Linux-Hams archive - May 1997: 100 Mbit Ethernet Problem

100 Mbit Ethernet Problem

Mike Bilow ()
Mon, 05 May 97 21:39:00 -0000


Britton wrote in a message to Mike Bilow:

B> This is wierd. The only thing I can think of is that by
B> coiling the wire, you are strengthening the signal it
B> carries by coupling the wires. A toroid is the perfect
B> electromagnetic shape. Still, if I understand correctly the
B> overall length of the line has not been diminished, so Im
B> not sure why this is working for you.

By coiling the cable, its balance with respect to noise is improved. Coils
naturally present a high impedance to high frequencies. Coiling cable to make
chokes is a traditional technique, even for coax.

B> Over CAT5 cable, and I think over CAT3 and 4 as well, you
B> shouldnt have any trouble with crosstalk. Hopefully for 100
B> Mbps you are running CAT5.

In fact, one of the main differences between Cat5 and Cat3 cable is avoidance
of crosstalk and other interference. Cat5 is much more tightly twisted than
Cat3, and the twists are more tightly controlled to be uniform in distance.

B> I forwarded this to my Communications prof. He always has
B> something to say.

You don't need to go to school for that. Just look at Usenet!

-- Mike