[time-nuts] Very challenging phase noise measurement, does anyone have an idea??

Bob Camp lists at rtty.us
Wed Dec 5 22:32:20 UTC 2012


Hi

The lower limit on the TimePod may not be a hard limit. I believe it's 200
KHz, so maybe double the frequency ...

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Azelio Boriani
Sent: Wednesday, December 05, 2012 4:57 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Very challenging phase noise measurement, does
anyone have an idea??

Yes, I have taken a look and the FSUP is 1MHz min at the signal analyzer.
Timepod? No, 500KHz min... an R&S FAM modulation analyzer?

On Wed, Dec 5, 2012 at 10:48 PM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> A "3048" style measurement with the carrier suppressed by lock should do
> pretty well. If the XOR's are out, there are a lot of mixers available
that
> work at 125 KHz. A simple op-amp buffer and a sound card could do what you
> need to do.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Adrian
> Sent: Wednesday, December 05, 2012 4:33 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Very challenging phase noise measurement, does
> anyone have an idea??
>
> For phase noise the frequency range is 1MHz to 8/26.5/50GHz
> The spectrum analyzer works from 20Hz to max.
>
> Adrian
>
>
> Azelio Boriani schrieb:
> > Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz
> shouldn't
> > be a problem. I had an FSUP for 25 seconds to play with... really
> > impressive but too limited test time to appreciate fully.
> >
> > On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp <lists at rtty.us> wrote:
> >
> >> Hi
> >>
> >> Just about any of the high speed CMOS parts should work. A 74AC86 is
> about
> >> the earliest part I would trust. Any of the fast logic families that
> came
> >> after that should do equally well.
> >>
> >> Bob
> >>
> >> On Dec 5, 2012, at 7:03 AM, Hans Rosenberg <Hrosenberg at catena.nl>
> wrote:
> >>
> >>> Hello Time-nuts,
> >>>
> >>> I have to do a phase noise measurement and I'm wondering if anyone
here
> >> has any ideas on that. We have to measure the phase noise of a 125kHz
> >> carrier (5Vp-p signal level). The measurement system should have a
noise
> >> floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the
> >> carrier.
> >>> Our current plan is to use 2 of these sources, have one in free
running
> >> mode and lock the other one to the first one using an XOR gate and then
> use
> >> the output of the XOR gate as an output signal. However, we are
> wondering
> >> if any of you know a better idea. Maybe there is an off-the-shelf piece
> of
> >> equipment that can do that that we could rent. Or maybe we could
> increase
> >> the frequency to a few megahertz using a pll, which means the signal
> comes
> >> into the measurement range of our FSUP phase-noise analyzer. Problem
is,
> >> the phase detector would then need to have an insanely low noise-floor
> (in
> >> our idea the XOR also has to have this insanely low noise floor as well
> off
> >> course) so does anyone have experience with anything like this? Does
> anyone
> >> know an XOR with these good specs? I don't have a clue what a standard
> >> 74lvc1g86 would do. Needless to say the supply of this XOR would have
to
> be
> >> ridiculously clean, but I do have a solution for that problem.
> >>> Any help is greatly appreciated!
> >>>
> >>> Best regards,
> >>>
> >>> Hans Rosenberg
> >>> _______________________________________________
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