Update - I attempted to look at the analog signal. I looked at the output of the crystal. With the scope's low-pass filter turned on I was able to see a very weak sine wave with a period of roughly 15us. It was too weak for any analysis.
http://www.fuzzythinking.com/wordpress/wp-content/uploads/2011/11/60khz.png I also looked at the demodulator out. This is a much larger amplitude signal, though it has already been rectified. However, I was able to see good correlation between it (blue) and the TCON output (yellow) http://www.fuzzythinking.com/wordpress/wp-content/uploads/2011/11/dem_out.png Most importantly, I've been reading up on the subject and have adjusted my expectations. I didn't realize that frequency measurements (like those done by the HP117 and Fluke 207) don't actually use the timecode part of the signal. Page 11 of http://tf.nist.gov/general/pdf/1383.pdf tells me that WWVB is 3-4 orders of magnitude better than WWV for frequency measurements, but that the two services' time uncertainties overlap and WWVB is at best 1 order better. As a matter of fact, my measurements of the C-MAX line up with the top end of that estimate (and Tom's :-)). I'm still planning on capturing a long set of timings, but I need to do some hardware mods first. Thanks, -Justin On Mon, Oct 31, 2011 at 1:04 PM, David J Taylor < david-tay...@blueyonder.co.uk> wrote: > Hi David, >> Thanks for pointing out the problem with the figures in my webpage. I >> have >> fixed it. I'm going to attempt to capture the analog signal by probing >> the >> QOut pin. >> > > The updated images make the effects clearer. It will be interesting to > see the image capture. > > > Good point about "precision" - it's all relative. This is an extension of >> a previous project of mine - a clock I built around an LPro. Setting it >> to >> the Thunderbolt is a bit of a pain and I was hoping to build in the C-Max >> to make it more "fire and forget". I was hoping for a time signal within >> several microseconds of UTC without the need of an outdoor antenna. Like >> most of my projects, the journey is more interesting than the destination, >> so even if I don't accomplish that goal I'm still having fun. Embedding a >> consumer GPS is probably the more practical solution. >> >> Thanks, >> -Justin >> > > Microseconds, no. Milliseconds perhaps. But sometimes nothing at all > depending on the time of day and season of the year etc. etc. Let's hear > more about the project as it progresses. > > > Cheers, > David > -- > SatSignal software - quality software written to your requirements > Web: http://www.satsignal.eu > Email: david-tay...@blueyonder.co.uk > > ______________________________**_________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/** > mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> > and follow the instructions there. > _______________________________________________ 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.