You shouldn't be seeing a 2Hz spread. It can happen but in my experience that is big. Check gain control and make sure you aren't seeing artifacts. There is an fmt-nuts on yahoo which may be more appropriate for this.
Doc Sent from mobile > On Sep 19, 2013, at 10:32 AM, "quartz55" <quart...@hughes.net> wrote: > > I knew it was not that easy. I didn't think about WWVB, and yes, I hear them > quite often on 20. So it's just a matter of averaging what you can measure > and assuming that the average will be close? I can imagine the shift can be > all one way or the other for extended periods and how would anyone know which > way? I'll have to check another signal that I know is not a double and see > what I see. With SpecLab, it's easy to see mHz, but it's constantly changing > so I guess one needs to log the data and use the spreadsheet to average it > and hope it's close. The other thing is the 2000 wanders around especially > when the fan goes on, so I've got a circuit to lock the MO to a GPS. > XRef-VS, there are others for other radios too. We'll see what happens when > I get the XRef installed and working. > > When I saw the WWV/B? signals I figured it was just how lucky you were. If > I'm seeing 2 Hz spread how can anything be measured with precision? You can > get close to anything once, it's doing it all the time that counts. > > Dave > N3DT > ----- Original Message ----- > From: Dan Rae > To: Discussion of precise time and frequency measurement > Sent: Thursday, September 19, 2013 10:07 AM > Subject: Re: [time-nuts] Doppler and FMT > > >> On 9/19/2013 6:48 AM, quartz55 wrote: >> I was playing with SpecLab and my TS-2000 just to see how accurately I could >> measure frequencies in the HF region. I notice when I set the rx on cw and >> listen to the 750 Hz output of WWV at 15 or 20 MHz with SL, I get like 2 and >> sometimes more tracks about 2 Hz apart constantly shifting around. I assume >> this is Doppler going in and out? If that's so, how can anyone reasonably >> expect to measure any ionospheric HF signal in the mHz range? > Dave, it's not that easy. I did the ARRL FMTs a few years back when > they were transmitting from the other side of the States and thought I > was doing well to get within 0.1 Hz. The phase shifts on 7 and 14 MHz I > was seeing due to Doppler were up to 360 degrees, and quite rapid. > > Mind you I was using non computer techniques [1], so averaging by > eyeball was possible. > > Also if you are using WWV / WWVH, here at least, you often get both > signals at similar strength, so you might well be seeing two different > offsets. > > Dan > > ac6ao > > [1] looking at the 100 kHz IF output of the receiver on a scope, both > scope trigger and Rx reference driven by homebrew GPS unit. > _______________________________________________ > 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. > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1432 / Virus Database: 3222/6180 - Release Date: 09/19/13 > _______________________________________________ > 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.
