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
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA485911&Location=U2&doc=GetTRDoc.pdf
<http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA485911&Location=U2&doc=GetTRDoc.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: [email protected] [mailto:[email protected]] 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
<edit to fix link>
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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