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802.3 signal levels

D

David N.

Jan 1, 1970
0
Can someone point me to documentation that explains the signal
waveforms seen on 10BaseTX and 100BaseT cables? I've read the IEEE
standard, but am having a hard time getting a complete understanding
from that document alone. A couple very basic questions...

1.) What are the max voltage levels for each speed?
2.) What is the max frequency for each speed?

I've read that the max frequency for 100BaseT is 31.25MHz, but I have
measured 62.5MHz. How can this be explained?

Thanks,
David
 
D

David N.

Jan 1, 1970
0
1.) What are the max voltage levels for each speed?

I found voltage specs. for 10BaseTX. It is 2.2V to 2.8V for all data
and -3.1V to +3.1V for link pulses. I am still searching for 100BaseT
numbers.
2.) What is the max frequency for each speed?

I've read that the max frequency for 100BaseT is 31.25MHz, but I have
measured 62.5MHz. How can this be explained?

I still don't understand why I am seeing 62.5MHz. Any help with this
would be greatly appreciated.

Thanks,
David


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M

Michael A. Terrell

Jan 1, 1970
0
David N. said:
I found voltage specs. for 10BaseTX. It is 2.2V to 2.8V for all data
and -3.1V to +3.1V for link pulses. I am still searching for 100BaseT
numbers.


I still don't understand why I am seeing 62.5MHz. Any help with this
would be greatly appreciated.

Thanks,
David

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What are you measuring it with? A spectrum analyzer would show you
all the signals involved.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
D

David N.

Jan 1, 1970
0
What are you measuring it with? A spectrum analyzer would show you
all the signals involved.


I measured it with a scope. I expect that it is normal, but I don't
understand ethernet well enough to know why. One source of information
claims that the max. frequency is 31.25MHz, but I clearly measured
double that.

Thanks,
David

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