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Should sonar sensors be able to detect land based units. What exceptions might exist and are they worth CPU time?

Thanks,

why would sonar be able to detect land based unit?
are you talking about passive sonar?

There is currently a problem on AGSI's List of Known Harpoon [ANW] Issues
[blockquote]Sonar detects facility

Land facility detected by active sonar.

[/blockquote]

Here's a chat log discussing one bug, but covering the Sonar detection vs. land facility discussion:

[blockquote]Session Start (Herman:#Harpoon): Sun Jul 26 18:22:05 2009
*** #Harpoon: @Herman
*** #Harpoon was created on Sun Jul 26 18:21:42 2009.
*** Mode change "-o Herman" for channel #Harpoon by Herman.
*** Russell has joined #Harpoon.
Herman: only reason I asked for the extra room is to ensure that we operate under Gilman doctrine -- anything said in here can be re-posted.  that okay with you?
Russell: Gilman doctrine?
Russell: You are melodramatic
Russell: But sure, we can repost anything
Herman: okay
Herman: do you know how the Transit mission operates in regards to its Formation patrols?
Russell: Not exactly.  I do not know how formation patrols operate any differently under one mission or the other.
Herman: do you remember playing any HC?
Russell: I've never played HC.
Herman: ok
Herman: here's how the Transit mission worked
Herman: if you put a CVBG on Transit mission and then set up the ASW/AEW/CAP formation patrols, they would stay with the formation until something was detected.  Then, they would detach to investigate/prosecute the target
Herman: Transit mission is the only mission that does this.  ASuW, AAW, Support, etc. do not
Herman: IMO, it is the most powerful mission in the game because it allows the AI the most discretion
Herman: that's why it was used the most in the H2 scenarios.  anyone re-building the original H2 scens would have seen most scens with this mission
Herman: this ability to detach was the most unique aspect for transit
Herman: now, in 3.10, the air patrols no longer stick with the formation
Russell: Ah, the bug report
Herman: instead, they immediately launch and fly off to the refPt assigned to the transit mission
Herman: and they SIT there
Russell: Okay, so CAP?
Herman: CAP, AEW, ASW, all the formation patrols do it
Herman: they don't stick to the formation until something is detected
Herman: what bug report are you talking about?  I haven't posted anything.  have you seen something else?
Russell: Just waiting for the preamble to finish.
Herman: no, that's about it.
Herman: just hoping that I was clear enough
Russell: Is this unique to transit missions?
Russell: Transit missions with formation patrols I mean.
Herman: I'm not quite sure what you are asking
Herman: all the other missions can have formation patrols, too
Herman: they just never detached
Russell: You say formation patrol aircraft are flying to the reference point instead of their patrol zones.
Russell: That's what I got anyway.
Herman: that's the general gist of the problem.  yes.
Herman: there is a bit more to it
Russell: Okay, simple enough.  I'll look into it.
Herman: let's say that there was a CAP formation air patrol
Russell: That is a major.
Herman: the CVBG would launch the CAP for the formation.  However, it would also launch the rest of the planes that would fly off to the Transit RefPts.
Herman: that's what is happening in 3.10
Herman: the replacement planes should be sitting on the deck until needed
Russell: Probably a result of the first issue.
Herman: yes
Herman: okay, do you need any other details?
Herman: there are plenty of sample scens to choose from to see this
Russell: Not right now.  I'll build a test scenario and see what's what.
Herman: okay, thanks for the time
[18:36] Russell: Wait a sec
Herman: ok
Russell: On the issue with Sonar detecting land units
Russell: There's no scenarios you know of that would be affected by exempting land units from sonar detection?
Herman: I can't think of a single one
Herman: the reason why I consider it a bug is because there are no Acoustic values for land units
Herman: so, I can't believe that the original designers intended for land unit detection by sonar
Russell: Neither do aircraft but there are situations where they are detected by passive sonar.
Herman: true
Russell: Just checking before I made the change.
Herman: but it is outside the game, IMO
Herman: are you saying that helos at low can be detected by sonar?
Russell: Ya
Herman: because I've never seen it
Herman: are you sure?
Russell: Vlow
Russell: Dipping sonar
Herman: righ
Russell: Yes.
Herman: it's the active sonar being detected
Russell: I'm sure it is intended.
Herman: isn't it?
Herman: I'll test, but I think I looked at it before
Russell: It's according to the paper rules.
Herman: if you take a transport helo and have it hover at VLow, subs cannot detect it
Herman: the subs seem to be hearing the active sonar from the dipper
Herman: (at least that was how I remember testing it)
Russell: Has to be 50 meters or lower.
Herman: give me a sec and I'll whip up a test right away
Russell: Harpoon3.ini setting
Russell: SonarLogOut=ON
Herman: this is 394 or 310?
Russell: 3.10
Herman: k
Herman: do I need AALogs on?
Russell: Let me check
Russell: No
Herman: sonar logs are blank
Russell: It will create a SonarLog.txt file alongside the scenario.
Herman: right.  I see the file
Herman: nope.  nothing
Russell: Hmm, checking.
Herman: helo does not appear
Russell: Sonar active?
Herman: it's a transport helo
Herman: I'm trying to show you that helos don't get detectd
Herman: it's the Active sonar that is detected, IMO
Herman: if you want to go messing with this, you might have to also account for planes that swoop down to VLow alt, won't you?
Herman: i.e. planes coming down to drop buoys or planes coming in at 30m
Russell: Sonobuoys aren't messed with. The helicopter with dipping sonar does have to be active.
Russell: The passive sonar sensor has a shot at detecting it.
Herman: the sub sonar sensor can detect a passive helo at VLow?
Russell: So saying it's detecting the active sonar isn't wrong.
Herman: can you tell me which sub/helo combo you are using?
Russell: I'm reading the code.
Russell: I didn't say a passive helo could be detected.
Herman: ah
Russell: The passive sonar sensor has a shot at detecting it.
Russell: It being an active dipping sonar.
Herman: ah, okay
Russell: Fixed the logging.
Russell: Was requiring a successful detection to write to the log file.
Herman: the only thing that is changed is the fact that the helos on sonobuoy mission might now be detected
Russell: Or maybe more.
Russell: I'd have to test it out to see if the code proves true (or if I'm missing something)
Herman: I guess planes are no longer able to get down to 10m alt
Russell: Low flying sonar active hovering (0 speed) aircraft seems to be the requirement.
Herman: I agree that any helo at VLow and Hover should stand a chance of detection by a sub, but it seems like so much work to add such little additional returns
Russell: Exempting land based units from sonar detection might actually give a speed boost.
Russell: Detection is the most expensive part of the game engine.
Herman: quite possibly
Herman: I'll ask Jason when he comes back
Herman: he's the former sub sonarman
Russell: Yep.  I'd like to hear what he has to say.
Russell: But, I think the sonar vs. land unit issue falls further down the scale of return vs. effort.
Herman: down?  I'd think it was high, given the fact that a lot of detection cycles can be removed
Russell: I mean there will be little return for high demand of cpu cycles.
Herman: are you sure there is a sonar vs land detection cycle?
Herman: ah, right
Herman: the only problem seemed to be in the Active
Russell: I've already made the change in the code but if anyone has a valid point I'll make it optional.
Herman: did sonar actually try to detect land units passively, too?
Russell: Does not appear so
Herman: I wonder if you make a blanket change if it will affect any other type of land detection
Herman: for example, if you are in command of a sub and the enemy land unit fires on your sub or on a land unit from your side, should it turn red/hostile?
Herman: (I don't think that there are many/any land units with ASW ordnance)
Russell: Would the sub detect the launch by sonar?
Herman: no
Russell: This is a strictly a change to sonar detection.
Herman: okay.  I'm just trying to think of potential side-effects
Russell: It's a simple change so I can put out a beta.  If we find something negative it's a simple change back or new option.  Whichever is appropriate.
Russell: But there's a few days before I even put out that build
Russell: So there is time to consider.
Herman: Is AGSI even considering putting out the old versions of H3 like Tony seems to be suggesting for HCE?
Russell: I believe it was Don's idea so ya.
Herman: okay, good to hear
Herman: need anything else from me?
Russell: Not now.  Thanks for the bug report.
Herman: okay. ciao

[/blockquote]

As discussed briefly with Russell on IRC, I think that a passive sonar might be able to detect a very loud or vibrating shore unit (such as a piece of heavy machinery operating close to water, like at a dock), but in most all cases noise from shore units are going to be drowned out by the surf. I don't think the detections would be worth the CPU power.

Low flying aircraft are detectable by sensitive passive sonars. Harpoon 4 paper rules account for this.

[Deleted by Admins]

ORIGINAL: VCDH

Also don't forget Acoustic Intercept, where a sonar set can detect other active sonars that are pinging in the region.  This accounts for the helicopter detection in the game.  Helo dipping sonars are typically HF [sometimes MF] and are usually very easy to detect via AIR.  So you do not detect the helicopter but rather the active sonar at the end of the cable that the helo is lowered, giving you the information that a helo is around. 

There is at least one exeption....... the Tu-95 Bear makes such noise that it can be detect by submerged submarines. [:D]

[Deleted by Admins]

ORIGINAL: rsharp@advancedgamin

Should sonar sensors be able to detect land based units. What exceptions might exist and are they worth CPU time?

Okay, I put the question to a former USN sonar tech and "Jonesy's" reply was along the lines of, [blockquote]'if the water conditions are right and you are in shallow water, you might hear the launch of the space shuttle from a sea-side location. You wouldn't get much bearing on it other than knowing it happened and you might be able to come to periscope depth fast enough to snap a picture of it.'[/quote]
With regards to the detection of low-flying helos, could the reason why sonar was never able to cross the sea-air interface in order to detect helos at hover and VLow altitude be that it would be too memory intensive?

Sonar could detect active sonar emissions from a dipping sonar, but it never actually detected the helo, itself. So, was this a handy work-around implemented to save CPU detection cycles?

If you decide to make sonar able to detect things in the air above a submarine, I suspect that this will really suck up CPU cycles because the game would have to track all the missiles, planes, helos that may be buzzing over a submarine. Even if the only case of possible detection is specified as "Helo at VLow and Hover", that still needs to be checked each and every time.

At present, I think that the only significant things not being detected by sonar are the helos which deploy sonobuoys. They lay them and are not currently counter-detected by sub sonar when they hover. Would the additional sonar detection capability for this specific situation justify the increased slowness to the game?

Sonar sensors would not be able to pick up land targets, but they can pick up helicopters and low flying aircraft....

RobP