New-car built-in GPS systems offered as standard equipment or as options on new vehicles are more expensive than add-on units, often much more expensive. However, the LCD screens are usually larger, allowing for better visibility, especially while driving. The navigation system's LCD display is usually shared with other systems in the car, such as radio, climate control, and hands-free cell phone. Also, with built-in units, the antenna and power attachment are already part of the vehicle. A disadvantage is that built-in sytems are usually a step behind in new features and map updates.
In-dash add-on navigation systems replace a vehicle's normal radio or radio/CD player and typically include a large LCD display, navigation system, AM/FM stereo, and CD player. Some even include a DVD player to watch movies on the LCD screen (not while driving, of course). The LCD folds into the unit when not being used. This type of system is ideal for RVs. These systems are moderately expensive, should be installed by professionals, and usually require installation of an outside antenna. These are not good for leased vehicles since vehicle modifications are not allowed.
Portable automobile GPS navigation systems , such as those from Garmin, Magellan, and TomTom, have more flexibility in where and how you use it, the ability to swap the unit from one car to another, can have more features, and are less expensive than a factory-installed built-in unit. If you frequently rent cars, drive business vehicles, or trade cars often, a portable unit is a great solution. Many such systems easily mount to a vehicle's dash or window, allowing quick removal when not being used. Most new devices have powerful satellite receivers and built-in GPS antennas, eliminating the need for an external antenna. Some work from batteries while others require the use of a power plug. It's easy to update portable GPS devices with new maps and updated software by attaching it to your PC and downloading from the manufacturer's web site.
A Brief History of GPS
For centuries people have been developing techniques to figure out their position on Earth. We have come from using the stars, all the way to sending satellites into orbit. GPS has “evolved” from the forerunners with the United States Navy to the twenty four-satellite constellation that it is now. Following the launching of Sputnik in the 1960’s the Navy ran two programs that were predecessors to GPS. The first operational satellite based navigation system was called Transit. Developed by Richard Kirschner in 1964, it consisted of seven satellites and used radio signals.
The second satellite navigation system built in 1967 was called Timation. This system improved upon the Transit system by using an atomic clock. The drawbacks for the Transit system were its accuracy and its inefficiency. (GPS History) In 1973, the Navy and Air Force teamed up and formed the Navigation Technology Program, which became Navigation System and Ranging or NAVSTAR. (Meyers, et al. 2003) The first four satellites were launched in 1978. It currently contains twenty-four satellites that circle the Earth every twelve hours. Availability is increased and mobile vehicles do not have to wait for readings, as with previous systems. |