Digital tone generation system with slot weighting of fixed width window functions

An electronic musical instrument comprising:

• player operated tone selection means including a keyboard with playing keys for selecting a tone to be played by the instrument,
• a tone generator responsive to said tone selection means comprising a memory in which one cycle of a waveform is stored, means repetitively for reading the stored waveform out of the memory and at a fixed rate wherein the period of time between successive readings is selectively adjusted depending upon the frequency selected by the tone selection means to thereby produce a train of said waveforms comprising a plurality of cyclically recurring series, each series having a predetermined number of said waveforms therein,
• an envelope generator responsive to the actuation of the key of a keyboard for generating a plurality of time varying piecewise linear amplitude envelopes each comprising a plurality of interconnected linear segments with each segment having a destination amplitude and a constant slope between its destination amplitude and the destination amplitude of the previous segment of that envelope and each including attack, sustain and decay portions each comprising diverse ones of said segments, said segments being assigned, respectively, to the waveforms in said series, and
• keying means responsive to the waveform train and to the piecewise linear envelopes for scaling each waveform by the envelope assigned to it thereby to enable selective varying of the amplitudes of the individual waveforms in the series independently of each other from segment to segment of the piecewise linear envelope assigned thereto so as to vary with the time the harmonic content of the waveform train.

An electronic musical instrument comprising:

• player operated tone selection means including a keyboard with playing keys for selecting a tone to be played by the instrument,
• a tone generator responsive to said tone selection means comprising a first memory in which one cycle of the waveform is stored, means repetitively for reading the stored waveform out of the memory and at a fixed rate but wherein the period of time between successive readings is selectively adjusted depending on the frequency selected by the tone selection means to thereby produce the train of said waveforms comprising a plurality of cyclically recurring series, each series having a predetermined number of said waveforms therein,
• an envelope generator responsive to the actuation of the key of the keyboard for generating a plurality of time varying piecewise linear amplitude envelopes assigned, respectively, to the waveforms in the series and each comprising a plurality of connected linear segments, said envelope generator including:
• a second memory in which is stored a plurality of increment values and a plurality of destination values, destination generator means for reading out of said second memory a destination value for each of the segments in each envelope, increment generator means for reading out of said second memory an increment value for each of the segments in each envelope, and means for generating the respective segments in each envelope by repetitively increasing the amplitude by the increment value for a segment until the destination for that segment is reached and then increasing the amplitude of the respective envelope by the increment value for the next segment in the respective envelope until the destination for the next segment is reached and so on until said all of said plurality of envelopes have been generated, and
• keying means for scaling the amplitude of each waveform in the series by its assigned envelope.

An electronic musical instrument comprising:

• player operated tone selection means including a keyboard with playing keys for selecting a tone to be played by the instrument,
• a tone generator responsive to said tone selection means comprising a memory in which one cycle of a waveform is stored, means repetitively for reading the stored waveform out of the memory and at a fixed rate and wherein the period of time between successive readings is selectively adjusted depending upon the frequencies selected by the tone selection means to thereby produce a train of said waveforms comprising a plurality of cyclically recurring series, each series having a predetermined number of said waveforms therein,
• an envelope generator responsive to the actuation of a key of the keyboard for generating a plurality of time varying amplitude envelopes assigned, respectively, to the waveforms in the series, and
• keying means for scaling the amplitude of each waveform in the series by its assigned envelope.

A method of generating a musical tone comprising:

• providing a memory in which a representation of one cycle of the waveform is stored,
• addressing the memory to read out the stored representation of the waveform always at a fixed rate and repetitively but selectively adjusting the period of time between successive readings to adjust the frequency desired so as to produce a series of a predetermined number of the read out waveforms, the series being cyclically repeated and wherein the waveforms are separated from each other by said period of time,
• generating a time varying amplitude envelope having generally an attack portion, a sustain portion, and a decay portion,
• keying the cyclically repeated series of waveforms with the amplitude envelope, and
• varying independently of each other the amplitudes of the waveforms in a series while the amplitude envelope is being generated wherein the relative amplitude levels of at least some of the individual waveforms with respect to each other change for different portions of the envelope.

A method of generating a musical tone comprising:

• providing a first memory in which a representation of one cycle of the waveform is stored,
• addressing the memory to read out the stored representation of the waveform always at a fixed rate and repetitively but selectively adjusting the period of time between successive readings to adjust the frequency desired so as to produce a series of a predetermined number of the read out waveforms, the series being cyclically repeated and wherein the waveforms are separated from each other by said period of time,
• generating a plurality of time varying amplitude envelopes assigned, respectively, to the waveforms in the series, each envelope having an attack portion, a sustain portion and a decay portion, and
• scaling the amplitude of each waveform in the series by its assigned envelope so as to vary with time the harmonic content of the tone.