A soft-processor-based FPGA implementation of a microphone array direction-of-arrival estimator

This paper presents the implementation of a digital system to estimate the direction-of-arrival (DOA) of a sound source signal using the multichannel cross-correlation coefficient (MCCC) method. The implementation is based on a Nios^® II soft processor incorporated in a four-microphone-channel signal processing system on a field-programmable gate array (FPGA). The MCCC algorithm is coded in C and executes on the Nios^® II soft processor on an Altera^® Cyclone^® II FPGA. The performance of the soft-processor-based FPGA implementation of the MCCC algorithm is investigated by applying simulated microphone input signals from a pre-recorded sound source stored on a secure digital (SD) memory card. The results for noisy and reverberant environments are in good agreement with simulations and they confirm that the DOA estimation robustness is suitable for practical applications.