[time-nuts] 1/f^2 noise

Magnus Danielson magnus at rubidium.dyndns.org
Tue Nov 25 16:21:33 EST 2014


Jim,

I assume from your previous comments that you went the FFT way.
As I was flying I had some time to kill, so I read some papers.

You should be reading "FFT-Based Methods for Simulating Flicker FM" by 
Charles A. Greenhall of JPL. If you read it carefully enough you will 
find several methods of operating it.

If you are nice, Chuck might hand you some code.

Cheers,
Magnus

On 11/24/2014 04:06 PM, Jim Lux wrote:
> Started plotting some sampled data from my experimental system, and
> interestingly, it seems to have a 1/f^2 slope, rather than a 1/f slope.
>   I had expected the amplifier noise to dominate, but perhaps one of the
> myriad other noise sources is contributing as well (e.g. sample clock
> jitter, ADC quantization).  ADC quantization should be white, though.
>
> only 6000 samples at 200 Hz here (30 seconds) so the data below 1 Hz is
> getting pretty sketchy..
>
> The input to the system wasn't necessarily AWGN or DC (it might be an
> oscillator beating against itself in a mixer with a very short
> difference in time (nanoseconds).  I'll run another test with the input
> shorted.
>
>
>
>
>
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