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ADSP-2189M SPORT hardware companding

Question asked by John.R.Strohm on Jul 15, 2016
Latest reply on Jul 26, 2016 by SachinV

We're using the ADSP-2189M DSP, and specifically the hardware u-law/A-law companding on the SPORTs.


ITU-T G.711 specifies u-law and A-law to work on "integer samples", with reduced sample widths (13 magnitude bits for u-law, 12 for A-law).


Do the hardware companders on the ADSP-2189M SPORTs align to the reduced sample widths specified in G.711, or do they align to 1.15 (shifting up a few bits)?


The example software in "Digital Signal Processing Applications Using the ADSP-2100 Family", Volume 1, chapter 11, works to 1.15.  I need to know if the hardware works the same way.  I have an application that needs to compand in hardware at one end and software at the other.  (You don't want to know.  Trust me.)


This is a modification to an existing, fielded product.  Changing the DSP to something more modern is not an option.