Sadly, the IEEE 802.3 Spec isn't available online, you have to purchase it
from IE3. I did come across a site that MIGHT help:

http://ece.wpi.edu/courses/ee535/hwk3cd95/harveywl.html

Another thing that might help is trying to find the nitty gritty on the OSI
layers.

Regards,

Tim Hamel

In a message dated 11/19/99 1:15:22 PM Pacific Standard Time,
firewall_fred@HUSHMAIL.COM writes:

> Parts of this are happening on a pic, so it's not entirly unrelated. I need
>  the actual specifications for a 10Base-T network. I'm talking about the
>  actual signals traversing the wire between the card and the hub, not the
>  packet formats, collision detection, etc. Is there a 10MHz carrier? Do the
>  two devices simply send serial data at 10MHz, or is some other system going
>  on here? How does a hub know when a card is connected - is there a certain
>  keep-alive signal to tell it this, or do the lines have DC voltages to
> indicate
>  a connection? I know there's an IEEE spec for this somewhere, but there
>  has to be some public domain info as well - I'm just unable to find it.
>  It may also be a possibility to use the AUI interface instead, but I have
>  the same issue with that - NO information available anywhere I look.
>
>  ANY pointers would be greatly appreciated.
>
>  Thanks!