Biphase:
This encoding technique is the best solution to the problem of synchronization in NRZ technique.
In this method, the signal changes at the middle of the bit interval but does not return to zero. Instead, it continuous to the opposite pole.
There are two types of biphase encoding techniques,
- Manchester
- Differential Manchester
Manchester:
Two consecutive bits of the same type force a transition at the beginning of a bit period.
1 forces a negative transition in the middle of the bit 0 forces a positive transition in the middle of the bit.
(means, it uses the inversion at the middle of each bit interval for both synchronization and bit representation. A negative to positive transition represents binary 1 and a positive to negative transition represents binary 0.)
Differential Manchester:
There is always a transition in the middle of a bit period.
1 does nothing 0 forces a transition at the beginning of the bit.
(means, the inversion at the middle of the bit interval is used for synchronization, but the presence or absence of an additional transition at the beginning of the interval is used to identify the bit. A transition means binary 0 and no transition means binary I)
