Ultrasonic sensor based contactless theremin using pipeline CORDIC as tone generator

Theremin is an electronic musical instrument controlled without physical contact by the performer. It has two antennas to control pitch and volume. By replacing the antennas with ultrasonic sensor, a new redefined theremin is implemented. The ultrasonic sensor will control the tone generator which is implemented in FPGA Altera Cyclone II EP2C35F672C6 of DE2-70 board. The tone generator is implemented by using a pipeline CORDIC circuit. CORDIC (Coordinate Rotation Digital Computer) is a digital circuit that can be used to compute several common mathematical transcendental functions with only basic hardware requirements. It is used to generate sine wave as a tone in specific frequency and volume. It is firstly implemented in iterative structure to carry out all of optimization needed to achieve higher performance, less area consumption, and higher precision. To increase the throughput, the CORDIC circuit is modified into pipeline structure at an expense of some area consumption.