Ears Gunshot Localization System
Uncovering a gunman's position is traditionally a deadly game of luck and patience. This year, the U.S. Army gets help from the Ears system, a wearable, palm-sized device that weighs less than 6.4 ounces and can pinpoint a gunshot in less than a tenth of a second, even when mounted to a Humvee moving at 50 mph. The system uses a set of four microphones situated an inch apart to triangulate the origin of the gunshot. Software borrowed from submarine noise-detection technology analyzes the shape of the sound wave to determine the bullet's precise angle. The results appear on an LED screen or as an audio prompt ("50 meters, 3 o'clock"). The device runs on less than a watt of power and lasts up to 13 hours on a single charge.
Is it just me or would this be a "killer app" of sorts for military HUDs (I know its a piece of hardware, bear with me). An LED screen would certainly be useful, and it sounds like audio would give you most of what you need, but if its really that accurate I would think having the location superimposed on your vision would be really valuable. From what I understand, HUDs haven't seen widespread military options both because they're still bulky and require a lot of power, and because in practice soldiers just haven't seen enough use for them. Maybe this device could help solve the latter problem?
Interesting technology. I wonder if analyzing the "shape of the sound wave" means correlating the waves received by each mic and finding the time differences. With mics 1" apart, the difference between 2 o'clock and 2:30 would be about 8 microseconds; between 2:30 and 3 o'clock a third of that. Maybe they are doing something more sophisticated for $8000.
I can see computing an angle, but is the article making up the idea of reporting distance? If that was possible at all with mic's an inch apart, it would be extremely complex, and would probably have to identify the type of weapon & ammo as well (does an AK-47 sound differently at 100 m than at 50 m, apart for loudness?) Environmental effects (what's the sound bounding off?) and noise would probably make that infeasible.
One issue for useful accuracy of reporting would be establishing a frame of reference (eg: precisely locating a 12 o'clock that the soldier understands immediately). The place I'd expect the mic's would be on the helmet to give 360 degree coverage, and use the helmet as the reference frame. This could feed audible or some degree of visual feedback directly to the soldier without a lot of extra wires.
Doing a heads up display (HUD) would be a major expansion - not only do you need some pretty fancy displays, you need some kind of inertial or magnetic or other means of synchronizing the frame of reference as the soldier turns his head (tipping as well as rotating). Making that affordable, portable, power efficient and keeping it working in the field might be quite a challenge.