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Musical-Applications-of-Microprocessors-2ed-Chamberlin-H-1987

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DIRECT COMPUTER SYNTHESIS METHODS 107<br />

1.0<br />

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o 0 50 100 150 200<br />

/<br />

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-1.0<br />

TIME (}I5.c)<br />

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oi=.If:!.l.J..!±!fJ-!,!:!:li~~~L.LLLlllll.WJ..U.IL.LLLL..rrTTT1TrrrTTTTTTTTTT1TmrTTTTTTTTTT1Trr~9;;:50;,;;1.0::e;OO<br />

50 100 150 200 250<br />

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g -25<br />

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ll.<br />

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'" -100 L....I ,AI,-----'c-~-...J/II ,-----,::'-:-----:::!:-:--...<br />

V 99 101 V 199 201<br />

FREQUENCY (kHz)<br />

(C)<br />

Fig. 4-1. (A) 1-kHz sine wave divided into 100 10iLSec portions. (B) Sine wave<br />

approximation from DAC. (C) Spectrum <strong>of</strong> B.<br />

pulses spaced at lO-fLsec intervals. Each individual pulse or the number it<br />

represents is called a sample because it gives the waveform amplitude at a<br />

sample point in time. The frequency <strong>of</strong> the pulses is called the sample rate and<br />

in this case it is 100 ks/s (kilosamples per second). The sample rate is almost

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