Handheld GPS receivers

If your PDA has a serial port, you can easily interface the PDA to a general purpose, handheld GPS receiver.
Because you’re using the handheld GPS receiver exclusively as a data input source — and really don’t care about what’s appearing on its screen — just about any GPS receiver that can communicate with a computer via a serial port will fit the bill. You don’t need a lot of features and whistles and bells on the GPS receiver if you’re primarily using it this way. This option makes a lot of sense because the GPS receiver can be used independently of the PDA, especially outdoors during bad weather.
The primary disadvantage is that you have to contend with two electronic devices and the cable that connects them together. This can sometimes get a bit messy in a car, with hardware and power and interface cables scattered all over your dashboard. Also, this type of PDA navigation setup is a bit cumbersome to deal with if you’re walking around.
One of the best sources of GPS receiver interface cables for a wide variety of PDAs is Pc-Mobile. Check out its extensive product Web site at http://pc-mobile.net.