[time-nuts] Question about DDMTD deglitching
bobdarby at triad.rr.com
Sat Feb 22 12:30:46 EST 2014
In August 2011 there was a brief mention on Time-Nuts of DDMTD's which
led me to The P. Moreira and I. Darwazeh paper "Digital femtosecond
time difference circuit for CERN’s timing system". I'm hoping that
someone can explain one item mentioned in this paper for me. For those
not familiar with this work, it is part of a sub-nanosecond network
synchronization scheme know as White Rabbit.
One of the elements of the DDMTD is a deglitching system and the authors
describe three possible deglitching strategies. The first two are quite
straightforward but the third method described as "Zero Count – counts
the numbers of “1” and “0” and selects as the best edge the time
position where the number of zeros is the same as the number of ones."
seems totally ambiguous. If I take the statement quite literally, there
must be dozens or hundreds of times when the number of 1's and 0's in a
glitch are equal. Can anyone familiar with this work explain what I am
missing? I realize that the answer to my question is probably at hand in
the FPGA code but that's well beyond my pay grade.
This paper is available at:
A list of White Rabbit papers is available at:
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