HF Sonar on subs

[HydroShok]

What does the HF sonar from a sub sound like to other subs?
What frequency does it use, and how far away can it be heard?

I'm guessing its between sonobuoy and torpedo frequency, and can be heard as far away as a torp can be heard. Anybody know the numbers?

[BigBadVuk]

HF uses so high frequency (20Khz+)that if u can hear that u r dead...Seriously sound of HF disipate after 2-3km(up to 1.5nm) and there is no way u can get so close to sub undetected..
Generaly the higher the frequency the shorter the range... :sunny:

[Sonoboy]

From my observations, you can't hear HFAS in DW.

[HydroShok]

HF uses so high frequency (20Khz+)that if u can hear that u r dead...Seriously sound of HF disipate after 2-3km(up to 1.5nm) and there is no way u can get so close to sub undetected..
Generaly the higher the frequency the shorter the range... :sunny:

AFAIK, a torp can be heard 5 miles away in the game. Of course, it doesn't lock on at that range. Maybe even ten miles away, you can hear it pinging.

The hf sonar in game....doesn't mark contacts unless its close, but you can clearly see much further away.

[Driftwood]

I believe (not certain) that HF range max is 5Kyds. And yes, in DW it can not be heard by other subs/ships.

[HydroShok]

I believe (not certain) that HF range max is 5Kyds. And yes, in DW it can not be heard by other subs/ships.

Thanks for the info. I know that the HF can see sonobuoys in some cases so I might use it more often now. Especially Bottom limited and sand bottom it comes in handy.

I'm curious to know if maybe its on a really high frequency in RL, past the range that the active intercept can receive, or if it was not really "working" in the game. IOW, is it unrealistic the way it is now in game? I figure the real life bubbleheads might know.


In the game, it shows so much detail, it looks like a side scan sonar that people use to find shipwrecks, etc. They seem to be like 100-600khz

[BigBadVuk]

AFAIK, a torp can be heard 5 miles away in the game. Of course, it doesn't lock on at that range. Maybe even ten miles away, you can hear it pinging.

The hf sonar in game....doesn't mark contacts unless its close, but you can clearly see much further away.

YEs but HF on subs has greater accuracy and frewuency than torpedo homing sonar...so it has shorter range becose the higher the f the shorter the range and u have higher definition of object that u r "looking" at...
If u r torpedo u only need to know where is the bigest return and u need to steer in that direction and u also need fair range to detect that object
In submarine u dont neet to see that far but u need to see with more details so u can recognise what is in front of u: mine,iceberg,wreck...

and yes u cant hear HF in DW! :rotfl:

[Kapitan]

22,000 herts for the MK48 ADCAP torpedo its cone has a range of what 2,500 yards so its not that far, id agree that higher the frequency less the range.

[Dr.Sid]

Anyway HW sould be detectable by active sonar threat detector (how the hell is it named ? One play the game ALL the time and can't remember). Since it can detect torpedoes pinging at 22khz, it should detect HF sonar too. Also, if torpedo pings on 22khz, does it mean that the pings you hear are generated by the threat detector ?
And once more please .. should not be pings and ping returns visible on broadband waterfall ?
I could understand that active sonar screen uses narrow frequency filtering so you can see only return from your own ping there. But on BB there should be NO filtering.

[BigBadVuk]

Human ear cant hear anything above 16-18Khz...so yes i guess u need some kind of "translation" from higher frequencies to more audible one!(oh my english suxx when it comes to detailed technical talks),But i dunno about broad-band..Hmm..well if any sensor can pick that it can be only spherical array becose he can pick high f but im not shure how much high?!?
In any case it is next to impossible to test that...Becose u will get fish on your bearing as soon as they find u..And TA is the best way to ght fix on sub becose lower frequencies can be picked up tens of miles away...So why then to waiste time and encode something in the game engine that noone will use ever!


BTW...now there is something on my mind...Maybe it is off topic but if u want i will post it in other thread...During cold war we all know that there wa a LOT of dangerous situation where subs almoust colied.....HOW??? i mean if they can detect other sub at least 2-3 nm away...how can u colide with her?!?! :damn:

[Dr.Sid]

Not all pings ar HF .. long range pings must to be in audible range, well in frequency range of the sphere sensor (and even the other sensors). In some Clancy book I remember raeding about 'chain of blips' on waterfall representing pinging active sonobuoys.

Check the pictures here (near the bottom of the page):
http://www.subguru.com/multimedia.htm

You either want to get close to get some info or you are just playing brave american soldier. Then you realize that the russian guy can play brave too.
I guess IRL really at least one of the subs, but most probably both knows the other sub is so close.

In DW I almost crashed once into Kilo .. it was at 0kts and gave exactly NONE sound. I had aged track and I just could not believe it is gone. I was snaking with HF sonar and when I saw it I had just time enough to avoid it.

[HydroShok]

Human ear cant hear anything above 16-18Khz...

You're right. Most people can't hear above 15Khz, some people can hear up to 20Khz. As you get older you lose the ability to hear higher frequencies.

I could've sworn back in sub command that the helo dipping sonar sounded higher pitched than the torpedo ping. Even though the frequencies don't reflect that. The helo would hover and ping at 15khz IIRC (not sure what sensor/s it was actually using, talking about AI helo) What came from the helo was so high pitched I had a hard time hearing it in game. But obviously the torp ping is very easy to hear. I'm almost willing to bet money, what came through the speakers was "backwards" in game.

I'm pretty sure in game, the sound file they use for a torp ping, is actually much lower than 20,000-22,000. Otherwise I'd never be able to hear it and most other ppl wouldn't either.

Make me wonder if its even realistic to hear a torp pinging in RL with the human ear? Or is it something about going through water that changes the pitch? Or perhaps a torp emits sounds at all sorts of frequencies, more than just 20Khz?

I found a link to a free tone generator. I can't hear anything when its playing a tone over 17,000 hz. Absolutely nothing. Could be my cheap speakers though. Funny though, I can barely hear a 10hz bassy sounding note. I'm not sure how accurate this thing is. But check it out. I betcha most ppl can't even here 20,000 hz come through their speakers.

http://www.nch.com.au/action/tnsetup.exe

[Zerogreat]

I dont think you do actually hear the torpedo's ping itself. Because on OHP, which has no active intercept you cannot hear torpedos pinging, so i assume that the active intercept makes the pings you hear in sub (and it makes them so people can hear them...it would be dumb if it made sounds no one can hear :) )

[Bort]

The HF sonar can be very useful in close quarters when you need a quick target ID, I've used it a few times to ID surface ships but never subs. Probably not too realistic...

[Sonoboy]

That tonal generator that HydroShok posted is not an accurate way of determining what frequency you can hear at.

Unless I really can hear a sound at 181,019.34 Hz...

[Zerogreat]

It depends on speakers, some behave strangely when they have to play sounds that are off their limits

[Wim Libaers]

That tonal generator that HydroShok posted is not an accurate way of determining what frequency you can hear at.

Unless I really can hear a sound at 181,019.34 Hz...

That is a frequency well above the limits of most soundcards, and sound drivers. What happens is that the program will sample a sine function of that frequency at intervals that are longer than a period of the function, causing aliasing and a signal that appears to have a much lower frequency.

Try this applet:
http://www.dsptutor.freeuk.com/aliasing/AD102.html
It is set to 8000Hz sampling frequency. Put checkmarks on "Input signal" and on "Sample points" or on "Alias frequency". Put in a value below 4000 Hz and click plot. They will be the same. Then try higher values. You'll notice differences. The rules can be found here:
http://www.dsptutor.freeuk.com/aliasing/AliasFrq.htm
If you know the sampling rate the tone generator uses, you can calculate which frequency really came out of the speakers.

[HydroShok]

That tonal generator that HydroShok posted is not an accurate way of determining what frequency you can hear at.

Unless I really can hear a sound at 181,019.34 Hz...


yeh, i just noticed that too. its a bug or something. Thats way overkill for a frequency anyways, i doubt it was designed for it. That, and if a soundcard could put out 181khz A/C to an antenna, you'd have a radio transmitter. The FCC is pretty nazi about that type of stuff. Once it gets above 30k, my speakers make wierd noises up and down in pitch. But its cutoff range is supposed to be 20k anyways

put it 10,000hz play the tone, then press increase button, it should fade out big time near 20khz, and then it returns at 30k but thats cuz the aliasing mentioned above i guess.

[LuftWolf]

* Bort]The HF sonar can be very useful in close quarters when you need a quick target ID, I've used it a few times to ID surface ships but never subs. Probably not too realistic...

Perhaps it is realistic... some civilian and commerical HF sonars give almost a photograph of things like underwater wrecks and topography. :know: :)

[MaHuJa]

In the game, I believe the sphere sonars can hear frequencies up to 2kHz. Most pings are above that.

Torpedo ping frequencies should be changed by the doppler effect - I don't think they really do that in DW. Though I haven't paid too much attention to the frequency readout in active intercept.


As for the shipmounted HFAS, I remember speculation that they may be operating up in the 75kHz area or something - though that's pure speculation, and it might even be possible to prove it wrong.
If you can identify ships by it, either you're really good at recognizing their undersides, they're sunk, or there's a bug. You should never be able to see anything above the water.

I believe that the current sonar engine, with its passive/active intercept split, would be detecting HFAS at the full ~20nm(?) it detects all other active sonar at.


On the matter of what your computers can output, the two sample rates commonly in use are 44100 and 48000. The highest frequency it can output cleanly is half of whichever is active.

Also, while most speakers claim a 20-20000 frequency range, none of them (that I've seen) document the signal loss at the extreme frequencies.


(Oh, and, I don't think the FCC controls a 140khz signal if it is of an acoustic nature... Only the EM, which most speakers, made as they are, would radiate while at it. I don't expect air to carry such an acoustic signal for a whole 1mm, however.)