Project Files
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Phased Array Microphone
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Phased Array Microphones greatly improve speech recognition
in speech-to-text applications by intelligently combining
signals from several fixed-position microphones to “focus
in” on the speaker.
Acoustic Magic had been contracted to develop a
customized low-power version as part of portable military
language translator. Bolton Engineering created this product
for Acoustic Magic by integrating key design features from
several previous Acoustic Magic designs. |
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System
Overview
The Phased Array Microphone is constructed around an
Analog Devices AD-21xxx series Digital Signal Processor
(DSP). It includes six microphone pre-amplifiers, six
audio CODEC channels, a USB interface to a host
computer, Flash boot memory, and on-board power
supplies. To ensure a long product life, the system is
designed to accept a wide variety of Flash memory chips,
plus several different oscillator packages. Most parts
in the design are second-sourced and all are ROHS-compliant.
The unusual circuit board shape was necessary to fit
the product into a tight hand-held enclosure; most areas
on the board had tight height restrictions as well.
Although the shape posed some challenges, Bolton
Engineering was able to keep to a four-layer board. To
ensure high ESD immunity and to reduce susceptibility to
external noise, much of the outer layers was “poured”
with copper. Weight was important as well, so a
half-thickness 0.031” circuit board was specified.
Project Scope
Bolton Engineering designed the schematics, designed the
4-layer circuit board, worked with an Acoustic Magic
software engineer to integrate software and debug the
board, and delivered six boards to the client.
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Consumer and Computer
