Importance

Loading Importance Indicators...

Abstract

A method and apparatus for self-tuning a piano that optically senses the vibration of all the piano's strings independently and simultaneously. Interference caused by alternating-current ambient lighting is removed by modulating the string's signal onto a high-frequency carrier wave, filtering out the low-frequency ambient light interference wave, then demodulating and removing the carrier to render the original signal. Digital pitch, diagnostic, and control parameter information is interchanged between a supervisory master microcontroller and the autonomous string sustainer circuits via a master-slave serial bus connected through a single, common cable. PWM duty cycles for the string tuning coils are handled autonomously by an FPGA or a decoder network, which also communicates with the master control circuit. Pulse-width modulated control signals are filtered to a DC control voltage and combined with a drive oscillator signal using a summing amplifier to eliminate audible noise due to magnetostriction in the tuning coils.

Loading the Abstract Image...

First Claim