Jorj's home page: Technophilia

Background: what went wrong in 2002

Essentially, nothing went wrong with the 2002 Bike Trip Replacement. But it had drawbacks: firstly, it involved reconditioning and managing a pile of old NiMH battery packs, and secondly (and more importantly) it was dependent on cellular phone coverage.

That last bit is fine as long as I'm biking somewhere that has actual cell phone coverage. The plan for 2003 was to bike in Nova Scotia, and all bets were off.

Late in 2002, I became a licensed Amateur Radio operator, and I figured that I could use it to fill this niche. I adapted the software and the hardware so that I could use the cell phone when coverage was present, but so that I would use the Automatic Position Reporting System (APRS) to upload all of the intermediate data.

The last thing was to modify the battery situation. I realized in mid-2002 that I have a lot of laptop batteries (because I use the laptop a LOT), and that it was probably possible to use them as a good 12 volt power source.

And that's what I did. The batteries are Dell C-class batteries. I bought an external charger (so that I wouldn't have to take the laptop), and grabbed a broken Dell Latitude from ebay (for $30 or so) in order to use the battery connectors and bottom of its case. The result is a case that holds two Dell batteries. It performed well, but the 5V regulator circuit that I built overheated, so I wound up putting the iPaq on D cells (a contingency plan that I had up my sleeve anyway).

The radio part is a Kenwood TH-D7e, a 35W 2-meter amplifier, and a homemade antenna and antenna mount. The iPaq collects data from the GPS; the TH-D7 is in TNC mode (not APRS mode), and the iPaq tells the TH-D7 when to transmit.

The venue changed a few times, and the bike trip finally wound up being through Virginia. For much of the trip, I had no cell phone coverage; I was pleasantly surprised with where I could make APRS connections, though. Data was relayed to the web page without any significant problems.

Looking forward to future trips, I'd like to reduce the cabling mess and reduce the number of pieces. I customized some tupperware containers to accomodate the gear and it all worked out, but I'd prefer not to have to pfutz around so much each morning and evening with setup and tear-down. And obviously I'll have to deal with the 5V regulator problem.