The digital realization of an audio gain controller can bypass some of the problems commonly encountered among analog companders, such as accurate setting of its input/output static characteristic (SC). This paper describes the implant of a programmable gain controller in a TMS32010 DSP. Its SC is graphically programmable to any desired shape. Furthermore, its dynamic characteristics are controlled by the input instant envelope. The latter is obtained by nonlinear filtering (demodulation through log conversion). This method avoids rise overshoots and decrease dropouts.
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