The given signal is first compressed using a logarithmic compressor and then it is given as input to the uniform quantizer. Both these steps together is called as companding.

In μ-law compression characteristics, we get linear amplification or uniform quantization when μ=0.

The standard value of μ in μ-law is 255.

According to signal to noise level ratio non uniform quantization provides better quantization for weak signals.

Signal to noise ratio is worse for weak level signals.so it provides better quantization for high level signals.

Another famous compression characteristic used is A-law. In this law, the standard value of A is 87.6.

The interval between the quantization levels is called as step size.

In sampling and quantization, the quantization noise is directly dependent on signal size.

The human ear is sensitive to quantization error in small values so non uniform quantization is more preferable than uniform quantization.

The weak signal experiences poorer SNR compared to high level signals. So if non uniform quantizer like logarithmic compressor is used the SNR ratio can be made independent of input signal level.