Abstract

An audio signal to color pattern display signal converter-modulator includes an input audio signal section, four frequency band filters, horizontal sync and sweep circuitry, vertical sync and sweep circuitry, a pulse width modulator section, a level converter-modulator matrix, a chroma encoder circuit section and a chroma and luminance modulator and video output circuit section. The pulse width modulator section includes a CMOS NAND gate associated with each of the four frequency band filters, each NAND gate and each filter combination corresponding to a different primary display color. Each NAND gate has one input coupled to an output voltage signal from its corresponding filter section and the other NAND gate input is coupled to a sine wave signal. There are four such sine wave signals each sequentially phase shifted by 90° from the preceding adjacent sine wave. The resulting pattern, which is displayed on a television receiver, is a vertical stack of four elliptical areas (when all four NAND gates are turned on) each area being of a different color. As the particular audio signal within each frequency band increases and decreases in amplitude, the corresponding elliptical area increases and decreases about a center point causing adjacent elliptical areas to overlap thereby creating color blending.