CompuServe Messages

Chris, AMTOR is an amateur form of the comunication system used for ships called SITOR. From what I remember, their specs are very close to each other. It has been used on amateur radio for about ten years now. AEA even had a box dedicated to AMTOR (the AMT-1). Amtor has two modes, FEC (forward error correction) and ARQ (Automatic Request). FEC is more of a broadcast format and is used by ARRL for their bulletins (pretty sure they still use it). ARQ is what is normally used from station to station. One station is a master and the other a slave. The master station sends three characters (6 bits a character if memory serves) and goes to receive for a short time interval. In this interval, the slave station is supposed to send a character to denote if the previous transmission was received okay or not. If the master does not hear an acknowledge, it retransmits the previous transmission – I think : Can't remember the details here too clearly. If you listen to it on the air, it sounds like a chirping. When it is time for the slave to send the text, the stations switch control, so the slave becomes master and master becomes slave. The biggest hangup to running AMTOR is you need a modern radio with fairly fast T/R times, and can take the beating of constantly going back and forth between T and R. QTH here is Marathon, Ontario – on the north shore of Lake Superior, or put another way, pretty close to being in the middle of no where, especially when it comes to terrestial VHF packet!!