During the shooting, two sound events will occur - muzzle explosion and supersonic shock wave. Acoustic sensors, such as single or array microphones, can capture these sounds and use them to estimate the shooter's position. As part of the 182nd meeting of the American acoustic Society held at the Sheraton Hotel in downtown Denver on May 23, Luisa still of the sensor data and information fusion department will discuss the important factors that determine the accuracy of shooter positioning. Her speech was entitled "prediction of shooter positioning accuracy in urban environment"**
In the urban environment, buildings or other obstacles can reflect, refract and absorb sound waves. The combination of these effects will seriously affect the accuracy of shooter positioning. This accuracy of prediction in advance is essential for task planning in an urban environment because it can inform the necessary number of sensors and their requirements and locations.
Still and her team used geometric factors to model acoustic sensor measurements. This modeling, combined with sensor characteristics, sensor to shooter geometry and urban environment information, enables them to calculate the prediction of positioning accuracy.
"In our approach, the prediction can be interpreted as an oval area around the real shooter's position," still said. "The smaller the elliptical area, the higher the expected positioning accuracy."
The team compared their accuracy predictions with experimental performance under various geometry, weapon and sensor types. The positioning accuracy largely depends on the geometry from the sensor to the shooter and the shooting direction relative to the sensor network. The smaller the distance between the firing line and the sensor, the more accurate their prediction of the source. Adding more sensors can improve accuracy, but the return is decreasing to some extent.
"Every urban environment is too special (for example, in terms of layout, building type, vegetation) to make general recommendations on the setting of sensors. That's the significance of our research. We can use our method to recommend the best setting with the highest accuracy for a specific location or area," still said