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Originally Posted by tscharlii
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Okay, for a start ought to warn you that if your new scripts are based, even in part, on TDW's code, you should give open credit to him and make it clear that your mod is an addon for his UI. I know from experience that he is quite jealous about his code
Let's go to the technical remarks now:
bearing accuracy: WWII hydrophones were not as accurate as we could think, and for sure in most cases they were much lesser accurate than in game.Talking about the G.H.G, the
Interrogation of U-Boat Survivors - Cumumulative Edition by the British Admiralty says that "Bearing accuracy is good". Nonetheless other sources say the opposite. Quoting an interesting article I have found on the web (
Some hardly known aspects of the GHG, the U-boat's group listening apparatus by Arthur. O. Bauer):
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The British carefully investigated the capabilities of the GHG (Elac) apparatus in the captured U-570, in May 1942.
On successive selections of the high pass filters it was found that on the 6 kHz high pass-filter (utilizing the sonic spectrum between 6 kHz - 7 kHz), the bearing proved to have an accuracy equal or lesser of 1°, for 3 kHz (utilizing the spectrum between 3 kHz - 7 kHz) the accuracy was ca. 1.5°, and for 1 kHz (utilizing the spectrum between 1 kHz - 7 kHz) the accuracy was ca. 4°, at 500 Hz, thus bypassing the high pass filters, the accuracy was decreased to ca. 8°.
Average merchant ships, cruising at 12-13 knots, produced a maximum sonic spectrum at ca. 100 Hz and only 10% at 4 kHz. For destroyers cruising at 15 knots, the maximum sonic spectrum was at . 200 Hz, but still supplying 30% of its harmonic spectrum between, 4 kHz and 8 kHz.
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In other words, lower frequency wavelenghts more abundant in ship sonic spectrums, givie the least accurate readings. Knowing that low-band waves are also the ones travelling further away from their source, we can also desume that bearing accuracy had to be better at short ranges than at long ones. This assumption seems to be confirmed by the fact
the K.D.B. had a better accuracy but a much shorter range than the GHG: besides being orientable, it was probably more sensible to relatively high frequencies than to low ones. For completeness, it is worth to note that, with its advanced electronics, the Balkon Gerat had the ability to filter efficiently low frequencies and to amplify higher ones, thus achieving a better accuracy and range than its predecessors. One last note on GHG's bearing accuracy; in an unreferenced article, uboataces.com refers that:
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the triangulation was most effective with sound sources coming from the sides, with deteriorating accuracy as the source moved to the front or rear of the boat.
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This issue was obviated in te next models through the adoption of orientable sensors, the increase of their number, and their technological enhancement.
Unfortunately, this aspect is totally neglectedin game. I suppose that randomizing hydrophone reports through python code wouldn't be a major issue. The point that I have not an aswer for is: can we make a script to apply different randomization ranges for different hydrophone models ad at different target ranges?
Speed, ship type, manoeuvre of the ship estimation. I have found a signed
article on uboat.net stating that:
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Experienced underwater sound detector operator was able to determine is a detected ship a cargo ship or a warship (type of the warship), approximate speed or manoeuvre of the ship (approaching, digression, increasing or decreasing of speed and depth, if detected object was a submarine).
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I also wish to point you to the following subsim threads which discuss more in detail the speed estimation topic:
http://www.subsim.com/radioroom/show...94#post2107994
http://www.subsim.com/radioroom/show...60#post1728160
The above sources should unravel any doubt on the fact that the hydrophone could be used for detecting more data than just target bearings. I agree with you that doing it would have required several minutes of continuous listening though. Talking more specifically about target range, target closing/moving away, and speeding up/slowing down, I find your method for determining them based on real measurement rather than throwing exact numbers, brilliant and probably realistic. I wonder if the doppler factor might have helped a skilled sonarman in this task, especially for close and fast moving targets.