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US 4,345,500 AGranted
High resolution musical note oscillator and instrument that includes the note oscillator
AssigneeNew England Digital Corporation
InventorsSydney A. Alonso, Cameron W. Jones
Life of this patent
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Abstract
A musical note oscillator producing notes at musical intervals having high resolution and high frequency stability achieved with an economy of components and control signals. The oscillator may be operated to provide multiple notes simultaneously and independently; and it is described in the context of a musical instrument.
Claims22
A digital electronic musical instrument comprising, in combination:
- means for selecting at least one desired note having a fundamental frequency, which means for selecting provides a binary output signal;
- digital calculator means connected to receive the binary output signal and operable to produce, in binary form, values of a fractional increment number;
- digital oscillator means comprising clock means for generating clock pulses at a predetermined periodic repetition rate, adder means having a first adder input and a second adder input respectively to receive a first binary input signal formed of binary bits having whole number significance and the fractional increment number, said adder means having a modulus, an adder sum output and a carry-out output, said adder means being operable to add the first binary input signal and, as a second binary input signal, the fractional increment number, said adder means being operable to provide a carry-out pulse on the carry-out output thereof whenever said modulus is exceeded, the fractional increment number being formed of binary bits, selected ones of which are aligned within the adder means to have a lower order of significance than the bits forming the first binary input signal, accumulator means having an accumulator input and an accumulator output, which accumulator means is connected to receive the clock pulses from the clock means and to receive the adder sum at the accumulator input and being operable to store the adder sum and to provide the stored adder sum at the accumulator output, said accumulator output being connected to provide said first binary input signal to said first adder input, so that an oscillator output is provided in the form of carry-out pulses having a rate proportional to said fractional increment number received by said second adder input;
- and
- means for producing said desired note in response to at least some of the carry-out pulses.
2 more elements
A digital oscillator comprising, in combination:
- clock means for generating pulses at a predetermined periodic repetition rate;
- adder means having a modulus and having a first adder input and a second adder input respectively to receive a first binary input signal formed of binary bits having whole number significance and, as a second binary input signal formed of binary bits, a fractional increment number, said adder means being operable to add periodically the first binary input signal and the fractional increment number, said adder means being operable to provide a carry-out pulse on a carry-out output thereof, in the course of the periodic additions, whenever the modulus of the adder means is exceeded, selected binary bits forming the fractional increment number being aligned within the adder means to have a lower order of significance than the bits forming the first binary input signal;
- accumulator means having an accumulator input and an accumulator output, which accumulator means is connected to receive the clock pulses from the clock means and to receive the adder sum at the accumulator input and being operable to store the adder sum and to provide the stored adder sum at the accumulator output, said accumulator output being connected to provide said first binary input signal to said first adder input, so that an oscillator output is provided in the form of carry-out pulses having a rate proportional to said fractional increment number received by said second adder input.
Dependencies are inferred from the claim text.