Interesting, indeed! It is certainly different from present-day doctrine, which is to first make contact using passive sensors. From accounts I have read, it is also somewhat different from WW2 IJN tactics. IJN did sometimes use active sonar for search, but more often would search initially with passive. Continuous pinging was not unheard of, but was unusual enough to cause comment. US submariners regarded it as a mark of an inexperienced ASW team. As Stiebler said, it was considered a "scarecrow" (good word!) tactic. The purpose was not so much to engage the enemy as to warn him off.

Sonar
 

It appears we have two different questions at play here. I have no problem when an active sonar ping picks my sub up. I can always hear it at greater range than the destroyers can hear the reflection, and therefore take whatever action needed to either attack or evade. The original question was the ability of the destroyers to always find you with passive sonar no matter how silent your sub is or how deep it is. Did this really happen? And what, if any, did thermal layers have on this effect (in game, via SH3CMDR)?

hello Irish,

i guess that with ''passive sonar'' you mean the hydrophones ,right?
this is good question that must be checked.

i don't believe that this is what happening in game. my suspicion is that it is the sonar (by sonar i mean the active device) which is detecting you and not the hydrophones.

it is easy to create a mini single mission and test your thought. we will put in this mission a destroyer which will be equiped only with a strong hydrophone and not an active sonar device at all.the destroyer will be setted to pass in front of us at about 300-400m and see what will happen.

i will make the test and let you know

Yes, hydrophones only.
Thank you for your quick reply.

Good idea, Makman. May I suggest an additional test? Program the escort to pass parallel to the sub on opposite course at the same range. If the sensor is modeled properly, there should be a large difference in detection probability between head-on and broadside-on. What do you think?

hello BigWalleye,
i did ,also, a mission as you suggested :up:

Irish, you were right but you were ,also, wrong too ! i will explain

get this mission:
http://speedy.sh/mMadn/TEST-SENSORS-...YDROPHONES.rar

drop it in your MODS folder and enable.
you will see two new single missions called as ''Fletcher - 400'' and ''Fletcher - 400 - 2''
at ''Fletcher - 400'' the Fletcher will pass at 400m in front of you and
at ''Fletcher - 400 - 2'' the Fletcher will pass at 400m on the starboard side. (as BigWallEye suggested)

at both missions the Fletcher is equiped ONLY with hydrophones ( specifically, with a type QClP ). don't raise your periscope as it will be spotted (Fletcher is allready too close and it is impossible ,through cfgs, to discard the ai-visuals). don't do anything, just wait for Fletcher to pass by.

now, why i said that you are right and wrong at the same time?

if you run the missions on STOCK sh3 everything works perfect on hydrophones and ,as long as you are silent , the Fletcher is not detecting you.
if you run the missions on gwx or nygm or wac (lsh3 is ok) ,the Fletcher is always detecting you ,through its hydrophones, although you are absolutely silent. so , i am guessing that you are a user of gwx or nygm or wac.

after a little search,i found that the cause of these anomalies at hydrophones are the settings of hydrophones at sim.cfg file. by setting to sim.cfg the STOCK hydrophone settings everything worked like a charm to all supermods (gwx,nygm and wac. LSH3,as i said, has not this problem).

the stock values that work ok are:
[Hydrophone]
Detection time=1 ;[s]
Sensitivity=0.03 ;(0..1)
Height factor=0 ;[m]
Waves factor=0.5 ;[>=0]
Speed factor=15 ;[kt]
Noise factor=1.0 ;[>=0]

once you use the above settings:
at some of your tests , challenge with the Fletcher by starting your engines.when you are detected ,play with the throttle and you will see that Fletcher immediately is loosing you ,especially when you stop the engines.(remember ,this Fletcher is equiped only with hydrophones).


edit:
i forgot something very critical and this is the ''Rig for silent running'' order.
with this order enabled , your boat is not detected by Fletcher's hydrophones ,as long as you keep silent, at all supermods too. so, maybe, the modders of supermods's sensors have that in mind when they were adjusting their hydrophone settings.
the boat ,even with stopped engines is a little noisy (repair works-torpedo loadings..etc) and this is what is detecting Fletcher's hydrophones.
at the above missions ,if you enable the ''Rig for silent running'' order, you will see that Fletcher's hydrophones are not detecting you, so my final conclusion is that supermods wanted it to be that way

Well-executed and useful piece of research, Makman. Answers a great many questions. Demonstrated the value of silent running at low engine speed. I was surprised, though, that there was no noticeable difference between bow-on and broadside aspects. That's useful information, also.

Thank you both for your work and information. I run GWX and NYGM only.
I will download the missions and play around with them when I have time, but this info explains a lot.
I should have done the work myself. I am really not lazy, but have been preoccupied with RL stuff.
What a great forum with polite, intelligent and congenial members. Thanks Neal.

I hate when RL intrudes on my gaming time!:D

hello BigWallEye,
i am glad that you found the post usefull :yep:
about your thought: i am not surprised as i see no factor for 'aspect' ratio or 'Enemy surface' at hydrophone settings. i don't think that devs have modeled this parameter for hydrophone.
on the other hand,there is the parameter ''MinSurface'' in the hydrophone sensor data (in AISensor.dat) but this is ''0'' for all types of hydrophones so it has no effect. maybe , there is the possibility ,by changing this value there, to get the desire result but not everything we see in s3d works in game. only tests will show you if this value is 'active' or not.

it was a good question Irish :up:

and , as there was a way to be checked , why not ?

Hi you all,

really interesting discussion! From uncountable tests with the sensors, I may tell about my experience how the sensors work in SH3.

makman

Correct, but further, the AI sonar is effected by your aspect ("bow on" or "bow off"). "Bow on" means according to NYGM 30° to each side of the bow.

Really well self explaining graphic, btw.

Hitman

Both acoustic sensors work for their own AND both sound sensors can be seperately used by the exe as trigger for attacking action. Both sensors are to be used as complete attack control sensor (in contrast to radar, btw. but that´s another thing).

In fact, the hydrophone always has the bigger range, so without counter measures, the fist contact is normally made by this passiv sensor. It doesn´t matter, if the active sensor could trigger any action too, if the contact was already made by the passive means.
Hearing the pinging is only a sound function and doesn´t mean that contact is kept by the active sonar. It´s just an acoustic effect if you are within the active sonar´s detection range.

Fahnenbohm

You´d rather not mix values from sensors.cfg and from sim.cfg. The first both belong to the simulation of your own hydrophone operator´s simulation (sensors.cfg), whereas the latter belong to the enemy AI (sim.cfg). In your describend situation, your own hydrophone doesn´t play any part for the enemy´s detection.

Irish1958

In theory and in real life yes, but not in the game. As already mentioned, the pinging sound can only be heard ingame, when you´re within the sonar range.

The original - real life - counter measure was: Silent running, deep diving, narrow aspect. These counter measures work perfectly ingame!

Only one thing has to be changed possibly: If you order rig for silent running, the speed will be reduced to "Ahead slow". This means in the stock configuration around 3 knots and around 150 revolutions (submerged). You may reduce the "Ahead slow" value in your NSS_Uboatxx.cfg to 0.25 from 0.40. With this, your boat will only run with about 90 revolves at 1.5 to 2 knots (like in real life) and you won´t be heard by the passive sonar. I use this value for years and if I keep also the bow to the sound source, I´m able to evade from a single enemy warship.

The reduction of the "Ahead slow" value from 0.40 to 0.25 is already included in GWX.


Big walley

The aspect doesn´t matter if there´s only a hydrophone mounted. Neither in real life nor in game. To be proofed by makman´s testing configuration.

makman

That´s it. One small annotation: If you order "rig for silent running" the boat´s speed will be reduced to "ahead slow" from all other speeds - besides if you are already stopped. Then you will stay stopped. If you compare the behaviour in different installations, you may keep that in mind.

Once more: Agreement! This is also my testing experience. Furthermore, I can confirm your test results with the Fletcher. Be it GWX or my own optimised sensors, you could only hide if you order "rig for silent running". Different in Stock: Here, the destroyer couldn´t here me even without silent running.

In my understanding, the "sensor data" functionality always contains the same bunch of values because they are needed to feed the exe, be they necessary or not.

Last annotation: The QClP sensor wasn´t touched in GWX. Thus the different results to the stock behaviour should be based on the sim.cfg settings. In NYGM, QClP has a strongly reduced range - so with this sensor you pobably won´t receive results that are comparable to other installations.

Happy testing :-)

Very nice test makman94, and very nice stuff of information posted by other memebers as well.
I'm a noob here, and not a modder so I really do not know a thing about SH3 internal workings even if I always read all the info I can get about the mods I use with GWX because I like to know what I am using and how thing works and because I'm just plain curious :D

Hoping to post some useful information I include the following links:

http://www.subsim.com/radioroom/images/icons/icon1.gif GWX's "uber" AI demystified
http://www.subsim.com/radioroom/images/icons/icon1.gif [TEC] Adjusting the AI - cliff notes version
http://www.subsim.com/radioroom/images/icons/icon1.gif Help me making GWX a bit easier....(AI sensors)

These threads helped me a lot in understanding how the sensors work in the game world.
The first one is especially useful to every user of GWX :)

Always the old good technique is the best. Goes ahead at silent 1- 2 kt speed when destroyer searching and is near from You. And You should turn left or right at ahed flank speed, when depth charges are in the water directly above on Your boat. Then again, is most safe to go back to 1 - 2 kt speed, and goes as deep as possible. When more than one escort hunting you, you should be more smart with your left or right turns strategy. Thats all.:ping:

EDIT. Each escort in SH3, has limited number of depth charges.

Could you please provide a source for that statement? Thank you.

yes ,you are right (as always ! :up:) and ,by looking now at sonar's settings ,i see that it is also effected by waves and uboat's speed too. pretty interesting modeled sensor,can we say that it is almost fully modeled ?


without having any idea at all, how the hydrophones worked back then , i am thinking , basis of common sense, that the sound a ship creates should be more easily heard if we are behind the propellers. i have the sense that if we are in front of ship ,the sound may should be reduced by the hull...or no?
yes, i know that in game has no difference but what about reality ?

didn't know that ! and this is explaining why some parameters i saw here and there in s3d are not 'active' ! thank you Leitender :up:


yes , i had checked that but then i saw that NYGM's QClP was at 4100 (? instead of 7500m on others, if i remember correct) and i said ok ,as it will pass from 400m away it will do its job so let it be.

ps: i really wish one day for Leitender to decide to share his work on sensors ! this guy has made ,allready, an enormous work on sensors but i know that he has still a long trip to ...completion:up: