As Bob stated thermal noise is equally divided between AM and PM
components when a carrier is present.
Both the AM and PM noise components are -177dBm/Hz their sum is
-174dBm/Hz.
Bruce
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?
--- Graham / KE9H
==
On 1/15/2013 1:38 PM, Bruce Griffiths wrote:
I've noticed a disturbing tendency to quote the thermal noise
contribution to phase noise as -174dBm/Hz instead of the corrent
value of -177dBm/Hz as verified by measurement by NIST:
http://tf.nist.gov/phase/noisemeas.html
This error occurs in papers from Spectrum Microwave, Wenzel
Associates and others.
Blindly propagating the results quoted in the early literature isnt
particularly helpful given that the definition of SSB phase noise has
changed in the intervening decades.
Bruce
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