Licentia Patent-verwaltungs Gmbh

Jurgen Wermuth

Ernst F Schroder

Gerhard Dickopp

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.

Circuit for dynamic compression and/or expansion

In a circuit system for the generation of a direct control voltage dependent upon an alternating voltage for a dynamic compander device, the system including a charging capacitor, a charging circuit connected to charge the capacitor, and a circuit connected to discharge the capacitor, a comparator unit is connected to effect comparison between the alternating voltage and a reference voltage and to produce an output voltage representative of the amount by which the alternating voltage exceeds the reference voltage, and at least one of the circuits is formed of a current source and an electronically controllable current path connected between the source and the capacitor and having a control input connected to the comparator unit for varying the conductance of the current path as a function of the output voltage of the comparator unit.

Circuit system for the generation of a direct control voltage which is

In a circuit for automatic dynamic compression or expansion the control voltage generator generates a control voltage which is linear against the logarithm of the input amplitude. This characteristic is achieved by a transfer member consisting of several transistors which are subject to different reference voltages and the series resistances of which are staggered.

Circuit for the generation of a control variable for the control of the

A variable gain alternating voltage amplifier having a d.c. negative feedback loop for setting the operating point of the amplifier wherein a change in gain of the amplifier is effected by a variable resistance feedback loop which is connected in parallel with the d.c. negative feedback loop and includes the series connection of a controllable resistor and a capacitor.

Variable gain alternating voltage amplifier

A compander system is described, in which the `compression` and `expansion` modes are established by the selective use of a compression or expansion circuit as such or as a negative feed-back branch for a back-coupled amplifier.

Circuit arrangement for the selective compression or expansion of the

An amplifier circuit whose gain bears a desired relation to a control voltage, including a differential amplifier, a plurality of impedances interconnected between the amplifier terminals and switches interconnected with the impedances and switchable between two states which create two impedance configurations that give the circuit mutually complementary gain vs. control voltage control characteristics.

Amplifier with controllable transmission factor and switchable control

In a circuit for the automatic dynamic compression or expansion of a signal between its input and its output, the circuit presenting a useful signal path connected between its input and its output and containing a setting member which is electronically controllable for varying the transmission factor between the circuit input and output, the circuit also presenting a branch path connected at one point to the useful signal path and containing a control voltage generator for generating, from the signal in the useful signal path, a control voltage applied to control the setting member, there is also provided a second setting member connected in the branch path and arranged to be electronically controllable for varying the transmission factor exhibited by the branch path, and means connecting the output of the control voltage generator to the second setting member for effecting a counterregulation of the transmission factor of the branch path, relative to the transmission factor variation imparted to the useful signal path.

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Stederdorf, Germany

Jurgen Wermuth