[hinkley]

The army has one of these for sniper triangulation, and Boeing made a civilian version for optimizing sound dampening on the 787. I don’t know if they kept doing that on subsequent planes but I would expect so given how enthusiastic they were about being able to apply the weight budget to greater effect.

You need really high clock rate sensing to differentiate the arrival time for sound from microphone arrays where they are all less than a nanosecond separated from each other.

[azalemeth]

A nanosecond? The speed of sound at sea level in dry air is approximately 330m/s. So at say 3.3 kHz, the rough logarithmic middle of the audible spectrum, K=2π/lambda is 2π/0.1 m=20 π rad/m. A phase difference from a source difference k. ∆r would therefore likely be far more easily resolved than that for many physical ∆rs then, no?

[hinkley]

Whups. Sound not light.

Sensors around 12.5 inches apart will be a millisecond separated. The actual device was from a fuzzy recollection of a picture I saw, was probably 700 microseconds across. But it was a sphere with many sensor so adjacent sensors were less than .1 ms of separation. They would have all the time in the world to calibrate such a thing.

My guess is rather than triangulation, they probably just find the two microphones with the widest phase separarion between their signals and draw a line back between them. I don’t actually know how much 3D sonic math they’re doing.

What I do recall is that it was tech that had recently reached the Cheap Enough to Use status at the time, which is about 20 years ago now?

[KaiserPro]

MAybe the high clock rate it to allow it to read the output of the ADCs serially?

[a_paddy]

Given that it was McDonnell Douglas, sorry Boeing, they probably cut it.

[hinkley]

Why don’t you give me a paper cut and pour lemon juice into it?