A-Law Expander

Implement A-law expander for source coding

Library

Source Coding

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Description

The A-Law Expander block recovers data that the A-Law Compressor block compressed. The formula for the A-law expander, shown below, is the inverse of the compressor function.

$$x=\{\begin{array}{ll}\frac{y(1+\log A)}{\text{A}}\hfill & \text{for }0\le \left|y\right|\le \frac{\text{V}}{\text{1+logA}}\hfill \\ \exp \left(\left|\text{y}\right|(1+\log A)/V-1\right)\frac{V}{A}\mathrm{sgn}(y)\hfill & \text{for }\frac{\text{V}}{\text{1+logA}}<\left|y\right|\le V\hfill \end{array}$$

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

Parameters

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.

Match these parameters to the ones in the corresponding A-Law Compressor block.

Supported Data Type

Port	Supported Data Types
In	double
Out	double

Pair Block

A-Law Compressor

References

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

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a