Importance

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Abstract

In a circuit for the automatic dynamic compression or expansion of a signal, the circuit presenting a useful signal path containing a first variable gain member which is electronically controllable for varying the transmission factor between the circuit input and output, a branch path connected at one point to the useful signal path and containing a control voltage generator for generating a control voltage from the signal at such point in the useful signal path, and a second variable gain member which is connected in the branch path and which is electronically controllable for varying the transmission factor exhibited by the branch path, with the transmission factor of the useful signal path being controlled to have a value dependent on the value of the control voltage and a counterregulation of the transmission factor of the branch path being effected relative to the transmission factor variation imparted to the useful signal path, the useful signal path includes a device causing the signal at one point along that path to have a value proportional to the logarithm of the signal at the circuit input, the branch path has its input point connected to the one point of the useful signal path, each variable gain member has an antilogarithmic transmission factor, and the output of the control voltage generator serves to vary the gain of each said variable gain member as an exponential function of the control voltage.

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First Claim