[time-nuts] Simulating Oscillator Noise: DifficultiesSimulatingFlicker FM Noise

Bob Camp lists at rtty.us
Fri Apr 23 17:06:27 EDT 2010


Hi

Stable-32 is a great program. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Kyle Wesson
Sent: Friday, April 23, 2010 4:32 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Simulating Oscillator Noise:
DifficultiesSimulatingFlicker FM Noise

Wow. Thanks Magnus, Tom, and Bob for all of the information you
provided to me about oscillator simulations and particular noise
types. I'm going to read and digest it and see if I can get some
better results. I'm also going to purchase stable32 since it seems to
be the gold standard for precise timing work and then compare it to
the output of my scripts.

Thanks again!
Kyle

On Fri, Apr 23, 2010 at 1:16 AM, Magnus Danielson
<magnus at rubidium.dyndns.org> wrote:
> Hi Bob,
>
> On 04/23/2010 04:10 AM, Bob Camp wrote:
>>
>> Hi
>>
>> Back in the late 70's HP was pushing their ADEV test setup to us. They
>> hauled one in (yes indeed
>> more than one box) for a demo. It took them most of the morning to get it
>> in from the parking lot
>> and set up / warmed up / running.
>
> To much amusement I am sure.
>
>> They ran us through a little presentation on how ADEV has two slopes (I
>> *wish* I'd kept a copy...).
>> We brought out some sample oscillators, and ran them through. *Surprise*
>> more than two slopes.
>> I then asked them "what do the other slopes mean?". No answer .... we'll
>> get back to you ....
>> mumble mumble .... They never did get back to me.
>
> Depending on the oscillator you expect to see white, 1/f and 1/f^3 phase
> modulation noise or white, 1/f^2 and 1/f^3 phase modulation noise. Looking
> at tabulated Allan variance:
>
> http://en.wikipedia.org/wiki/Allan_variance#Power-law_noise
> (see also Tom's PDF)
>
> We see that white and 1/f is weakly different such that they can be
expected
> easilly be mistaken for having the same slope. The 1/f^3 noise has a flat
> Allan variance response. So, their oscillator during testing may simply
have
> been of one kind and the oscillator you brought out of the other.
>
> The Allan variance unability to separeate the white and 1/f noise
triggered
> the development of the modified Allan variance, but that only happend
after
> that incident.
>
>> Needless to say they would have been a lot more likely to make the sale
if
>> they had one of your
>> one page charts.
>
> A copy of Leesons paper (a two-page thing) in 1966 would have helped a
lot.
>
> Cheers,
> Magnus
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at 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 at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.







More information about the time-nuts mailing list