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
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
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
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
: 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
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
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
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
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
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