Mumbai University >IT>Sem3>Principles of Analog and Digital Communication

Marks: 5M

Year: Dec 2013

• A-law companding

• In the A-law companding , the compressor characteristic is piecewise , made up of a linear segment for low level inputs and a logarithmic segment for high level inputs.

• The characteristic corresponding to A=1 corresponds to the uniform quantization

• The practically used “A” is 87.56.The A-law companding is used for PCM telephone systems in Europe.

μ-law companding

• In the μ-law companding , the compressor characteristic is continuous.It is approximately linear for smaller values of input levels and logarithmic for high input levels.

• The characteristic corresponding to μ = 0 corresponds to the uniform quantization.

• The μ-law companding is used for speech and music signals. It is used for PCM telephone systems in US, Canada and Japan.