EE 345S Real-Time Digital Signal Processing Laboratory - Lecture 8
Lecture by Prof. Güner Arslan
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Lecture
Supplemental Information
- An anechoic chamber has about a 10 dB SPL noise floor.
- Mark A. Castellano, Todd Hiers, and Rebecca Ma,
"TMS320C6000 mu-Law and A-Law Companding with Software or the McBSP",
Texas Instruments Application Report, SPRA634, April 2000.
- The lecture discusses mu-law companding used in the US and
Japan (u = 255) and A-law companding in Europe (A = 87.6).
In the companding formulas, the log is the natural logarithm.
- A student asked what happens when a call is placed from the
US to Europe. Companding in telephony is to eight bits, with
one bit for the sign. Hence, the formulas in terms of |x| in
[0, 1] would be used to generate a seven-bit number. To the
precision of seven bits, there is no difference between A-law
companding (A = 87.6) and mu-law companding (u = 255) for |x|
in [0.18, 1].
- There is a mu-law pulse coded modulation (PCM) audio format.
The format is an eight-bit floating-point format: 1 bit for
the sign, 4 bits for the mantissa, and 3 bits for the exponent.
This is a common audio format on Sun workstations.