I use GPS and LORAN. Always nice to have a backup With LORAN being shut down, have resurrected the ole wwvb rcvr and built an amplified loop ant. Can work but it takes about 3-5 hours to get to 1X10^11 accuracy. Still observing various strange ness shuch as diurnal shift ... Odd wwvb works at least for me most stable in the day. I seem to remember night was supposed to be better. The signal is much stronger at night. So I guess its a play but sure not as easy as gud ole LORAN C has been.
On Fri, Nov 13, 2009 at 12:48 PM, Brian Kirby <kilodelta4foxm...@gmail.com>wrote: > You will need a receiver to compare your references to. It appears that > LORAN will be shut off, so that leaves two services available, either WWV 60 > Khz or GPS. I do not use WWV any more, I can tell you about GPS. > > To compare against GPS you will need a timing receiver, there are several > available. A lot of us got Motorola Oncore VPs, UTs, or M12+, The Rockwell > Jupiter is one and there are several more. They provide a 1 PPS signal that > is locked to the on board standards on the GPS satellite. You put this > signal in one input of a time interval counter. You use a 1 PPS divider on > your local reference and put its signal in the other input of the time > interval counter. You can record continuous or take daily 24 hour readings > and derive your drift rates. > > GPS corrections are published at NIST; > http://tf.nist.gov/service/gpstrace.htm > > You can also compare against a GPS disciplined oscillator. In the long > term it should be dead on, you will have to have it characterized for the > short term. The HP Z3801A was on the surplus market several years back, its > probably one of the best. The Trimble Thunderbolts were available to the > group a while back. > Brian KD4FM > > > Glenn Little WB4UIV wrote: > >> While I was in the US Navy we had two Cesium standards for the navigation >> center on SSBN submarines. >> While in port, we would track LORAN C and compute the drift rate of the >> two cesium standards. >> Is there a service, that has drift rates published, that I can compare my >> standards to, so that I can determine the standard drift rate. >> I do not remember the drift rates that we determined on the submarine, >> that was a few years ago, but, I seem to remember that the rate was in the >> low nanoseconds. >> If a rubidium standard drifts in one direction (does it?) a drift rate >> could be calculated and, after a comparison to a known standard, with known >> drift rate, a very accurate standard could be had for the lab. >> >> What would I expect the drift rate, or jitter, to be in a FRK class >> rubidium oscillator? >> >> Is the drift rate constant enough that a drift rate could be applied to a >> rubidium oscillator to determine it's real frequency at any given time. >> >> We calibrated the submarine Cesium standards every three months. >> We had to know the drift rate of our standard as well as the drift rate of >> the standard in each of the LORAN stations to be able to do the type of >> LORAN navigation that we did. >> >> I would like to be able to verify that my PTB-100 rubidium oscillator is >> on frequency. >> >> If I compare two rubidium oscillators, what would I expect the relative >> drift rate to be? >> >> Thanks >> 73 >> Glenn >> WB4UIV >> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
