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A-Law Compressor

Implement A-law compressor for source coding


Source Coding


The A-Law Compressor block implements an A-law compressor for the input signal. The formula for the A-law compressor is

y={A|x|1+logAsgn(x)for 0|x|VAV(1+log(A|x|/V))1+logAsgn(x)for VA<|x|V

where A is the A-law parameter of the compressor, V is the peak signal magnitude for x, log is the natural logarithm, and sgn is the signum function (sign in MATLAB® software).

The most commonly used A value is 87.6.

The input can have any shape or frame status. This block processes each vector element independently.


A value

The A-law parameter of the compressor.

Peak signal magnitude

The peak value of the input signal. This is also the peak value of the output signal.

Supported Data Type

PortSupported Data Types
  • double

  • double

Pair Block

A-Law Expander


[1] Sklar, Bernard. Digital Communications: Fundamentals and Applications. Englewood Cliffs, N.J., Prentice-Hall, 1988.

Introduced before R2006a

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