PULSE CODED MODULATION

[dihan]

Will it be a realizable concept of digitizing a voice signal not only to 0's and 1's but also to 4 states as 0 , 1, 2,3 with their respective voltage level? The idea can be incorporated with the standard pulse coded modulation technique.But I am not sure what will be the degree of interference or other complexities likely to arise after a bpsk or qpsk modulation of the baseband signal during transmission through wireless channel.I will be grateful to receive suggestions from the experts in the field.

[charan langton]

Essentially that is what is done in the telephony, but instead of 4 level, they do 8 level. Then for a QPSK transmission, you take each level which is represented by a 8 bit word and break it apart in 2 bit sets.
For wireless, there is additional compression on the basic 64 Kbits that are generated this way.

Charan Langton