Mu-Law is the standard codec (compression/decompression) algorithm for pulse code modulation (PCM) from the CCITT (Consultative Committee for International Telephone and Telegraph).
THE GENERATION OF A-LAW '55' AND MU-LAW '7F' CODES CAN BE USEFUL FOR NOISE TESTING.
μ-Law Companding
The μ-Law compander operates on a logarithmic curve as expressed by:
ln(1 + μ|x| | sgn(x) = sgn (+/-) of x
Output = sgn(x) ________ | x = normalized input (between -1 and 1)
ln(1 + μ) | μ = compression parameter (255)
Note that if μ=0 (compression parameter), linear companding occurs.
The maximum level (Tmax) supported with μ-Law PCM is +3.17 dBM0.
A-Law Companding
The A-Law compander operates on a logarithmic curve as expressed
by:
Output = sgn(x) ;
1 In(A)
A| x |; when 0 ≤ LE |x| ˂LT 1/A
or Output = sgn(x) ;
(1 In(A))
(1 InA| x |; when 1/A ≤ LE |x| ≤ LE 1
Sgn(x) = sgn (+/-) of x
x = normalized input (between -1 and 1)
A = compression parameter (87.6)
Note that if A=1 (compression parameter), then linear companding results.
The maximum level (Tmax) supported with A-Law PCM is +3.14 dBM0.
