frustration on TMA

[KungPao]

I have some frustration on TMA
"Redbook" says the dual sensor tracking should represent the truth, but looks like it doesn't work in DW

I am tracking an oiler ship, I got it on sphere passive and TA. I try to find the place where the two line connect but it doesn't work. After 20 min 's frustration on where to put the ruler, I turned the truth on. Mark the accurate location, and this is a TMA solution to reflect the ship's accurate location.

I don't understand why there is a huge difference from the two dots on the top. Did I do something wrong?

Thank you

[ET2SN]

You probably turned or changed speed.
That will throw off the towed array data.

Don't think of TMA like its a radar, TMA works over time and is, at its best, an estimate.

[FPSchazly]

In addition, the two lines from each sensor must come in at the same time, otherwise it will not depict an accurate intercept. Also, the towed is known to produce data with a noticeable error at times. However, I have yet to figure out the conditions for this to happen. With the slim angle between the two sensors' data, any small error will have large implications for where the intersection lies. In my experience, sensors like the spherical/cylindrical or conformal don't get this noise in their data. Traditional TMA techniques are by far the more reliable method than the intersection technique. Intersection can be good for a ballpark range, but really just for contacts that are rather close where the large angle between sensors' data will far outweigh the towed bearing error.


For clarification, I was not talking about the bad towed data you get when the towed is moving around from a depth or course change. That is also something that invalidates the intersection range method. Sometimes even when the towed is in steady state, I'll get noisy data. Typically for faint, distant contacts.

[KungPao]

Hi ET2SN and FPSchazly. Thank you for your answer
I reload my save. I can confirm there was no course change. I wish I can upload the save file here.
the save was recorded on 12:10, there was a depth change on 12:07. I am not sure if that causes the error.

I can image that in RL and in game, the TA's data will have error. But for this case, it is the sphere passive generated the most error. If you can take a look at that TMA again, you will see there is gap between the head of the ruler and the first white line. And the dot leanning to the right side is the data from sphere pass.
I can take a guess on what's going on. But I am a newbie, so I will need vetern divers' opinion, my guess the root of cause is : I assigned the cotact via broadband on sphere pass.

Originally Posted by FPSchazly

In addition, the two lines from each sensor must come in at the same time, otherwise it will not depict an accurate intercept.

My understanding is the sensor in DW will provide an update to TMA once a minute, so the updates come in at different time should not be an issue?
From my save , I assigned contact through sphere pass' BB at 12:04:55. assigned contact through TA's NB at 1205

Originally Posted by FPSchazly

Traditional TMA techniques are by far the more reliable method than the intersection technique.

Is there any good read or viedo to learn this Traditional TMA Techniques?



Thank you

[KungPao]

Another a little OT question:
Does LA class have DTA indicator in RA mod?

[ET2SN]

Originally Posted by KungPao

Is there any good read or viedo to learn this Traditional TMA Techniques?



Thank you

Yes, watch Chazly's vids on YouTube. (blatent FPSChazly plug)
Honestly, Charlie does a really good job of explaining TMA and target tracking. Check his YouTube page for his "basics" vids and mission play-thrus.

You need to think about how that towed array works, its a long cable that streams out of the back of the sub. Since its a cable, it bends when you turn.
DW also tries to model how sound travels underwater and that discussion would take about a week.

[FPSchazly]

Originally Posted by ET2SN

Yes, watch Chazly's vids on YouTube. (blatent FPSChazly plug)
Honestly, Charlie does a really good job of explaining TMA and target tracking. Check his YouTube page for his "basics" vids and mission play-thrus.

I've wanted to come up with a more advanced tutorial but it's tricky. I'm not sure it would be anything more than just going over several tracking scenarios. So much of TMA is just developing a feel for it, once you get some basics down.

Looking at that plot up there again, the towed data is diverging towards the end there (by "end", I mean the arrow of the ruler and the top of the data in the dot stack, as both of those places are where the most recent data show up). I also notice that each sensor has 6 pieces of data but the data don't appear to be for the same track - it doesn't look like the latest towed data and spherical data would intercept anywhere based on the lines of bearing I can see on that plot. Were there any other contacts? You know about mirror contacts, yes? Merging two contacts that aren't the same target can be the hardest error to diagnose when doing TMA. I don't always do this myself, but it would be a good idea to try and develop solutions for contacts independently to see if they indeed line up before merging.

Also, I could be completely wrong, but I think redbook was written for Sub Command, yes? From my experience, that game models no error in sonar data and it doesn't even model the towed giving bad data when it's turning. Both phenomena happen in Dangerous Waters, as mentioned.

Hope this helps!