Digital envelope modulator for digital waveform
AssigneeNorlin Industries, Inc.
InventorGlenn Gross
Life of this patent
Estimating the term…
Abstract
An envelope is imposed on a sequence of binary waveform samples representing a musical waveform signal by repetitively summing selected ones of a group of scaled representations of each of the waveform samples of the form A/2.sup.m, A/2.sup.m+1 . . . A/2.sup.m+p, where A represents the magnitude of the waveform sample, p is a predetermined integer, and m is an integer changing by a factor of unity each time a predetermined number of the groups have been developed. The sum of each group of scaled representations differs from the sum of the preceding group by the factor A/2.sup.m+p whereby a staircase signal is produced amplitude modulating the musical waveform signal, the step size of the staircase signal charging each time said predetermined number of groups have been developed.
Claims39
In an electronic musical instrument of the type having means developing a plurality of series of successive binary waveform samples representing a musical waveform signal, apparatus for imposing an envelope on said plurality of series of waveform samples comprising:
- scaling means operable for developing a plurality of different scaled representations of each of said binary waveform samples;
- control means operating said scaling means for developing a group of scaled representations of each of said binary waveform samples, the sum of each of said groups representing the product of the associated binary waveform sample and a multiplication factor, said multiplication factor changing by a predetermined amount during each of said series of binary waveform samples with the predetermined amounts characterizing consecutive ones of said series differing by a multiple of two;
- and
- output means responsive to said scaling means for successively summing the scaled representations forming each of said groups for developing an output staircase signal comprising an amplitude modulated representation of said binary waveform samples.
In an electronic musical instrument of the type having means developing a sequence of binary waveform samples representing a musical waveform signal, apparatus for imposing an envelope on said sequence of waveform samples comprising:
- scaling means operable for developing scaled representations of said binary waveform samples of the form A/2.sup.n, where A represents the magnitude of a waveform sample and n is an integer;
- means for programming said scaling means for developing, in response to each of said waveform samples, a group of said scaled representations A/2.sup.m, A2.sup.m+1. . . A/2.sup.m+p, were p is a predetermined integer and m is an integer changing by one at selected time intervals;
- means for selectively enabling said scaling means for developing said scaled representations such that the sum of the scaled representations of each of said groups differs from the sum of the last preceding non-identical one of said groups by the factor A/2.sup.m+p ;
- and
- output means responsive to said scaling means for successively summing the scaled representations forming each of said groups for developing an output signal comprising an amplitude modulated representation of said sequence of waveform samples.
Apparatus for amplitude modulating a plurality of sequentially generated binary waveform samples comprising:
- scaling means operable for developing a plurality of different scaled representations of each of said binary waveform samples, said scaling means having a data input connected for receiving said sequentially generated binary waveform samples, a program input and an enable input;
- first means for repetitively developing and coupling a sequence of enabling signals to said scaling means enable input, each of said sequences of enabling signals comprising a plurality of logic bits representing a binary number whose value changes by unity at selected time intervals;
- second means for repetitively developing and coupling a sequence of programming signals to said scaling means program input, each of the sequences of programming signals being identical to each other for a predetermined time interval, said programming signals of each of said sequences comprising an incrementally changing multibit logic signal;
- and
- output means for developing an output signal representing the sum of the scaled representations developed by said scaling means in response to each of said sequences of enabling signals.
A method of imposing an envelope in the form of a multistep staircase signal on a plurality of sequentially generated binary waveform samples comprising the steps of:
- deriving a first continuous segment of said multistep staircase signal by developing a group of scaled representations of each of a first series of successively generated ones of said waveform samples, each of said groups associated with a waveform sample of said first series representing the product of a selected waveform sample of said first series and a multiplication factor which is allowed to change in increments representing a first constant amount;
- and
- deriving a second continuous segment of said multistep staircase signal contiguous with said first segment by developing a group of scaled representations of each of a second series of successively generated ones of said waveform samples, each of said groups associated with a waveform sample of said second series representing the product of a selected waveform sample of said second series and a multiplication factor which is allowed to change in increments representing a second constant amount, said first constant amount being related to said second constant amount by a predetermined factor;
- whereby said first and second segments of said multistep staircase signals comprise an envelope imposed on said sequentially generated binary waveform samples.
Dependencies are inferred from the claim text.