Explain in detail companding.

Companding: It is the process of compressing and expanding. This includes compressing the signal at the transmitter and expanding this at the receiver. The modulating signal to be transmitted is passed by an amplifier that has correctly adjusted non linear transfer characteristic, favoring minute amplitude signals. Such are the artificially large while they are quantized and therefore the effect of quantizing noise upon them is decreased. The correct amplifier relations are restored at the receiver by expander. This is desirable to agree to several standards for companding as order to realize hardware efficiencies and to permit sending and receiving with a variety of users. The most general application of companding is in voice transmission. Japan and North America have adopted a standard compression curve termed as µ law companding. The law µ companding formula is specified by

V_out = ( V_max X In (1+ µ Vin / V_max) / In (1+ µ ) Where

V_max = Maximum uncompressed modulating input amplitude.

V_in = Amplitude of the input signal at particular immediate at time

µ = Parameter used to describe the amount of compression

V_out = Compressed output voltage.

FIG - Companding Curves for PCM