Electronic sound synthesizer
First Claim
1. An electronic sound source apparatus comprising;
- a first addressable memory means for storing fundamental wave wave-form data as a digital value,an operating means for producing a modulation index (J(t)<
B(t) (C+Sin wm t) that changes with time according to modulation envelope data and modulation wave wave-form data wm t, and wherein C is a constant,a first multiplying means for multiplying fundamental wave frequency data (wc) and said modulation index data J(t), andmeans for applying the multiplied result of said first multiplying means to said first memory means as read out address data, thereby changing a rate at which said fundamental wave wave-form data is read out of said first memory means, and further comprising;
a D/A converting means for converting the digital value read out from said first memory means into an analog signal to produce a sound signal (e=Sin J(t)·
wc t).
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Accused Products
Abstract
An electronic source synthesizer that employs frequency modulation. Wave-form data of both a fundamental wave and a modulated wave are stored in a RAM as 6-bit digital data. A sine wave signal is produced by modulation wave frequency data and the wave-form data from the RAM. The sine wave signal is multiplied with amplitude data of the modulation wave to obtain the modulation index data (J(t)). The frequency data (wc) of the fundamental wave and the modulation index data are multiplied. A result of the multiplication provides a read out address of the RAM for storing the wave-form data of the fundamental wave, thereby changing the read out speed of the RAM. The digital data read out from the RAM is converted to an analog sound signal by a D/A converter. Amplitude data (A) of the fundamental wave is pulse-width modulated, and the digital data from the RAM is gated by the modulated pulse. Thus the output of the D/A converter is activated and, forms a sound signal represented by the equation e=A sin J(t) wc t.
82 Citations
14 Claims
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1. An electronic sound source apparatus comprising;
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a first addressable memory means for storing fundamental wave wave-form data as a digital value, an operating means for producing a modulation index (J(t)<
B(t) (C+Sin wm t) that changes with time according to modulation envelope data and modulation wave wave-form data wm t, and wherein C is a constant,a first multiplying means for multiplying fundamental wave frequency data (wc) and said modulation index data J(t), and means for applying the multiplied result of said first multiplying means to said first memory means as read out address data, thereby changing a rate at which said fundamental wave wave-form data is read out of said first memory means, and further comprising; a D/A converting means for converting the digital value read out from said first memory means into an analog signal to produce a sound signal (e=Sin J(t)·
wc t). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An electronic sound source apparatus comprising;
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a wave-form data output means for outputting wave-form data, said wave form data having a plurality of bits, means for producing amplitude data of a modulation envelope signal, means for outputting a time-width signal having time-width corresponding to said amplitude data, a D/A converter means for converting the wave-form data from said wave-form data output means into an analog signal, and an activating means for activating said D/A converter in response said time-width signal. - View Dependent Claims (12, 13, 14)
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Specification