Olin wrote:
> Jan-Erik wrote :
> > Partly correct, but it's not *between* the bits, it's in the *middle*
> > of the bits. (The 1 and 0 could also be interchanged)
>
> Remember that "middle" is somewhat up for interpretation.

Well, you have to start and stop your transmission with whole bits,
right ? And "middle" would be referenced from the start of this
first bit, not ?

Yes, there are similarites between Bi-Phase and
Manchester encoding. And I still claim that the coding
Tal and you described matches (best) Bi-Phase, not Manchester.
And that's why I got a bit lost in your descriptions.


Tal wrote :
> That is, you always have a transition between bits and have
> another transition in the middle of a '1' bit.

100% correct for Bi-Phase, 100% wrong for Manchester (no matter how
you shift the Manchester stream to redefine the "middle" of a bit).
(And Olin started his reply to this specific part with "Yes,...")


Olin wrote:
> Yes, the direction of the transition between bits identifies the bit
> value.

Wrong for both Bi-Phase *and* Manchester. Manchester coding does not
*have* to have a transition between bits.(But correct, in a way, if
you shift the Manchster code a half-bit to redefine the "middle"
and "between" of bits, but, IMHO, that does not make it easier to
understand how Manchster coding works...)

The Masters 2002 document that Steve pointed at clearifies this
pretty well.

Olin wrote:
> In this view, each bit can be thought of as being represented by the
> polarity of the bit edge, or the level of the 1/2 bit time immediately
> following the bit edge, or the inverse of the level of the 1/2 bit time
> immediately preceeding the bit edge.  These are all perfectly valid ways
> of talking about the same signal.  The difference is only in the words we
> use to describe it.

Correct for Manchester code, if we define "bit edge" as the edge in the
*middle* of a transmitted bit, yes. Now, other things written in this
thread has clearly been wrong for Manchester coding, so it's been a bit
confusing.. :-)

I'm stopping here, there are fine docs that clearly shows all this, the
Master PDF docs beeing on of the best, since it shows Bi-Phase and
Manchster side-by-side which clearly shows the confusion in this thread.


Regards, and my apologies to everyone who thought this should have been
moved out of [PIC] long ago...

Jan-Erik.

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