Dbx Corporation

C Rene Jaeger

David E Blackmer

Lawrence E Blakely

Joseph B Seale

A device is described for modifying the charging behavior of a charge storage device, such as a capacitor, so that the device charges substantially in accordance with a square law function responsively to a linear charging input current. The device has particular utility in a signal-conditioning system of the type including an averaging detector, a gain stage and a charge storage device coupled between the output of said detector and the input of said gain stage so that the input to said gain stage behaves in a similar manner to the output of an RMS detector.

Square law charger

An improved expanding system is described for enhancing transmitted or recorded audio signals previously processed by anyone of several nonlinear amplifying techniques. The system is designed to divide the audio signal received into substantially discrete frequency bands and each band is separately expanded, independently of the other bands, so as to minimize 'breathing' and 'pumping'.

Signal enhancement system

An adaptive signal weighting system for use in electrical signal transmission along a signal path comprises a variable filter disposed in the signal path having electrical transmission characteristics capable of varying in response to a first control signal the relationship between the spectral region of dominant energy in a transmitted signal relative to the other spectral regions of the transmitted signal. Frequency discrimination means senses the spectral region of dominant signal energy in the transmitted signal and provides the first control signal as a function of frequency of the dominant signal energy. Gain control means disposed in the signal path and coupled in series with the filter means provides a gain variable on the transmitted signal responsively to a second control signal. This second control signal is logarithmically related to the amplitude of the transmitted signal over at least a portion of the frequency range of the signal.

Adaptive signal weighting system

An adaptive signal weighting filter for use in a compander performs a frequency response weighting function so that during the encoding process the spectral region of dominant signal energy of the program signal is preemphasized with respect to other spectral regions and during the decoding process the corresponding spectral regions of the encoded signal are deemphasized with respect to one another in a complementary manner.

Adaptive filter

A current mode operational rectifier has an output terminal connectable as a DC current source of a predetermined polarity, and comprises a high gain amplifier having an inverting input terminal for receiving an input signal current from an AC current source and two alternative transmission paths for providing full wave rectification. The first transmission path includes a first transistor having its base connected to the output terminal of the amplifier and its emitter and collector connected between the output terminal of the rectifier and the input terminal of the amplifier. The first transmission path conducts DC current to the output from the input terminal of the amplifier at an instantaneous level substantially equal to the instantaneous level of the input signal when the input signal is of a first polarity. The second transmission path includes matched second and third transistors. The second transistor has its emitter and collector connected between the input and output terminals of the amplifier while the emitter and collector of the third transistor are connected between the output terminal of the amplifier and the output terminal of the rectifier. The second transistor conducts the input signal from the input terminal of the amplifer to the output terminal of the amplifer and the third transistor simultaneously conducts current to the output from the output of the amplifier at an instantaneous level substantially equal to the instantaneous level of the input signal when the input signal is of a polarity opposite that of the first polarity.

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South Lyndeboro, NH, United States of America

C Rene Jaeger