[time-nuts] is there a cheap and simple way to measure OCXOs?

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jun 1 21:02:16 UTC 2012


The AP192 exhibits an input noise floor of around 100nv/rtHz ( for a low 
impedance source) or so (IFIRC - when I measured it.) so with an HP 
10534A/B or 10514A/B a post mixer amplifier gain of 60db or so is 
required to ensure that mixer/phase detector noise dominates. The 
equivalent input noise tends to be somewhat higher in the vicinity of 10Hz.

Other high performance sound cards should have similar input noise.

Bruce

shalimr9 at gmail.com wrote:
> If you can offset one enough to have the output from the dbm in the audio band, you could use a sound card based spectrum analyzer to evaluate phase noise. Some sound cards may work down to 10 Hz, but their performance there is usually not specified. Bruce Griffiths has information on some high performance audio cards and maybe he can chime here.
>
> Using the 3 corner hat method, you could identify the relative phase noise performance of three oscillators.
>
> It will not help with longer term variations though.
>
> Didier KO4BB
>
> Sent from my BlackBerry Wireless thingy while I do other things...
>
> -----Original Message-----
> From: Attila Kinali<attila at kinali.ch>
> Sender: time-nuts-bounces at febo.com
> Date: Wed, 30 May 2012 16:59:39
> To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
> Reply-To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] is there a cheap and simple way to measure OCXOs?
>
> On Wed, 30 May 2012 07:18:12 -0700
> Jim Lux<jimlux at earthlink.net>  wrote:
>
>    
>> Got a mixer around, so you can beat them against each other (or against
>> your 5680)?
>>      
> Not yet. I'm currently thinking about geting an mixer from minicircuits
> for the ZX05-1L[1] and a low pass filter BLP-1.9[2].
>
> But what then? The frequency offset is low enough that it is still
> problematic to measure with standard measurements instruments.
> And the phase noise.. out of question.
>
> 			Attila Kinali
>
>
>
> [1] http://217.34.103.131/pdfs/ZX05-1L+.pdf
> [2] http://217.34.103.131/pdfs/BLP-1.9+.pdf
>    





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