[time-nuts] Close-in phase noise measurements
Jeff Mock
jeff at mock.com
Wed Mar 26 19:34:22 UTC 2008
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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