A completely different active sonar question

[Palindromeria]

In several novels I've read , the sub skipper refers to the enemies use of active sonar (lets call it a dd for simplicity) as painting a picture of the entire area for the sub, in addition to giving away the dd's pos

in other words

the active sonar (presumably omnidirectional)
from the nasty dd allowed our hero sub
to detect 2 nasty subs that were otherwise silent.

i am assuming this is realistic, simply because it makes sense.
if so,

is this at all do-able in dw ?

thoughts ?

[Palindromeria]

no thoughts ?

k - i am sure 1 of the novels that describes this was SSN by clancy, in which cheyenne effectively renders the chinese navy useless.


i think i also came across it in one of Patrick Robinsons books, but dont recall which.

I am sure it was NOT "Slider"

[Dr.Sid]

I think you should see pings and returns on BB. I think half-active can't give you range, only direction.

I'm quite sure in DW you can't do this. You only see pings in active display, and only yours.

[Palindromeria]

Originally Posted by Dr.Sid

I think you should see pings and returns on BB. I think half-active can't give you range, only direction.

this kinda makes sense to me as well.

i am fairly certain that clancy describes cheyenne pinpointing range and bearing
of enemy subs as result of the dd pings though.

maybe the range is a result of triangulation from the
source bearing to return echo bearing ?

k - so its not at all do-able in dw.

still, any more insight would be interesting to learn about.

thanks,
pal

[Wim Libaers]

Originally Posted by Palindromeria

this kinda makes sense to me as well.

i am fairly certain that clancy describes cheyenne pinpointing range and bearing
of enemy subs as result of the dd pings though.

maybe the range is a result of triangulation from the
source bearing to return echo bearing ?

k - so its not at all do-able in dw.

still, any more insight would be interesting to learn about.

thanks,
pal

If you know the position of the dd, it should be possible.

[Henson]

Sound does not move two-dimensionally. We pretend that it does so that TMA becomes do-able. When you get into active sonar, it is one of the worst-modeled parts of the game for that very reason. Take active in DW with a LARGE grain of salt.

[Wim Libaers]

Apparently, some people have even been able to perform passive sonar imaging of objects, using the background noise provided by shrimp. Extremely short-ranged though, and low resolution http://extreme.ucsd.edu/Research/Aco...cDaylight.html

Another technique that can be used is detonating an explosive charge, and checking for anything that reflects the resulting pulse. The idea is similar to the detection of secondary reflections of someone else's active pings, except in this case you usually know exactly where and when the charge will be detonated.

[Dr.Sid]

Yeah .. if you know source of the sound, you can get range too. If he pings for some time, you can obtain sound source fix with TMA. Then you get also fix to the source of the return.

[SeaQueen]

Originally Posted by Henson

Sound does not move two-dimensionally. We pretend that it does so that TMA becomes do-able. When you get into active sonar, it is one of the worst-modeled parts of the game for that very reason. Take active in DW with a LARGE grain of salt.

The whole sonar model should be taken with a grain of salt until we have to worry about things like cutoff frequencies, doppler, shallow sound channels, multistatics, waveforms, etc.

If you're shrewd you can make a scenario that captures some of the flavor of things but it still falls WAY short of how complicated things really are.

[SeaQueen]

Originally Posted by Wim Libaers

Another technique that can be used is detonating an explosive charge, and checking for anything that reflects the resulting pulse. The idea is similar to the detection of secondary reflections of someone else's active pings, except in this case you usually know exactly where and when the charge will be detonated.

Yes, that's how EER sonobuoys work. It's called multistatic acoustics.

[Palindromeria]

ok doke !

in the Clancy writing im pretty sure they were tracking the dd with passive and therefore knew its position.

so i guess the answer is
YES it is realistic that the "Hero sub" was able to suss out the 2 nasty subs as result of the dd ping, which is really what i was hoping to understand.

i always appreciate learning something new and
thank you all for the responses and enlightenment.

-----
as for dw - no i dont expect this type of detail.
Besides even if it was occuring i likely wouldnt be able to see the blip anyway

but
JUST out of sheer curiosity ,
IF it were occurring within DW - how do YOU think it would affect gameplay ?

(dramatically , minimally , not at all, not worth discussing)

maybe those human Orions wouldnt drop 100 active sonobuoys cause theyd give away their allies ? etc

thanks again !
dave

ps- "Slider" is truly a good read if you like baseball .

[SeaQueen]

Originally Posted by Palindromeria

so i guess the answer is
YES it is realistic that the "Hero sub" was able to suss out the 2 nasty subs as result of the dd ping, which is really what i was hoping to understand.

I'm not convinced. That sort of multistatic arrangement might be theoretically possible, but you'd have to pull some stuff off first. To take advantage of that kind of specular reflection, you'd need to have a pretty good idea of where the sound source was. If you didn't know that, then you wouldn't know what to make of the energy. It'd just be noise. My instinct is that there'd also be all kinds of signal processing issues. Multistatics is NOT a trivial thing, and I think the author is definitely making a bit of a leap there. Because of that, it's extrordinarily unlikely that by turning on your active sonar, you'd illuminate targets for the enemy.

JUST out of sheer curiosity ,
IF it were occurring within DW - how do YOU think it would affect gameplay ?

I don't see it discouraging me from using active sonar at all. First off there's the reasons I've already stated. There's also a waterspace management issue, what business does a friendly SSN have in the same area being searched by a P-3? He's begging to have a torpedo dropped on him! If that was the case, he'd deserve whatever was coming to him just for being dumb.

If multistatic acoustics were implemented in DW, I'd be very happy because P-3s would be able to use EERs which have source levels WAY beyond what a dinky little DICASS can manage. I'd actually enjoy it because it'd add a new layer of sophistication to the game if it was implemented correctly. I'd be very complicated, though. You'd bang, and then you'd have to somehow monitor all the listening sonobuoys for a while, then bang again after a while, etc. I don't see any easy way of doing it.

[XabbaRus]

I read that in Tom Clancy's SSN, which should say it all really.

Tom Clancy tends to embelish things a little bit.....

[Palindromeria]

ok - sounds like im back to "maybe but unlikely"

ive only read a couple of his works and was not aware of such embellishment.

the ssn book did read like an arcade game,
and i really was wondering if it was all on the mark.

thanks !

big red triangle to ya !

dave

[SeaQueen]

Originally Posted by Palindromeria

ok - sounds like im back to "maybe but unlikely"

I'd say it's more like an ice cube's chance in hell. Multistatic acoustics are pretty cool, but there's a fair amount of voodoo to it. Pulling what they described off is not nearly as straightforward or they make it sound like.

ive only read a couple of his works and was not aware of such embellishment.

Early Tom Clancy was actually pretty good compared to a lot of stuff other there. I think there was an attempt at trying to bring some authenticity to his work. The thing is, ultimately it's fiction. At the points it breaks down, though, it's kind of a joke to people involved in actual naval matters.

Tom Clancy isn't a navy man. He's an insurance salesman with a penchant for right-wing radio talk shows and macho man military fantasies. He got into wargaming and made friends with people who actually did have a great deal of experience in naval matters and used them to lend a certain authenticity to his early books.

The thing is, he's just that. I don't even think he writes his own books anymore. He just hires ghost writers. He's become a brand name more than anything else.