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Cool! Lots of little radio telescopes, except tuned for audio. I wonder how the triangulation was done: Were the relative sound intensities fed into a compute

Cool! Lots of little radio telescopes, except tuned for audio. I wonder how the triangulation was done: Were the relative sound intensities fed into a computer, to work out the approximate position of the incoming zeppelin?

JanSolo 8y ago
Nope. No computers with signal processing capability yet. There was usually just a wave guide (or voice tube) leading to a man listening with his ears, or later models had a microphone. The waveguide was rotatable so that sound direction could be roughly determined. This was done by slowly turning the guide until the sound was at its loudest and then reading off the angle.
mattlondon 8y ago
Not many computers about from 1910s to 1930s! :) (apart from mechanical ones used for e.g. artillery) My guess is basic lines being drawn on a physical map using observations spaced over time, and then humans trying to spot the pattern. I think these sort of sound mirrors are fairly directional, so with a bunch pointing in various slightly different directions you might be able to find the "sweet spot" and at least get an idea of where the enemy is, even if it is not precise. From my own personal half-forgotten memories of seeing these as a kid in the 90s, they always seemed to be aligned with the coast, e.g. facing directly out to sea, not at an angle. This I guess would get you a lot of subtlety different directions to take a sounding from. Very interesting.
- londons_explore 8y ago
  The mirrors focus sound to a different point depending where it originated from. With a movable microphone, an operator can pinpoint to within a fraction of a degree the direction the sound came from, and if it can be heard on two sound mirrors, that gives an exact location.
NeedMoreTea 8y ago
The intent was there would be several microphones that could be triangulated. With a hut full of human computers and sets of trig tables presumably. The chap mentioned here, Tucke, was active in developing sound artillery ranging, which survived well after WW2. Artillery didn't have the speed issues that killed off sound mirrors before they ever really got going. Watson Watt and his team fortunately gave us workable radar with height and direction finding by war's outbreak. Just.

JanSolo 8y ago

Nope. No computers with signal processing capability yet. There was usually just a wave guide (or voice tube) leading to a man listening with his ears, or later models had a microphone. The waveguide was rotatable so that sound direction could be roughly determined. This was done by slowly turning the guide until the sound was at its loudest and then reading off the angle.

mattlondon 8y ago

Not many computers about from 1910s to 1930s! :) (apart from mechanical ones used for e.g. artillery) My guess is basic lines being drawn on a physical map using observations spaced over time, and then humans trying to spot the pattern. I think these sort of sound mirrors are fairly directional, so with a bunch pointing in various slightly different directions you might be able to find the "sweet spot" and at least get an idea of where the enemy is, even if it is not precise. From my own personal half-forgotten memories of seeing these as a kid in the 90s, they always seemed to be aligned with the coast, e.g. facing directly out to sea, not at an angle. This I guess would get you a lot of subtlety different directions to take a sounding from. Very interesting.

londons_explore 8y ago
The mirrors focus sound to a different point depending where it originated from. With a movable microphone, an operator can pinpoint to within a fraction of a degree the direction the sound came from, and if it can be heard on two sound mirrors, that gives an exact location.

NeedMoreTea 8y ago

The intent was there would be several microphones that could be triangulated. With a hut full of human computers and sets of trig tables presumably. The chap mentioned here, Tucke, was active in developing sound artillery ranging, which survived well after WW2. Artillery didn't have the speed issues that killed off sound mirrors before they ever really got going. Watson Watt and his team fortunately gave us workable radar with height and direction finding by war's outbreak. Just.