Hybrid Systems Limited

Deltalab Research, Inc.

Richard E De Freitas

Samuel Wilensky

Peter W Mitchell

John J Blake

Peter D Tribeman

In an electrical system of the type in which a digitally-encoded signal is determined at least in part by the difference between a present value of an analog input signal and a reconstructed signal representative of a past value of the input signal and including signal generating means for generating said reconstructed signal, which means is responsive to a reference signal, improved circuitry for generating the reference signal. The improved circuitry comprises a ladder network which increases the magnitude of the reference signal as a function of the length of time the digitally-encoded signal continuously remains in either digital state without a change to the other digital state.

Digital encoding circuitry

A digital delay line for an analog signal having an improved efficiency in converting between the analog and digital signal formats. The delay line operates by converting an analog output into a representative series of binary ones and zeros which are applied through a shift register at a set clock rate. The shift register output, at a selected delay interval, is reconverted to the original analog levels. The conversions are governed by a logic network which increases the conversion efficiency to permit a lower clock rate and shorter shift register without a corresponding loss in frequency response.

Multiple state responsive delta-sigma converter and delay line

An audio system which achieves a concert hall reverberation effect from a stereo input signal. From two stereo input signals the audio system produces quadraphonic signals suitable for application to four speakers in the pattern of a quadraphonic sound reproduction system. The system applies the stereo input signals to a front pair of speakers substantially without alteration while reverberation is added to the stereo input signals for application to the rear speakers which realistically reproduces the impression of concert hall acoustics in the sound reaching the listener from all four speakers. The reverberation is provided by a channel signal delay scheme in combination with a channel interconnection network which achieves long reverberation times with a high echo density that eliminates objectionable, discrete echo effects.

Growing community of inventors

Westford, MA, United States of America

Richard E De Freitas