Pactor Modem

Not yet installed - planned for next trip

The SSB (Single Side Band) radio has the capability, when operated in the right frequency range, of reaching across vast distances - over oceans and continents. It offers an ideal means of communicating not only by voice but also digitally in places where no phone lines or cellular towers are to be found. While many readers probably haven't had the dubious pleasure of having to work with modems in the past, a large number of us most likely have - in the days before direct digital connectivity at home or via WiFi, the modem was coupled with a telephone line to set up communications between two computers. I admit that I even used the modem's predecessor, an acoustic coupler; only seen these days behind glass in computer museums.

Modem communication speeds are measured in baud, initially starting under 300 bit/s and growing to the V.92 standard of 56kbps - still relatively slow compared to today's broadband throughput. These telephone modems were produced by several companies in very large number and thus became relatively inexpensive (I just realized that my notebook still has a built in modem, although I've not used it yet).

The principles for using a modem for radio communication via SSB are the same as those used in land lines. The main difference is that the rate at which these signals are sent out are much slower due to the frequency restrictions of radio waves. Since the number of potential users of this type of communication is much smaller, the modems are quite a bit pricier and there are few manufacturers. The German company SCS created the PACTOR protocol for this type of modem and remain the market leader. The protocol allows for efficient data compression and reliability and their modems can also be used to control certain SSB radios, allowing the program to quickly and efficiently choose the optimal frequencies and speeds with which to communicate.

The modem alone just allows digital communication, in order for the system to function for e-mail and other communication one needs to set up an account with one of the organizations offering SSB services. The system of choice is SailMail.

The PACTOR modem and the Sailmail account are the only two items in the list of modifications that I currently don't have installed; but upon returning to Zanshin I will install the Pactor modem and activate my SailMail account and thus have yet another alternate method of communication.