[time-nuts] Thermal noise contribution to phase noise

[Bob Camp]

Hi

That's another confusing point if you go back far enough. There was a
tradition of assuming no correlation for broadband noise and correlation for
anything with a noise slope. That gave you a 3db / 6 db switch point in the
data as you went flat.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bruce Griffiths
Sent: Tuesday, January 15, 2013 4:10 PM
To: Graham / KE9H
Cc: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thermal noise contribution to phase noise

Graham / KE9H wrote:
> Bruce:
>
> The last time I looked, the thermal noise floor was still -174 dBm/Hz 
> (at 300 Kelvin).
>
> http://en.wikipedia.org/wiki/Thermal_noise
>
> Are you saying Boltzmann's constant is off by 3 dB, or are we mixing 
> apples and oranges here?
>
> Is there a 3 dB adjustment between noise floor (at room temperature) and
> the "single side band" phase noise measurement, which only looks at half
> the noise, since it only looks on one side of the reference signal?
>
No the noise in the upper and lower sidebands are correlated
Thus the DSB PN is 6dB greater than the SSB PN.


Bruce


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