Digital waveform generator having constant signal to noise ratio
AssigneeNorlin Industries, Inc.
InventorGlenn M. Gross
Life of this patent
Estimating the term…
Abstract
An electronic musical instrument includes a p-bit memory sequentially storing the resolution contributing bits of a sequence of n-bit samples, the n-bit sequence representing a percussive-type waveform. The p-bit memory is sequentially addressed with each stored sample being suitably scaled for reestablishing the magnitudes of the corresponding n-bit samples, the scaled samples being coupled through a digital to analog converter for producing an output signal representing the percussive waveform and having a uniform signal to quantizing noise ratio.
Claims14
The method of forming a binary representation of an analog waveform of the type having a gradually decaying or increasing envelope comprising the steps of:
- sampling said waveform for producing a sequence of n-bit binary samples representative thereof;
- sequentially storing in a memory a predetermined number of the resolution contributing bits of each of said n-bit samples, said predetermined number being less than n;
- sequentially recalling said stored samples from said memory;
- and
- scaling each of said recalled samples for conversion to an n-bit signal having a magnitude corresponding to the magnitude of the associated n-bit sample.
The method of forming a digital representation of a waveform having a gradually decaying or increasing envelope comprising the steps of:
- sampling said waveform for producing a sequence of n bit binary samples representative thereof;
- grouping said sequence into first and second continuous portions, said second portion comprising that portion of said sequence in which none of said n bit binary samples have a magnitude exceeding 1/2.sup.m the magnitude of the largest of said n-bit samples, where m is an integer greater than zero;
- shifting each binary sample of said second portion m places to the left;
- storing the p most significant bits of each of the n-bit binary samples of said first and second portions;
- and
- reconstructing said sequence by recalling from storage each of said stored binary samples and converting it to its corresponding n-bit binary sample by shifting each recalled sample of said first portion n-p places to the left and each recalled sample of said second portion n-p-m places to the left.
A method utilizing a p bit memory for forming a digital representation of a waveform having a gradually decaying or increasing envelope comprising the steps of:
- forming a representation of said waveform in terms of a corresponding sequence of n-bit binary words, where n is an integer greater than p;
- grouping said sequence into a plurality of continuous portions Ao-Am equal in number to n-p+1, each of said portions representing a segment of said envelope having normalized amplitudes ranging between 1/2.sup.m and 1/2.sup.m+1, where m takes on consecutive integer values beginning with zero;
- shifting each binary word of each of said portions Ao-Am m places to the left;
- storing the p most significant bits of each of said n-bit binary words in said memory;
- and
- reconstructing said sequence by recalling from storage each of said stored binary words and converting it to its corresponding n bit binary word by shifting each recalled word of each of said portions A.sub.o -A.sub.m (n-p-m) places to the left.
Apparatus for forming a digital representation of a waveform having a gradually decaying or increasing envelope comprising:
- a first memory sequentially storing a predetermined number p of resolution contributing bits of each of a sequence of n-bit binary words, said sequence comprising a digital repreentation of said waveform;
- means for developing an address signal for sequentially addressing said first memory;
- and
- means responsive to said first memory and to said addressing means for converting each addressed p-bit binary word stored in said first memory to an n-bit word having a magnitude corresponding to the magnitude of the associated n-bit word of said sequence.
Dependencies are inferred from the claim text.