mu law/A law links 
The first 2 links will give you an idea of how these companding schemes
work. The 3rd is a spec sheet for a Texas Instrument part. You can get
more by searching on PCM, u-law, mu 255, A Law, etc. These come from the
CCITT and Bell specifcations for telephony transmission.

http://www.hut.fi/Misc/Electronics/docs/telecom/ulaw_alaw.html

http://www.tcm.hut.fi/Opinnot/Tik-110.551/1997/seminar_paper.html

http://www-d.connect.ti.com/dsp/tpcat/tpcodec.nsf/SoftwareForExternal/3B3BF2E87F3D01BC862567290051F39D

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Dana Trantham
dctranth@eos.ncsu.edu
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