Well, I finally got around to documenting and publishing the code a couple weeks ago, open source. The answers to the FAQs are:
- I've run it on Linux and Mac OS X only, but it should run on any operating system with a Perl interpreter, including Windows, maybe. But I can't help you if it doesn't run on Windows - please find someone with Windows programming experience if you run into trouble.
- The POCSAG message encoding happens within the POCSAG::Encode Perl module. On the computer. Not within the Arduino modem. The Arduino modem software is not useful on it's own, the perl code is required to send POCSAG messages.
- The Arduino modem is needed because (1) my computers don't have serial ports any more, and (2) bit-banging synchronous 512/1200/2400 bit/s FSK using handshaking pins of a serial/parallel port, like the Baycoms did, is not possible using an USB serial adapter cable (the timing is too strict). The Arduino is a convenient and relatively low-cost platform with a good bunch of TTL level I/O pins and an USB port, and could be easily programmmed to drive the transmitter. If you wish, you can write a kernel driver to drive the FSK bits generated by the encoder, baycom-style, on a serial port (if you have one) and skip the Arduino part.
- If you feel the Arduino Duemilanove/Uno boards are too expensive, you can look at the other boards too. Just get one with enough SRAM. If you're brave, you can also put the CPU and a few necessary components on a breadboard or a custom printed board of your own. Instructions here and here and here.
- The POCSAG::Encode module is published on the CPAN, and the Arduino modem on the wiki.
- Yes, the POCSAG encoder can be connected to any VHF/UHF radio which has a suitable FSK input. Many radios (including some that do have a 9600 bit/s data input) aren't up to the task. I've tried the Motorola GM340 and the Teknomen POCSAG radio only. The GM340 needed some configuration (using the programming software) to make the data input work the way it should for this application. See the comments on the previous post for wiring tips.
- Yes, the POCSAG::Encode perl module should be useful when trying to transmit POCSAG with other kinds of modems.