Deltalab Research, Inc.

John J Blake

Richard E DeFreitas

Richard E De Freitas

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

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 input signal and a reconstructed signal representative of a past value of the input signal and including a filter for extracting from the digital signal information relating to the time derivative of the input signal, peak detection means for determining the peak value of the output of said filter, and a signal generating means responsive to a reference signal determined from the output of said peak detection means for generating the reconstructed signal, improved circuitry for generating the reference signal. The circuit comprises weighting means for increasing the magnitude of the input to the filter as a function of the preponderance of one or the other state in said digitally-encoded signal.

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Pepperell, MA, United States of America

John J Blake