One way to compare any WWV receiver to a local standard is to use the PPS output of a standard against the PPS tick modulated on WWV. The tick is five cycles of a one KHz signal derived from the master frequency. See https://www.nist.gov/pml/time-and-frequency-division/time-services/wwv-a nd-wwvh-digital-time-code-and-broadcast-format
It will be a bit tricky to determine the onset of the first cycle amid the noise on shortwave radio. A computation that determined that there were just 5 cycles and worked backwards to determine the timestamp of the beginning or middle of the tick could then allow calculation of the offset between the standard PPS and the tick. Limit of accuracy might be 100 microseconds. Years ago, I had a standard calibrator made by Lavoie that had a vacuum tube WWV receiver. IIRC, the WWV carrier caused a circular sweep on a 2 inch CRT. The sine wave from a standard modulated the intensity of the circular trace, so that a bright half moon appeared on the CRT and rotated at the error rate between the two frequencies. On several evenings the dominant signal varied between WWV and WWVH (identified by the voice broadcasts). Here in Minneapolis the phase difference between the two stations was about 180 degrees, causing the bright arc on the CRT to change sides. So yes, this could be interesting for a hobbyist, but it won't add anything to Science. A MASER is overkill. Heck, so are Rubidium and Caesium. A naked crystal will be rock solid compared to received WWV. OTOH, NTP has marvelous mathematical tricks to reduce Internet propagation delay. A scheme to reduce varying atmospheric delay would be useful, if there weren't much better ways to get a standard frequency. Bill Hawkins -----Original Message----- From: time-nuts [mailto:[email protected]] On Behalf Of Patrick Barthelow Sent: Thursday, December 07, 2017 7:48 AM Hello Friends, I am picking up locally a couple of vintage analog Radio Shack SW time cube radios, 70s vintage, 3 switchable SW frequencies. Two types, the one pictured and a Radio Shack model also that has WWV and Weather channel VHF frequencies. I am interested in an accurate bench test to compare the analog shortwave radios time reporting hopefully UT-1 against other available references. For accuracy, and repeatability. Could eventually add an SDR to the mix, too. The 5,10,15 mhz radios obviously are subject to the WWV Ft Collins site, propagation distance delays, somewhat calculable, and the vagaries of Ionospheric propagation, and, propagation delays between the antenna and the measured tap point to the seconds ticks of WWV. I have some friends, microwave professionals, who are also hams here in Auburn who may enjoy doing a bench test, with published results, etc. But wonder if anyone else would be interested in borrowing a RS Timecube radio (and/or use an SDR) and designing an accurate bench test against available modern standards? We are talking probably HUGE UT-1 errors compared to what this group plays with, and that is OK but I think still a worthwhile test, especially if the errors using available and cheap equipment are predictable, and repeatable. https://forums.qrz.com/index.php?attachments/dscn1187-jpg.400844/ ----- %< ----- [snip of microwave stuff] Best, 73, Pat Barthelow AA6EG apol <[email protected]>[email protected] _______________________________________________ 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.
