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U-law

Description:

Companding technique commonly used in North America and Japan.  U-law is standardized as a  64-kbps CODEC in ITU-T G.711. This is a  CCITT-ratified audio encoding  and compression technique supported by Windows 95  and Web phones. Among other  implementations, u-law was originally intended as a  phone-communications  standard.

Complete  Definition:

The µ-law algorithm (pronounced mew-law) is a companding algorithm, primarily used in  the digital telecommunication systems of North  America and Japan. As with other  companding algorithms,  its  purpose is to reduce the dynamic range of an audio signal. In the analog   domain, this can increase the signal-to-noise ratio (SNR) achieved during  transmission, and in the  digital domain, it can reduce the quantization error  (hence increasing signal to  quantization noise ratio). These signal-to-noise  ratio (SNR) increases can be traded instead for reduced bandwidth for equivalent  SNR.

Both a-law and u-law are  companders for the G.711 voice  codec

U-law Compander formula (from Cisco's Waveform Coding Techniques)

U-law-formula.gif

u-Law  Wikipedia  Definition

Also useful is the : ITU  website and  search on u-law

Also See:

Version history
Revision #:
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Last update:
‎06-17-2009 06:08 AM
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