Ahh.. so... Now since my TCXO is drifting to and fro by 1-2 Hz over
the period of 45 minutes, why don't I see similar drift in the 100 Hz
audio signal, down around 5 mHz amplitude?
This happens to be about the same size at the FFT bins. So I am led
to conclude that "interpolated" peak frequencies are a bogus
technique, and you can only truly count on variations on the order of
the FFT cell size as being measurable...
Dr. David McClain
Chief Technical Officer
Refined Audiometrics Laboratory
4391 N. Camino Ferreo
Tucson, AZ 85750
email: d...@refined-audiometrics.com
phone: 1.520.390.3995
web: http://refined-audiometrics.com
On Oct 12, 2010, at 17:57, Bob Camp wrote:
Hi
Yes it is a reasonable expectation as long as you don't have a lot
of drafts. A good TCXO can get down to sub 0.1 ppb over that period.
Bob
On Oct 12, 2010, at 8:21 PM, David McClain wrote:
Okay, perhaps I should rephrase the question... Is is reasonable
to expect a TCXO to perform at 4e-9 over the FFT window period of
about 87 sec? I can only imagine that the enormous (87 s)
averaging period is making my measurements look so good.
Dr. David McClain
Chief Technical Officer
Refined Audiometrics Laboratory
4391 N. Camino Ferreo
Tucson, AZ 85750
email: d...@refined-audiometrics.com
phone: 1.520.390.3995
web: http://refined-audiometrics.com
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