In fact, I wonder why there are no windows in a sub? With a window, we can see each other. :-j

No, seriously. I wonder why there are no Infra-Red detector. Using InfraRed detector, we can still remain stealthy.

Hope nobody minds me butting in, but I'll take a stab at it. This'll partly repeat what's already been said by others, so please don't take offense.

Ad. 1+2) The noise any object makes is composed of several noises with their own frequency. Think of it as an orchestra, where the sound is made by a set of instruments all playing their own part and together making a sound that you recognize as Mahlers 9th (frequency BTW means how many oscillations per second a soundwave makes. Lower frequencies are low-pitch noises, higher ferquencies are higher-pitched noises)

In the BroadBand display all frequencies are listened to at once and the direction from which a noise is heard is displayed as the trace.

In NarrowBand, the noise is broken down into the frequencies that make up the noise (like unmixing a music tape and seperating the different instruments onto different tape tracks). Those frequencies are then displayed as separate lines in the NB display. The pattern of frequency-lines in the NB display is called the signature.

Every entity has it's own NB signature. You don't have to memorize them, their stored in the ships filter, which you can find in the NB screen. Match up the signature with a signature from the database and you have an identification.

In theory.

In practice, you will more often then not only see the first couple of lines of the signature. Lower freqs travel farther through water then do higher pitched noises. Depending on the distance and the noisiness of the contact you'll get one or more signature lines in NB.

Ad.3) The troughs do indeed correspond to the bearings where the ships hull in obscuring the sonar.

In the lower display of the NB, where the noise is displayed, you can recognize a contact as a peak rising above the background noise at a specific bearing (that particular display repeats the broadband signal, but in real time, not in a waterfall manner). Put the cursor over the peak and in the upper display you should see the freq-lines corresponding to the contact.

Ad. 4) Before the torpedo goes active it doesn't know where abouts the target is. You do (or you ought to, anyways). Usually you have a rough indication of the depth of the target (above or below the layer). Set the runout depth of the torpedo accordingly and it'll find the target when it goes active.

Ad.5) The temperature of the water isn't homogeneous. It changes with depth. The layer is a region of water where the watertemperature changes rather abruptly. Since the temperature of the water also determines the speed of sound through the water, such a sudden change of temperature also radically changes the path sound takes. In fact, the layer more often then not acts like a halfmirror radically reducing the volume of sound traveling through it.

So it is possible to hide on the opposite side of the layer to your target. He'll not be able to hear you as clearly. But you won't hear him as clearly either. It's like pilots hiding in a cloud: There's pros and cons in doing that.

For evading torpedos a layer is almost indispensable. But beware: It isn't a silver bullet. Ever since Sub Command Sonalysts have modelled the effects of watertemps a little more sophisticated then in 688i H/K. The effectiveness of the layer is really dependent on the rate of changes of the watertemperature. If the change is not very radical, the layer will let more sound through (in that case the layer is more like a slight haze then an actual cloud).

Ad. the TMA) I'm guessing you're playing with auto-crew for the TMA on? TMA isn't modelled as an automated system in DW. It's more like a bunch of guys drawing bearing lines from your OwnShips position to the contact every couple of minutes. They take their cues from the different sensors, which is represented by different colors of bearing lines. From those they try to figure out where the ship is, and with what speed it is traveling in which direction.

The problem is, though, that more often then not there's more then one solution that fits the data. If you have three bearing lines running almost parallel to each other a solution of 10nm/7knots is just as valid a solution as 15nm/10knots.

The trick is to manouvre your boat to obtain as much different data points as possible. This reduces the number of solutions untill ideally you have just one solution left. For instance: If you find your target is running roughly parallel to you (lead), try to make two tacks of a couple of minutes: One on a course corresponding to the last noted bearing line and one 30-45 degrees in an opposite direction of where the target is travelling. The information your TMA guys get from those is usually sufficient to workout the position, speed and course of the target accurately.

Ad. DEMON) The Demon 'demodulates' the noise the screw of a target ship makes. It's broken down into a lines for the rotating shaft and a number of lines corresponding to the blades of a screw. So having 6 lines in the DEMON means you're tracking a ship with a 5-bladed screw (that is also a piece of info you can use for identification purposes).

To work out the speed, you have to first have a rough identification. Then enter the TPK (= turns per knot) corresponding to the targets class (you can find this in the USNI database). Then you can put the cursor on the left most line (the shaft line) in the DEMON display and read off the speed of the target.

The accuracy of this obviously depends on the accuracy of your classification. But determining the speed of the target using the DEMON radically reduces the number of possible solutions, earning you the gratitude of your sweaty, stressed out TMA guys.

There's some excellent guides (both TopTorps TMA guide as TimmyG00s Tactical Manual) that I'd suggest you download and read. They explain all this a lot better then I ever could. You can find them over at Bills SubGuru site in the downloads section.

Layer
 

Yet once I feel important to say that in DW, layer effects are quite weak. There has to be very specific conditions to see any effect at all. To 'loose contact' due to depth change is possible only on the border of detection range. You definitelly won't evade torpedo because of the layer. Being on the other side of the layer can delay detection and classification a bit, but again, it takes place only at the detection range border. When they shoot at you, you are much closer and layer can be ignored.

In DW much more important factor is surface noise. It masks contacts. For beter sonar reception go as deep as possible, especially with high seas. In most conditions deep sonobuoys gives better results than shallow ones. I think this is because of surface noise.

This is how it works in DW. I don't know how it works in real.

So, as was said, the layer effect is very small in DW, so the depth where we fire the torpedo has almost no effect on its ability to detect the target. And how does it know the depth of the target? Well... it just does know it :) Its sonar has ability to detect target bearing both horizontally and vertically, i suppose :)

In all honesty, I know absolutely nothing about operating the layer instrument. I read somewhere about this tactic, so I just asked the question.

But about torpedo, I am still very unsure about it. What is the difference between firing it SNAPSHOT and assigning a contact to it? I find there is no difference. By the way, do you steer the torpedo? For once, one of the torpedoes missed the target by over 2,000 yards. I changed the bearing to steer it back towards the target and it hit the hull. But naturally, how does the torpedo know if it should dive deeper towards the target or surf upwards? Does it have a homing radar onboard?

Oh...yes, please also tell me how do I put another torpedo into an empty tube? I have torpedo stocked, but can't use them!?

Michiel de Ruyter,

Thanks a million. The information is precious to me.

No, I run every mission without auto. Everything is manual.

By the way, does Difficulty means the AI level?

Now, looking back, I wonder how useful the identification process is. I mean as long as I get the Course, Bearing and Range. Be it a surface target, or a sub-merged one, the torpedo will hit it anyway, right? For sake of immersion, maybe the identification is to be completed.

I tried to search in blind. Started at course bearing 45, speed 10 knots. Commanding the Seawolf of SC, not DW yet. Nothing happened for the first 30 seconds or so, then I turn right to 90. As the boat did, I keep starring at the NB display, switched to the BB nervously. Then repeat the same steps from 90 to 135, from 135 to 180, from 180 to 225, and from 225 to 270, 270 to 315 and finally 315 to 45. Nothing.

In another mission I made up myself, I managed to pick up a track. So I put it into the TMA. The TMA gave me a bearing, range and speed. How accurately is the information I obtained from Sonar? Also, by the time I put them to TMA, I clicked "Enter Solution". Why nothing came up? Now what's next I should do? Go back to the Sonar room and keep monitoring the displays, or I stay in the TMA room. If I stay in the TMA room, I have nothing to do. So how TMA fits into the whole picture of firing my torpedo?

Are there any procedures in entirety, from contact to targeting the contact and finally fire the torpedo? Use SNAPSHOT or Assign target? After firing the torpedo, do I just wait for it to hit the target or I need to steer the torpedo at some stage?

Let me see if I can explain TMA... This was actually in the 688(I) H/K manual, but that manual is really rare... Any way...

Say you have a sonar contact, bearing 090. No range into,no blade count. You don't even know if it's a surface or subsurface contact.

Assuming it does NOT change course, you have to keep moving to generate a bearing change. THEN you can use Pythagorean theorem and the triangle you have formed to take a guess at the range.

YOU2
^
YOU CONTACT

You know the distance YOU travelled, you know the bearing change, so you can take a guess at the range, and the enemy speed.

This assumes that sound travels in a straight line. It actually bends due to salinity, temperature, and so on. You have to take that into account when you do the range calcs.

The smaller the bearing change, the more error-prone it will be. On the other hand, the larger the bearing change, the faster the enemy could be moving. So there are an infinite number of solutions if you go that that alone. Enemy could be really far away moving really fast, or really close and moving really slow.

So every once in a while (say, 10-15 minutes of tracking) you do a turn, preferably CROSS his bearing, to get a different aspect angle off the contact in order to determine his REAL range and speed.

In TMA, that ruler is your current "solution", i.e. your guesstimate at what his course and speed is. As your bearing lines increase, you can see that your ruler can be pulled in closer but tight (slow but close), or pushed further but spread apart (far but fast). By matching up the notches with the bearing lines you got a solution. It is right? Not sure yet.

If you have crossed his bearing and the solution STILL looks right, then you have locked down his range and thus, his speed as well (since one affects the other), assuming his doesn't zig-zag or change speeds, of course.

Another way to get a true range is by getting his blade count, then analyze his revolutions via DEMON. By that, you can get his speed, and using the TMA, you can back calculate his range.

Is that making any sense?

YES ! Torpedo has its own homing device. Either active or passive sonar, or wake-folowing device. Read USNI reference, each torpedo has different modes available.

When you fire the torpedo, you set bearing and 'enable distance'. Torpedo will blindly run on the bearing. At given distance it will 'enable'. It will start to look for the target. For ANY target. While searching, it follows predefined pattern of movement (circle/snake).

Torpedo can find target only in narrow area in front of him, in so called acquisition cone. If the depth of the torpedo and depth of the target differs, it is no problem until target gets into the cone.

When it finds target, it follows the target, changes course AND depth until it hits or losses it.

Your task is to set bearing and enable distance so torpedo would enable as close to the target as possible, but far enough so you are sure the target will get acquired.

If you assign track to torpedo, firing computer will automatically set bearing and enable distance. If you use snapshot, you must set both manualy.

Some torpedoes can be wire-guided. You can change their bearing until they are enabled, and you can 'preenable' them. This is used to avoid countermeasures or to follow changes in target position.

As for procedures in entirety, I believe my 688(I) H/K FAQ may be of some help, though it needs a bit of revision to be applied to DW.

You want the one by KChang

http://www.gamefaqs.com/computer/doswin/game/44566.html

SNAPSHOT is firing a torpedo at a specific bearing, no idea on what the range is. In general the default setting is used. It's generally used as counter-fire, firing one down the bearing of incoming torpedo and hope the enemy flinches, giving you time to evade.

Sonar, dude. Sonar. Multi-freq anti-jam with decoy avoidance logic and all that.

Close the tube (i.e. all three buttons), then click on the tube graphic and keep clicking until the payload you want is shown, then leave it for a little while as the loading crew goes to work.

You generally want to know who you are attacking. Otherwise, your torpedo might sink a friendly sub or an innocent fishing boat!

The other vessel might have been too far. Which sonar array did you use? You did "scan the bearings" in the NB display, didn't you?

I see kschang has already explained this stuff about TMA. I hope I don't create any confusion if I add my version...

Without autocrew, the TMA station doesn't give you anything. What you are seeing are the default range (10000yds), speed (10kts) and course (directly towards you), that are assigned to every new contact, until a proper solution can be determined. TMA is a tool you use to figure out a valid solution for a contact. How?

Say you have assigned a tracker to a sonar contact. Now sonar will report the contact's bearing to the TMA station every two minutes. You must first wait until you see several bearing lines in the TMA screen. When you have that, you grab the TMA ruler, and try to position it so that the tick marks in the ruler line up with the bearing lines. You'll notice that the numbers in the trial solution fields change as you move the ruler. In the upper left corner of the screen you see three vertical lines and some dots. The dots will move as you move the TMA ruler. When you see the dots stack vertically on the center line, you'll have what is called a candidate solution. This means that the solution you have obtained is not in conflict with the bearings that the sonar has generated over time. You might still have a wrong solution, but at least it's possible your solution is correct. If the dots don't stack, your solution is definitely incorrect.

To verify the solution, order a new course. After your sub has steadied to the new course, wait until the sonar has reported three new bearing lines along the new course 'leg'. This should take six minutes. Do the dots still stack nicely along the center line? If they do, there's a good chance your solution is valid (i.e. correct). Usually, however, you'll have to make some adjustments before the dots stack vertically again. After that, you might order yet another course and verify the solution again!

This was hardly more than a scratch on the surface, and there are a lot of real experts around that could drown you with information about the subject. TMA is the most challenging task in SC/DW, and it takes a lot of practise to master! My advise: let the autocrew handle TMA for now, and concentrate on sonar, fire control and tactics. That's what I still do most of the time, and I'm not exactly new to these sims, either! :|\

Sorry, I really can't make anything out of it.

Can you tell me if TMA bears no error? But then TMA doesn't update my first contact does it? So far, I can only see the range keeps moving but the bearing never changes.

Quite often after I have found out torpedoes I fired failed to find target, I switched to "Show Truth". And the target is always "elsewhere"!

personaly i skip TMA and work it out for myself takes alot longer but my way works bit to hard to explain but it works

Point taken.

I used all of them, switching between Towed, Hull and Sphere hoping to see something comes up on the display.

Welcomed.

Ok.

Not every two minutes. I have never noticed, would you clarify.

Ah...now we are getting somewhere. I understand what the dots are and the meaning of them being overlapped on the centre line.

Very clear.

What course should I turn to?

I don't understand this part. Do I do the Sonar work, or you mean I should enable Autocrew to do it for me?

If I understand the above, I think I can make sense out of this one.

So, how long have you been doing this, I mean manually operate except the TMA?

i dont use TMA but i been on sub sims since SSN came out and started full time play when SC came out

i use my own methord and by pass TMA