RE: Maximum run length of 64/66b
Mike and Shen,
Sorry I didn't get to answering sooner. I was busy getting
clause 49 ready for D2.0 and other tasks.
The maximum run length is 66 which can occur when a data frame is
followed by a control frame or vice versa. There is always a transition
between the two bits of the sync header. The probability of a run of
65 or 66 bits is 2^64 ~ 16 * 10^18.
One can AC couple just as one can with any scrambled code. On the average
about half the bits will be zero and half will be one. The cut-off frequency
will be much lower than for something like an 8B/10B code, but it does not
have to go down to zero.
From: Mike Jenkins [mailto:jenkins@xxxxxxxx]
Sent: Tuesday, November 14, 2000 2:45 PM
Subject: Re: Maximum run length of 64/66b
Perhaps I missed it, but I haven't seen any responses to the
question below, so let me hazard a guess and hope that someone
corrects me if I'm wrong:
1) The max run length is 66, since the sync bits are not
2) I suspect the frequency content is sufficiently low that
any AC coupling would be impossible.
Improved theoretical or empirical results might help 64b/66b
serve other applications as well as this one, I would think.
> Hi :
> This maybe a silly question, but if someone can
> tell me, would be much appreciated.
> (1) the Maximum run length of 64/66b:
> Before scramble, the worse run length is
> 65 when it has 01111...... (one "0", 65 "1").
> What would be the maximum run length after
> (2) DC balancing aspect of 64b/66b + scramble
> thanks in advance.
> Best Regards
> steven Shen
> Silicon Bridge
Mike Jenkins Phone: 408.433.7901 _____
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