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

SAIDJACK at aol.com SAIDJACK at aol.com
Wed Dec 5 23:03:02 UTC 2012

would mixing your 125KHz with a 2.5MHz or 5MHz low noise reference to get  
it into a range that the analyzer can read work?
You could use a system like the Miles timepod phase noise analyzer, a  
mixer, a 5MHz low-noise reference, and a low-pass filter to make use of the  
>500KHz lower range of the timepod.
You could divide your 5MHz reference by 2 to get 2.5MHz  +/-125KHz, with a 
2.5MHz carrier being easier to filter out one of the  two side-bands with a 
high/low-pass or notch filter?
Maybe the FSUP itself could be used to remove one of the sidebands and the  
2,5MHz carrier, and analyzer the remaining side-band?
In a message dated 12/5/2012 13:27:28 Pacific Standard Time,  
azelio.boriani at screen.it writes:

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 
>  the earliest part I would trust. Any of the fast logic families that  
> 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  
> mode and lock the other one to the first one using an XOR gate  and then 
> 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 
> 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 
> 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 
> our idea the XOR also has  to have this insanely low noise floor as well 
> course) so does  anyone have experience with anything like this? Does 
> 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 
> ridiculously clean, but I do have a solution for that  problem.
> >
> > Any help is greatly appreciated!
>  >
> > Best regards,
> >
> > Hans  Rosenberg

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