SSP Type

[xav]

What are the differences between the 3 SSP type?

[paladin5]

hmm this is a good question since i have often wondered abotu this my self. I know that each type has and effect on SONAR performance, But i don't know how much of an effect it is.

[xav]

So nobody knows?

[Mike D]

I was hoping that some of the sonar pros on the forum would chime in but I'll give a breif of how it works in NWP/FC.

From then FC manual:

Propagation path of sound in water. Either a direct path (DP) or Bottom(BB) or Convergence(SSP)BounceZone (CZ).This is wrong as there is no Bottom Bounce(BB) in FC


Toggle SSP (Sound Speed Profile). The selections for SSP types include Surface Duct, Bottom Limited, and Convergence Zone. These SSP types determine the sound propogation paths available for acoustic sound energy to travel. Bottom Limited has the shortest ranges and Convergence Zone the longest ranges.This is correct but lets break them down;



Bottom Limited: Think of this as shallow water. The shallow depth of the bottom is limiting the propagation of sound in the water. Shallow water, short range.



Surface Duct: medium depth water. This is where most of the sound is channeled and trapped in the "duct" or region above the negative thermocline. This means no matter how deep the water is sound is trapped by the thermal layer. This means ships have real problems hearing on active or passive sonar anything below the thermal layer. And subs below the thermal layer have problems hearing anything above the thermal layer. So medium range and depth limited to the thermal layer, not the bottom or top.



Convergence Zone: This one is really complex but think very deep water like the mid-Atlantic. Think of a donut. Your ship/sub is in the center of the hole, your sonar can hear everything in the hole but once it reaches the inner edge of the donut you loose sound. But you can hear a ring around the outside edge of the donut, and this pattern keeps repeting. So you may be able to hear out to 10nm and then have a dead zone from 10-30nm where you pick up sound again from 30-50nm then dead from 50-60nm and then toy have fading sound from 60-90nm. So very long range with large rings of dead zones of sound.

You have to tie into this the bottom type, sand, rock, mud. Mud absorbs sonar, rock scatters but is an excellent sound reflector, sand reflects sound well and only attenuates a bit.

Here are a few links.

http://www.fas.org/man/dod-101/navy/docs/es310/SNR_PROP/snr_prop.htm

http://en.wikipedia.org/wiki/Sonar

http://www.ee.duke.edu/~jk/SAM%20Group_files/radarsonarcompare.pdf (http://www.ee.duke.edu/%7Ejk/SAM%20Group_files/radarsonarcompare.pdf)

http://web.nps.navy.mil/~brutzman/vrtp/rra/HollidayRRApresentation.ppt (http://web.nps.navy.mil/%7Ebrutzman/vrtp/rra/HollidayRRApresentation.ppt)

This is only a quick primmer on sonar, if you have more specific situations about a scenario your working on then ask.

***If I have made erroneous statements I invite some of our sonar experts that are always around to correct me. ***

[xav]

THanks Mike.

So these are not "sonar modes" but really an engine limitation. If I create a scenario with shallow water, I have to manually pick bottom limited.
(Yet I am sure a majority of people leave the default setting).
If Fleet Command was perfect, the engine would support all three types at the same time on the same map.

What setting is the most realistic and fits most situation/scenarios? Surface duct?

[Fleet Command CC]

Thanks from me to Mike some very Interesting info there niceone. :cool:

[Mike D]

THanks Mike.

So these are not "sonar modes" but really an engine limitation. If I create a scenario with shallow water, I have to manually pick bottom limited.
(Yet I am sure a majority of people leave the default setting).
If Fleet Command was perfect, the engine would support all three types at the same time on the same map.

What setting is the most realistic and fits most situation/scenarios? Surface duct?

Think of it as an environmental setting like how clouds and rain effect visual sightings. And yes, the SSP profile should be selected by the scenario designer but rarely is.

Your probably right that Surface Duct is probably a good generic setting.

Your right in that the game engine should automatically determine the sonar conditions. Conditions always change by season, air temperature, water temperature, salinity, weather conditions and other things all effect sonar conditions. Yet you can come up with generic environmental conditions, FC has selections for sea state and month that can give you temperature and weather. Raster Data is available that can be added to the DEM to give bottom type and salinity just as it currently gives depth. With temperature, salinity, bottom type, depth, etc. the game engine should be able to adjust SSP on the fly. Also SSP profiles aren't necessarily symmetrical, if your off the east coast of America and near the edge of the continental shelf then you might have Surface Duct to your west towards the coast and Convergence Zone to the east out to deep water. But all this takes time and money to code. In my dreams.... If I won the lottery...

[steel_selachian]

As a check, I ran a copy of one of my FC scenarios on Sub Command (2-sub attack on a Russian carrier group, commanding USS Seawolf) and set the SSP to Surface Duct. I had a pretty nice layer at about 680 feet to hide under and went on a tear - I've tried that mission twice and the second time the only thing that stopped me from almost single-handedly taking out the entire task force (Kuznetsov, Pyotr Veliky, Moskva, 1 Udaloy, 2 Sovs, 1 Neustrashimy, 1 Krivak) was that the Besstrashnyy's Helix avenged his crewmates by dunking his sonar under the layer and dropping a torp on my head. I still killed the Veliky, one Sov, and Neustrashimy and accidentally put at least one ADCAP into the Kuznetsov; the 688I on the other flank got the Moskva.

When I ran the same scenario on the same settings in NWP 19.0, Seawolf and Virginia between them managed to wipe out both cruisers, both Sovs and both frigates without getting so much as a shot fired back (I left the carrier, the Udaloy, and the AOR for my ASUW F-35s). Granted, I did monkey around with the database editor a little to halve their sound level, but I've tried that scenario on other SSP settings before and ended up running screaming from an angry mob of Silex and Starfish ASROCs.