John welcome to time nuts. This won't be a super long post have other things to do. Search for d-psk-r and you can see a few of my exploits. Summation. "It ain't easy". It appears to be really easy unless you are far away like the east coast. Then the propagation gods enter into the picture along with the 60 KHz station in England that shows up most nights. The simplest of approaches was indeed the old doubling trick and the many flavors of it. I built most along with regenerative dividers and other trickery. Fact is it simply drops a count and that flips the phase quite annoying. I finally created two approaches. One specifically for spectracom devices essentially adding a third mixer and checking for the flip. Works but requires internal hacking of the spectracom. The other pretty much a freestanding receiever using a classic costas loop approach. All details were released to time nuts over a year ago. My next stab is more of a digital approach using the STM discovery board. Have to say I seem to get lost in some of the basics of getting all of the crazy registers set. However its value is it can run very very fast. So you can do some nice sampling. Regards Paul WB8TSL
On Sat, Jun 28, 2014 at 5:38 PM, Charles Steinmetz <[email protected]> wrote: > John wrote: > > I discovered an article on the web that uses an AD835 multiplier chip to >> square the WWVB signal * * *. I built a five section synchronous filter >> tuned to 60 KHz to get rid of interference and its output feeds the 835 >> chip. This all works fine. * * * the 599J won't tune that high so I >> have to divide this 120 KHz frequency by 2. * * * I've tried to >> generate a pulse train from the 120 KHz signal and then use a flip-flop to >> divide the frequency. This does not work well. Apparently generating the >> pulse train picks up noise and I end up with a 60 KHz signal with >> fluctuating phase. Now I'm trying to get a Miller frequency divider working >> > > Why are you trying to generate pulses, rather than just squaring > (clipping) the output of the 835 in a saturated amplifier? Pulses have > less energy and therefore higher noise. All you need is a > signal-conditioning squarer matched to the level coming out of the 835 (see > Bruce Griffith's pages at <ko4bb.com> for ideas, as well as the Wenzel > site and any number of illustrations in Experimental Methods in RF Design > -- for example, both Figures 5-46 and 4-45 show complete simple squarers > with FF dividers). Even a CMOS gate biased to half-voltage should work > fine. I like the NC7SZ74 Dflop for the divider. Half of a 74HC74 works > fine, too. > > This should be the kind of thing you throw together in 15 minutes and it > works first time. > > Best regards, > > Charles > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
