Briefly describe Return to Zero RZ encoding scheme-00225

Any time, data contains long strings of 1's or 0's, Rx can loose its timing. In unipolar, we have seen a good solution is to send a separate timing signal but this solution is both expensive and full of error. A better solution is to somehow include synch in encoded signal somewhat similar to what we did in NRZ-I but it should work for both strings of 0 & 1. One solution is RZ encoding which uses 3 values : Positive, Negative and Zero Signal changes not b/w bits but during each bit like NRZ-L, +ve voltage means 1 and a -ve voltage means 0, but unlike NRZ- L, half way through each bit interval, the signal returns to zero. A 1 bit is represented by positive to zero and a 0 is represented by negative to zero transition. The only problem with RZ encoding is that it requires two signal changes to encode one bit and therefore occupies more BANDWIDTH But of the 3 alternatives we have discussed, it is most effective value.