question on detection rules

[VictorInThePacific]

Can someone please tell me what the mechanics of detection are, in the following 2 situations:

1) Can passive sonar detect a stationary sub which has its own sonar on standby?

2) If I stuff enough ECM pods into my air group, can I guarantee that radar and radar-guided missiles cannot get a lock-on?

[NefariousKoel]

1)&nbsp; Yes, but it'll be the most difficult and probably have to be almost on top of it.&nbsp; The speeds were categorized, in the tabletop versions, which included speed < 5 kts or something to that effect.&nbsp; Not sure if HCE has the individual speeds separated more, though.

2) Dunno this one for sure, there's likely a limit or most likely, a minimum burn-through range depending on the power of the radar.

[TonyE]

1) Yes, the sub has what is for lack of a better name called a BSL (base sound/source level) that is the amount of noise produced even if the sub isn't moving.&nbsp; The noise level increases the faster the sub goes (it increases very little up to the creep speed and increases more per knot above that.&nbsp; Eventually it may cavitate meaning bigtime noise.
&nbsp;
2) There isn't much benefit to ten million jammers in the game.&nbsp; The rule of thumb is to have a jammer to protect the air group and a second jammer to protect the first jammer.&nbsp; That isn't the whole answer, due to positioning it can help to have more jammers to cover the situation more completely but I would say there are steeply diminishing returns above two jamming planes.
&nbsp;

[hermanhum]

ORIGINAL: TonyE

1) Yes, the sub has what is for lack of a better name called a BSL (base sound/source level) that is the amount of noise produced even if the sub isn't moving. The noise level increases the faster the sub goes (it increases very little up to the creep speed and increases more per knot above that. Eventually it may cavitate meaning bigtime noise.

So, if a sub has a creep speed of 5kts, does that mean that it radiates the same noise level if it is running at 3, 4, or 5kts? Or is it quieter at 3kts than it is at 5kts?

[TonyE]

ORIGINAL: hermanhum

ORIGINAL: TonyE

1) Yes, the sub has what is for lack of a better name called a BSL (base sound/source level) that is the amount of noise produced even if the sub isn't moving. The noise level increases the faster the sub goes (it increases very little up to the creep speed and increases more per knot above that. Eventually it may cavitate meaning bigtime noise.

So, if a sub has a creep speed of 5kts, does that mean that it radiates the same noise level if it is running at 3, 4, or 5kts? Or is it quieter at 3kts than it is at 5kts?

The sub is quieter at 3 kts than 5 kts, yes.

[CV32]

3 kts is minimum (steerage) speed in HCE, btw.

[FransKoenz]

The sub is quieter at 3 kts than 5 kts, yes.

But only when the crew does not sing the national anthem.......[:D]

One ping Vasily, one ping only.........

[VictorInThePacific]

1) Yes, the sub has what is for lack of a better name called a BSL (base sound/source level) that is the amount of noise produced even if the sub isn't moving. The noise level increases the faster the sub goes (it increases very little up to the creep speed and increases more per knot above that. Eventually it may cavitate meaning bigtime noise.

Thanks, Tony, for that information.

My next follow-up question is where can I get the numbers for base sound levels? The basic thing I am looking for is a) are there subs that will NOT be detected by passive sonar if the sub is moving sufficiently slowly (or the converse, are there subs that CAN be detected by passive sonar regardless of how slow they move and b) how fast can the "quiet" subs move before they MIGHT be detected by passive sonar?

And then I will ask about range effects.

And then I will ask more questions.

[CV32]

ORIGINAL: VictorInThePacific
Thanks, Tony, for that information. My next follow-up question is where can I get the numbers for base sound levels? The basic thing I am looking for is a) are there subs that will NOT be detected by passive sonar if the sub is moving sufficiently slowly (or the converse, are there subs that CAN be detected by passive sonar regardless of how slow they move and b) how fast can the "quiet" subs move before they MIGHT be detected by passive sonar? And then I will ask about range effects. And then I will ask more questions.

There is no "source" for the BSL values. When we changed to the BSL system, we worked up a table of all the platforms existing in the game at the time, compared them using their Harpoon paper rules' acoustic signatures (EQuiet, VQuiet, Quiet, Noisy, Loud), and then assigned BSL values by ranking them accordingly.

[TonyE]

ORIGINAL: VictorInThePacific
Thanks, Tony, for that information.

My next follow-up question is where can I get the numbers for base sound levels? The basic thing I am looking for is a) are there subs that will NOT be detected by passive sonar if the sub is moving sufficiently slowly (or the converse, are there subs that CAN be detected by passive sonar regardless of how slow they move and b) how fast can the "quiet" subs move before they MIGHT be detected by passive sonar?

You questions depend on the listening sonar, the target sub, speeds, biologics, depth, wave action, some randomness, a little bit on location. In this case I'd say run a raft of tests to come up with the answer yourself. It helps to have the platform editor open and handy when doing so. Of course share with the world [:)]

[Shark7]

Also keep in mind that even if the sub evades passive sonar by not moving, some search aircraft and helicoptors can still detect it using MAD gear. There is no 100% foolproof way to sneak around with a sub. While moving at very low speeds can certainly reduce the chance of detection, there will always be a small chance of detection.

[VictorInThePacific]

Also keep in mind that even if the sub evades passive sonar by not moving, some search aircraft and helicoptors can still detect it using MAD gear. There is no 100% foolproof way to sneak around with a sub. While moving at very low speeds can certainly reduce the chance of detection, there will always be a small chance of detection.

I do understand that there there are active mechanisms of detecting subs. My original question was worded in such a way as to exclude those.

The basic problem, as I see it, and have stated elsewhere in this forum, is that once a sub fires a torpedo at you, you have only two defenses: 1) luck, 2) flight. I do not want to rely on luck, and it is not a reasonable strategy in any case. But if the sub is close enough, flight may be ruled out.

THEREFORE you have to locate the sub before you are in its lethal range, which of course, depends on the speed of the target ship.

I have got a bit of information about when a sub can be "invisible" to passive detection mechanisms, and I am still seeking more. I am looking for actual numerical data such as (hypothetically) "The passive sonar on an Oliver Perry FF has a 1% chance per 30 s round of detecting a stationary, silent Victor II sub within 50 nm." Clearly the data would be much more complex than this, especially considering Tony E's immediately preceding post. Nevertheless, let's just work with the hypothesis. Suppose further that the FF sonar has a range of 35 nm and the sub's lethal range is 25 nm. The the FF can close by 10 nm in relative safety (other things being equal), which at a speed of 15 kn translates into 2/3 h, or 40 min, or 80 rounds. This gives you ON AVERAGE an 80% probability of detecting that sub before it launches the killing torp. Is that good enough?

Not for me. I want to locate the sub as far away as possible, so SOMETHING will be using active sonar, where the detection probability is on the order of 50% per round.

I have much more to say about this topic, but I want to working with real numbers, not hypothetical ones.

[Shark7]

ORIGINAL: VictorInThePacific

Also keep in mind that even if the sub evades passive sonar by not moving, some search aircraft and helicoptors can still detect it using MAD gear. There is no 100% foolproof way to sneak around with a sub. While moving at very low speeds can certainly reduce the chance of detection, there will always be a small chance of detection.

I do understand that there there are active mechanisms of detecting subs. My original question was worded in such a way as to exclude those.

The basic problem, as I see it, and have stated elsewhere in this forum, is that once a sub fires a torpedo at you, you have only two defenses: 1) luck, 2) flight. I do not want to rely on luck, and it is not a reasonable strategy in any case. But if the sub is close enough, flight may be ruled out.

THEREFORE you have to locate the sub before you are in its lethal range, which of course, depends on the speed of the target ship.

I have got a bit of information about when a sub can be "invisible" to passive detection mechanisms, and I am still seeking more. I am looking for actual numerical data such as (hypothetically) "The passive sonar on an Oliver Perry FF has a 1% chance per 30 s round of detecting a stationary, silent Victor II sub within 50 nm." Clearly the data would be much more complex than this, especially considering Tony E's immediately preceding post. Nevertheless, let's just work with the hypothesis. Suppose further that the FF sonar has a range of 35 nm and the sub's lethal range is 25 nm. The the FF can close by 10 nm in relative safety (other things being equal), which at a speed of 15 kn translates into 2/3 h, or 40 min, or 80 rounds. This gives you ON AVERAGE an 80% probability of detecting that sub before it launches the killing torp. Is that good enough?

Not for me. I want to locate the sub as far away as possible, so SOMETHING will be using active sonar, where the detection probability is on the order of 50% per round.

I have much more to say about this topic, but I want to working with real numbers, not hypothetical ones.

I think I see what you are driving at. Those are the Harpoon 4.1 rules. And while the computer game is based on those rules, it is not exactly the same thing. I am not the nuts and bolts guy, so I can't tell you exactly how it works, but what I can tell you is that you do always have a small chance of detecting a sub with passive sonar.

Speed of each platform does affect it. Obviously a faster moving sub is easier to detect, while a ship moving at higher speeds impedes its own detection capability. Platform speed is probably the only thing you have direct control over to affect detection probabilities.

One thing to keep in mind, active sonar on ships 1) warns the sub you are coming, active sonar can be heard from a much greater distance than it can detect at and 2) active sonar usually has a far shorter range than passive.

Honestly the best way to detect a sub is either with another submarine, or with an aircraft or helicoptor.

[TonyE]

Victor, you might find the sonar (passive sonar for the most part) logging helpful.

Code: Select all

 Command Line Options
   GE, Winharp32.exe
     -a
       Turns on autotesting which means each dialog during play of the scenario will be automatically clicked. This emulates the game playing against itself. The command line option aids in making batch files to run through a number of scenarios without user intervention.
 
     -f
       Defines log file name, must be followed by Path/Filename of log file
       Example: Winharp32.exe -f C:\temp\mynewlog.txt
       Without the -f command line option a log name of ge.log in the same directory as Winharp32.dxe is used.
 
     -i
       Ignore registry options such as window positions, battleset path, etc.
 
     -l
       Enables extended logging in one or more areas. List one or more logging areas after the –l
       init_annex
         Logs detail when loading platform data from the database
       ac_ai
         Logs aircraft artificial intelligence items
       sub_ai
         Logs submarine AI actions in detail
       sonar
         Logs detail of attempted and successful sonar runs
       refuel
         Logs refueling event information, but not in much depth
       mission
         Long Range patrol logging, possibly other items as well (formation patrols?)
       intercept
         Information about all intercept events but a focus on planes
       res_file
         More database logging
       load
         Logs information about scenario and saved game loading
       radar
         Logs active radar detail
       ecm
         ECM (mainly active radar jamming) logging
       missile
         Logs critical hits, Nuclear triggers, etc.
       areadef
         Doesn’t do anything at present, if the newareadefense was turned on, it would log details about that (SAMs firing against aircraft and such)
       perf
         Performance logging, indicates which sections of code will make the game faster with optimization
       bad_db
         Unused
       graphic
         Logs graphic palette information and related minutia
       all
         Turns all of the logging on in one shot. Be aware, this will make huge logs, and the game will run slowly.
         A large text file viewer for looking at humungous logs is available at http://harpgamer.com/harpforum/index.php?autocom=downloads&showfile=241
 
       Ex: Winharp32.exe -l sonar radar
         That will enable detailed logging for sonar and radar
     -s
       Enable iterative saving of games to the temp directory on your system drive. If Windows is installed on your C: drive, then the saves will be in C:\Temp\
     -t
       Defines the interval for the iterative saving
         Ex: Winharp32.exe -s -t 0.5
         Saves the game roughly every 30 real life seconds (0.5 minutes)
     -x
       Disable the submarine AI, there isn’t really a reason to do this anymore. It is a legacy of the submarine AI replacement in HC2002
 

Enjoy

[hermanhum]

Wow, that's interesting.&nbsp; I've got some questions, too.&nbsp; Could you post up the rest of the source code for HCE in its entirety....?&nbsp;[;)]

[noxious]

Anyone else seeing Tony's last post escape from its box and rampage all over the page ?
Specifically, looks like the code quote box is bigger than the post frame, or somesuch...
Prevents me from reading or copying pasting it for reading in notepad

[hermanhum]

Same here.&nbsp; I just forwarded a copy to your e-mail address.&nbsp; Does it help any?

[TonyE]

ORIGINAL: noxious

Anyone else seeing Tony's last post escape from its box and rampage all over the page ?
Specifically, looks like the code quote box is bigger than the post frame, or somesuch...
Prevents me from reading or copying pasting it for reading in notepad

Hehe of course you can read the original (PDF and Word), in the General beta tester forum under the Beta Tester Guidelines <g>.