[time-nuts] Thermal noise contribution to phase noise

Mike Feher mfeher at eozinc.com
Sat Jan 19 14:34:34 EST 2013


I would think that you would not be able to tell the difference between AM
or PM noise. 73 - Mike

Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bob Camp
Sent: Saturday, January 19, 2013 1:07 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thermal noise contribution to phase noise

Hi

If:

1)  You have a carrier. Let's say it is an ideal signal with absolutely no
noise on it.
2) That carrier is in a real 50 ohm system

..there will be thermal noise at -174 dbm per Hz.

The model for a carrier includes both AM noise and PM noise. Correct?

The practical difference for small angle PM vs AM is the phasing of the
sidebands. Correct?

Either:

a) All of the noise is AM noise. 
b) All of the noise is PM noise.
c) Half of the noise power is AM and half of the power is PM.

Pick one, a,b, or c.

If you pick a or b, *why* and equally importantly *how* does all the random
thermal noise go only to one process? Since it's (by definition) random
(amplitude and phase), it's going to be tough to get it all in just one
bucket or the other. 

If the noise splits equally, then -177 is what you are going to get.

Bob

On Jan 18, 2013, at 11:52 PM, Joe Leikhim <jleikhim at leikhim.com> wrote:

> I have just sent off an e-mail to David Howe of NIST Metrology requesting
clarification about this assertion that KTB is revised -3dB.
> 
> --
> Joe Leikhim
> 
> 
> Leikhim and Associates
> 
> Communications Consultants
> 
> Oviedo, Florida
> 
> JLeikhim at Leikhim.com
> 
> 407-982-0446
> 
> WWW.LEIKHIM.COM
> 
> 
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