Method and apparatus for detecting an input signal

Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression

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327558, 327337, 327341, 327362, 327552, 333 14, 708312, H03K 500

Patent

active

060231912

ABSTRACT:
A level detector detects an input signal level. A rectifier (210) receives the input signal and provides a rectified signal. A prefilter (220) receives the rectified signal and attenuates high frequency components at frequencies near multiples of a decimation sample rate. The prefiltered signal is decimated (230) and low pass filtered by a lowpass filter (240) having a passband below the input frequency of the input signal. The level detector can be provided to control a variable gain stage circuit (935, 1010) which applies a gain to the input signal based on the level to form a dynamic range compressor or expander.

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