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100Mb Ethernet cable waveforms etc
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Fred
electronics forum beginner


Joined: 14 Oct 2005
Posts: 34

PostPosted: Wed Jul 12, 2006 3:31 pm    Post subject: 100Mb Ethernet cable waveforms etc Reply with quote
I've Googled but not found any helpful articles. I am aware there is a
preamble to a packet but not found any further information. Can anyone
point to a useful website?

What is the theoretical maximum throughput with 100Mb Ethernet? Does the
100Mb include any other characters in addition to the preamble and the
packet?

Many thanks in advance.
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pbdelete@spamnuke.ludd.lu
electronics forum Guru Wannabe


Joined: 15 Sep 2005
Posts: 273

PostPosted: Thu Jul 13, 2006 11:00 am    Post subject: Re: 100Mb Ethernet cable waveforms etc Reply with quote
In sci.electronics.design Fred <fred@nowhere.com> wrote:
Quote:
I've Googled but not found any helpful articles. I am aware there is a
preamble to a packet but not found any further information. Can anyone
point to a useful website?

What is the theoretical maximum throughput with 100Mb Ethernet? Does the
100Mb include any other characters in addition to the preamble and the
packet?

Asfair it's just the preamble + data. Ofcourse there's numerous twists to it
but the basic is just those two. Search for MLT-3.
Waveform consist of three levels Vmax, Vneutral, Vmin. Where highest voltage
is 3.3v asfair. To calculate maximum throughout, you have to consider preamble,
overhead data and minimum packet spaceing.

So what are you going to construct ..? Wink
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Fred
electronics forum beginner


Joined: 14 Oct 2005
Posts: 34

PostPosted: Thu Jul 13, 2006 2:25 pm    Post subject: Re: 100Mb Ethernet cable waveforms etc Reply with quote
<pbdelete@spamnuke.ludd.luthdelete.se.invalid> wrote in message
news:44b627e6$0$495$cc7c7865@news.luth.se...
Quote:
In sci.electronics.design Fred <fred@nowhere.com> wrote:
I've Googled but not found any helpful articles. I am aware there is a
preamble to a packet but not found any further information. Can anyone
point to a useful website?

What is the theoretical maximum throughput with 100Mb Ethernet? Does the
100Mb include any other characters in addition to the preamble and the
packet?

Asfair it's just the preamble + data. Ofcourse there's numerous twists to
it
but the basic is just those two. Search for MLT-3.
Waveform consist of three levels Vmax, Vneutral, Vmin. Where highest
voltage
is 3.3v asfair. To calculate maximum throughout, you have to consider
preamble,
overhead data and minimum packet spaceing.

So what are you going to construct ..? ;)


Many thanks for the steer. It was a great help and found some useful
articles.

I was trying to see what overheads there were to limit theoretical data
rates. I see the only overhead symbols are the Start of Stream and End of
Stream.
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Tauno Voipio
electronics forum beginner


Joined: 26 May 2005
Posts: 8

PostPosted: Thu Jul 13, 2006 6:21 pm    Post subject: Re: 100Mb Ethernet cable waveforms etc Reply with quote
Fred wrote:
Quote:
pbdelete@spamnuke.ludd.luthdelete.se.invalid> wrote in message
news:44b627e6$0$495$cc7c7865@news.luth.se...

In sci.electronics.design Fred <fred@nowhere.com> wrote:

I've Googled but not found any helpful articles. I am aware there is a
preamble to a packet but not found any further information. Can anyone
point to a useful website?

What is the theoretical maximum throughput with 100Mb Ethernet? Does the
100Mb include any other characters in addition to the preamble and the
packet?

Asfair it's just the preamble + data. Ofcourse there's numerous twists to
it
but the basic is just those two. Search for MLT-3.
Waveform consist of three levels Vmax, Vneutral, Vmin. Where highest
voltage
is 3.3v asfair. To calculate maximum throughout, you have to consider
preamble,
overhead data and minimum packet spaceing.

So what are you going to construct ..? ;)



Many thanks for the steer. It was a great help and found some useful
articles.

I was trying to see what overheads there were to limit theoretical data
rates. I see the only overhead symbols are the Start of Stream and End of
Stream.


For the 100 Mbit/s Ethernet, there is one point to note if you're
going to scope the signal: the clocks are embedded in the stream
by a 4 bit to 5 bit coding, so the base speed is 125 million encoded
bits / second.

There are more signifcant overheads in the upper-level protocols, if
you're not going to use raw Ethernet frames. A raw Ethernet frame
has a 14 byte overhead for addressing and 4 bytes for CRC after
the payload of the frame, and this is in addition of the framing
overhead (preamble & co).

HTH

--

Tauno Voipio
tauno voipio (at) iki fi
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Google
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