[Ronja] 100Mbit over LEDs

[Bruce M Simpson]

Gregory Maxwell wrote:
> Many years ago I measured the bandwidths of some leds that I had and
> found that they had a decent response to about 20MHz. I do not know
> what the ronja hardware delivers, but I would assume that it is around
> that, since about that much is required for 10mbit performance.   This
> is not anywhere near enough bandwidth to do 100mbit using the binary
> NRZ encoding that ronja uses.  It is also not enough to do 100mbit
> using the three level encoding used on 100TX (which needs about
> 35MHz).

Quite aside from NRZ, surely the 4B5B encoding used by 100BaseTX can 
readily be converted to light? or am I missing something?
    http://en.wikipedia.org/wiki/4B5B

regards
BMS