Bob The generator sig is 60 Khz sinewave.but as a I build up a divider chain and such your idea makes great sense. Then filter to 60 KHz. But I see the issue with the Chronverter carrier its 120-150 Hz high. Bounces around a fair amount. There could be a secondary issue in that the carrier may not actually be phase stable. It really doesn't matter as for the Truetimes and Spectracoms its simply not good enough. I still need to try the cheapy clocks as that is what it was intended for. Not throwing stones as so much of what it does saves me a bunch of coding and doing exactly what Dave did. Regards Paul WB8TSL
On Sat, Aug 25, 2018 at 5:31 PM, Bob kb8tq <[email protected]> wrote: > Hi > > You can do the 14 db deep modulation with a tristate gate and a pair of > resistors. > Ground the input and feed the “modulation” signal to the tristate control. > > Bob > > > On Aug 25, 2018, at 4:35 PM, paul swed <[email protected]> wrote: > > > > From the earlier threads OOK modulation does not work for high end clocks > > like spectracoms and truetimes. Have not tried it on the cheapy clocks > yet. > > > > I added an external modulator. A dg419 analog switch and then with a few > > resistors added DC offset and anttenuation so that the carrier drops by > -14 > > db per the wwvb spec. The logic control is driven from the chronverter > and > > it totally works. Spectracom Netclock 2 locked up in the normal time. > > There are far better modern single supply analog gates that will work. > Just > > did not have any. > > > > The 60 KHz carrier is supplied by a fluke 6060 generator. This eliminates > > any chance of being off frequency and is not the long term answer. > > > > The chronverter actually uses a dallas semiconductor clock chip thats > > reasonably accurate.(dangerous to say on time-nuts) So that even if you > do > > not add the GPS receiver it will run quite some time correctly after > > setting the time. > > > > Chronverter draws 6 ma from a 5 V supply. I always like low power. > > > > All in all a very nice answer to what do we do if WWVB goes away. > > As mentioned it handles timezones and DST and you can change DST if those > > silly politicians screw with it again. > > > > Speculation > > The chronverter actually puts out carriers for the popular LF stations > > along with the time codes for them. > > > > Though the modulator allows quality clocks to lock I speculate the > > frequency from the chronverter is not tight enough. All of these clocks > > have very sharp crystal filters in them. 10 Hz. Plan to measure the > output > > of the chronverter see what the 60 KHz is actually at. Though listening > on > > a HP3586 receiver it appears pretty close to frequency maybe its just not > > good enough. Or the fact is OOK modulation does not work because it gaps > > the PLL in these clocks. > > > > Next steps > > > > - Determine and lay to rest the OOK/need for external modulator. > > - Power amplifier and loopstick transmitting antenna staying at or > below > > 30uv@30 meters. > > - Integrate a neo6 GPS receiver in. (Seriously easy) > > - > > - Box it up. > > > > Have my eye on one of the Truetime DC468 units and the classy panelplex > > display. > > > > Hope this helps those of you concerned with what to do should WWVB go > away. > > Regards > > Paul > > WB8TSL > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to http://lists.febo.com/mailman/ > listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to http://lists.febo.com/mailman/ > listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
