[LibWhacker]

Interesting. Thanks. Is it possible that microphone technology has advanced to the point that the array is no longer needed; i.e., is it possible for a microphone to pick up the faint whistling and buzzing a bullet makes in flight, even from a great distance? And even during the racket of combat?

[conservatism_IS_compassion]

Is it possible that microphone technology has advanced to the point that the array is no longer needed; i.e., is it possible for a microphone to pick up the faint whistling and buzzing a bullet makes in flight, even from a great distance? And even during the racket of combat?

Indeed, I think the main trick to this whole deal is exactly picking out the data only from a single shot, from a cacphony of noises to be expected in any actual battle. But if you actually had a simple problem--a single gun firing a single shot--you would still need information from no less than two microphones just as your brain can only estimate the direction of a source of sound if you have two ears.

I'm confident that directional information from a reasonably compact microphone will not be extremely accurate directionally. You've seen directional microphones made with large parabolic reflectors, used to eavesdrop on football huddles from the sideline. It's true that such a microphone would discriminate fairly well directionally, down to maybe 10 degrees or so perhaps. But then, the loudness of the report and the sound of the (hopefully missing) bullet's flight when detected doesn't tell you a whole lot about the direction unless you can tweak the direction and listen to another report.

If on the other hand you had two microphones spaced some distance apart laterally, then you can infer something about direction from the difference in time of arrival of the report at the two locations. If there is none that implies that the shot came from somewhere on the plane which is the perpendicular bisecter of the line between the two microphones; otherwise there will be a more complicated surface on which the source must lie. If you add in the time of arrival at each microphone of the snap due to the shock wave off the supersonic bullet, that could suggest how far the bullet missed by, and if you guess the speed of the bullet that could give you an idea of range to the source of the shot.

But I think to have any hope of a definitive solution for the location of the shooter, say nothing of the trajectory of the shot, you must have three microphones or probably more.

And I would assume that the reason they derive the trajectory of the shot is just for show; you are much more concerned about where the next shot might go than about where the last one went in detail. If you know accurately where the shooter is and can communicate with artillery you might prevent the next shot altogether. Not sporting but then, that's pretty much the point of military technology.