problem with passive sonar BQQ-10 in Improved LA,please help

[abc]

First few (3 or 4) LOBs are always totally wrong, then I cannot calculate any fire solution in TMA because everything looks pretty unlogical?
but, then after first few LOBs - other LOBs are OK !!!!???? and I don't know why???

[abc]

And one more question - is it possible to stop propeller on nuclear submarine??
sorry on my bad english

[HydroShok]

The towed array gets pushed around in the water so it kicks back slightly inaccurate bearings.

I haven't seen the sphere or hull array get like that though.

[sonar732]

Originally Posted by abc

First few (3 or 4) LOBs are always totally wrong, then I cannot calculate any fire solution in TMA because everything looks pretty unlogical?
but, then after first few LOBs - other LOBs are OK !!!!???? and I don't know why???

Sounds more like your problem is TMA and not sonar. Do you have the auto-crew set for TMA? A thought to help is to create a simple mission with a tanker or trawler and change the course or speed. Granted, you can change your course also.

[OKO]

Originally Posted by abc

First few (3 or 4) LOBs are always totally wrong, then I cannot calculate any fire solution in TMA because everything looks pretty unlogical?
but, then after first few LOBs - other LOBs are OK !!!!???? and I don't know why???

in fact, the first LOB is never to use on the TA.
It takes 4 minutes to calculate the first LOB then 2 minutes for other LOBs

you have also to check you didn't tracked the mirrored image, comparing TA to SA, and, if it's not possible, making a turn at least 20° from your previous course.

read manual page 13-12 : towed array contacts

[Bellman]

While making such a turn you have to consider firstly whether you may baffle the contact/s
and secondly whether a much greater degree turn is also required to clear the prow TA baffle and the 120 deg (LwAmi)
stern SA baffle. Much greater thought has to be given to planning turns which rarely seem to be merely for TMA purposes.

[abc]

well, it's not towed array contact, it's spherical array contact
and I made simple mission in mission editor, tracking Perry class fregate, few miles away
and even I know exact course - 26 and speed - 29knots of target
but still I cannot calculate solution in TMA (without autocrew) because LOBs are very inaccurate
but after some 10 minutes of tracking, LOBs become OK!!!??? Just firsts few LOBs are inaccurate, othhers LOBs are totally OK, I don't know why???

[abc]

but Active Intercept - every yellow LOBs are very precise
with just 3 or 4 of them I can easly find right fire solution in TMA
looks very nice in TMA

[LuftWolf]

The LOB's will be corrupted for any passive sonar sensor if you are changing speed or course during their recording, and I beleive if you are going too slow (say under 5kts)

If you are going at least 5kts and are not making any speed, depth, or course changes, then the LOB's should be recorded accurately.

You should also be aware than less than 10 minutes of LOB recording is rarely ever enough to get TMA. Often you have to track the contact for more than 20 minutes and make multiple course changes to actually get reasonably good TMA on a contact, so your expectation of having a 10 minute TMA solution is probably adding to your frustration here.

[abc]

Well I'm not changing speed, course and depth,
things are very simple;
my speed - 14 knot, my course - 90, my deth - 185 fts - constant without any changing
and target - speed 29, course 26 - constant without changing too
but still I cannot calculate any solution because LOBs are inaccurate and they looks totally unlogical in TMA??? why?

[abc]

Well I'm not changing speed, course and depth,
things are very simple;
my speed - 14 knot, my course - 90, my deth - 185 fts - constant without any changing
and target - speed 29, course 26 - constant without changing too
but still I cannot calculate any solution because LOBs are inaccurate and they looks totally unlogical in TMA??? why?

[LuftWolf]

Are you taking into account the fact that the first LOB occurs when you mark the contact and the second LOB occurs four minutes later?

[OKO]

Originally Posted by abc

Well I'm not changing speed, course and depth,
things are very simple;
my speed - 14 knot, my course - 90, my deth - 185 fts - constant without any changing
and target - speed 29, course 26 - constant without changing too
but still I cannot calculate any solution because LOBs are inaccurate and they looks totally unlogical in TMA??? why?

if you make a TMA on a single tracker, you need at least 7 LOB and the speed (easier) to make an accurate one.
You need 3 LOB with merged trackers (TA & SA).

If you try a TMA with only 3 LOB on a single track, you just can't find anything accurate, because there is wide choice of different solutions.

so ... wait at least 7 clean LOBs.

[MaHuJa]

The problem he is speaking about is that you have to disregard at least the first LOB.

The first line is created as you assign the tracker, and the second one some 2-4 minutes after that. Only the first line isn't at the exact 2-minute step, but the tma screen still seems to assume that it is.

At least, that's what I think the problem is.

[Bellman]

abc:

then after first few LOBs - other LOBs are OK

OKO:

so ... wait at least 7 clean LOBs.

MaHuJa:

The problem he is speaking about is that you have to disregard at least the first LOB.

QED.