Tracking Active Sonar Contacts

[Mob1us0ne]

Originally Posted by PL_Harpoon

I'm far from being an expert here, but aircraft RWR can give an accurate bearing. I'm sure ECM systems on submarines is even more sophisticated.

Originally Posted by Shadriss

Also, in reply to the comment about Signal Strength being an indicator of range, I know a few people who have been involved in collisions who would argue against that.

I'm a former USAF ECM troop and can confirm the bit about accurate bearings from RWR and I'm sure the RX mode on a sub or sea based ESM mast uses the same method of operation. Bearing info is highly accurate, it has to be as the operator needs to inform the vehicle commander threat direction for evasion.

Using single strength for range info is very dicey. As a general rule the processors can estimate range, but even on our TSF display (tactical situation format, B-1 version of RWR) there's only three rings: close, mid, and far. But they really mean low, mid, and high signal strength as it's mainly for threat prioritization.

Does that make sense? I talk a of jargon

[PL_Harpoon]

Originally Posted by Mob1us0ne

I'm a former USAF ECM troop and can confirm the bit about accurate bearings from RWR and I'm sure the RX mode on a sub or sea based ESM mast uses the same method of operation. Bearing info is highly accurate, it has to be as the operator needs to inform the vehicle commander threat direction for evasion.

Using single strength for range info is very dicey. As a general rule the processors can estimate range, but even on our TSF display (tactical situation format, B-1 version of RWR) there's only three rings: close, mid, and far. But they really mean low, mid, and high signal strength as it's mainly for threat prioritization.

Does that make sense? I talk a of jargon

I guess the problem is that a sub is using a single antenna. Am I right in saying that an aircraft have multiple RWR antennas scattered in different places and so it is easier to get an accurate bearing?

[Mob1us0ne]

Originally Posted by PL_Harpoon

I guess the problem is that a sub is using a single antenna. Am I right in saying that an aircraft have multiple RWR antennas scattered in different places and so it is easier to get an accurate bearing?

Those antennas are actually rather small. I don't know this for a fact (and I'm sure of the Navy vets here could confirm, though probably unable to) you could easily place those types of antennas on a mast. In fact as an ECM guy the near perfect 360 degree search area you get from that is pretty much.

BTW. I hope I'm not stepping on any toes as a newbie here. I've been lurking here for a long time because I love sub stuff and have dabbled with subsims. Though honestly most have been a tad over my head besides RSR. And I don't have the game yet but it seems more up my alley. So yeah, hello!

[Capt Jack Harkness]

Originally Posted by PL_Harpoon

I guess the problem is that a sub is using a single antenna. Am I right in saying that an aircraft have multiple RWR antennas scattered in different places and so it is easier to get an accurate bearing?

Newer planes, sure. Older systems could only tell you the quadrant.

[Destex]

Originally Posted by Mob1us0ne

I'm a former USAF ECM troop and can confirm the bit about accurate bearings from RWR and I'm sure the RX mode on a sub or sea based ESM mast uses the same method of operation. Bearing info is highly accurate, it has to be as the operator needs to inform the vehicle commander threat direction for evasion.

Hi Mob1us0ne, and welcome.
No one claimed it's not possible to analyze accurate bearing to electromagnetic transmissions. However, Ground or aerial ECM systems are not relevant as the technological challenge in a submarine is different.

First, as Harpoon says, there's a single mast.
Second, that mast is small and can't contain a lot of nodes which are necessary for signal strength interpolation - the basis of bearing measurement. As much as the nodes are fewer and smaller the bearing analysis is less accurate.

Aerial systems have the luxury of size, number of nodes and different locations on a rather large body in comparison. Try to cram all that into a tiny tiny sub mast, there will be several compromises, bearing accuracy being the first casualty. Also, on aircraft the fast self movement can be used to some extent (just a theory, I don't know for sure if indeed it is), another aspect lacking in submarines.

Therefore, at least up to the 80's if not later than that, submarine ESM systems could not provide accurate enough bearing measurements that can be used for reliable passive TMA calculations.

[Mob1us0ne]

Originally Posted by Destex

Hi Mob1us0ne, and welcome.
No one claimed it's not possible to analyze accurate bearing to electromagnetic transmissions. However, Ground or aerial ECM systems are not relevant as the technological challenge in a submarine is different.

First, as Harpoon says, there's a single mast.
Second, that mast is small and can't contain a lot of nodes which are necessary for signal strength interpolation - the basis of bearing measurement. As much as the nodes are fewer and smaller the bearing analysis is less accurate.

Aerial systems have the luxury of size, number of nodes and different locations on a rather large body in comparison. Try to cram all that into a tiny tiny sub mast, there will be several compromises, bearing accuracy being the first casualty. Also, on aircraft the fast self movement can be used to some extent (just a theory, I don't know for sure if indeed it is), another aspect lacking in submarines.

Therefore, at least up to the 80's if not later than that, submarine ESM systems could not provide accurate enough bearing measurements that can be used for reliable passive TMA calculations.

Ok, Yeah that makes a lot sense. Like I said, I'm a zoomie not a navy guy and mind is geared to the clouds lol

[Shadriss]

Originally Posted by Destex

...
Second, that mast is small and can't contain a lot of nodes which are necessary for signal strength interpolation - the basis of bearing measurement. As much as the nodes are fewer and smaller the bearing analysis is less accurate.

You're mixing things up there. Signal Strength is NOT an indication of bearing... it's an indication of how strong the signal is compared to background. Kind of a Radio version of Sonar's SNR values. You can have an extremely low SS and still get very accurate bearings. What SS will NOT give you is a range estimate. As I hinted at, there have been a few collisions at sea that were caused, in part, by operators assuming that lower SS equated to more distant contacts, that that is not always a true statement.

Now, needing multiple receptors for bearing accuracy is a true thing - that's basic beamforming, and those principles work the same way for radio and sound waves. So, going back to some of my earlier comments on this, depending on the ESM suite and equipment installed, bearings can be taken from the system with some degree of accuracy.

[Destex]

Originally Posted by Shadriss

You're mixing things up there. Signal Strength is NOT an indication of bearing... it's an indication of how strong the signal is compared to background. Kind of a Radio version of Sonar's SNR values.

I never wrote that SN is an indication of strength. However, the way bearing is analyzed in at least a large portion of naval ESM systems is by calculating the different strengths on the different antenna nodes, and interpolating the bearing. There might be other methods for bearing analysis, but the process I described is definitely in use.

Originally Posted by Shadriss

What SS will NOT give you is a range estimate.

Definitely true. I'm not sure what I wrote that gave you the impression.

Originally Posted by Shadriss

depending on the ESM suite and equipment installed, bearings can be taken from the system with some degree of accuracy.

In the Cold War era? Enough for TMA?

[Shadriss]

Originally Posted by Destex

Definitely true. I'm not sure what I wrote that gave you the impression.

Misread what I quoted. My mistake.

In the Cold War era? Enough for TMA?

A lot of ships are still plowing around with tech and systems from that era. It would be a pain, and would involve a bit more mast exposure than most skippers would be comfortable with, but yes, it could be done. But as I also noted, it would be far easier and safer (for the ship) to just use PBB and PNB instead.

[Destex]

Originally Posted by Shadriss

it would be far easier and safer (for the ship) to just use PBB and PNB instead.

That's for sure. In the context of Cold Waters gameplay, do you think that tracking ESM contacts should contribute to TMA solutions?

Personally, I would rather have ESM tracks to provide classification (ignoring that in real life different platforms might use the same radars for the sake of simplicity), and active intercept tracks to create targets that can be TMAed (slowly, unless tracked by a passive Sonar array).

[The Bandit]

Originally Posted by Destex

That's for sure. In the context of Cold Waters gameplay, do you think that tracking ESM contacts should contribute to TMA solutions?

Personally, I would rather have ESM tracks to provide classification (ignoring that in real life different platforms might use the same radars for the sake of simplicity), and active intercept tracks to create targets that can be TMAed (slowly, unless tracked by a passive Sonar array).

Well I'd suggest the same way it was done in SC / Dangerous Waters (don't really mean the classification part but that would be nice).

What I'm talking about is, when you get either an active intercept return or an ESM contact with a lot of uncertainty a contact is placed on the map at an arbitrary position (say 10 miles out?) with a NIL listed range (in other words when you click on it, instead of saying 5.5k yards, it has a NIL/Unknown value for range, letting you know the range is not known and its not necessarily where its marked on the map, other than along that approximate bearing, so you get some visualization as to the number of contacts you have out there).

My (admittedly limited) understanding of both ESM (with the obvious exception of its reconnaissance / information gathering value) and Active Intercept is that both of these exist as warning systems first and foremost (something is pinging / radiating somewhere off to the NE of us) than they are a means for classifying (obviously they can do this and probably pretty well) or even localizing a contact.