[time-nuts] PM-to-AM noise conversion (was RE: New Question onHP3048A Phase Noise Test Set)
mfeher at eozinc.com
Thu Jan 17 16:11:15 EST 2008
Well, in my opinion, it was no more complex than what you had to offer, and
there was never a mention of an FFT analyzer. FFT or not, it still has to
see a detector first prior to an A/D. As I said, modern analyzers read No
out directly in dBm/Hz, so, no correction is needed. The problem is more
complex than you state as the -100 Hz does fold back and depending on the
phase relationship with the + 100 Hz could cause discrepancies in readings
of actual values. A typical spectrum analyzer usually allows you to go below
DC, therefore the -100 Hz would probably be visible. The fact is, it does
exist. A simple energy detector would measure the vector sum of the two.
Pretty basic to me after doing it for close to 30 years. However, I am
always open to new ideas and am happy to learn from any experience you may
have to share. I just do not appreciate answers that do not contribute
anything of additional value. Unfortunately, I did not see anything in your
post that provided that additional value. Regards - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bruce Griffiths
Sent: Thursday, January 17, 2008 3:50 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] PM-to-AM noise conversion (was RE: New Question
onHP3048A Phase Noise Test Set)
Mike Feher wrote:
> So - Bruce - what did you say that I did not? -
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
You didnt clearly indicate why the 3048 reports the spur amplitude as
6dB lower than the spectrum analyser does.
Your explanation is overly complex and confusing.
You also mention several factors that are irrelevant when using an FFT
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