[time-nuts] DMTD to MMTD

Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Feb 17 22:09:39 UTC 2010

```The latest version actually records time stamps from a continuously
running counter clocked at some at a constant frequency (100Mhz??)for
all channels simultaneously.
They may use a flag bit for each for each channel to indicate to which
channel or channels the zero crossing time stamp belongs.
I posted the link to the relevant paper which doesn't seem to have made
it to the list yet.

http://tycho.usno.navy.mil/ptti/ptti2006/paper11.pdf

http://tycho.usno.navy.mil/ptti/ptti2006/paper26.pdf

The first link is the relevant one.

They make use of the multichannel data to identify out sources that have
a problem.
This isnt possible when just monitoring 2 channels at a time.

Bruce

Bob Camp wrote:
> Hi
>
> Thanks for the quick response.
>
> The impression I've always had of that system is that it is comparing the
> sources two at a time. They can select between a number of sources, but only
> one pair is looked at.
>
> I'm after stuff on a system that simultaneously looks at several sources. My
> assumption is that you could simply use a bunch of DMTD's and then do the
> math. You might also be able to simplify things a bit....
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Bruce Griffiths
> Sent: Wednesday, February 17, 2010 3:57 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] DMTD to MMTD
>
> Bob Camp wrote:
>
>> Hi
>>
>>
>>
>> DMTD looks at a pair of sources (crystal, rubidium, maser .) and tells you
>> the difference between them. If you looked at more than two, you can
>>
> better
>
>> characterize the individual sources.
>>
>>
>>
>> Any good papers out there on taking the DMTD approach and extending it to
>> simultaneous observation of a number (like 3 or 5) of oscillators?  I'm
>>
> sure
>
>> I've missed at least one ..
>>
>>
>>
>> Bob
>>
>>
>>
> Bob
>
> JPL have had such systems for many years:
>
> http://tmo.jpl.nasa.gov/progress_report/42-169/169B.pdf
>
>
> http://tmo.jpl.nasa.gov/progress_report/42-169/169B.pdf
>
> http://tycho.usno.navy.mil/ptti/1994/Vol%2026_25.pdf
>
> Bruce
>
>
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