To David re: finding mortar fire

[BruceZ]

Apparently the military uses large radars or infrared for this. I wonder if it can be done with 3 microphones by triangulation. Two microphones at different locations receive the sound of a mortar launch at different times, and from this time difference the possible originating locations will lie on a hyperbola. A third microphone produces additional hyperbolas. Where the hyperbolas intersect is the originating location. This is one way that we find the location of a cell phone user. Triangulation is done with 3 antennas at 3 different locations.

[Bob T.]

If there was only one mortar, this would work.

[BruceZ]

There could be more than one mortar as long as multiple mortars do not always fire within the time it takes the sound to travel from the source to the microphone. This would be the case since they take time to reload, and they are not all synchronized. They could also be distinguished by their signature, amplitude being one possible discriminator.

[Bob T.]

Also, the wavelength of the sound waves is going to be much longer than either radar, or infrared, so the result will be much less precise in a perfect world. The medium that the sound waves are transmitted through, air, is also not very consistant, wind velocity, humidity, precipitation, and probably some other things that I am not thinking about will cause your results to degrade.

I think that you might be able to get an answer as a demonstration, but I don't know if you could get an reliable solution that would allow you to target with reasonable accuracy.

[AceHigh]

The military uses radar to track incoming shells. Often times they can fire a counter-battery salvo before the shells coming in land. They couldn't do this with sound if the shells were fired from something besides motars because most of the other guns fire at speeds close to or greater than the speed of sound.

[El Dukie]

Once the Firefinder picks up the incoming shells, if everything is sync-ed up, it takes less than a minute for a counterbattery barrage to be on the way. Often from a MLRS for the saturation effect. Another drawback to a sound-based system is that acoustic waves don't travel as quickly as radar (and ergo would add to your response time). Add to this the problems of echoes, atmospherics, etc. I imagine the military will stick with radar...