There's a simple way to put an upper bound on the ADEV due to a spur,
by treating the spur as random noise. Assume that the carrier is 1 volt at
10 MHz and the spur is 80 db down. Then the spur has 10(-4) volt amplitude.
The slope of the carrier is 1/(2 pi f) or 16 ns/volt. Then 10(-4) volts
On Monday, August 6, 2018 07:12 CEST, "Richard (Rick) Karlquist"
wrote:
> I need to measure ADEV on a source that has spurious
> sine wave frequency modulation on it. I am looking for a
> formula that would tell me ADEV, vs FM deviation and
> carrier frequency. I'm not sure if modulation
Hi,
On 08/06/2018 08:22 AM, Poul-Henning Kamp wrote:
>
> In message <84a802ff-88f1-5f50-1f79-71d8ba3c4...@rubidium.dyndns.org>, Magnus
> D
> anielson writes:
>
>> What does exists is a formula for how a single sine spur would produce
>> ADEV. A FM deviation with low enough modulation
I am thinking that I should simply make a very simple notch filter
that suppresses the spurious line by 10 or 20 dB. I can then do
an A/B comparison of the measured ADEV with and without the filter.
If there is no change, I'm done. Otherwise, I add filtering in
steps until the ADEV reaches an
Surely all that's required is a simplistic worst case analysis.
Just assume that the value of Tau is always the worst possible so the full
effect of the modulation is always seen.
If the worst case phase modulation is say phi
then the worst case ADEV (Tau) will be proportional to phi*T/Tau
One might also do some trials based on comparing ADEV results between a
clean carrier signal
and ones corrupted with varying degrees of FM (for example), to get a feel
for the problem. If
nothing else, one ought to be able to get some feel for the sensitivities
involved.
Dana K8YUM
On Mon,
On 8/5/18 11:22 PM, Poul-Henning Kamp wrote:
In message <84a802ff-88f1-5f50-1f79-71d8ba3c4...@rubidium.dyndns.org>, Magnus D
anielson writes:
What does exists is a formula for how a single sine spur would produce
ADEV. A FM deviation with low enough modulation index creates two
In message <84a802ff-88f1-5f50-1f79-71d8ba3c4...@rubidium.dyndns.org>, Magnus D
anielson writes:
>What does exists is a formula for how a single sine spur would produce
>ADEV. A FM deviation with low enough modulation index creates two
>side-bands of opposite sign but same amplitude.
I
Hi Rick,
On 08/06/2018 07:12 AM, Richard (Rick) Karlquist wrote:
> I need to measure ADEV on a source that has spurious
> sine wave frequency modulation on it. I am looking for a
> formula that would tell me ADEV, vs FM deviation and
> carrier frequency. I'm not sure if modulation frequency
> or
In message <596c5939-d99e-0b01-7ff8-2b5194fc6...@karlquist.com>, "Richard
(Rick) Karlquist" writes:
>I need to measure ADEV on a source that has spurious
>sine wave frequency modulation on it.
The biggest factor is the ratio between the tau's
you do allan for, and the modulation
I need to measure ADEV on a source that has spurious
sine wave frequency modulation on it. I am looking for a
formula that would tell me ADEV, vs FM deviation and
carrier frequency. I'm not sure if modulation frequency
or tau matter. I am hoping to determine how much
I need to clean up the
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