[time-nuts] Help understanding an ADEV

Bob Stewart bob at evoria.net
Sat Sep 13 17:36:25 EDT 2014

Hi David,

It's an odd situation.  From the datasheet:

"Note: The DAC module is designed specifically for audio applications and is not recommended for control type applications."

I had hoped that it wouldn't be a problem for driving an OCXO, but my mistake.  The datasheet also notes that the DAC has 16-bit resolution but only 14-bit accuracy.  It didn't seem to have even that at DC.  The PWM version doesn't have any escape clauses.  You set "x" parameters and it's supposed to be 16-bits wide.  Maybe "audio" means within the human auditory passband?


 From: Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk>
To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
Sent: Saturday, September 13, 2014 4:27 PM
Subject: Re: [time-nuts] Help understanding an ADEV

On 11 Sep 2014 04:35, "Bob Stewart" <bob at evoria.net> wrote:
> I've ordered the PWM version of the PIC, and hopefully, since it's the motor control version (as opposed to the audio version) it will have much better noise performance.
I don't know the PIC but I would have thought chips for audio would be optimised for low noise far less than one for driving motors.
Dr David Kirkby
Managing Director
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT, United Kingdom
Registered in England and Wales as company number 08914892
Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT)

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