The PING is supersonic. So why do we hear it?

[Quagmire]

I cant get enough of the Fleet Type Submairne manual at this website: http://www.maritime.org/fleetsub/ I have read to the Sonar operators section now and the more I read the more I cannot wait for SHIV! Those uboots are in the stone age compared to the average USN fleet boat!

Anyway the manual describes echo ranging or "pinging" as supersonic meaning that the ping cannot be heard without receiving gear. So why do we hear it when we are crapping our pants in the control room?

Also the manual states that escort vessels ping constantly due to the noise they make at high speeds? This doesnt seem to happen in SHIII. They only seem to ping when they detect you.

Or am I missing something???

Here are the links that I am referring to:

Supersonic listening: http://www.maritime.org/fleetsub/sonar/chap5.htm#5A

Single Ping Echo Ranging: http://www.maritime.org/fleetsub/sonar/chap6.htm#6A

[Drebbel]

Those uboots are in the stone age compared to the average USN fleet boat!

Then why where new designed post-war subs around the world mainly copies of the German type XXI ? ;)

[Quagmire]

Well the XXI was a whole new class of boat. When I say stone age I am comparing the average VII or IX to the average USN fleet boat.

From the air and surface search radar to the ice cream machine I would rather be in the USN for sure! :up:

[Keelbuster]

Kindof a cool question. Not sure, but - from the single-ping echo ranging link:

4. Keep your eyes on the revolving slit and listen intently for the echo. Disregard the rolling reverberations, and concentrate on catching the clear note of the returning echo from the target. At the instant it comes, note the reading on the scale. This is the range.

But this 'audible' ping is through a transducer - i.e. a hydrophone of some kind. So why do we hear it inside the sub? Well, I think long-range sonar pings are high amplitude. The hull probably acts as a kind of transducer (like a big drum) and you get some kind of sound from the transformed ping energy - even if it was originally a frequency that humans can't hear audibly, the hull may act as a low-pass filter/transducer that warps a high frequency ping into the audible range. Not sure - just a guess. I know that modern subs also use High-frequency sonar that doesn't travel a long distance and is not detectable except at close range. I feel like the ping-echo we hear has something to do with the amplitude of signal required to travel long distances. But I'm not sure. I don't even know how a hydrophone works.

Edit: Also - think of diffraction of light - when it passes from a good conductor to a poor conductor, it's frequency gets warped downward (i think). So the good sonar medium is water, carrying a high frequency signal, and the air inside the sub is a poor medium, resulting in the high frequency signal being warped into a lower frequency signal that happens to be in the audible range.



Kb

[Sailor Steve]

The most common description I've read of hearing the ping inside the boat is "it sounds like someone throwing gravel against the hull".

[Quagmire]

A logical enough explanation Keelbuster. However can any ex-navy guys give us any hard facts? Any ex-sonar operators with us?

Thanks!

[Vikinger]

Iam not an sub crew :) but there is difference between active and passive sonar.

Active sonar is much more lauder and use a frequency that human ear can detect.

It was surface weasels that used active sonar and today also used by helicopters.

No submarine is using active sonar coz of the risk of detection today.

Difference is also that active sonar works like a radar. It detect objects by bouncning sound. While passive sonar is more listen to the surrounding like propchafts, engines etc.

If u want to know about sonar u can check it out here:

http://en.wikipedia.org/wiki/Sonar

[Konnrade]

Iam not an sub crew :) but there is difference between active and passive sonar.

Active sonar is much more lauder and use a frequency that human ear can detect.

It was surface weasels that used active sonar and today also used by helicopters.

No submarine is using active sonar coz of the risk of detection today.

Difference is also that active sonar works like a radar. It detect objects by bouncning sound. While passive sonar is more listen to the surrounding like propchafts, engines etc.

If u want to know about sonar u can check it out here:

http://en.wikipedia.org/wiki/Sonar

Also used by helicopters? Do they drag a sonar probe through the water beneath them?

[Cerberus]

Iam not an sub crew :) but there is difference between active and passive sonar.

Active sonar is much more lauder and use a frequency that human ear can detect.

It was surface weasels that used active sonar and today also used by helicopters.

No submarine is using active sonar coz of the risk of detection today.

Difference is also that active sonar works like a radar. It detect objects by bouncning sound. While passive sonar is more listen to the surrounding like propchafts, engines etc.

If u want to know about sonar u can check it out here:

http://en.wikipedia.org/wiki/Sonar

Active sonar sends out a loud 'ping' which is like holding up a big sign saying 'I am Here!' - but does allow you to get (fairly) accurate range & bearing data on your target of interest.
Passive sonar produces no noise but doesn't give any range data & (sometimes) only approximate bearing data. You need to plot stuff over time to develop a picture of what it is, where it is & where it's going.

Subs all carry active sonar but never use it, except possibly in the last few seconds before firing on their target.

Surface ships are so noisy that subs already know where they are, & hence using active sonar is a practical measure.

The operating frequency of an active sonar is determined by it's purpose.
High frequencies don't propagate as well, so for long range detection, the optimum frequency is slap bang in the human audio range.
(The sound frequency that propagates best in water, is the frequency to which the human ear is most sensitive. The light wavelength that propagates best in water, is the wavelength that the human eye is most sensitive to - coincidence or evolution at work?)
For shorter range stuff (like an echo-sounder) higher frequencies are useful because shorter wavelengths allow you to 'see' finer detail and the transmit/receive transducers can be smaller.

[BigBadVuk]

Huh...First when i stumbled upon this topic i was confused but after few seconds i realised what are you trying to say and ask...Let me try to explain:
1st..There is no supersonic sound..lol..sound has variable speed of traveling wich depends on many factors, so i will stick to water as enviroment.In sea water sound speed depends on many factors like salinity,temperature,depth...etc..BUT sound can`t be supersonic supersonic is a word for something traveling FASTER than sound like jet fighter..You probably was talking about infrasound(below human capabilities of detect <60Hz) or ultrasound ( above human capabilities of hiring,greater than 19kHz)

Now,the greater the frequency of sound(pitch) the greater is definition of "image" u can get as echo becose u have lets say higher resolution of image.But there is a problem:Higher frequencies dont travel far enough to be useful in most cases.For ASDIC purporse u cant use infra sound becose u need high definition,to see where is the Uboat.So u will most probably use freq.around 7kHz or more..up to 15kHz and that is within the human hearing range.Infra sound u can detect on modern subs up to 20nm or even more but u cant hear them, u can only see them on sonar waterfall screen.
As for NAVY Helicopters ,yep ,they use dipping sonar,but u cant hear much if u drag that little thing becose of the nose of water run over hydrophones.That is why (in most cases) hello has to be stationary while dipping and pinging or just listening...

P.S. sory for bad english but my english start to sucks when technical things are about :damn:

[Vikinger]

Iam not an sub crew :) but there is difference between active and passive sonar.

Active sonar is much more lauder and use a frequency that human ear can detect.

It was surface weasels that used active sonar and today also used by helicopters.

No submarine is using active sonar coz of the risk of detection today.

Difference is also that active sonar works like a radar. It detect objects by bouncning sound. While passive sonar is more listen to the surrounding like propchafts, engines etc.

If u want to know about sonar u can check it out here:

http://en.wikipedia.org/wiki/Sonar

Also used by helicopters? Do they drag a sonar probe through the water beneath them?

Hehe No. its very common in most navy that they use helicopters for submarine hunt. Helicopters hover (or how it is spelled ) and drop the sonar probe into the water and then listen for sounds.
A typicaly picture how it can look like can u se here:

http://svt.se/content/1/c6/13/92/50/Ubaatsjakt.jpg

If they find something they can then drop either depth charges or torpedoes. ( If they have that kind of weapon fitted)
Or call in reinforcement.

[caspofungin]

british ww2 asdics used pings in the range 14-20Hz -- well w/in the hearing range of humans.

re constant pinging -- that's true, in ww2 escort vessels constantly had the asdic operating. unfortunately, that's not implemented in sh3 (although i seem to recall it in silent service 2).

[mheil]

I haven't totally read the link you post about supersonic, but my guess is that by supersonic is that the sound waves travel faster through the water than through the air and at a frequency that humans can't hear (dolpins, any one?). When these sound waves hit the poor doomed submarine hull, the hull then vibrates into sound waves that can be heard by the ear.
Great link to the manual. I'm ckjeckin' it out now.

[theluckyone17]

From "Iron Coffins" by Herbert A. Werner (p.293):
... However, the thunder of the barrage was not nearly as frightening as the noises that preceded and followed the attack. At first it sounded as if something like a chain or an iron net were being dragged along the hull; then came a wild clattering, as if a great load of pebbles were bing dumped upon the boat. These were brand new sounds to all of us - and a terrifying turous experience... But I concluded - correctly, as I later learned - that the British were using a new search device akin to the Asdic.
If I've got the dates right, that would've been March 19th, 1944. I imagine that at some point prior to that, the Allies started playing around with sound frequencies higher than previously used, causing the shift from the high pitched ping that could be heard earlier to that "load of pebbles" sound.

[Engel der Vernichtung]

http://www.l-3com.com/os/imgs/products/airborne/img_lrg_aqs18a.gif

Possibly better picture for dipping sonar.

Basically, to do this, the helo stops and hovers a few meters above the water, then lowers the sonar probe, and listens. If they hear something susupicious, then they go active, and try to immediately locate the sub. If they don't hear anything, they winch in the probe, fly over a few hundred meters, and try again (usually also being given steering commands by the ship they're operating from; the ship's sonar, being a lot bigger is also a lot more sensitive, and between the two they can pinpoint a sub pretty quickly). Usually helos in this mission are armed with 2 homing torps.

[Vikinger]

http://www.l-3com.com/os/imgs/products/airborne/img_lrg_aqs18a.gif

Possibly better picture for dipping sonar.

Basically, to do this, the helo stops and hovers a few meters above the water, then lowers the sonar probe, and listens. If they hear something susupicious, then they go active, and try to immediately locate the sub. If they don't hear anything, they winch in the probe, fly over a few hundred meters, and try again (usually also being given steering commands by the ship they're operating from; the ship's sonar, being a lot bigger is also a lot more sensitive, and between the two they can pinpoint a sub pretty quickly). Usually helos in this mission are armed with 2 homing torps.

Yeah its a better illustrating picture :).

A bit off topic but i remember when i was in the Swedish Army and the russian submarine went aground on an small island in a military secured area.

After that incident the Swedes saw submarine everywhere and hunted them like maniacs in the archipilago.

I was on watch duty on my regiment when we got a call and they sent our platoon in as reinforcment. Mainly to secure some bridges and roads along the coast.

I was placed on a small bridge whit some mates. We got sharp ammo and a few handgrenades. It was quite thrilling , specially in the night where both sound and movement can play trick on your mind.

We had order to use our weapon if we had to.

But to make a long story short. We never saw or heard any indication of hostile activity but some guys managed to kill a few ducks and swanes. They thought they saw some scubadivers in the water and throw a few handgrenade at them.

But it was a lot of talking about it after wards. Swedish army kill ducks whit handgrenades hehe.

But iam sure that thos guys that threw the grenades did it on purpose to , well, have some fun during the boring patrol. :)

And the picture i posted is one of thos moments i saw when swedish navy used hellicopters to search for sub activity. So its a real action picture. ( and to clarifie, i did not take the picture but it show how it looked like)

To bad i never saw any sinkbombs attack. They was to far out from where i was stationed. But they dropped quite few of thos barrels.

But it would be intressting to se sharp sinkbombs in action :)

[Seminole]

A bullet travels at supersonic speed and you won't hear one traveling until it smacks into the wall of your house and creates vibrations in the air that your ear can pickup on.

Same thing with a sonar pulse hitting the hull of a submarine.

[tycho102]

british ww2 asdics used pings in the range 14-20Hz -- well w/in the hearing range of humans.

re constant pinging -- that's true, in ww2 escort vessels constantly had the asdic operating. unfortunately, that's not implemented in sh3 (although i seem to recall it in silent service 2).

It's been my understanding that the lead escort would race forward and cut engines back, then zig-zag with active sonar while the rest of the convoy caught up. The side escorts were responsible for the quartering attacks, and would do ovals -- racing forward, then cutting their engines and circling until the convoy was abeam, then racing foward again.

I've also heard that some WW2 sonar was ultrasonic. Whether it was the Yanks, the Jerries, the Brits, or the Japs, I don't know. It may have been late 1940's sonar that went ultrasonic for awhile. You get better "resolution" with higher frequencies, but the power efficiency drops as with any transducer/speaker (basic induction).

[Sailor Steve]

A bullet travels at supersonic speed and you won't hear one traveling until it smacks into the wall of your house and creates vibrations in the air that your ear can pickup on.

Same thing with a sonar pulse hitting the hull of a submarine.
Actually you will hear a supersonic bullet go by even if it doesn't hit anything. I leaves a sonic boom behind just like a supersonic plane, but much quieter. It sounds sort of like a hand clap right near your ear. You can hear them as much as 5 feet away.

[Ula Jolly]

There are some misunderstandings here.
Basically, imagine a rod in space that is the length of one lightyear (ehrm, LONG). If you push in one end, will the other end move accordingly after one year, because it takes the light that much time to travel there? Not at all, it will move after time that is a product of the speed of sound in that material, which is much slower. When you push a rod, you push one atom, which hits the other atom, which hits the other atom, and so forth. This does not happen instantly, but with microscopical delays. THIS is speed of sound. In air, the speed of sound is rather slow (341 m/s I think) because there's a distance between the particles. In higher elevations the speed is slower, because the particles need to travel even MORE of a distance.

The speed of sound in water can be found (in feet/second at least) by use of
4388 + 11,25(temperature °F) + (0.0182 x depth + salinity (in parts-per-thousand, which I think is close to 35))


If I am not commmpletely off, that speed should be about 1500 m/s. I'm not doing the maths, though. :know: Basically, as with a RADAR, this also means that the TARGET hears the ping before anyone else. The time from the ping being sent out by the attacker, till it hits the target, is X. The time from the ping being sent out till it is heard by the attacker, is 2X, because the sound wave travels double the distance. These mechanics are not like those of a bullet in air.

Now, the pulses... are just pulses. The pushing of atoms, the frequency being how often the atoms are pushed in a second (translating to hertz).

Active sonar does not automatically give you a bearing of the contact unless you can distinguish his shape (a long boat's silhouette points in two directions, you figure out which he is facing by). A user of active sonar can not expect to make NO use of other sensors, unless the target is stationary. However, then he'd have to KNOW the target is stationary - only two or more pings may determine that. In a submarine, the user would definitely need use of hydrophones (passive sonar) and any other data he might be able to find.

Note that I do not claim to know the mechanics behind HEARING the ping. I, as someone posted before, expect that the hull of the submarine might act as a converter of sorts.

[MENTAT]

I cant get enough of the Fleet Type Submairne manual at this website: http://www.maritime.org/fleetsub/ I have read to the Sonar operators section now and the more I read the more I cannot wait for SHIV! Those uboots are in the stone age compared to the average USN fleet boat!

Anyway the manual describes echo ranging or "pinging" as supersonic meaning that the ping cannot be heard without receiving gear. So why do we hear it when we are crapping our pants in the control room?

Also the manual states that escort vessels ping constantly due to the noise they make at high speeds? This doesnt seem to happen in SHIII. They only seem to ping when they detect you.

Or am I missing something???

Here are the links that I am referring to:

Supersonic listening: http://www.maritime.org/fleetsub/sonar/chap5.htm#5A

Single Ping Echo Ranging: http://www.maritime.org/fleetsub/sonar/chap6.htm#6A

I think you are mistaken buddy, USN was worst in "underwater" warfare in WW2. being gato class submarine was the worst considered by many.

[Sailor Steve]

I think you are mistaken buddy, USN was worst in "underwater" warfare in WW2. being gato class submarine was the worst considered by many.
I've never heard of anyone who served on a Gato saying it was "the worst"; anyone who did not serve on one wouldn't know the difference. Please give references, preferably quotes.

[CCIP]

Also, how was USN "the worst", if it's the only sub fleet in WWII that fought and won a commerce war (give or take a number of other allied boats, of course)? They must've done something right, even if we all know that their fleet boats were not built for the role they ended up performing... :hmm:

[Subnuts]

I think you are mistaken buddy, USN was worst in "underwater" warfare in WW2. being gato class submarine was the worst considered by many.
Tell that to Japanese. :rotfl:

[Clint1]

Wow!

Usually the simulation fans are quite smart with basic physics, but this subject clearly was over someones head. First of all, the poster apparently did not mean supersonic, because the sound travels at a constant speed in a designated medium, in this case salinated water (pressure does affect the speed a little, but ALL SOUND travels at the SAME SPEED in SIMILAR CONDITIONS!) I think he ment ultrasonic (above our hearing treshold, 20 KHz) Someone was right to point out that the allied ASDIC during WWII was well within our hearing treshold. Somebody else totally missed the boat by "scientificly" bringing passive sonar (which does not emit any sound at all. Period) into this conversation.

To sum it up: it is realistic to hear the ASDIC in a WWII simulation, unless the sailor is middle aged, which would in average mean, that he could not hear the asdic anymore due to age related degradation of high frequency hearing.

Ilkka Pakkala M.D. PhD
Finnish Armed Forces
Active medical officer
(Navigation officer in naval reserves)

[Vikinger]

Also, how was USN "the worst", if it's the only sub fleet in WWII that fought and won a commerce war (give or take a number of other allied boats, of course)? They must've done something right, even if we all know that their fleet boats were not built for the role they ended up performing... :hmm:

Iam not criticise anyone but there was a huge difference between the uboat war in the pacific aka atlantic.

The japanese boats did nearly never go in convoys and most of the time whitout escorts. Also the japanse intelligence was easy for the US to crack and therfore they knew when boats sailed off. japanese refused to belive, during the entire war, that the US had cracked thier code so therefor they didnt change it.

Japanese had a different way to think and act. More or less they belived that the warships should stay togheter as a strong an powerfull fleet and didnt not commence any warship for commercial protection.
So i have to say that the subwar in the pacific was way much easier for the US Navy than it was for the germany Navy.

If same thing had happend in the Atlantic. No convoys, No escorts and when the sub crew knew when ships left port. The germany would won the atlantic war also.

But US Navy did a greate work in the pacific so i dont critcise what they achived. I just point out some major difference. :)

Vikinger.