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While I was shopping for a HT I came across the Kenwood TH-D7. This rig intrigued me since I have an interest in computers. By the way, the TH-D7 doesn't require extra gear to operate APRS or Packet. Those features and functions are somewhat limited. With my curiosity peeked and I started looking into APRS and Packet. As I researched that, a thought a cured to Me. I wonder if it would be possible to use my PDA in lue of a PC or laptop? To my surprise this was not a new idea. The Pocket APRS software was already avlable, thanks to Mike Musick, N0QBF
The next thing I looked into was GPS for position input. I opted to go with a Garmin Etrex because I only needed the NMEA output. I didn't need the map display since that would be taken care of on the PDA. In addition, the Etrex is a very compact unit, not to mention it's one of the least expensive.
The last hurdle to cross was to put it all together. Both the Palm and the Etrex have proprietary connectors, so I had to do some scrounging to get things together. First I had to find out how to wire the Palm to the radio. Pocket APRS has a good resource available at their connector page. I decided to cannibalize a portable hotsync cable instead of building my own. The portable cable makes a more compact package, but is not without it's disadvantages. This cable doesn't fit very tight, seems to get dislodged at the most inopportune moment. If you don't mind the extra balk, or if it's to be used in a vehicle, then it may be advantageous to use a standard cradle and make an adaptor. Second was the GPS to radio, which wasn't too difficult. One thing to remember is that data out on the GPS goes to data in on the radio. This also applies to the PDA to radio connection.
*** IMPORTANT ***
NEVER use more power than is necessary to reach the closest digipeater! APRS is a relay type mode. The use of high profile stations should be discouraged. Beacon rates should be kept to a minimum. In addition, the protopath should be kept short. Each additional digipeater you reach and wide in your path multiplies your packets exponentially. Resulting in packet collisions that can stop your packets short, not to mention what that does to others.
A few months prior to getting my license I had decided to upgrade my pocket organizer. After looking over the products available at the time I opted to go with a Palm IIIxe. I made this chose based cost versus capacity & flexibility and also company reputation. This, as it turned out, was a fortuitous choice, as not all PDA's are created equal. There are a couple of operating systems; the Palm OS and Windows CE. In addition, there is a difference in processors, although this doesn't affect most programs, it may make a difference with resource intensive ones like Pocket APRS.
So if you're considering the use of APRS on a PDA, then you should do a little research before you decide witch one is right for you.
Automatic_Position_Reporting
Pocket_APRS
Kenwood
Garmin
Palm
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