[FIXED] MAD detection of subs

[JamesHunt]

Always wondered about this.

I have read alot about MAD/SAD and all military sources that I have sighted state the effective detection of MAD vs subs is about 500 - 1200 feet and almost all sources state that MAD is not viable for first contact pick-up but that it is almost exclusively used for final comfirmation and final weapon solution determination.

Account by an Naval officer who worked with MAD in anti-submarine-warfare:
"The MAD gear is sensitive to about to 1200 feet depth; considering you are at 200 feet, you can detect a sub at aproximately 1,000 depth below the water."
https://books.google.de/books?id=nhgpDw ... or&f=false

Note the "to about 1200 feet". Conditions and submarine construction countermeasures can lower this range. Also note that this is calculating the plane´s height into it.

This account is consistent whith what most other military sources state about the performance of MAD.

I had incidents where my old Helix ASW helo was casually strolling back to base and accidentally located distant + deep enemy subs like the Seawolf or modern diesels via MAD and instantly killed it [:D]

The ingame MAD range of 1 nautical mile aka ~6000 feet is "extremely generous". Taking the theoretically best possible performance calculation provided by the naval officer and almost all other sources into account, Command´s MAD still overperforms by ~500% in regards to distance. Considering that magnetic fields decrease as the inverse cube of distance you may get an idea on how big the MAD sensor sensitivity discrepancy is: 4000%, but don´t quote me on that last number, no math pro.

[AndrewJ]

Here's a repost of some information I'd added to another thread last year, with a bit more added.



I have to admit that as a player I love MAD on my side, since it makes sub detections so easy. Flying over a sub within a little under a mile slant range (half that for non-magnetic hulls) will give you a perfectly accurate positional detection. I hate it when it's on the enemy side, since it's pure luck of the draw whether an aircraft on its random patrol path happens to pass nearby, in which case you almost always lose the sub if the enemy's armed.

Up to this point I'd not seen any hard figures about the range to which actual MADs worked in the real world, but the other day I accidentally came across a report titled "AR70-14 Soviet Antisubmarine Warfare: Current Capabilities and Priorities". This is is a formerly Top Secret report from the CIA's Directorate of Science and Technology, which was published in 1972, and declassified for public release in 2017. You can read it on the CIA's website here:

https://www.cia.gov/library/readingroom/docs/DOC_0005512850.pdf


As of the early 1970s, it gave the following summary:

[font="Times New Roman"]"Presently operational saturable-core magnetometers are sensitivity limited and can provide detection ranges of 1,000 to 1,400 feet under favorable conditions. The newest optically pumped magnetometers have a sensitivity of 0.1 gamma, and can obtain detection ranges of 2,000 feet under good conditions."[/font]

and

[font="Times New Roman"]"Present Soviet aircraft MAD gear is estimated to have a detection range of 1,500 feeet. The Soviet's extensive effort in MAD sensor technology should allow them to extend this somewhat. Evidence from recent naval aircraft operations indicates that improvements have been made. Their weakness in signal and data processing will probably limit them to at most a 50% increase in range in the near future."[/font]


What strikes me about this is that the ranges are much shorter than those currently modeled in CMANO, where reliable detections occur out to ~1 nm, which is 6076 ft. Here they're talking about operational and newly developed sensors with ranges of only 1,000 to 1,400 feet (0.23 nm), 1,500 feet (0.25 nm), or 2,000 ft (0.33 nm) and that's only when conditions are good. Presumably the situation would be worse in shallow waters, where the seafloor could interfere, or near other naval vessels, which would generate false signals. The report does mention potential technological improvements to improve magnetometer sensitivity (superconductivity!), but also seems to imply that it may be difficult to make use of such improvements given the natural environment.


It turns out that sensor platform speed (helicopter vs MPA - it's easier to spot the signal when you pass over it quickly), wave (magnetic) noise, altitude (better to be further away from the waves), geomagnetic noise (space weather), geological noise (local anomalies) all have effects on MAD detection ability. This 1976 report (Speed and Depth Effects in Magnetic Anomaly Detection) for the US Navy suggests these factors combine to give useful detection ranges of approximately 1350 feet.
https://apps.dtic.mil/dtic/tr/fulltext/u2/a081329.pdf


A 1994 thesis for the Naval Postgraduate School, "A Limited Analysis of some Nonaccoustic Antisubmarine Warfare Systems", suggests that these factors would give an effective range for the P-3's AN/ASQ-81 of a little under 500m (1640 feet) against a typical diesel sub.
https://apps.dtic.mil/dtic/tr/fulltext/u2/a281747.pdf


The most recent MADs seem to have improved their performance somewhat; no doubt advances in signal processing have helped greatly. CAE, makers of the later AN/ASQ-508 MAD, and the recently developed MAD-XR, mentions detection ranges of "approximately 1,200 metres" (3937 feet) in their most recent promotional literature, although this is somewhat at odds with lack of recent enthusiasm for MADs in general. (Treat all promotional literature with caution, of course.)
https://www.cae.com/media/media-center/documents/datasheet.MAD-XR.pdf
https://bricanflightsystems.ca/wp-content/uploads/2018/05/%C2%A9_BFS_TD_100_Class_II_UAV_ASW_SubDetect.pdf


One complication is that it turns out that the strength of the magnetic anomaly varies greatly depending on the relative orientation of the searcher's flight-path, the orientation of the sub, and the specific local magnetic field. A system which may give a good detection range in one pass, may have a much smaller detection range in another. See these papers for detailed mathematical examples:
https://apps.dtic.mil/dtic/tr/fulltext/u2/1012958.pdf
https://apps.dtic.mil/dtic/tr/fulltext/u2/1012961.pdf

This recent (2015) Chinese paper on MAD detection highlights the variability. A sub detection which happens at nearly 800 m (~2,600 feet) flying at very low altitude in ideal orientation can drop to less than 100m (~ 300 feet) if you fly higher and the sub changes direction. (Yes, vertical separation does matter.)
http://www.jestr.org/downloads/Volume8Issue4/fulltext84172015.pdf



That's a lot of variation!


So based on my highly informed opinion (translation: after few hours of bewildered Googling), it looks like the current MAD model in Command is somewhat optimistic. Even the most modern figures I found don't reach the current 1 mile range that's in the database.




I think that think that reducing the range for the generic MAD in the game would be a good idea. Although identifying the performance of individual MAD systems would be very difficult, given the scarcity of information, it might be a good idea to replace the one 'Generic MAD' sensor with several generations of generic sensor, each covering a decade or two, and gradually stepping up detection ranges from generation to generation. Given the amount of variation MAD sensors seem to encounter, I'd suggest stepping back the detection range claims for the most modern systems a bit. I'm not sure if it would be worth modelling different magnetic signatures depending on sub size too.


I want to add that there is a game-mechanics caveat about this.

Currently MAD detections seem to be be checked every 15 seconds. (Hover a helicopter near a sub you have detected by MAD only. I think you'll see the white contact age numbers counting up to 14 seconds and then resetting in a continuous cycle.) For a fast-moving aircraft, such as a P-3 loitering along at 205 knots, this means one detection is resolved every 0.85 nm. If the MAD had a more realistic range of 0.25 nm, for example, then there would be gaps in the search pattern. Since the MAD sensor is presumably receiving continuously, a quicker detection check interval would be needed to simulate the continuous coverage.

[AndrewJ]

Just a note to add, it is not completely unrealistic to use MAD as a search sensor. Although it is usually for refining a pre-existing contact, MAD patrols across straits and chokepoints are actually used for primary target detection.

MAD patrols of this type were used in combat in WWII. Here's an example from 1944, where a PBY patrol across the Straits of Gibraltar successfully detected a submerged U-boat with MAD, and then participated in sinking it.



https://apps.dtic.mil/dtic/tr/fulltext/u2/221590.pdf

[SSN754planker]

I want to add that there is a game-mechanics caveat about this.

Currently MAD detections seem to be be checked every 15 seconds. (Hover a helicopter near a sub you have detected by MAD only. I think you'll see the white contact age numbers counting up to 14 seconds and then resetting in a continuous cycle.) For a fast-moving aircraft, such as a P-3 loitering along at 205 knots, this means one detection is resolved every 0.85 nm. If the MAD had a more realistic range of 0.25 nm, for example, then there would be gaps in the search pattern. Since the MAD sensor is presumably receiving continuously, a quicker detection check interval would be needed to simulate the continuous coverage.

If this is the case, wouldn't that make MAD detection a bit harder because the p-3 may fly right over between "ticks"

But helicopters would not have that problem. But a heli on top of you as a sub driver means certain death a lot of the time. But this is also true IRL. A heli is always the larger threat than fixed wing MPA.

[SSN754planker]

Also the way "random" way ASW patrol boxes set up by ref points work now, i have noticed it may take a good amount of time for a MAD contact to happen, if ever. The sonobouys being dropped nail them before a MAD flyover would.

[Herman_Hum]

Its too strong in the sim. The best `in your dreams` MAD range you can hope for is about thousand to 1200 ft. This is not different for Soviet, nor Russian, nor PLAN mad systems. First contact utility is almost nil. Subs in great depths are basically undetectable by it.

[c3k]

If those reports are being released (and unclassified) I would think that means they've been superseded by better detection methods, such as the gravity-based referenced above. But that's supposition.

[Dimitris]

We're still looking into this.

[Dimitris]

We are introducing some changes in this, you should see them on the next update release.

[JamesHunt]

I didn´t keep track of the changelogs. Was the MAD range modified in the meantime of July up to the CMO release?

[Rory Noonan]

v1.15.6 (Build 1009.31.2) – July 26, 2019
• Major overhaul of MAD sensor modelling:
o MADs are no longer precision sensors, they have bearing ambiguity and absolutely no range estimate (the range estimate is essentially "anywhere from right in front of us up to max sensor range")
o The practical MAD detection range is affected by the displacement ratio (target displacement vs max reference figure) and under-keel depth (shallow is worse, because of the bottom background)
o MAD scan rates have been increased (only in DB3000 v478+, see below). This rewards faster sensor platforms (e.g. P-8 vs P-3 vs helicopter) as they are able to cover more distance per given time and thus refine the contact position through triangulation faster.


There's 'readme.doc' and 'whatsnew.pdf' files in your game directory that list all changes since V1.00.

[JamesHunt]

Thanks for the info