I don't understand the sensors
 

Hello,

I'm trying to understand how the AI sensors work.

For example, for the ASDIC, I've set the max range to 2700 meters, and an elite destroyer detects me only at 500 meters, why? :doh: :06:

Here the files (there is even a mission to make tests): https://www.mediafire.com/file/ew8fa...nsors.zip/file

Man it was Asdic wasnt Sonar that the reason Because asdic was effective from close range than long range For long range was Passive Sonar but it effective if the ship was not in fast speed because it could be make the Sonar man Cant hears Because of engine + Propeller Noise :haha:

ASDIC = Sonar

Well i have the Book That Asdic More Like Active Sonar For close Range And For far Rang Was Passive Sonar Because it will not use Ping Sound but If Active sonar[Asdic] Has ping sound wich mean it work with close Range and passive sonar will deactive if Sonar active was Activated

Yes, there is a confusion nowadays. But in WW2, SONAR was the American name for the device called ASDIC by the British.

http://jproc.ca/sari/asd_gen.html

"Passive sonar" as you call it was called hydrophone only (IMHO).

Yes ASDIC and Sonar are the same thing.

Regarding your original question: I've worked on the sonar systems quite a nit and currently use an active mod like yours that extends range to 2500 meters (which is pretty historical). The problem you are facing is that AI escorts won't use active sonar until they know a U-Boat is in the area--usually due to a ship being hit by torpedos or a visual/radar contact. That means they rely on passive detection prior to one of those events and that seriously limits their effectiveness as long as you do a silent approach.

Sonar ranges are decreased by several factors--weather, contact aspect and--especially--crew quality. As far as I can determine, the only crews that enjoy full sensor ranges (of any kind) are elites. The other classes seem to drop down the scale by a factor of 20% per quality level. So if you're up against a novice crew, you should not be in any danger at all. Elites also have a disturbing trend in their accuracy and will drop dc's on target all the time (as ir should be IMO). They also know your depth which really wasn'r possible until the introduction of Type 147 (Sword) sonar which, while short ranged, could be aimed like a searchlight. They could point it down as they passed over a submarine and obtain its depth. That wasn't introduced until mid 1943.

The best I've been able to do to get a more challenging contest is exactly what you have done by extending the range. And it does keep me a bit more challenged)

Cheers!

@Grumpy Pete: Thank you for this answer.

At the beginning of the mission, I sail full speed to make noise and give my position. Then, the destroyer starts moving towards me, and I dive to 50 meters, then I go silent. My noise indicator is now green. It goes red when the elite destroyer is about only 500 meters and starts to ping me... That's very different than 2700 meters as I've specified in the Library file...

And I've set the Waves factor to 0 for the sonar to avoid to add other modifiers (for now).

Yes, I've come to the exact same conclusions some time ago.

The passive sonar sensors (range/sensitivity/etc) are not impacted by the settings used for active sonar. Passive settings are a whole different kettle of fish that are a serious pain to tweak. I actually think they are OK. It seems like everything I've done to "improve" them only messes them up for the worse. They're also much more painful to test.

I also tried to figure out how to get escorts to use active before a submarine contact but couldn't figure out a way to do it. That's probably for the best because it might result in them Never turning off active. That much pinging would likely break game immersion even more than the lack of active we have now (imo).

Unfortunately, the escort AI in SH3--while artificial--is far from intelligent.

:03:

Hi Grumpy;
Via a quick look at your file, it appears you changed the hydrophone ranges vs. the sonar ranges, though sonar changes are mentioned in this thread?
Those are the only things I noticed changed to 2500m anyway.

How can something so wrong be so right?
 

There;s an old RN training film on ASDIC here. It's not very exciting but shows how it was used (in 1943).
https://www.dailymotion.com/video/x7qjuo7

I've found a good overview of escort tactics here:
https://kclpure.kcl.ac.uk/portal/fil...317/408475.pdf


The passive side of the ASDIC system was sometimes used to detect submarines, but the performance seems to have been poor compared to the Uboat equipment. The allies never achieved an instant "detect+direction find" system like they did with their HF radio detectors and I think you would need a continuously noisy uboat and a slow moving escort for it to work. I'd be interested in more information on this.

The escort positions around the convoy were designed based on the capabilities of ASDIC in its active mode, and I think most convoy escorts pinged more or less continually. The operator would need to sweep manually when searching, so a uboat would only hear a couple of pings every minute or so as the operator swept the system past the uboat's direction. Once a target was detected the operator would "lock on" and the pings would be continuous. Some US systems were ultrasonic and were perceived as a rattle noise rather than a ping.
So does SH3 model this correctly? I don't think so. However the perception from the uboat is probably not so bad - you only hear continuous pings when you are very likely to be detected. Also the reluctance of the escorts to ping sort of simulates the various problems ASDIC had (I'm thinking of HMS Jervis at the sinking of HMS Barham). I'm of the opinion that the game is irretrievably broken but somehow works if you don't look under the hood.

Great post, thanks. Yes, the game is a mess in reality, including escort positions for that matter. I'd add to your statement; "....but somehow works if you don't look under the hood or can ignore it's many historical/realism etc. errors". No fault of any modders though; they all did the best they can with what the game allows.

I'll check that out. Thanks for the heads up.

I see the confusion. It's been a Long time since I worked on these sensor files so I opened them up again in S3D. I changed the ranges for the following sonars--147A, 144A, 128A, 123A, QGAA, QCIA and QCeA. The important designation is the "A" at the end of each sensor name. That means the file is for active sonar. While it does say "Hydrophone" in those files, it actually pertains to the active sonar ranges (99.78% Positive).

These ranges are then modified by SH3 weather, surface factor (your profile aspect to the hunting escort) etc. The most important factor is escort Crew Quality. Only elite escorts get the benefit of the full 2500 meter range. Decreasing crew experience levels drops that range quickly. If I remember correctly, a veteran crew will only use 80% of that range. Average 60% (and so on).

I've been using the mod and it seems to me to be working well. I get pinged a Lot more and if there are 2 or 3 escorts after me, it can take some work to elude them. I had 3 on me for a couple hours the other night and I couldn't get away even though I went 180 meters in March of 41. Finally 2 of them went away (after dropping all their dc's, naturally) and I was able to give the last one the slip by keeping in him in my baffles between 160 and 200 degrees and running at 2 knots.

In summation, I believe the mod is working. However, results vary wildly when considering all the modifiers. It's quite different from stock in my experience though the difference can be very subtle to determine.

If I'm wrong about how I modded the sonars, I'd sure be happy to be corrected so I can try to fix any errors.

:salute:

You really nailed that one! Escort behavior is hard-coded way too deep to be modded by an old pensioner like me! The only way to fix escort positions is to Script the convoys and place them correctly (which does work but is a tremendous amount of tedious tinkering). I wish there was a way to fix convoy positioning as well with 1000 meters between columns and 500-600 meters between ships in the same column.

It still makes me sigh...

:hmmm:

Yes, I was wondering if that was the case; the file naming confusion. I recall years ago that was addressed (the mismatching of sonar/hydrophone labeling) but am to lazy to look it up again. :) I bet you're correct in thinking they're actually sonars you've changed.
But I also seem to recall that the escorts won't ping you without having a phone contact first (which is wrong, but anyway), so increasing the phone range could also have the affect of more pinging if so. Really nice work regardless Grumpy.
Another trick that can help making the escorts less dumb (and they need all the help they can get) is to not have the thermal layer effect used with Sh3 Commander.

I'm retired too. :) Yes, I looked into changing their positions long ago and it's a mind numbing job to do so.
Plus even if done, they still will do their silly, ahistorical tactic of completely leaving the convoy on a routine basis and sail off into the distance for a few minutes.
All one has to do for a successful attack is wait for them to do that, reload, do it again, etc., etc. :haha:

Based on my previous tests, it seems to me that the AI uses both (hydrophone + ASDIC) at the same time.

That would be news then as years ago iirc it was established no asdic until a phone contact.
Maybe things changed.

After plying a couple more patrols while considering this thread, I can say you're both right. John is correct that the stock sensors never seemed to use active sonar unless a hydrophone contact had occurred first. That was my experience as well. However, extending the active sonar range seems to have changed that. Here is the proof.

After attacking a convoy, two escorts headed to my probable location. I was in a pretty good spot so I remained at periscope depth to make my escape easier (it's always easier to escape from an escort you can see and I play with disabled external view). I maintained slient running and there had been no indications I had been spotted. The escorts started doing circles and dropped no depth charges. Then one of them started to ping me from about 1600 meters. I was at 2 knots speed and it was my baffles so in the course of 10+ pings it never gained contact. I continued to pull away and on its next "lap" it pinged me four or five times again, failing to find me. After that I went and made a snack as I knew I was going to be clear when they gave up the chase. They never contacted me, never dropped any depth charges but still tried to acquire me using active... I had the same thing happen on my next patrol although I was at 100 meters and couldn't observe the escorts. However, while they pinged me, they never made contact or made any attacks.

I believe the escorts only use one of their sensors at a time and the hydrophone is their "run-home-to mama" default. However, with active sensor range increased, the sim seems to know it has 2 methods of making contact. The original ranges were so short that it didn't even try active on an undetected target. So--it appears that has changed. I really hadn't thought about it since I was trying to avoid "going under the hood" again and just have some fun actually playing the game rather than improve it.

For the record, I'm currently running the OneAlex Grey Wolves compilation and the only additional mod is my active sonar tweaks. Another thing to consider is that both of these cases happened in early '41 so the escort are probably usinfg Type 123 or 128 systems (I don't remember the dates systems become available). Later systems have similar ranges but better sensitivity.

I though about tweaking the passive ranges like John suggested but that puts my farther under the hood than I want go right now. I'm really just having fun playing the game right now after a significant hiatus.

Off topc: The carreer previous to the one I am playing now was the shortest in all the rediculously many hours I have played this game. I get on my new boat and was leaving the dock at Lorient when we came under air attack. We got straddled by 2 bombs which immediately destroyed the engine rooms. The boat sank with the loss of all hands before making the first turn to leave Lorient. I went and made a snack.

Good stuff Pete thanks, and thanks for your work. I haven't played SH3 for quite a while now, but as dumb as the escorts are and as overly affective as the silent running is, I also just many times let the game run and went to do other things while escaping an attack, etc. :)
I wouldn't mess with the passive settings unless you want to drive yourself crazy; dog chasing it's tail scenario that ends up being a waste of time.