Automatic sound source detector

This event‐driven system determines sound source location using CMOS‐EPROM technology and a microprocessor interface. The time delay between a pair of microphones is measured. This time delay gives one direction. Another pair of microphones yields a necessary second direction. The source location is determined precisely by considering hyperbolic equations and the linear approximation. The microphone outputs are ∼200 mV. These signals, amplified to logic high level, are inputs to the Altera EPM5032 erasable programmable logic device (EPLD). The EPLD is programmed using MAX+PLUS software and a hardware programmer. A circuit designed to determine which microphone belonging to a pair received the sound first together with a 2‐MHz crystal oscillator and a 12‐bit binary counter used to measure the time delay. The counts are fetched by an assembly code in the NSC888 microprocessor board and sent to a program in the Macintosh, to calculate the sound location, through the RS232 modem port. The program calculates a...