Types of Conversions Cont

™   Manchester

o    Uses inversion at the middle of each bit interval for both synchronization and bit representation ŠNegative-to-Positive Transition= 1 ŠPositive-to-Negative Transition = 0 ŠBy  using  a  single  transition  for  a  dual  purpose,  Manchester acheives the same level of synchronization as RZ but with only two levels of amplitude ™   Differential Manchester o    Inversion  at  the  middle  of  the  bit  interval  is  used  for  Synchronization  but presence or absence of an additional transition at the beginning of bit interval is used to identify a bit o    A transition means binary 0 & no transition means binary 1 o    Requires  2  signal  changes  to  represent  binary  0  but  only  one  to  represent binary 1 •     Bipolar Encoding o    Like RZ, it uses three voltage levels: o    Unlike RZ, zero level is used to represent binary 0 o    Binary 1's are represented by alternate positive and negative voltages Types of Bipolar Encoding