Linear Delta Modulation (D.M)

PCM systems, N no. of binary digits are transmitted per quantized sample. Hence the signaling rate and transmission channel b.w. of PCM systems are very large.

These problems can be overcome using delta modulation

Principle of operation:

Delta modulation transmits only one bit per sample instead of N bits transmitted in PCM. This reduces its signaling rate and b.w. requirement to a great extent.

In the basic or linear DM a staircase approximate version of the sampled i/p signal is produced.

The original signal and its staircase representation are compared to produce a difference signal.

And this difference signal is quantized into only two levels namely ± S corresponding to + ve and –ve difference respectively.