Hi interesting. It appears all Citizen atomic watches purchased recently use the newer protocol. Mine syncs every night even in a drawer and maintains the time to 1/4 of a second a day. How in the world does such a small antenna work at 60 kHz?
On Nov 28, 2014 3:18 PM, Ken G Kopp <kengk...@gmail.com> wrote: > > I have a long-time close friend who's retired from > the NBS in Boulder and was the project engineer > on the NBS #7 cesium standard. After the recent > reflector postings about WWV / WWVB I thought > I would get first-hand recent information from him. > > The GPS satellites all carry on-board cesium > standards that are synchronized with NTIS, and > because of changes (below) to WWVB, cell phones > remain the most accurate source of time for most of us. > > All the HF transmitters at Ft. Collins are the same TMC > units that were put in service when the facility was built. > The 2.5 and 20 MHz transmitters run at lower power due > to propagation considerations. > > The time and other station-related voice info is sourced > on site in Ft. Collins, and the various propagation and > weather info comes from various "dial in" land-line > sources. Hence the widely varying quality of these > announcements. I forgot to ask about the individual > who made the voice recordings ... > > Here's the most important info .... as of about a year > ago the modulation scheme on WWVB (60 kHz) was > changed (phase reversal each minute) and this has > rendered most of the end-user equipment inoperative. > Most (all ?) tracking receivers like the HP-117's are > now useless without extensive modification. > > Most of the "atomic" clocks now in use ->do not<- synch > to the current modulation scheme on the 60 kHz signal. > This will explain the differences in displayed time on > supposedly identical clocks and how some appear to > not be getting sufficient enough signal to synchronize. > > He offered no comment on how to locate "consumer" > clocks that -do- respond to the "new" modulation scheme. > > The 60 kHz transmitter is indeed an ex-LORAN C unit, > and because of the higher power of the "new" transmitter > the antenna system was rebuilt using material from the > LORAN C site. > > The 20 kHz transmitter was "home made" by NBS staff > at the old Beltsville, MD facility and moved to Ft. Collins. > There is no longer an antenna for this transmitter and it > will not return to the air. Trivia: The antenna was of > such high-Q that a near-by thunderstorm system would > often detune the system and cause the overload protection > to trip the transmitter off. > > He suggests that a visit to the NBS website would be > "informative". > > 73 > > Ken Kopp - K0PP > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to tom...@videotron.ca ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
