Aperiodic waveform generation using stored markers identifying scaled waveform sections

Claim 1

A waveform generator for generating an aperiodic waveform of the type having a gradually decaying envelope, comprising: a memory sequentially storing a sequence of digital samples representing the magnitude of said waveform at sample points, said digital sample being grouped into first and second continuous portions, said second portion comprising that portion of said sequence in which none of said digital samples has a magnitude exceeding 1/n the magnitude of a largest one of said digital samples, wherein n is an integer greater than unity, each of said digital samples of said second portion being scaled by a factor of n, said memory further storing a code indicating the beginning of said second portion; a source of clock pulses; an address counter for developing an address signal for sequentially addressing the stored digital samples and the stored code from the memory in response to said clock pulses; first means for supplying an additional clock pulse to said address counter in response to said stored code being addressed by said address counter; and second means responsive to said memory and to said first means for scaling each of the addressed digital samples of said first and second portions and converting it to a signal having a magnitude corresponding to the magnitude of the associated digital sample of said sequence, said second means comprising a shift register having a most significant bit position and a least significant bit position and a series of intermediate bit positions therebetween and means for writing a binary 1 into the most significant bit position of said shift register in response to operation of the waveform generator, said shift register being arranged to shift said binary 1 by a predetermined number of places toward the least significant bit position in response to said first means.