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Remembered Today:

any ideas what this is,some kind of listening post


douglynn
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It may have been linked to a Benois sound ranging box

post-9885-0-20852400-1404055729_thumb.jp

The French also used much larger horn arrays for aircraft detection

post-9885-0-59085500-1404055805_thumb.jp

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would need quite a big neck strap to carry these around

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Sound ranging seems unlikely, microphones don't need 'horns', particularly a clip of 3 all pointing in the same direction. Sound ranging mikes detect the low pressure wave when a gun fires. Furthermore the microphones don't need to be manned. That said, the Germans used a system of men with stopwatches listening and recording, but proper sound ranging did use a forward listening post which told the recording device when to switch on. UK ones used the MK 1 human ear without any technical assistance, but perhaps the French used the 'ard of 'earing in this role.

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And not just the French. This has always been my favourite, although quite a bit later.

Can't wait to see the trombone section :lol:

khaki

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Sound ranging seems unlikely, microphones don't need 'horns', particularly a clip of 3 all pointing in the same direction. Sound ranging mikes detect the low pressure wave when a gun fires. Furthermore the microphones don't need to be manned. That said, the Germans used a system of men with stopwatches listening and recording, but proper sound ranging did use a forward listening post which told the recording device when to switch on. UK ones used the MK 1 human ear without any technical assistance, but perhaps the French used the 'ard of 'earing in this role.

You are conflating the British and French systems. The British system using the sub sonic (and in audible) shock wave produced when a gun was fired did not indeed need horns. The French system used higher frequencies and did. Both British and French detection devices were small enough to be taken aloft in observation balloons

The Germans were indeed technically behind the British and in 1918 Ludendorff offered a substantial reward to any German troops capturing British sound ranging equipment - it was never won.

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Probably to keep out the cattle you can see grazing in the background if you look closely!

And possibly to discourage inquisitive tampering by any passer-by civilian or military

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Are we sure this is sound ranging? Seems VERY small compared to the other devices pictured and the bloke next to it seems to have a microphone of some sort.

Rgds

Tim D

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Are we sure this is sound ranging? Seems VERY small compared to the other devices pictured and the bloke next to it seems to have a microphone of some sort.

Rgds

Tim D

As stated the devices above are for aircraft detection and needed to pick up a relatively low noise from a long way away. Sound ranging devices which I believe the OP photo is (having seen a photo of a similar array fitted to a French observation balloon) were designed to pick up a very loud noise ( an artillery piece firing) from a shorter distance. They also had to be portable.

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I will take another look at the week end to see if there is any more on the clip, the ww2 photo shown I have allso some where I allways wondered what it was

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... Sound ranging devices which I believe the OP photo is (having seen a photo of a similar array fitted to a French observation balloon) ...

Is there other evidence that sound-ranging was carried out using balloon-mounted sensors? I'm just wondering how you would determine where the sensor was continuously with sufficient accuracy.

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Is there other evidence that sound-ranging was carried out using balloon-mounted sensors? I'm just wondering how you would determine where the sensor was continuously with sufficient accuracy.

Observation balloons were tethered and didn't move about much they were also used for flash spotting. One of the observer' first jobs on ascending was to check the position of the balloon as to exactly its position over the ground using the maps which they carried . As the balloons were kite balloons this would only change if wind direction did ( and not by very much.)

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Post #1 is correctly identified by a few forum pals as sound ranging - it forms part of the Bull system and was used in the French front as Vosges in September 1915. It could detect, in quiet conditions, German guns and a position could then be calculated using the shell-wave alone. By fitting a known series of curves to a normal to the shell-wave, the location could be deduced.

Sound capture relied on six microphones, each of which had a light paper horn gummed to the diaphragm.

The disadvantage is pointed out in post #9 - it could actually detect any sound (wind, voice, rifle etc) and relied on the operator to identify when artillery had been recorded. Under ideal conditions early in 1916, mathematical processing could fix a battery to within 100 yards. It was the basis for the big dividends of 1916 which culminated late in the war in correctly predicting the position of a newly arrived German 8-in and destroying it with a direct hit on the third round. At its best, the technique could find a German gun emplacement 20 kilometers from the front line.

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The Bull system also had other issues as Bragg discovered when he tested it

It could not always pick up the sub sonic shock wave generated when a big gun fired and sometimes collected the supersonic wave generated by the shell as it passed overhead thus providing misleading data for the calculations. It was best used in conjunction with the flash spotting as this could effectively give the time when the gun was fired and the Bull could tell when the shell passed over. The two could be used to give the range. Later French systems attempted to combine both Bragg's system and the Bull system to produce a plot that showed both the sub sonic firing signature and the supersonic shell shock wave

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That's not a failure in the recording equipment, it's the microphones picking up higher frequency sounds and sending them to the recorder. This was the problem that affected all SR equipment until Tucker invented the low frequency microphone in 1916, and it wasn't until quite late in that year that these started to become widely available. UK had adopted the French equipment (microphones and recording devices) in October 1915.

As I said in my previous post, these devices could have had one or two purposes, and possibly both. Either to enhance the hearing of an advanced post, which had the job of telling the recording device when to switch-on, for obvious reasons these were not kept continuously running (recording was on photographic film). Or they could have been using aural methods. Its often forgotten that UK made some use of this in early 1916 and other armies made extensive use (eg Germany). There's no reason why the French didn't try it as well. Basically aural methods involved men listening with stop-watches and reporting times. There's a page or two on the technique in Ortner's tome on Austro-Hungarian artillery but I suspect there was a bit of variation in the detail between armies.

SR and FS did not work together as such although they were both part of the corps Field Svy Coy/Bttn, their product was integrated with that from other sources by the Corps CBSO.

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That's not a failure in the recording equipment, it's the microphones picking up higher frequency sounds and sending them to the recorder. This was the problem that affected all SR equipment until Tucker invented the low frequency microphone in 1916, and it wasn't until quite late in that year that these started to become widely available. UK had adopted the French equipment (microphones and recording devices) in October 1915.

Mikes and recording equipment all part of the system (that's what system means). And yes of course Britain had adopted the French system in 1915 that's why Bragg was assigned to it

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