Implementation of octave repeat in a computor organ

Claim 2

An electronic musical instrument comprising: tone generation means for computing in real time the amplitudes at successive sample points of a musical waveshape, said means including first circuitry for separately evaluating the constituent Fourier component, an accumulator for summing these components to obtain each sample point amplitude, and a converter for converting the obtained amplitudes to musical tones, the fundamental frequency of the generated tone being established by a frequency number utilized by said first circuitry in each Fourier component evaluation, note selection switches, a frequency number memory containing frequency number values associated with selectable notes, and octave repeat control means, operatively connected to said frequency number memory, for alternately providing to said first circuitry a first frequency number associated with a note selected by said switches and a second frequency number associated with a different note, said tone generation means correspondingly, alternately generating tones at the nominal pitch of said selected note and at the pitch of said different note.

Claim 3

An electronic musical instrument according to claim 1, said instrument further comprising: a harmonic coefficient memory storing a set of harmonic coefficients which establish the relative amplitudes of the individual constituent Fourier components evaluated to obtain each sample point amplitude, said harmonic coefficients thereby establishing the timbre of the generated tones, attack/decay control means, cooperating with said octave repeat control means, for providing during each repetitive tone generation interval successive scale factors which establish the amplitude envelope of the tone generated during that interval, and harmonic coefficient scaler means for accessing from said harmonic coefficient memory the harmonic coefficient associated with the individual constituent Fourier component currently being evaluated and for multiplying said accessed harmonic coefficient by the scale factor currently being provided by said attack/decay control means, the resultant product being a scaled harmonic coefficient that is provided to said first circuitry for utilization thereby to establish both the relative amplitudes of the evaluated Fourier components and the amplitude envelope of the generated musical waveshape.

Claim 4

An electronic musical instrument according to claim 2 wherein said attack/decay control means comprises; a memory storing a set of attack/decay scale factors that define the amplitude envelope of the generated tone, an attack/decay rate clock, and memory access control circuitry for successively accessing said stored attack/decay scale factors from said memory at a rate established by said clock, said accessed scale factors being provided to said harmonic coefficient scaler means.

Claim 5

An electronic musical instrument according to claim 2 wherein said octave repeat control means comprises; an octave repeat clock which establishes the alternation rate of the repetitive tone generation intervals, said clock providing a ''''repeat'''' signal at the beginning of each such interval, alternate provision of said first and second frequency numbers being controlled by said ''''repeat'''' signal, and wherein said attack/decay control means repetitively provides said successive scale factors beginning upon occurrence of each ''''repeat'''' signal.

Claim 6

An electronic musical instrument according to claim 2 further comprising: sustain logic, operatively connected to said note selection switches and said octave repeat control means, for continuing to provide said first and second frequency numbers alternately to said tone generator means for a sustain period following release of the selected note switch so that said alternate tones continue to be generated during said sustain period, and sustain control means, operative during said sustain period, for progressively decreasingly scaling the attack/decay scale factors provided by said attack/decay control means prior to utilization of said attack/decay scale factors by said harmonic coefficient sealer means.

Claim 7

An electronic musical instrument according to claim 1 further comprising: sustain logic, operatively connected to said note selection switches and said octave repeat control means, for continuing to provide said first and second frequency numbers alternately to said tone generation means for a sustain period following release of the selected note switch so that said alternate tones continue to be generated during said sustain period, and sustain scaler means for progressively decreasing the amplitude of the constituent Fourier components evaluated during said sustain period so that the maximum amplitude of each repeated alternately generated tone is less than that of the proceeding tone.

Claim 8

In an electronic musical instrument of the type wherein a musical waveshape is synthesized by computing in real time the amplitudes at successive sample points of that waveshape, said waveshape amplitudes being converted to musical signals as the computations are carried out, said instrument including generation means having first circuitry for individually calculating the constituent Fourier components of that musical waveshape and an accumulator for summing these Fourier components to obtain each waveshape amplitude, the relative amplitudes of said Fourier components being established by scaled amplitude coefficients derived from a set of unscaled harmonic coefficients stored in a first memory, the improvement comprising: octave repeat control means for causing said generation means alternately to synthesize said musical signals at a selected pitch and at an interval of said selected pitch, a scale factor memory storing a set of scale factors for establishing the attack/decay characteristics of the alternately synthesized selected pitch and interval musical signals, and a harmonic coefficient scaler, connected to said first memory, to said scale factor memory, and to said first circuitry, for multiplying the harmonic coefficients obtained from said first memory by a scale factor obtained from said scale factor memory, the products of said multiplication being scaled amplitude coefficients that are supplied to said first circuitry for utilization thereby.

Claim 9

In an electronic musical instrument of the type wherein a musical waveshape is synthesized by computing in real time the amplitudes at successive sample points of that waveshape, said waveshape amplitudes being converted to musical signals as the computations are carried out, said instrument including generation means having first circuitry for individually calculating the constituent Fourier components of that musical waveshape and an accumulator for summing these Fourier components to obtain each waveshape amplitude, the relative amplitudes of said Fourier components being established by scaled amplitude coefficients derived from a set of unscaled harmonic coefficients stored in a first memory, the improvement comprising: octave repeat control means for causing said generation means alternately to synthesize said musical signals at a selected pitch and at an interval of said selected pitch, a scale factor memory storing a set of scale factors for establishing the attack/decay characteristics of the alternately synthesized selected pitch and interval musical signals, and a harmonic coefficient scaler, connected to said first memory, to said scale factor memory, and to said first circuitry, for multiplying the harmonic coefficients obtained from said first memory by a scale factor obtained from said scale factor memory, the products of said multiplication being scaled amplitude coefficients that are supplied to said first circuitry for utilization thereby.

Claim 10

An electronic musical instrument according to claim 7 further comprising: an attack/decay rate control clock, and memory access circuitry for accessing from said scale factor memory successive ones of said set of scale factors at a rate established by said attack/decay rate control clock, said accessed scale factors being provided to said harmonic coefficient scaler, and attack/decay control circuitry for directing said memory access circuitry to repeat said accessing of successive scale factors each time said octave repeat control means causes alternation of the synthesized pitch.

Claim 11

An electronic musical instrument according to claim 8 wherein said memory access circuitry comprises; a first shift register containing a single 1 bit, the register positions of said first shift register having a one-to-one correspondence with storage locations in said scale factor memory, the scale factor in the storage location corresponding to the register position of said single 1 bit being provided to said harmonic coefficient scaler, the position of said single 1 bit being incremented by timing pulses from said attack/decay rate control clock.

Claim 12

An electronic musical instrument according to claim 9 further comprising: a circuit for progressively decreasing the maximum amplitude of the selected pitch and octave musical signals during a sustain interval, comprising; a sustain rate clock, a second shift register storing a single 1 bit and having a one-to-one correspondence with storage locations in said first shift register, said single 1 bit being in the first position of said register at the beginning of said sustain interval and being incremented in position by output pulses from said sustain rate clock, and load means, operative each time said generation means is caused to synthesize an alternate pitch, for resetting the single 1 bit in said first shift register to the position corresponding to the position of the single 1 bit in the second shift register at the time of said resetting, so that successive accessing of scale factors from said scale factor memory begins with decreasing maximum values during succeeding generated note repetitions during said sustain interval.

Claim 13

An electronic musical instrument according to claim 8 further comprising: note selection switches connected to said generation means for selection of the synthesized pitch, sustain logic operatively connected to said note selection switches and said generation means to continue alternating synthesis of said selected pitch and interval musical signals during a sustain interval following the release of a note selection switch, and a circuit for progressively decreasing the maximum amplitude of the alternately produced selected pitch and interval musical signals during said sustain interval.

Claim 14

An electronic musical instrument according to claim 11 wherein said circuit comprises; another memory storing a set of sustain scale factors defining a waveshape amplitude envelope, a sustain memory access controller operatively connected to said other memory and to said sustain logic, for accessing successive sustain scale factors from said other memory during said sustain interval, and a sustain scaler for multiplying each attack/decay scale factor by said accessed sustain scale factor before said attack/decay scale factor is provided to said harmonic coefficient scaler for utilization thereby.

Claim 15

An electronic musical instrument according to claim 12 wherein said sustain logic provides a ''''start sustain'''' signal when said note selection switch is released, and wherein said sustain memory access controller includes a sustain rate clock, said controller causing access of said sustain scale factors beginning upon occurrence of said ''''start sustain'''' signal and continuing at a rate established by said sustain rate clock, said controller providing an ''''end of sustain'''' signal at the end of said sustain interval, said sustain logic terminating generation of said musical signals in response to occurrence of said ''''end of sustain'''' signal.

Claim 16

An electronic musical instrument according to claim 7 wherein said scale factor memory contains a first subset of scale factors of progressively increasing value and a second set of scale factors of progressively decreasing value, successive accessing and utilization of said first and second subsets resulting in repeated selected pitch and octave musical sounds each having a non-abrupt attack followed by a non-abrupt decay amplitude envelope.

Claim 17

An electronic musical instrument according to claim 7 wherein said attack/decay scale factors are accessed from said scale factor memory successively beginning from a selected starting location in said memory, together with means for controlling said selected starting location as a function of time.

Claim 18

An electronic musical instrument comprising: note selection switches, a tone generator which produces a tone at a pitch established by a signal provided thereto, the amplitude envelope of said produced tone being established by scale factors provided thereto, said sCale factors having values which change in time so as to define a predetermined amplitude envelope for the generated tone, octave repeat control means, operatively connected to said note selection switches, for alternately providing to said tone generator a first pitch establishing signal associated with a note selected by said switches and a second pitch establishing signal associated with an interval of said selected note, said tone generator correspondingly, alternately generating tones at the nominal pitch of said selected note and at the pitch of said interval, and attack/decay control means, operatively connected to said octave repeat control means, for providing to said tone generator during each repetitive tone generation period successive ones of said scale factors to establish the amplitude envelope of the tone generated during the period.

Claim 19

An electronic musical instrument comprising: note selection switches, a tone generator which produces a tone at a pitch established by a signal provided thereto, the amplitude envelope of said produced tone being established by scale factors provided thereto, said sCale factors having values which change in time so as to define a predetermined amplitude envelope for the generated tone, octave repeat control means, operatively connected to said note selection switches, for alternately providing to said tone generator a first pitch establishing signal associated with a note selected by said switches and a second pitch establishing signal associated with an interval of said selected note, said tone generator correspondingly, alternately generating tones at the nominal pitch of said selected note and at the pitch of said interval, and attack/decay control means, operatively connected to said octave repeat control means, for providing to said tone generator during each repetitive tone generation period successive ones of said scale factors to establish the amplitude envelope of the tone generated during the period.

Claim 20

An electronic musical instrument wherein tones at the nominal pitch of a selected note and at an interval thereof alternately are produced, comprising: first means for computing at regular time intervals tx the amplitudes Xo(qR) of a waveshape, where q is an integer incremented each time interval tx, in accordance with the relationship

Claim 21

An electronic musical instrument wherein tones at the nominal pitch of a selected note and at an interval thereof alternately are produced, comprising: first means for computing at regular time intervals tx the amplitudes Xo(qR) of a waveshape, where q is an integer incremented each time interval tx, in accordance with the relationship

Claim 22

An electronic musical instrument according to claim 17 wherein said first means further comprises; a frequency number memory storing a set of values R for selectable notes, note selection switch circuitry for accessing from said frequency number memory a value R associated with a selected switch, a note interval adder incremented by the accessed value R at each time interval tx to obtain the value qR, and multiplier circuitry operatively connected to said octave repeat rate control circuitry for multiplying said obtained value qR by K d/12 where d has said other value only during occurrence of said interval tone indicating signal.

Claim 23

An electronic musical instrument according to claim 17 wherein said first means further comprises: a frequency number memory storing values of R for selectable notes, said values being stored in octave-related subsets of twevle, note selection switches, and access circuitry operatively connected to said octave repeat rate control circuitry, for accessing from said frequency number memory the value of R associated with the note selected by said switches during occurrence of said nominal pitch indicating signal, and for accessing the value (kR) associated with said interval of said note selected by said switches during occurrence of said interval tone indicating signal.

Claim 24

An electronic musical instrument according to claim 17 wherein said attack/decay scale factor circuitry comprises; an attack/decay scale factor memory storing a set of scale factor values O(t) an attack/decay rate control, incuding a rate control clock, for successively accessing said scale factors from the attack/decary scale factor memory at a rate established by said rate control clock, said successive accessing beginning repetitively in response to each occurrence of said alternating signals from said octave repeat rate control circuitry.

Claim 25

An electronic musical instrument according to claim 20 wherein the entire set of stored scale factor values D(t) is accessed from said attack/decay scale factor memory between successive occurrences of said alternating signals except during said sustain period, and further comprising; third circuitry, operative during said sustain period and connected to said attack/decay rate control, for causing less than said entire set of stored scale factor values D(t) to be accessed from said attack/decay scale factor memory between successive occurrences of said alternating signals during said sustain period.

Claim 26

An electronic musical instrument according to claim 21 and having note selection keys, further comprising; sustain logic, operatively connected to said first means, for continuing tone production during a sustain period beginning upon release of a note selection key, said sustain scaler including a sustain rate clock and being operative, during said sustain period, to direct access of gradually decreasing subsets of said stored scale factors from said attack/decay scale factor memory, thereby progressively decreasing the maximum amplitude of the repeated nominal pitch and interval tones in response to successive timing signals from said sustain rate clock.

Claim 27

An electronic musical instrument according to claim 20 and further comprising; a sustain scale factor memory storing a set of sacle factors S(t), a sustain rate control, including a sustain rate control clock, for successively accessing said scale factors S(t) from said sustain scale factor memory, at a rate established by said sustain rate contrOl clock, during said sustain period, and a sustain scaler for multiplying the attack/decay scale factor D(tl ) accessed from said attach/decay scale factor memory by the sustain scale factor S(t) concurrently accessed from said sustain scale factor memory, and for providing the product S(t)D(t) to said attack/decay scale factor circuitry.