Palm PDA & Garmin GPS

The newer units are smaller, use fewer batteries and have expanded memory. In particular the tracklog memory of the GPS12 is only 1024 points as compared to 10,000 points in the latest units. Like most people I bought a GPSr intending to use for navigating to predetermined points or determining where I was on a map. A quite unexpected use for me turned out to be keeping a record of where I've been. I collect tracklogs, lots of them!

The 1024 point capacity of the GPS12 is fine for most day trips but that's about it. If you can't download to a computer at the end of the day you either stop recording or start losing what you've already recorded. So I was faced with the problem of how to extend the duration of my tracklogs. You can do this by setting a longer interval between points but if you take this to far a lot of detail is lost and the tracklog becomes a series of straight lines like a route. I like to leave mine set in the auto mode where it logs more detail on a twisty trails and less on the straight stretches.

I like my 12 and didn't want to have to upgrade just to get more tracklog capacity. Luckily I discovered that PDAs can be used in place of a computer to download data from a GPSr. After researching a bit on the GPS News Group and geocaching forums I shopped around for a basic unit and ended up getting a Palm m100.

The m100 is an older PDA which still has a regular serial port. This was an important consideration for me as I didn't want to have to deal with a USB/serial adapter. It only came with a computer (HotSync) cable rather than a desktop docking cradle which wasn't a concern as I intended to use it mostly "in the field". It's 2 mB of memory would be more than enough for all my track storage needs.

My research had also revealed that some wonderful people have written freeware for Palm PDA's to work with GPSr's. Dale DePriest's excellent site has a summary of Palm OS programs available. From all these I selected GPilotS which works with Garmin receivers to upload and download waypoints, routes, and tracklogs.

It also supports Garmin host mode which allows the PDA to emulate your GPSr to transfer the saved data to mapping programs. This means that the PDA can be hooked up to a desktop computer and the mapping programs would see it as a normal GPSr. I was able to transfer data to and from my GPSr without having to translate it from the Palm PDB format.

The only additional hardware I needed was a null modem adapter to allow the my GPSr and PDA to talk to each other. Both units had cables that were configured to hook up to the com port on a computer. The null modem adapter allows the transmit and receive wires from each to hook up in the proper order. Rather than have two full length cables joined by an adapter I constructed a null modem cable from half of an old serial cable and a Pfranc Garmin plug to connect the Palm cable to my GPSr. This kept the tangle of cables to a minimum.

GPilotS works perfectly to save my data on extended trips away from my home PC. In this application the PDA remains powered down and safely packed away until needed so it's a very efficient and compact solution to the data storage problem.

I can also take previously recorded tracks with me and upload them to my GPSr as needed. Stored tracks of 1022 points only require 18.2K per track so 57 full tracklogs from my GPS can be saved in 1 MB of memory on my Palm. Alternately, selecting the "compact tracks" option in GPilotS strips the time information from the downloaded tracks lowering the size of the saved tracks to 10.3K allowing 101 full tracklogs from my GPS can be saved in 1 MB. The results are similar in proportion for my new GPS76 which has a 2048 trackpoint capacity.

This is way more capacity than the average person would ever need.