greyrider
06-07-18, 08:25 AM
well, we all know how important the soundheads are to a submarine, especially when the submarine is submerged and under depth charge attack, they are the only sensor the submarine has to survive and defend itself against something like that, they are the eyes and ears of a submarine submerged below periscope depth. in this post i want to analyze the sound signal coming from a sound contact of shipping. we definitely can get alot of information with the hydrophones, if we know how to use it and what to look for when tracking or searching. id like to share some things i learned using the hydrophones over the years.
as far as the sounds coming into the headphones of hydrophones, in sh4 we only have 3 sounds, ambient, propeller, and engine sounds. in order to at least get a handle on estimating a range to target using the hydrophones, we would have to compare these sounds in relation to each other at ranges where a good abstract range can be estimated and plotted on a map. with a few more things , like a relative movement line, we would be in pretty good shape to tell where the contact is and where its going. using the same idea that made the sonabouy recordings of world war two, or alittle after, for the sonar school, i made a test mission, with the test ship starting beyond the listening radius of the hydrophones. you could say, why bother, we have radar, and then you could read clear the bridge and see in real life how many times the SJ burned out, how they took it all apart, and had all of the components on the conning tower floor, looking for the components that failed or burned out, replacing them, and then putting the SJ back together again. while it was getting repaired, tang would double the watch on the surface.
the test ship's course was made to start outside the listening radius, cross into it, and then steam right for the submarine, going right over it. the listening radius of the hydrophones is 18.3 nm. as it enters the listening radius, the three sounds, ambient, propeller, and engine sounds will be compared with one another as the range decreases, to try and identify certain ranges which would give a clue as to how far away the contact is.
i made comparisons every 10 minutes, until the target ship passed over head, the test ship is the iowa battleship, (i knew i would hear engines sounds from it), the iowa will travel 1.5nm in ten minutes, the results are below.
when the test ship crossed into the radius, it appears as an unknown, then identified as a warship by me, thats important for the ai sonarmen.
from the time the ship enters the listening radius, until it gets 1.5nm into the radius, (16.8 nm from the submarine.)
1.5nm in - 16.8 away
ambient amplitude is greater than propeller sounds, the ambient sound varies and sometimes sounds like a roaring hurricane, which masks a beat or two of the propellers, there is no engine sound at this range. the ai sonarman will respond to the command, "report contacts", when asked to follow target, will not respond. sound cone is a full 20 degrees. this is a good range to plot if you hear skipped or masked propeller beats (16.8nm) from submarine.
3.0nm in - 15.3nm from submarine
no change, ambient sound greater than propeller sound. very small increase in decibels of propeller sounds, no engine sound, ai sonar responds to "report contacts", will not respond to follow command.
4.5nm in - 13.8nm from submarine.
ambient sound greater than propeller sound, no engine sound, ai responds to report contact, will not respond to follow contact command.
6.0 nm in - 12.3nm from submarine
ambient sound greater than propeller sound, propeller sounds more crisp, clear, amplitude increasing, every beat can be heard, no masking of beats. no engine sound, ai responds to report contact, does not respond to follow contact.
so far, in the above ranges, theres not much to go on to get a good estimate of range, accept at 16.8nm and that the ai sonar cannot follow at these ranges, those are the only clues for these ranges.
7.5nm in - 10.8nm from submarine
ambient sound greater than propeller sound, propeller sound increasing, no engine sound, ai responds to report contact, ai responds to follow contact, begins following.
here is a good range to plot when the ai sonarman can follow contacts, (10.8nm) from submarine
8.17nm in - 10.13nm from submarine
faint engine noise, ambient sound greater than propeller sound, greater than engine sound, propeller sound greater than engine sound, ai sonar will respond to both report and follow commands. another good range to plot when engine sound detected. (10.13nm) from submarine
9nm in - 9.3nm from submarine
ambient sound greater than engine and propeller sounds, ai responds to commands
10.5nm in - 7.8nm from submarine
ambient sound and propeller sound equal in amplitude, engine sound less than both, ai responds
a good range here can be estimated when both ambient and propeller sound equal, (7.8nm) from submarine
12nm in - 6.3nm from submarine
propeller sound greater than ambient sound, ambient sound greater than engine sound, ai responds
another good range to estimate when propeller sound greater than ambient sound, (6.3nm) from submarine
13.5 nm in - 4.8nm from submarine
propellers the dominant sound, ambient greater than engine sound, ai responds
15nm in - 3.3nm from submarine
propellers the dominant sound, ambient greater than engine sound, ai responds
16.5nm in - 1.8nm from submarine
ambient sound cannot be heard, propeller sound completely dominates ambient sound, engine sound less than propeller sound, ai responds
another good range to estimate on the map (1.8nm) from submarine
18nm in - .3nm from submarine
propeller and engine noise only sounds in hydrophones, ambient sound gone, ai responds.
so there are about 6 good comparisons of sounds that will produce a range that could be plotted on a map, the ranges closest to the submarine help determine how close the escorts are when depth charging.
theres alot more to say about the hydrophones, tracking convoys by picking out one ship in the front row or by picking out one ship in the back of the convoy, and tracking that one ship, where it goes, the rest of the convoy goes to, determining relative movement, using the fringe bearings of the sound cone to determine direction..and more.
as far as the sounds coming into the headphones of hydrophones, in sh4 we only have 3 sounds, ambient, propeller, and engine sounds. in order to at least get a handle on estimating a range to target using the hydrophones, we would have to compare these sounds in relation to each other at ranges where a good abstract range can be estimated and plotted on a map. with a few more things , like a relative movement line, we would be in pretty good shape to tell where the contact is and where its going. using the same idea that made the sonabouy recordings of world war two, or alittle after, for the sonar school, i made a test mission, with the test ship starting beyond the listening radius of the hydrophones. you could say, why bother, we have radar, and then you could read clear the bridge and see in real life how many times the SJ burned out, how they took it all apart, and had all of the components on the conning tower floor, looking for the components that failed or burned out, replacing them, and then putting the SJ back together again. while it was getting repaired, tang would double the watch on the surface.
the test ship's course was made to start outside the listening radius, cross into it, and then steam right for the submarine, going right over it. the listening radius of the hydrophones is 18.3 nm. as it enters the listening radius, the three sounds, ambient, propeller, and engine sounds will be compared with one another as the range decreases, to try and identify certain ranges which would give a clue as to how far away the contact is.
i made comparisons every 10 minutes, until the target ship passed over head, the test ship is the iowa battleship, (i knew i would hear engines sounds from it), the iowa will travel 1.5nm in ten minutes, the results are below.
when the test ship crossed into the radius, it appears as an unknown, then identified as a warship by me, thats important for the ai sonarmen.
from the time the ship enters the listening radius, until it gets 1.5nm into the radius, (16.8 nm from the submarine.)
1.5nm in - 16.8 away
ambient amplitude is greater than propeller sounds, the ambient sound varies and sometimes sounds like a roaring hurricane, which masks a beat or two of the propellers, there is no engine sound at this range. the ai sonarman will respond to the command, "report contacts", when asked to follow target, will not respond. sound cone is a full 20 degrees. this is a good range to plot if you hear skipped or masked propeller beats (16.8nm) from submarine.
3.0nm in - 15.3nm from submarine
no change, ambient sound greater than propeller sound. very small increase in decibels of propeller sounds, no engine sound, ai sonar responds to "report contacts", will not respond to follow command.
4.5nm in - 13.8nm from submarine.
ambient sound greater than propeller sound, no engine sound, ai responds to report contact, will not respond to follow contact command.
6.0 nm in - 12.3nm from submarine
ambient sound greater than propeller sound, propeller sounds more crisp, clear, amplitude increasing, every beat can be heard, no masking of beats. no engine sound, ai responds to report contact, does not respond to follow contact.
so far, in the above ranges, theres not much to go on to get a good estimate of range, accept at 16.8nm and that the ai sonar cannot follow at these ranges, those are the only clues for these ranges.
7.5nm in - 10.8nm from submarine
ambient sound greater than propeller sound, propeller sound increasing, no engine sound, ai responds to report contact, ai responds to follow contact, begins following.
here is a good range to plot when the ai sonarman can follow contacts, (10.8nm) from submarine
8.17nm in - 10.13nm from submarine
faint engine noise, ambient sound greater than propeller sound, greater than engine sound, propeller sound greater than engine sound, ai sonar will respond to both report and follow commands. another good range to plot when engine sound detected. (10.13nm) from submarine
9nm in - 9.3nm from submarine
ambient sound greater than engine and propeller sounds, ai responds to commands
10.5nm in - 7.8nm from submarine
ambient sound and propeller sound equal in amplitude, engine sound less than both, ai responds
a good range here can be estimated when both ambient and propeller sound equal, (7.8nm) from submarine
12nm in - 6.3nm from submarine
propeller sound greater than ambient sound, ambient sound greater than engine sound, ai responds
another good range to estimate when propeller sound greater than ambient sound, (6.3nm) from submarine
13.5 nm in - 4.8nm from submarine
propellers the dominant sound, ambient greater than engine sound, ai responds
15nm in - 3.3nm from submarine
propellers the dominant sound, ambient greater than engine sound, ai responds
16.5nm in - 1.8nm from submarine
ambient sound cannot be heard, propeller sound completely dominates ambient sound, engine sound less than propeller sound, ai responds
another good range to estimate on the map (1.8nm) from submarine
18nm in - .3nm from submarine
propeller and engine noise only sounds in hydrophones, ambient sound gone, ai responds.
so there are about 6 good comparisons of sounds that will produce a range that could be plotted on a map, the ranges closest to the submarine help determine how close the escorts are when depth charging.
theres alot more to say about the hydrophones, tracking convoys by picking out one ship in the front row or by picking out one ship in the back of the convoy, and tracking that one ship, where it goes, the rest of the convoy goes to, determining relative movement, using the fringe bearings of the sound cone to determine direction..and more.