Hi I don't know of any phase tracking receiver that would be bothered by the modulator in Paul's schematic. You could implement it a couple of ways, but the net result would be the same. The AM is a bit more square wave than the WWVB signal. Modulation depth and timing would / could be dead on.
Bob On Jun 17, 2013, at 9:29 PM, David I. Emery <[email protected]> wrote: > On Mon, Jun 17, 2013 at 06:11:15PM -0400, Bob Camp wrote: >> Hi >> > >> The Costas loop already has the AM component available. There's no >> need for a second receiver, just wire the AM output over to the output >> modulator. > > That is standard for most Costas loops with an I arm... haven't > looked at his schematics carefully yet... possibly one might need some > kind of AGC to use it as input to a second double balanced mixer > serving as modulator in order to get the right 14 (?) db AM as signal > fades slowly. Not sure how deep the diurnal fades are... > > But I guess if everything is quite linear over enough of a range > one could perhaps just remodulate without AGC and create a replica of > both the modulation and fades on the local 60 KHz carrier. > > > > >> >> Bob >> >> On Jun 17, 2013, at 5:57 PM, "David I. Emery" <[email protected]> wrote: >> >>> On Mon, Jun 17, 2013 at 02:41:13PM -0700, Burt I. Weiner wrote: >>>> Chris, >>>> >>>> The 8170 was originally intended to be a frequency reference source >>>> tied to the USFS (United Stated Frequency Standard). It also gave >>>> the time of day, but I believe that wasn't it's primary purpose. As >>>> I recall, there were some versions that did not have the clock >>>> readout and some that had a chart recorder. Back in the 80's I used >>>> to drool (it was a disgusting sight!) over the Spectracom receivers >>>> with the chart recorders. At that time I was usuing a Gertsch RLF-1 >>>> with an external Moseley 680 chart recorder. The remodulator >>>> precludes it from being used as a frequency standard, but in my >>>> opinion, so does the fact that WWVB is now phase shifted a bunch. >>>> >>>> The 8170 uses a coherent detector and that's where the problem >>>> lies. While the 8170 still locks to the WWVB carrier, the new BPSK >>>> scheme causes the detector to output bad data in spite of the >>>> original dips in the carrier still being present. I had always >>>> wondered how it was able to pull the data out the noise, but never >>>> had a manual until just recently. I had naively assumed that the >>>> WWVB new BPSK scheme would not affect the time of day aspect of the >>>> 8170. Like I said, I only use it as a clock in my shoppe, and being >>>> an old dog I don't easily learn new tricks such as looking in a >>>> different direction for one of the other clocks. >>> >>> I suppose I am stating the obvious, but why not combine Paul >>> Swed's Costas loop and this scheme to output a phase locked 60 Khz >>> with the right AM modulation ? >>> >>> >>> >>> -- >>> Dave Emery N1PRE/AE, [email protected] DIE Consulting, Weston, Mass >>> 02493 >>> "An empty zombie mind with a forlorn barely readable weatherbeaten >>> 'For Rent' sign still vainly flapping outside on the weed encrusted pole - >>> in >>> celebration of what could have been, but wasn't and is not to be now >>> either." >>> >>> _______________________________________________ >>> 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. > > -- > Dave Emery N1PRE/AE, [email protected] DIE Consulting, Weston, Mass > 02493 > "An empty zombie mind with a forlorn barely readable weatherbeaten > 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in > celebration of what could have been, but wasn't and is not to be now either." > > _______________________________________________ > 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.
