Abstract

A system for creating and displaying colored roulette curves representative of music on a screen includes an X-,Y-deflection control circuit which is driven in part by at least two musically-related fixed frequency signals. These frequencies are taken from an arithmetic progression of pseudotempered scale tones and are very nearly equal in frequency to frequencies of tones in the geometric progression of tempered scale music tones. In addition, they form a ratio of integers, one to the other, approximately equal to [N(1.0594631)n]/N, where N is an integer, n-1 is the number of tones skipped between two corresponding tones in the tempered scale, and (1.0594631)/1 is the common ratio relating adjacent tempered scale music tones as well as the common difference in various arithmetic progressions of pseudo-tempered scale tones as related to changes in musical key. These fixed frequency signals are each divided into quadrature components and, after being amplitude modulated by audio-derived music signals, applied to the X-,Y-deflection control circuits. A circuit for determining the colors of the roulette curves receives audio-derived music signals, separates these signals into various frequency bands, splits these frequency bands into components phase-shifted from one another and applies respective like phase-shifted components to respective color producing elements. Audio-derived music signals are also used to vary the brightness of the display. The tint of the roulettes is determined by the phase relationship between the audio-derived music signals which are used to control brightness and those which are used to control color. Solo-tone-produced roulettes are given added color and tint by insertion of fixed musically-related tones. A high-frequency signal may be used for amplitude modulation of the X-,Y-deflection signals to increase the width of the trace.