Smart Microphone Technologies

The University of Maryland faculty, Johns Hopkins University, the University of Sydney (Australia), and Signal Systems Corporation are part of a $ 2.2 million, three-year Defense Advanced Research Projects Agency (DARPA) contract for "Intelligent and Noise-Robust Interfaces for MEMS Acoustic Sensors." The goal of this contract is to formulate, design, and implement signal processing systems and technology that can adapt, control and utilize the noisy MEMS sensor signals.

The project is part of DARPA's Air-Coupled Acoustic Microsensor Technology program.

SSC's technology transition efforts for Smart Microphone technology is included in our Acoustic Surveillance Unit (ASU) product. As part of a DoD contractor team, we are using smart microphone technology as part of a low power sensor system design.

Project details

Air-coupled acoustic MEMS offer exciting opportunities for a wide range of applications for robust sound detection, analysis, and recognition in noisy environments. The most important advance these sensors offer is the potential for fabricating and utilizing miniature, low-power, and intelligent sensor elements and arrays. In particular, MEMS make it possible for the first time to conceive of applications which employ arrays of interacting micro-sensors, creating in effect spatially distributed sensory fields. To achieve this potential, however, it is essential that these sensors be coupled to signal conditioning and processing circuitry that can tolerate their inherent noise and environmental sensitivity without sacrificing the unique advantages of compactness and efficiency.

The fundamental challenge that we address in this proposal, one that is critical to any real application of MEMS sensors, is how to formulate, design, and implement signal processing systems and technology that can adapt, control, and utilize the noisy MEMS sensor signals.

More specifically, we focus our technology transition efforts on developing a smart microphone, suitable for outdoor acoustic surveillance on robotic vehicles. This smart microphone incorporated MEMS sensors for acoustic sensing, wind noise flow turbulence sensing, platform vibration sensing, and a VLSI-based (analog very large scale integration) adaptive noise-reduction circuitry.

These intelligent and noise robust interface capabilities enable a new class of small, effective air-coupled surveillance sensors. These sensor interfaces and noise reduction circuits are be small enough to be mounted on future robots. Our interfaces consume less power than current systems. By including silicon cochlea based detection and localization processing, these sensors can perform end-to-end acoustic surveillance. The resulting smart microphone technology is very power efficient, enabling a networked array of autonomous sensors that can be air-dropped, integrated onto miniaturized robots, or deployed by hand.

To achieve these goals, we propose to develop and utilize novel technologies that can perform these functions robustly, inexpensively, and at extremely low power. An equally important innovation is the formulation of algorithms that are intrinsically matched to the characteristic strengths and weaknesses of the technology. These theoretical and technological innovations are fully intertwined in our research program, and we believe that both approaches must be developed simultaneously so as to achieve truly functional and well-integrated smart sensory systems that exploit the exciting potential of acoustic MEMS sensors.

The fundamental innovative thrust of our work focuses on the development of biomimetic auditory interfaces and algorithms, and their implementations an analog or hybrid analog-digital VLSI circuits.

The ASU, pictured is housed in a 4.5-inch circular “hockey puck” enclosure, which is a minimum of 1.5 inches in height.  

While small, the individual ASU node has been designed for high performance, and has demonstrated bearing accuracies of 5 degrees or less with standard algorithms (on the order of 1 degree with specialized algorithms). 

Results

This is our Acoustic Surveillance Unit (ASU) , a state of the art microphone that is able to pinpoint the location of vechicles and with the help of the VAWS system locate gunfire. Below is the basic structure for our current ASU prototype. Smaller, more power efficient designs are underway.

The diagram below shows the accuracy of our several ASUs deployed in a recent field test. The system uses a network of ASUs to locate vehicles and gunfire.

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