system. You should be able to update and add to the database as and when needed, and select different guidance options.
The GPS device should have plenty of storage space to store the map database as well as all other information you need to store.
Get a portable GPS with a built-in and rechargeable battery that can last at least eight hours on a charge.
Get a GPS with a text to speech capability. If you have a device that announces aloud all street names and directions, you don’t have to take your eyes off the street to check the screen.
Your GPS should have a traffic reporting capability so you can avoid rush and jams or get around slow moving traffic. Get a GPS with a 12 channel parallel receiver system for quicker transmissions.
It won’t hurt to have a GPS with additional special features like a video player, MP3 player, an FM transmitter, an iPod connection, and hands-free calling.
The GPS unit should be small in size and not too weighty to make it easy to lug around. Just make sure to get one with a screen that is at least 3.5 inches. Anything smaller than that will be harder to decipher.
If you plan on mounting the portable GPS unit in your car, get one that is equipped with a suction cup or rigid arms.
If you are going to put it to some rough usage on bumpy roads, get a portable GPS devices that comes with a shock-proof case. You can also get water-proof and floatable GPS units which are a great boon if you want to use them on a boat.
Just keep in mind that while you can get an amazing amount of information and directional help from a GPS navigation system, it isn’t completely fool-proof. You may encounter a few errors here and there. These days we have something called Differential GPS (DGPS) which uses a stationary GPS unit to help calculate and convey position information to other non-stationary GPS receivers. This is more accurate than normal GPS.
| By Sonal Panse Published: 11/17/2007 |
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