Sat Nav for PDA's

Written by Zoe Hellar Wednesday, 09 September 2009 09:49

What could be more convenient than a hand-held device that reminds you appointments, stores your records and tells you how to get there? Adding a SAT NAV system to your personal digital assistant is one of the latest ways to upgrade your PDA.

How Precise do you need to be?


As usual for new technology, the price of a PDA SAT NAV depends in part on the amount of help you want in the global positioning department. The SAT NAV unit alone allows you to send a signal to the network of satellites surrounding the earth. The signal transmits the time that it was sent and the three or four satellites not blocked by the earth compare the time with the time the signal was received.

Each satellite calculates the amount of time it took for the signal to reach it and they all compare those time calculations and the position of each satellite with each other to come up with a triangulation of your position. It takes the information from three satellites to gather enough data to come up with your latitude and longitude. A fourth satellite can add enough extra information to figure your altitude, too.

Before you add a PDA SAT NAV, you should ask yourself how precise you need your information to be. Although all PDA SAT NAV units depend on information from the same satellites, the precision of the data is affected by the precision of the time-keeper in your PDA or SAT NAV.

The satellites themselves are equipped with extremely precise atomic clocks. Your PDA SAT NAV won’t have a clock quite that precise or quite that expensive. If you don’t think you’ll need to know your position to within a foot or so, you can opt for a PDA SAT NAV unit with the less expensive time piece.

Where will you use it?


Your next choice is what you want to see on your screen. A top-of-the-line PDA SAT NAV comes equipped with a map that will show your position on a changing map and tell you out loud when to turn and in which direction. Less expensive choices will allow you to download one or more static maps from your computer and allow you to compare where you are to where you want to be.

If you plan to use your PDA SAT NAV in a car where choices have to be made quickly and accurately, you might want to invest in all the bells and whistles. If you only need a rough guide for a walking tour, the less expensive alternatives are probably adequate.
The point is, decide what you want from a PDA SAT NAV and get the features you need.