Muzahid Huda wrote:
I have just finished measuring the intra-pair skew in seven samples of =
a
6-foot twin-ax cable. This cable consists of 4 twisted pairs (ie. 8
lines) and an individual shield for each pair (ie. 4 shields). The enti=
re
bundle is enclosed by an outer shield.
In all seven samples, the measured intra-pair skew in three of the pair=
s
was within 50ps. The fourth pair consistently exhibits at least
150ps-200ps of skew. In these samples, it is always the <underline>same=
pair</underline> that consistently measures this variation.
I have checked my measurement technique and equipment to eliminate any
systematic errors. I have also cut open a cable to check for physical
length differences, etc. The cable assembly has a molded ferrite choke=
on one end; I have even removed this choke and remeasured the skew.
Nothing seems to make a difference.
Any suggestions/ideas/theories will be greatly appreciated.
Muzahid Huda
Staff Engineer
=