[Onkel Neal]

Signature numbers explained

ramjbjb: Those numbers are the essence of measuring how stealthy you are, and how close to detection by an enemy you are. Which in a sub, as you might understand, is pretty much everything.

First Own ship numbers: Those describe the strenght of the signature you're receiving. Negative numbers are calculated outputs. Essentially anything negative means you're receiving nothing through that channel. For instance is perfectly viable that being over the layer (and dragging the towed array under it) you receive nothing in your MF sonar (the one at your bow), yet you can hear a faint signature with your towed array (which is under the layer).

The utility of this numbers is obvious. The stronger the signal, the better your TMA over time will be. It also gives some tactical hints about the enemy before the TMA is done. If you know he's not very close, but the signal is very strong, that means the platform is being VERY noisy (which usually means it's steaming at full speed). COnversely if you know the enemy is relatively slow moving a very strong signal means it's REALLY close, and you might want to react accordingly.


Now, about the numbers for enemy platforms:

First, how are those numbers are calculated: all platforms in game have sensors. Each sensor has a specific capability. Some are more sensitive than others. All platforms in game make noise. Said noise depends on how fast they're moving and on the inherent properties of the platform, as some are more silent than others.

The numbers you see are the calculated result of your own submarine loudness at the speed is travelling vs the capabilities of the sensors aboard the enemy ship, appropiately modified by things as background noise, if you're in the opposite side of the thermal layer, the strenght of said thermal layer, general sea conditions,etc.

Keep in mind you NEED a correct ID for this to be accurate. If you class an enemy Sierra as a Whiskey and you trust you've not been detected based on the numbers you see there, chances are you're in for a nasty suprise.

Also those values apply in the zones the sensors actually cover. This is easy to check if you're behind an enemy submarine (that lacks a towed array). If you're in a 60 degree arc behind him, all his numbers will be -50 db. Which means you can go flank speed and cavitate like a maniac, and the enemy will still not hear you.
Be conscious however that you also have non-detection baffles in your own sensors. the same 60 degrees behind for the active and hull sonar, and directly forward for your towed array (as your own submarine noise will mask whatever is beyond).


Now, how do those numbers apply vs the simulation?.

-anything negative means that the sensor in question will NOT detect you, period.

-anything under two digits (0 to 10) means that the sensor in question will NOT detect you but will keep you detected if the enemy has already a fix on you.

-anything over 10 means that sensor has detected you. To completely vanish off the enemy picture you need to get all the enemy sensor values under 0 at the same time, or they'll keep you detected.


so when you're doing an approach to an enemy sub, for instance, and you see the numbers for his hull and towed array as -5 and -3 respectively, you know you can increase speed a bit and you won't be detected, for the enemy still doesn't know you're there, and the values are under 10. Then you can decrease speed as you come closer and you're closer to be detected.

couple more things:
Silent running (shift-S) is EXCEEDINGLY useful to creep and remain undetected by passive sensors. And is a noticeable decrease in detectability from 1/3 forward.

Being totally stopped in the water doesn't mean you're not getting detected. Nuclear subs of this time used, without exception (well one would be the Ohio SSBN) coolant pumps to keep the reactor going. And you can't shut down your reactor (it'd be the most stupid thing to do in any nuclear powered vessel anyway). So you're making some noise even when stopped.


Now, the active sonar. This one is particular because there's a heavy modifier to that number, because that number is the expected signal strenght the enemy sonar will get off your sub if you're full broadside on towards him. If you're end-on (bow or rear towards the enemy), that number gets divided by a modifier (not sure how much, talking to the devs they told me is a factor of 25% when fully dead on towards of from the enemy).

So for instance, the enemy has an active signal strenght of 10. You're broadside on. He will detect you if he pings.

The enemy has an active signal strenght of 20. You're totally bow on towards him, so he actually gets 25% of that. Which is 5. 5 < 10, so the enemy won't detect you if he pings.


Same obviously applies to your own active sonar vs enemy vessels, so keep that in mind if you want to open up with your active sonar.


So, as is obvious to see, those numbers are EXCEEDINGLY important because they control if the enemy detects you or not, and how close (or far) you're from shaking off being detected.

In fact I'd say those numbers are the most important single thing in the whole simulation.