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Acoustic Sensors & Windscreens for Ground Vehicles


 

The Technology

SARA's MA-8 microphone sensor and windscreen system meets the special needs of acoustic sensors in outdoor military and security applications, on the ground and on ground vehicles.

  • Good Frequency Response
  • Low Phase Distortion
  • Environmentally Rugged

Vehicle Mounted

The Applications

All-weather sensor for ground vehicle-mounted acoustic detection and locations systems

  • Vehicle, aircraft detection
  • Mortar, small arms, or rocket fire detection

Low noise and ground mounted applications

  • Pole mounts
  • Robotic vehicles, aerostats, balloon-mounted

Acoustic sensor systems must be able to detect sound from ground vehicles, aircraft, and rotorcraft, as well as impulsive sounds, such as mortar fire, must be effectiveat low frequencies (20-400Hz). Wind noise is a serious problem in this range, and can overwhelm signal levels entirely. When acoustic sensors are mounted on moving robotic or manned vehicles, the increase relative wind, high turbulence, and vehicle-generated noise from the engine, transmission and ground contact all work against the sensor system.

The traditional solution is to cover microphones with soft open-celled urethane foam balls. Four inch diameter balls are needed to be effective at low speeds, and greater diameter balls, up to 9 inches in diameter, have been used on moving vehicles. The foam material is water-absorbent, and has been shown to become degraded in performance due to dust absorption in deployments to Iraq. The foam is also sensitive to UV and oxidation deterioration and is easily damaged in use. Large foam balls are visible from a distance, and are not easily camouflaged.

The Advantages

Rugged Design

  • Robust, rainproof and dustproof
  • Calibrated temperature-resistant design
  • Physically robust, all-metal housing
  • Low-current electronic elements that can withstand vibration and solar heating

More Effective than Foam Balls

  • Better wind-noise reduction in strong winds and in the high turbulence associated with air flow over a moving vehicle
  • No signal reduction or phase distortion
  • Phase delay remains constant with frequency
  • Vibration cancelling sensor removes up to 18dB of vibration-induced noise
  • Design can be tailored to your application