M. Adam Davis wrote:
> If you have a bit error of 0.94%,

It's not a "bit" error any more than a byte or character error.  0.94% was
just the mismatch between the two clocks.  This is the mismatch per bit, and
per character.

> then over ten bits (start, 8 data,
> stop) you have a bit that is off by nearly 10%.

Of a bit, which is really pretty close.

> Now let's assume a non-ideal receiver.  Let's say that its bit error
> is 2%,

What's with this bit error?  All that matters is the mismatch ratio between
the sender and receiver.  Specifying them separately creates confusion.  You
said the send was off by .94% and now the receiver has an error of 2%.  We
can't tell if that is relative to the sender or relative to the absolute
ideal baud rate that the sender is .94% off from.  So the total error
between sender and receiver could now be 1.06%, 2.00%, or 2.94%.

> and that it samples the middle 50% of each bit 3 times.  This
> means that it takes three samples per bit - once at 25% of the bit
> time, once at 50% of the bit time, and once at 75% of the bit time.

You can assume that, but that's not how most receivers work.  Just about all
receivers sample at 16x the baud clock.  Some just pick the sample that
should be closest to the middle of the bit.  Some to a majority vote of the
3 middle samples.  A few others may do a few other things, but I don't know
of any that sample at 25%, 50%, and 75% of the assumed bit.


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