Compander in Pulse Code Modulation

Compander is a Signal processing technique which uses both compression and expansion to improve dynamic range and signal-to-noise ratio.

            Before the conversion of analog to digital in PCM, the compander boost up the low amplitudes of the voice.

In leaner quantization we give a low signal to distortion ratio and high ratio for high amplitudes. This is not useful, because if we get a low signal to distortion ratio, it let know the distortion is higher, compare to signal’s amplitude. Therefore we use compander for overcome that problem. What compander do is it only boost up the low amplitudes of the voice.

And also receiving end compander (expander) reduce the amplitude value of the boosted up signal.

But when we use nonlinear quantization there is a solution for this matter. It has lower gaps in quantized levels for low amplitudes and higher gaps in quantized levels for high amplitudes. Therefore we can achieve high signal to distortion ratio in both cases. And it is useful.