Re: [time-nuts] Doppler and FMT

2013-09-21 Thread Magnus Danielson
On 09/20/2013 04:34 AM, quartz55 wrote: But when working with clocks (time, frequency, stability measurements) this assumption often not true and it's helpful to think of averaging more as a disease than a cure. /tvb I can understand that. Dave

[time-nuts] Doppler and FMT

2013-09-19 Thread quartz55
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

Re: [time-nuts] Doppler and FMT

2013-09-19 Thread quartz55
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

Re: [time-nuts] Doppler and FMT

2013-09-19 Thread Dan Rae
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

Re: [time-nuts] Doppler and FMT

2013-09-19 Thread Bill Dailey
: 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

Re: [time-nuts] Doppler and FMT

2013-09-19 Thread Bob Camp
Hi Remember - there's more than one station on 5, 10, 15 and 20 MHz. You may be picking up the modulation from one of them. Ionospheric shift can easily give you a few Hz on HF. Back when I was doing FMT stuff there was no ionosphere involved. I was within ground wave of Newington …. Bob

Re: [time-nuts] Doppler and FMT

2013-09-19 Thread Tom Van Baak
So it's just a matter of averaging what you can measure and assuming that the average will be close? Two quick comments. 1) A gradual phase drift over time is identical (by definition) to a frequency offset. 2) In general, averaging a moving target gets you *less* accuracy, not more. We

Re: [time-nuts] Doppler and FMT

2013-09-19 Thread Bob Camp
Hi As with most complex questions the real answer is that depends … Blind averaging will indeed get you in trouble. Curve fitting (a straight line is a simple one) often is the better approach to phase data. You can get an averaging like improvement (square root of the number of samples). You

Re: [time-nuts] Doppler and FMT

2013-09-19 Thread quartz55
But when working with clocks (time, frequency, stability measurements) this assumption often not true and it's helpful to think of averaging more as a disease than a cure. /tvb I can understand that. Dave ___ time-nuts mailing list --