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0 pointsbogomipz3y ago0 comments

Thanks, I had another question after a second reading of your post:

>"The first bit of an Ethernet frame is always one, which means there might or might not be an extra edge in the beginning depending on the idle state of the amplifier. This extra edge, if it comes, needs to be filtered out."

Practically speaking what is the cause of the "extra" edge here? Would it be that the last bit of the FCS from the previous frame caused it to be a 1 and then the transceiver is immediately getting another edge from a preamble on a new Ethernet frame? Or am I confusing bits and edges?

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ynoxinul3y ago

A manchester-encoded bit 1 is a low-to-high transition: there should be "low" on the line which will change to "high". Before the "low" the line was idle (zero voltage difference), this state is interpreted by the differential amplifier as "high", so it's "high-low-high" at the beginning, but we are interested in the "low-high" edge and not in the "high-low" one.

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