Active sonar, useful for anything other than basic ranging?
 

Hey all, figured I'd start a new topic since this has only a slight bearing on my other thread. This one is a simple question.

Does anyone use active sonar for anything other than obtaining range? I'm playing around with my Kilo scenario and have found that I can effectively use the return sound to get the exact range for a target that I've already pretty much localized. Thanks to some of the advice in my other thread, I've started using it to help me re-steer my fish when the target starts evading, however I can't seem to find any other use for active. I get no bearing data because I can never see the contact which also means that while CMs do make an audible return, I can't use active to steer fish past them. I also get quite confused when my fish get pretty close to the target as they also create return pings and no visual mark.

Anyone ever use active effectively?

Are you using the god-damned Akula sonar? Because the others, IIRC, DO show the blips reasonably well, so you can use it to search for both range and bearing...

Well, I'm using the KILO active sonar, but I have swapped out all the sonar interface graphics for the easier-to-see green ones from the Alfa. I have occationally been able to see contacts using the 688I active, but only if they ar closer than 3000 yards or in a full on beam aspect in which case I gain about 2000-3000 yards detection distance.

Russian sonars are seriously flawed in the game. But US should work quite well. Don't forget all sonar conditions affect active as well, especially SSP and sea state.
Getting ping not sooner then at 3000 yds sounds to me like cross-layer ping. Layer always blocks sound completely in DW, but when you get closer, the effect disappears.

Here is my older post about DW sound propagation model.
http://www.subsim.com/radioroom/showthread.php?t=117814

So let us know about your depth, target depth, sea state, and SSP.

Hey Dr.Sid, I actually read all those old threads about the hydroacoustics in DW and learned quite a lot.

I just performed a series of pretty controlled tests and I will share my results. First, I'm using DW 1.04 with the most up to date RA mod available. I used a Los Angeles FLT III as my test platform and an Iranian Kilo as the target. Sea state 1, time of day 12, weather clear, bottom type rock, SSP surface duct, layer on average slightly less than 1000 ft. Both subs were in deep water, approx. 11500 ft. My sub was oriented 000 and the target was north of me oriented 090, both were at 200 ft, 0 kts.

(Side note: I found that when editing the scenario using notepad, about 1 nm y-axis distance is 1850.0 in the POS value.)

I started the target at 2 nm from me and increased distance each time by 0.1 nm. It seems that between 2.8 and 2.9 nm, it becomes nearly impossible to see the target. Usually a second ping would help brighten the target, but at about 3 nm even this did not make the target visible.

As a disclaimer, I am slightly visually impaired. However, once the target brightness is about the same as some of the random patches in the water, I assumed even a fully sighted person would have real trouble telling it apart.

EDIT: Just did the same test with LwAmi 3.09 and got basically the same results so it's not the RA mod.

Kilo active
 

Just ran the same tests only I switched the platforms around so that I was driving the Iranian Kilo (the one with the nice green sonar displays) and the target was an LA FLT III. All other conditions were exactly the same.

The Kilo's sonar wasn't as weak as I expected. I was able to get a reliable visual return out to about 1.8 nm and a sporadic one out to about 2 nm. The biggest difference I found was that double pinging didn't make the contact any brighter at any range.

Oh, I forgot to mention in my last post that I always brought the display scale down to 10 for all tests and used single-ping mode. I haven't tried this test with any of the red displays and don't intend to since I have a hard time even seeing some passive sonar contacts with them (my vision again, green on black is much better contrast than red on black). I may do some more tests later with a bow aspect, a stern aspect and a semi-beam (45 degrees bow and stern) aspect, but not right now.

I find the short range of the active sonar's visual returns make it pretty useless for anything other than a knife fight type situation since even a Kilo would have a strong passive contact at these ranges. The audible return is still useful, as I mentioned above, for ranging of a target which is already pretty well localized.

But if you are able to receive an active sonar return you should allready have a passive signal of the same contact. Combine the bearing of the passive signal, with the range(indication) of the active audible return and you have a pretty good fix.

I usually fire a torpedo well in advance towards the target (prefferably opposite on the layer) before I ever make use of a ping. The ping alerts to your pressence. It probably notices that a torpedo is fired, but it doesn't allways respond to it immediately. Only if it get's too dangerously close. So I let the torpedo close the distance, and only ping and finetune steering when it is allready close to the target.

This is just a problem that DW has with the way it models active sensors. There is a detection threshold, which is a discrete range at a given aspect. At that threshold, the contact is theoretically detectable and produces an audio return. But, for the visual representation, there is a brightness scale going from strong to weak that doesn't even begin to become visible until the target is well within the detection threshold. It's not your eyes, it's just the way the interface/model is set up.

It's actually the same way with the radar model--but without the audio cue. :damn: You don't see it yet because all the databases out there (maybe RA is an exception) go from the detection threshold to a very strong contact in very, very little space, so you never have to deal with the "invisible" returns.

Molon, is it possible to do the same thing for the active sonar? I mean make the space between detection threshold and very strong contact a lot smaller?

I'll have to try out the radar in RA now...

Oh .. I agree with Molon. The sound can be heard all the time, and you will never ever hear weak return. Such think does not exist in DW.
Screen is something else. Also if you are talking about RA mod or something like that, I have no experience with it, the ranges can simply be that small.

Btw. I fixed the link in my previous post ..

Dr.Sid, are you using LwAmi? Cause I did do the same test with LwAmi 3.09 using the LA and got pretty much the same results. Can you see the contact at a much further range?

with a few maneuvers against the transmitting source, you can triangulate the sources' location. This is a tactic known as ping stealing.. I've used this a couple of times and works really nice with bracketed subroc salvos.
If you can't tell already, I'm an akula skipper, and will be an Ak2 improved skipper in RA(love the digital sonar gear and WAA), :D

also, I'd say active sonar is really a trade off of luxury and consequence. Any platform capable of subroc ordinance can literally throw their weight around with active sonar and get weapons on target ASAP. With that kind of firepower, the threat dares not generate a TIW against the transmitting source.. But those that are not capable of such ordinance, use of active sonar is more of a consequence for obvious reasons. :salute:

The radar works perfectly, at least in RA. I was able to detect an Oiler all the way out to the maximum range, more than 15 nm, using an Iranian Kilo. It was in about a 30 degree aspect heading toward me and the contact was a bright dot even at max range. Haven't tried it with any military ships though, undoubtably their radar signatures are much smaller, but the radar works well enough for my tastes.

Actually I don't have DW even installed at the moment. But I played mostly with LWAMI. And I only guess it should be more. :damn:

Not without turning active sonar into an all-seeing eye for all contacts inside display range. We had that once before, it was a game-killing defect, and we got a patch for it.

Like I said, you don't see the same thing happening with the radar because the database values are too ****ed. And testing with a large platform at short range isn't going to tell you much, that comes in nice and bright and it should. The problem is that all objects, regardless of size, are all picked up at about the same ranges. A good radar model would have a surface search radar pick up an aircraft carrier at much greater ranges than a FAC, a bomber at much greater ranges than a small missile or stealth fighter. DW as is, all those things pop up in about the same spot. Once this is fixed, you get the same display problem as you do with the active sonar.