Delta Modulator Transmitter:

Operation: X(t) – i/p signal to comparator

X’(t) – quantized version of x(t)

In comparator,↑ high if x(t) > x’(t) and goes low ↓ if x(t) < x’(t). Thus the comparator o/p os either 1 or 0.

The sample and hold circuit will hold this level (0/1) for the entire clock cycle period.

The o/p of sample and hold is transmitted as o/p of DM system. Also, one bit per clock cycle is sent. Thus bit rate and b.w is reduced.

The sig is used to decide the mode of operation of an up/down counter, the counter o/p increments by 1 if $S_o (t)=1$ and it decrements by 1 if $S_o (t)=0,$ at the falling edge of each clock pulse.

Delta Modulator Receiver

Advantages:

1. Low signaling rate and low transmission channel b.w because in delta modulation, only one bit is transmitted per sample.
2. The d.m transmitter and receiver are not complicated.

Disadvantages:

1. The 2 distortions, i.e., slope overload error and granular noise are present.
2. Practically the signaling rate with no slope overload error will be much higher than that of PCM.