why no rebound sound ?

[KriegsMarine]

hi, captians! I'm always confused when i play the Silent Hunter 3 and Silent Hunter 4, that is when you are at periscope depth, then an escort is pinging your sub,why you and your crew could not hear the ASDIC ping rebound sound when the escort found your sub. As far as i could remember, when i played the old Silent Hunter Commander's Edition, you really could hear a sonar rebound sound when the tin can caught you, which is a good warning of losing your stealth. So which situation indeed is historically accurate ?

[Sailor Steve]

If you had Asdic/Sonar it would echo the original signal. The soundman would hear it, and if he put it on the speakers the whole crew could hear it. If you had no Asdic or it was shut off you would not hear it as a signal, but the sound travelling through the water would make a noise inside the boat like "...pebbles bouncing off a roof" (I currently cannot find the source for that quote, so make of it what you will).

[U301]

I heard Asdic sounded like..."gravel on the hull",
"a hawser being dragged across the hull"
and "a hammer hitting the outside of the U-Boot!"

(Not all at once but depending on your depth and the water temperature!)



KUrtz

[Kpt. Lehmann]

It seems to me that only the sender of the pulse would hear it's return.


ie: ASW SONAR guy up top hits 'send sound pulse' and hears that ping.... if nothing is down there, he gets no return ping. He can then send more pings at will... ping... ping... ping.... (individual events.)



... now he sends a ping and hears the return/rebound ping... a double event if you will... ping-PING...



Now from the hunted submarine crew perspective, they only ever hear abient individual pings that may be distant, or perhaps individual louder pings with increasing rapidity as the sender fixes the target. The sub crew never hears a ping-PING because the rebound of the pulse happens the instant it strikes the hull...


... but in a quick moment, that rebound is heard by the sender as above.






If my post looks funny, it is because Major Wifey is pinging me now...

[d@rk51d3]

Originally Posted by U301

I heard Asdic sounded like..."gravel on the hull",
"a hawser being dragged across the hull"
and "a hammer hitting the outside of the U-Boot!"

(Not all at once but depending on your depth and the water temperature!)



KUrtz

Also heard it could sound like a chain being dragged over the hull.

[KriegsMarine]

thanx guys

and Kpt. Lehmann, the explanation is very impressive, salute !

so the situation in SHCE is not technically and historically accurate, it just

gives the game more fun.

[U301]

Originally Posted by Kpt. Lehmann

If my post looks funny, it is because Major Wifey is pinging me now...

Often thought by KUrtz under attack... "you ping away (babe)!"

[Pisces]

The only case the sub would hear a second (delayed) ping is through reflections on nearby objects. Like bottom bounce or bounce off a vertical shelf.

The suggestion that the sub notices the detection through double or modulated pings is a fake mechanism.

[Kpt. Lehmann]

Originally Posted by Pisces

The only case the sub would hear a second (delayed) ping is through reflections on nearby objects. Like bottom bounce or bounce off a vertical shelf.

The suggestion that the sub notices the detection through double or modulated pings is a fake mechanism.

I agree. I think we are saying the same thing. The ASW vessel hears the ping he sends, and that same ping rebounding from the submarine. The submarine crew would generally only hear one ping.

(Although the pings may come faster as the ASW vessel fixes onto the submarine before attacking it.)

[Pisces]

Well, not quite. You can hear a difference in the sound around you when you are standing next to a large flat building. Those secondary paths of the sound come in delayed from the direct path, but weaker. This could also happen underwater I think. But I am no sonar technician.

[Kpt. Lehmann]

Originally Posted by Pisces

Well, not quite. You can hear a difference in the sound around you when you are standing next to a large flat building. Those secondary paths of the sound come in delayed from the direct path, but weaker. This could also happen underwater I think. But I am no sonar technician.

The situation I refer to is the most common scenario in the open ocean where it is deep and where there is pretty much nothing else to reflect the pulse. I realize that there are a few exceptions, but they are not generally common.

Hearing a double ping from within the sub.... that's mostly Hollywood.

[Pisces]

I never said it was common. But I agree with that certainly.

[Kpt. Lehmann]

Originally Posted by Pisces

I never said it was common. But I agree with that certainly.

I was just trying to keep it simple for ping's sake.

Fine. I'll see your ping, and raise you five pongs AND a boing.... for ALL the ping-pings.

< sigh >

[KriegsMarine]

thanx again, you two remarkable skippers.

We've learned a lot from your great explanations regarding the rebounding pulse.
So now the situation is never clearer, we could conclude that the SHCE Ping-Pong simulation and some Hollywood submarine films are both fake and inaccurate.

So keep fighting in the great SH3 and SH4 simulations which give us great immersion and technical accuracy.