PDA's can come with GPS technology and it works through the same function as other GPS systems, via satellite.

GPS

The Garmin Approach GPS is technology at it's finest. If you've ever wondered how you can benefit from GPS technology, you won't ever have to worry about getting lost again with this device. Featuring the latest in advanced satellite technology on it's site, this GPS device will have you wanting to know when you can buy it.

SiRF Technology, Inc. was a pioneer in the commercial use of GPS technology for consumer applications. The company manufactured GPS navigation software, and GPS navigation devices.

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