[time-nuts] Close-in phase noise measurements

Richard (Rick) Karlquist richard at karlquist.com
Mon Mar 31 04:05:50 UTC 2008


The relationship between phase noise and Allan variance is
a complex one and was described in papers at FCS in 1976
and 1978 by my previous manager Mike Fischer (then of HP).
I think these papers come closest to answering your question.

Rick Karlquist

Jeff Mock wrote:
> This is a half-baked idea I've thinking about for awhile.  I wonder if 
> it might be possible to create a single measurement to combine allan 
> variance and phase noise in the same plot.  Allan variance usually plots 
> tau in seconds on the x-axis.  Instead, you might plot 1/s or frequency 
> on the x-axis.  This way, allan variance looks more like very close-in 
> phase noise.
> 
> For example, a point where tau=1000s becomes the phase noise at 1mHz 
> (milli-hertz) from the carrier.  Combining this with more typical phase 
> noise measurements, you can create a single log-log graph covering 
> micro-hertz to hundreds of kilo-hertz.  The advantage of combining the 
> measurements into a single entity is that you get most of the 
> characterization parameters for a timebase in a single graph.
> 
> Would this work?  Half-baked, I know...
> jeff
> 
> 
> Shane wrote:
>> Do you know much about the R&S FSUP50?
>>
>> http://www2.rohde-schwarz.com/en/products/test_and_measurement/product_categ
>> ories/spectrum_analysis/FSUP-%7C-Key_Facts-%7C-4-%7C-966.html
>>
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Bruce Griffiths
>> Sent: Tuesday, March 25, 2008 8:22 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Close-in phase noise measurements
>>
>> Shane wrote:
>>> Wenzel has a setup you can purchase at low cost.  
>>>
>>> http://www.wenzel.com/pdffiles1/PNTS%201000/BP-1000-SC.pdf
>>>
>>> Phase noise test sets can be pricey... $200K
>>>   
>> Shane
>>
>> Their calibration method is somewhat problematic at the low frequency 
>> end where the effect of the PLL and the audio amplifier low frequency 
>> cutoff may be significant.
>> The NIST calibration technique: 
>> http://tf.nist.gov/timefreq/general/pdf/1000.pdf is far superior.
>>
>> Bruce
>>
> 
> 
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