Architecture for source localization with a linear ultrasonic array

We present an architecture for applying synthetic aperture processing to determine the direction of arrival of ultrasonic waves. Three linear arrays of MEMS ultrasonic microphones have been designed and fabricated for this purpose. The microphones´ diameters are 0.8, 0.4 and 0.2 mm, for resonance frequencies of approximately 34, 110 and 520 KHz, respectively. The arrays are interfaced with receiver circuitry that samples and digitizes the incident wavefront. A pure analog implementation is also described. Carefully designed low noise, pre-amplifiers and analog-to-digital converters are used in the proposed receiver circuit. FIFO buffers are used to store the sampled values and interface with a CPU. Both continuous and pulsed techniques can be used to stimulate the array. We describe the microphone array, the receiver circuits, and the beam-steering algorithm. Lastly, we present an integrated architecture for realizing this type of ultrasonic source localization and directional acoustic transmission and reception in VLSI