RJH wrote:

On 26/01/2018 21:15, Roger Hayter wrote:
snip
Don't forget that high speed digital signals or
*not* binary at the physical layer, but more like RF digitial signals,
multi-level and phase dependent. !0GBe for instance.

JOOI, in what way are they not binary?

They are binary as far as the computer at each end is concerned, but
they are carried over the copper pairs (or fibre, but we are talking
about gold contacts!) as multi-level signals, effectively analogue
signals.

http://www.ieee802.org/802_tutorials/99-July/mastut.pdf

--

Roger Hayter