+++++++++++++++++++++++++++++++++++++++ Date: Thu, 14 Jun 2001 21:58:11 -0400 From: kb1dxc at discovernet.net (kb1dxc) Subject: re: [Elecraft] MOJO SQUARED Jim, I do not know what is meant by "coherent cw." Please elaborate. Thanks, Mike - kb1dxc Reply-To: Jim Wineteer Hi Gang, I feel a kindred delight when I run into another k2 (or k1), and I think that feeling is very common amongst our community of Elecraft customers. So, I thought coherent cw might be successful amongst the cw subset and especially qrp innovators. I haven't tried it yet, and I think it would be a lot of bother if I only had one buddy somewhere using the same scheme. But if there is major interest that would change everything! Please reply directly to me if you are doing ccw, or if you are interested. If you are interested, then at what level ? Engineer, homebrewer, or kitbuilder. I'll wait until after the weekend and post a compilation of what was said. 73's Jim ++++++++++++++++++++++++++++++++++++ Date: Thu, 14 Jun 2001 21:13:17 -0700 From: Louis Hlousek Subject: Re: [Elecraft] Coherent CW There is are several QST articles on the subject available on the ARRL web site in the Technical Information Service area. Lou W7DZN +++++++++++++++++++++++++++++++++++ Date: Mon, 25 Jun 2001 19:42:14 -0400 From: Jim Wineteer Subject: [Elecraft] PIC18C Here is a summary of replies from my coherent cw post. 4 what is ccw? and no responses about people using it. If anyone is attending microchips seminar on the new pic18c pic/dsp please tell all about it. I'd love to go, but Mass. and Calif. aren't very convenient from the swamp here. I would be interested in knowing if they could be taught to speak aux bus. There is a good possibility I'm going to get one between my speaker wire and speaker someday. Jim +++++++++++++++++++++++++++++ Date: Mon, 25 Jun 2001 19:02:36 -0700 From: "Ron D' Eau Claire" Subject: [Elecraft] Coherent CW Jim wrote: > Here is a summary of replies from my coherent cw post. > 4 what is ccw? > and no responses about people using it. It's been over 20 ears since I messed with coherent cw, so I did not reply on the assumption that I was hopelessly "out of date" on the subject. Since you have not heard from anyone, I'll offer what I know: Coherent cw is a means of sending and receiving cw using a 'clock' that tells the receiving station when the sending station is starting each dot or dash (or spaces between them). That way, the detection equipment knows when to look for a signal and when not to expect one. We are talking about very high precision in the generation of the r-f waveform AND in the timing of each dot and dash. Typically, the keyer would be run from the same master clock as the rig's master oscillator (synthesized VFO) so that the receiving end could determine when to expect the next dot, dash or space by analyzing the r-f waveform just received. This precision allowed for extremely narrow filters, even by today's standards. We used bandwidths as low as 10 HZ with very steep filer skirts. That was just enough to allow clean keying at 12 wpm to be used. These very high orders of selectivity pulled very weak signals out of the noise. Back in the 70's synthesized VFO's were very expensive gadgets using lots of very expensive discrete components and about as tough to deal with as an XYL when you forget her birthday. So that brings me back to where I started. I'm certain that in the quarter century since I last messed with it, the world of coherent cw is likely to have changed as much as every other aspect of Ham radio! A quick scan of the internet for anyone with web pages on the subject turned up http://www.njqrp.org/mbrproj/ccw.html You might start with George, N2APB, who posted this page. Ron AC7AC K2 # 1289 +++++++++++++++++++++++++++++