The idea started more than a year ago: 161. PEAC for line encoding

So PEAC has many advantages and I wanted to turn it into a "line coder" for differential twisted pair transmission, for example. It didn't work back then but I finally cracked it !

As you can see, this is the same scrambler as in 79. Taxonomy and I added a pair of gates (AND+XOR) to form a half-adder. The result is concatenated in front of the first 2 bits of a scrambled word, and that's it.

With only this circuit, you get:

• enhanced parity,
• spectrum spreading / scrambling
• clock resynchronization,
• DC suppression
• strict run-length limitation (up to w+1 bits)

Packet-start signaling is added by ORing a 11 pattern to the prefix, and replacing the payload with a "start" symbol. This forced prefix can't map to any valid transmitted data, and can be used for signaling other conditions as well.

This system works for any PEAC width, be it 4, 10, 16, 26 bits, depending on the BER, the medium's bandwidth, the timing constraints and the maximum length of a sequence of identical bits (000000... or 111111....).

I worked all the theory and it only begs to be implemented, maybe in a future #Tiny Tapeout project ?

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dropping the mic.