Concerning my query about what's good enough to count as a contact... > We've done Moonbounce with 3mW (Hobart - Dwingeloo) in JT65 - but a > 26m and a 25m dish is stretching 'amateur' a bit again.
Googling for JT65 finds a nice paper: http://www.arrl.org/FandES/field/regulations/techchar/18JT65.pdf The JT65 Communications Protocol Joe Taylor, K1JT It's a fun read. 17 pages. The basic idea seems to be that amateurs (hams) have to exchange station IDs. That's more than a few bits, but not a huge number. JT65 is a compact protocol for doing that in a (very) weak signal environment. Their packet format is 72 bits expanded to 378 by forward error correcting. On top of that, they use half of the time for a synchronizing signal so the receiver can find the transmitter's time and frequency. Each 72 bit packet takes 1 minute to send. Their modulation scheme is 1 of 65 tones. 6 bits per baud. The extra tone is the synchronizing signal. -- These are my opinions, not necessarily my employer's. I hate spam. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.