Electrical audio signal processing systems and devices – Including amplitude or volume control – With amplitude compression/expansion
Patent
1995-06-06
1997-05-20
Isen, Forester W.
Electrical audio signal processing systems and devices
Including amplitude or volume control
With amplitude compression/expansion
333 14, H03G 700
Patent
active
056319681
ABSTRACT:
A signal conditioning circuit compresses an audio signal by producing a gain signal that is a function of the time-averaged audio signal and a compression ratio, and amplifying the audio signal by an exponential function of the gain signal. The conditioning circuit merges the functions of buffering the audio signal and producing a full-wave rectified version of the audio signal into a single buffer circuit. An averaging circuit generates a time-averaged signal in response to the full-wave rectified signal. An interface circuit includes downward expansion, compression and limiting circuits for scaling the time-averaged signal with a low compression ratio when it is less than a break point, with a selected compression ratio when it is between the break point and a rotation point, and with a high compression ratio when it exceeds the rotation point. The interface circuit produces the gain signal in response to the time-averaged signal and the corresponding compression ratio. A voltage controlled amplifier amplifies the buffered input signal by an exponential function of the gain signal to produce a compressed output signal.
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Copley Patrick
Frey Douglas R.
Analog Devices Inc.
Isen Forester W.
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