Sound contacts on the surface?

[Rockin Robbins]

I am official director of misinformation for the RFB conspiracy, ensuring that those who make people mad and those who take the heat are different people and switch places occasionally. This week's official roster:

swdw: dictatorial genius and evil plotter of various bloody and painful ways to kill you while you are playing with your submarine. Leave him alone. He's working.

LukeFF: direct all your anger here. Nasty notes about features or omissions you hate need to be sent to Luke. It's HIS MOD so swdw can get some work done

Everybody, me included, clear about this? We'll be reviewing next week for possible changes.

[AVGWarhawk]

What a minute.........I'm reading this as the peoples mod! Volksmod if you would.

At any rate, I'm glad someone picked up were Beery left off! A few good individuals playing with the files and who knows what this could grow into

[Ducimus]

So then is it possible to adjust this geometric search area when the sub is surfaced? If so, make it a smaller area thus clipping the sonar into a tighter circle of detection area?

Shame im at work, or id make with my MS paint skills again. Trying to think of a metaphore here.....

Pretend your washing dish's for a moment (cause the wifes too lazy, or whatever), you have a plate or some other round object in the water, and little bits and pieces of food float on the surface, and underneath in the water itself.

The plate is submerged, do these floaty bits get on the plate?
No.

While the plate is totally submerged do the bits in the water get on the plate?
Yup.


If you lift the plate, closer to the surface so its just incontact with the surface of the water, do the floaty bits get on the plate then?
Yup.

Are the submerged bits still getting on the plate?
Yup.


You could use a smaller in diameter plate, and hence have less surface area for bits to come in contact with, but the action of getting surfaced bits or not, still depends on raising the plate, and the plate is smaller both submerged and surfaced.

If that makes any sense.

[Ducimus]

Damn that was one sucky metaphore.

[Rockin Robbins]

Originally Posted by Ducimus

Damn that was one sucky metaphore.

But very entertaining!

[Ducimus]

Well i was desperate, and lacking on creativity.

Or maybe i was too creative. :hmm:

[LukeFF]

...I upped the Hydrophone Speed Factor settting all the way to 1, and even at flank speed on the surface I could pick up contacts without any issues. So, I did some more research on the matter, and here's what I've found. First, here are some excerpts from Naval Sonar, NAVPERS 10884, 1953:

JP Sonar (the hydrophone head mounted on the bridge, later replaced during the war by JT):

The original J-series listening equipment was designed for use on submarines. Most modern listening equipment, such as the JP and JT, is designed for patrol craft, picket boats, and submarines. The JP-series listening equipment is now in use on submarines as a unit of the JT equipment.

The JP is a sonic equipment-that is, it receives audible sounds, amplifies them, and applies them to either headphones, loudspeakers, or a tuning-eye indicator. Because the line hydrophone used with the JP is moderately directional, bearings on the sound sources can be made by use of the tuning-eye indicator. The JP equipment was designed for small surface craft. The JP-1, JP-2, and JP-3 are used on submarines.

Models JP-1, JP-2, and JP-3 equipments are used on submerged submarines to obtain bearings on other vessels by directional detection of underwater

WCA Sonar (the balls mounted on the keel):

When the sonar range to the target is desired, the echo-ranging transducer is trained to the target bearing and a single short ping is emitted. The echo-ranging equipment on a submarine is used most often for navigation and only as required for target ranging.

During World War II, combination sonar equipments that provided ranging, listening, and sounding were installed on submarines. The model WCA is such a combination sonar equipment.

As shown in figure 14-2, the WCA-2 consists of three systems. One system, the QC-JK, uses the combination sound head for echo ranging and listening. The QC magnetostriction element is used for echo ranging. The JK crystal hydrophone, which is more sensitive than the QC magnetostriction transducer, is used for listening only. The QC and JK units cannot be used simultaneously.

And from the earlier 1945 manual:

The WCA system of sonar gear is used for supersonic listening, and also for echo-ranging and depth-sounding. It consists of three main divisions: QB, JK/QC, and NM.

Sonic listening was covered in the same book and was directly linked to the use of JP Sonar.

That would pretty much solve the issue, right? Well, not quite. From the same manual:

(From the section on "Sound in Water"):

Propellors generate a wide band of sonic and supersonic frequencies. Consequently, they can be detected with either type of gear.

And, again from the section on supersonic listening:

Contact !

Maybe your whole watch will be spent in just routine searching. But at any moment you may pick up enemy propellers.

So, with all that said, how do we make picking up surfaced sonar contacts realistic without making radar and the watch crew irrelevant? What would really help out is if we could find out what the maximum range was of both the WCA and JP sonar gear. I have found nothing on the web that says what the performance of this gear was. So again, if you have spec sheets on WCA on JP sonar, please let me know or post the data here for all of us to see. It would really help in getting a handle on this matter. So far I can only find referencs to kilocycles, which may or may not be of use.

[Rockin Robbins]

Originally Posted by LukeFF

...I upped the Hydrophone Speed Factor settting all the way to 1, and even at flank speed on the surface I could pick up contacts without any issues. So, I did some more research on the matter, and here's what I've found. First, here are some excerpts from Naval Sonar, NAVPERS 10884, 1953:

JP Sonar (the hydrophone head mounted on the bridge, later replaced during the war by JT):

WCA Sonar (the balls mounted on the keel):

And from the earlier 1945 manual:

Sonic listening was covered in the same book and was directly linked to the use of JP Sonar.

That would pretty much solve the issue, right? Well, not quite. From the same manual:

(From the section on "Sound in Water"):

And, again from the section on supersonic listening:

So, with all that said, how do we make picking up surfaced sonar contacts realistic without making radar and the watch crew irrelevant? What would really help out is if we could find out what the maximum range was of both the WCA and JP sonar gear. I have found nothing on the web that says what the performance of this gear was. So again, if you have spec sheets on WCA on JP sonar, please let me know or post the data here for all of us to see. It would really help in getting a handle on this matter. So far I can only find referencs to kilocycles, which may or may not be of use.

Pretty much a repeat and confirmation of the manual we've already looked at. Sounds like one is most likely the source for the other!:p I still think the contact logs are going to be our only source of answers, if they contain enough data. Tater has all that stuff but hasn't been watching these threads, apparently. The answers will come.

Another emerging (from your exerpt above and my personal knowledge) factor is quite interesting and I haven't thought about it before this. The higher the frequency, the more directional the sound appears. It can be localized with considerably more accuracy than a lower frequency sound.

Familiar example: If the sound is low enough to come out of a subwoofer, when all impression of direction vanishes. It doesn't matter where you put the subwoofer. It matters completely where you put your surround speakers.

Notice above it mentions that the JP/JT sound apparatus is "moderately directional." The QB and QC/JK would be much more precisely directional.

Another factor, which can be illustrated with familiar radio signals. Low frequency sounds, while non-directional carry much further and penetrate more barriers than high frequency sounds. Your AM radio at lower frequency, bounces off the ionosphere and refracts readily around obstacles to give much wider coverage than higher frequency FM signals, which pass right through the ionosphere and reflect off every possible barrier. A GPS satellite signal is so high frequency that the signals will not even pass through the roof of your house. The tradeoff is that the high frequency is part and parcel of its accuracy.

We would expect the same thing with the different sonar signals. JP would be mildly and not so precisely directional. If you really wanted to get a precise bearing it would be from the JB or JC operator. That is, if the higher frequency sound wasn't interfered with. With the sub below the thermal layer, high frequency could be totally gone. But low frequency sounds would penetrate much better, giving much less precise but usable location data. Wouldn't it be great to have a simulation that properly rendered all these nuances?

[-Pv-]

Range is something which can't be locked down to a single number. Because of the complex properties of sound transmission through water involving layers created by several means: Temperature, salinity, contamination, density pressure, and transmission frequency (sounds can be wide-band with some of the sound traveling a few feet and other parts of the same transmission traveling for miles) distances are highly variable from a few feet to many miles. Layers can propogate at various speeds. Some sound can arrive by direct line-of sight while others can be reflected once or many times. You guys are never going to have perfectly historical reproduction.

You also need to realize you can lose sound contact as much from diving (in the real world) as you can from surfacing so I say take what you can get.

Keep in mind the game was created to provide a certain amount of minimum activity so players will actually have something to do once in a while.
-Pv-

[Reno]

While we're on the subject of hydrophones, I don't think the T-shaped JP hydrophone topside is supposed to be rotating when the boat's surfaced. That was turned manually when submerged, and according to Claude Conner (Nothing Friendly in the Vicinity) it was quite a workout. Of interest in the sonar operator's manual is the JP shut down procedure...

Securing JP gear
As soon as your submarine surfaces, secure the JP gear,
1. Turn the power switch off.
2.Train the hydrophone to 090 degrees if it is installed on the port side, or to 270 degrees if it is on the starboard side. 3. Hang up the headphones carefully. They are a special kind that cannot be replaced while you are on patrol. Other headphones do not work as well on JP gear.