Bill Tynan wrote: > > It sounds like CCW would be the nuts for EME if it's capable of digging > signals out of noise. But, I'm afraid I'm in the dark as to what CCW is. > > Someone, please enlighten me. > >
CCW attracted quite a bit of interest back in the late 70s and early 80s, but I have heard little mention of it since then. It required some fairly elaborate hardware, so didn't become very popular. Basically, the idea was to have the CW bit-rate defined very precisely, and the hi/lo transitions be synchronous with a reference derived from UTC. Thus, based on the expected propagation delay from the sending station, the timing on the received pulses would be known allowing some processing gain. Also, the transmitting frequency would be held precisely, allowing very narrow filters. Nowadays, with GPS derived time and frequency references, and elaborate DSP being widely available, pretty much all that is needed could be implemented in the SDR architecture. It would a really cool area to experiment with, although as has already been pointed out, modern digital modes are already far superior. See WSJT for example. CCW was never really a candidate for EME because of the timing and frequency issues. I was mostly interested in CCW for weak-signal terrestrial work on VHF, but I never did get to complete the processing hardware. At the time, it was mainly an HF mode. The only easily available reference I have here is from: VHF Communications, 1/82, Woodson, W6NEY, Coherent Telegraphy Transmissions. That article references: QST, Sept 75, Petit, W7GHM, Coherent CW: Amateur Radio's New State of the Art? Hope that helps. GL & 73, Alf NU8I Scottsdale AZ DM43an _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
