The Acoustic Vector Sensors (AVS) is embedded in the AMMS by a small disc provinding a X-axis and Y-axis. The AVS can detect, classify and locate all sorts of acoustic events in 3D space, for instance impulses, like Small Arms Fire (SAF), Rockets, Artillery and Mortars (RAM), but also tonal sound sources like ground vehicles and helicopters. AVS have a compact size (1cm), low weight (100 gram) and low power (<1 Watt), they can be deployed on all sorts of platforms, such as unattended ground sensors, vehicles, Unmanned Aerial Vehicles (UAV), dismounted soldiers and helicopters.
At any point in space, a sound field can be described completely by its two dimensions; the scalar value, and the vector value. The scalar value, sound pressure, is well known and well measured. But the other quantity in acoustics, the vector value Acoustic Particle Velocity, only recently became a directly measurable quantity with the invention of the Acoustic Vector Sensor (AVS) by Microflown.
The extremely small and light-weight Acoustic Vector Sensors are capable of detecting, localising, identifying and tracking sound sources in 3D space. This makes them beneficial for the defence industry, as source (target) locating sensors, increasing situational awareness. The key benefit of Acoustic Vector Sensors (AVS) is their ability to locate all types of sound sources from all types of platforms. Microflown’s sensors are already established in the automotive industry, but the novel Acoustic Vector Sensors (AVS) are now being used for the detection and localisation of gunshots, artillery, aircraft and vehicles.
In acoustics this movement of air is called particle velocity. The Microflown sensor is based upon MEMS technology, and uses the temperature difference in the cross section of two extremely sensitive platinum wires that are heated up to 200°C in order to determine Acoustic Particle Velocity. When air flows across the wires, the first wire cools down a little and due to heat transfer the air picks up some heat. Hence, the second wire is cooled down with the heated air and cools down less than the first wire. A temperature difference occurs in the wires, which alters their electrical resistance. This generates a voltage difference that is proportional to the Particle velocity and the effect is directional: when the direction of the airflow reverses, the temperature difference will reverse too.
Assembling a sound pressure transducer and three orthogonally placed Microflown sensors in one single point, a very compact (5x5x5mm) AVS can be produced. Direction and elevation of sound sources are direct outputs of the sensor. Further algorithms and/or additional Acoustic Vector Sensors allow distance to be determined.
The unique Acoustic Vector Sensor Technology means multiple sources can be located simultaneously even in complex situations such as urban environments or on noisy plaforms such as UAVs and ground vehicles.