differential & manchister encoder

Discussion in 'The Projects Forum' started by Asif2011, Jan 2, 2011.

  1. Asif2011

    Thread Starter New Member

    Jan 2, 2011
    salam to all friends, i m new commer in this community. I have to make a differential & manchister encoder for digital communication. plzzzzzz help me
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    Differential encoders in the digital simple sense are using 2 wires, sending Q over one wire and !Q over the other. e.g. Q signal is output of non-inverting buffer, while !Q is output of inverting buffer, so they are opposite. This signal is typically sent over twisted pair. The receiving end subtracts the two inputs, which subtracts any noise common to the two wires, leaving you with the original signal.

    There are Manchester encoder/decoder IC/Drivers (Datasheet). The biggest benefit of Manchester encoding is the clock signal for recovery or sync is sent with the signal. The actual method is a number of gates (Data XOR Clock + buffers) to ensure the output is toggling on every bit, whether it is a zero or one. Manchester encoding can be used with differential signals for higher noise immunity, such as Ethernet.

    Both of these are "4 wire" communcations, needing a Tx+, Tx-, Rx+ and Rx- for bidirectional communication. Differential encoding is often part of the manchester encoding/decoding ICs.