sonar performance

raduz · 08-06-07, 04:45 AM

This is what I found on wikipedia:
http://en.wikipedia.org/wiki/Sonar

"Sound waves that are radiated down into the ocean bend back up to the surface in great arcs due to the increasing pressure (and hence sound speed) with depth. The ocean must be at least 6000 feet (1850 meters) deep, or the sound waves will echo off the bottom instead of refracting back upwards, and the loss at the bottom reduces performance."

Then why the DDs were able to ping the subs even in shallows water?

switch.dota · 08-06-07, 05:33 AM

Active sonar *should* be less effective at finding a sub in shallow water, especially when the sub is close to the bottom. This is not modelled into the game, however.

John Channing · 08-06-07, 07:05 AM

The operative word there is "reduces"... not eliminates!

JCC

SteamWake · 08-06-07, 10:17 AM

The subs of that era did not have sound absorbing materials applied to their hull. Also they had plenty of 'right angles'. Also they (subs) were typically suspended above the ocean floor. They made a much better uhhhh sound bouncer than the ocean floor.

Sailor Steve · 08-06-07, 10:36 AM

First of all, that portion of the article seems to me to be talking about using sonar to map the ocean bottom. Spotting an underwater object that is much closer to the transponder than the ocean bottom will obtain a echo sooner. Also, anti-submarine sonar never pointed anywhere near straight down. Spotting a submarine in shallow water was more difficult, but not by much. Most difficult was spotting a sub actually lying on the bottom - it was easy to confuse other objects with the intended target.

This might be of some help:

SteamWake · 08-06-07, 11:11 AM

Quote:

Originally Posted by Sailor Steve

Most difficult was spotting a sub actually lying on the bottom - it was easy to confuse other objects with the intended target.

Unfortunatly this does not seem to be modeled in the game. Trust me Ive tried.

Sailor Steve · 08-06-07, 11:23 AM

Quote:

Originally Posted by SteamWake

Quote:

Originally Posted by Sailor Steve

Most difficult was spotting a sub actually lying on the bottom - it was easy to confuse other objects with the intended target.

Unfortunatly this does not seem to be modeled in the game. Trust me Ive tried.

I agree. It worked quite well in Aces Of the Deep. Unfortunately so did getting stuck in the mud. I died that way once.

Peto · 08-06-07, 12:04 PM

LOL Sailor Steve! That happened to me more than once with me banging on the dive/rise commands (which did work once in a while). I wonder why no one has incorporated some of the basic things that were in AOD--escorts doing search patterns, lying in wait for you to surface etc.

AOD was a great sim in many ways.

Cheers!

Peto

WernerSobe · 08-06-07, 12:37 PM

well unless a sub is lying on the ground an expirienced sonar operator should be able to separete the ground echo from sub bounce.

ground echo sounds different to returns from a sub and you know the first echo is the sub, the second is the ground. I think they could even setup the filters to reduce the ground echo amplitude.

But anyway the ground echo is not modeled in game.

John Channing · 08-06-07, 12:48 PM

Quote:

Originally Posted by Peto

LOL Sailor Steve! That happened to me more than once with me banging on the dive/rise commands (which did work once in a while). I wonder why no one has incorporated some of the basic things that were in AOD--escorts doing search patterns, lying in wait for you to surface etc.

AOD was a great sim in many ways.

Cheers!

Peto

Not sure what you mean there. If you don't think the escorts in SH4 lie in wait for you then you have been very lucky.

On several occasions I have seen one escort stay behind after the others rejoin a convoy and just sit there at all stop... waiting for you to surface. If you out wait him he will then search on both sides of the convoy track all the way back until he rejoins the formation.

JCC

SteamWake · 08-06-07, 01:55 PM

Quote:

Originally Posted by John Channing

Quote:

Originally Posted by Peto

LOL Sailor Steve! That happened to me more than once with me banging on the dive/rise commands (which did work once in a while). I wonder why no one has incorporated some of the basic things that were in AOD--escorts doing search patterns, lying in wait for you to surface etc.

AOD was a great sim in many ways.

Cheers!

Peto

Not sure what you mean there. If you don't think the escorts in SH4 lie in wait for you then you have been very lucky.

On several occasions I have seen one escort stay behind after the others rejoin a convoy and just sit there at all stop... waiting for you to surface. If you out wait him he will then search on both sides of the convoy track all the way back until he rejoins the formation.

JCC

Ive also witnessed them working in teams with one darting about pinging away and dropping the occasional can while the other drifts and listens.

Sailor Steve · 08-06-07, 02:13 PM

Quote:

Originally Posted by SteamWake

Quote:

Originally Posted by John Channing

On several occasions I have seen one escort stay behind after the others rejoin a convoy and just sit there at all stop... waiting for you to surface. If you out wait him he will then search on both sides of the convoy track all the way back until he rejoins the formation.

JCC

Ive also witnessed them working in teams with one darting about pinging away and dropping the occasional can while the other drifts and listens.

They did the 'tag team' thing in SH3 too. The one searching the sides on his way back sounds cool.

Peto · 08-06-07, 02:35 PM

I agree that they're there BUT!!!---I always know that they're there. In RL (and AOD) they would lie quiet. You'd think they were gone but they would catch you when you came up. In SH4 (which I love playing btw--great sim) I can evade them as long as I know where they are.

This is better and they're more persistant since 1.3 patch though and I think it's a great improvement.

Cheers!

SteamWake · 08-06-07, 02:47 PM

Quote:

Originally Posted by Peto

I agree that they're there BUT!!!---I always know that they're there. In RL (and AOD) they would lie quiet. You'd think they were gone but they would catch you when you came up. In SH4 (which I love playing btw--great sim) I can evade them as long as I know where they are.

This is better and they're more persistant since 1.3 patch though and I think it's a great improvement.

Cheers!

If a ship is sitting 'up there' at a dead stop how do you know hes still up there short of using the exterior cam ?

Only reasoning I can think of is you have his last known position and did not 'hear' him move off so you can assume he is still there.

John Channing · 08-06-07, 02:55 PM

Since 1.03 and TM 1.03 I often lose sonar contacts when they shut down (and even when they don't). This is one of the best features as far as I am concerned as it introduces an element on incertainty.

Now if only I could resist the urge to F12 to take a peek

.

JCC

08-06-07, 04:45 AM	#1
raduz Engineer Join Date: Sep 2006 Location: Slovakia Posts: 205 Downloads: 3 Uploads: 0	sonar performance This is what I found on wikipedia: http://en.wikipedia.org/wiki/Sonar "Sound waves that are radiated down into the ocean bend back up to the surface in great arcs due to the increasing pressure (and hence sound speed) with depth. The ocean must be at least 6000 feet (1850 meters) deep, or the sound waves will echo off the bottom instead of refracting back upwards, and the loss at the bottom reduces performance." Then why the DDs were able to ping the subs even in shallows water?

08-06-07, 10:36 AM	#5
Sailor Steve Eternal Patrol Join Date: Nov 2002 Location: High in the mountains of Utah Posts: 50,369 Downloads: 745 Uploads: 249	First of all, that portion of the article seems to me to be talking about using sonar to map the ocean bottom. Spotting an underwater object that is much closer to the transponder than the ocean bottom will obtain a echo sooner. Also, anti-submarine sonar never pointed anywhere near straight down. Spotting a submarine in shallow water was more difficult, but not by much. Most difficult was spotting a sub actually lying on the bottom - it was easy to confuse other objects with the intended target. This might be of some help: __________________ “Never do anything you can't take back.” —Rocky Russo

08-06-07, 05:33 AM	#2
switch.dota Captain Join Date: May 2007 Location: Romania Posts: 492 Downloads: 0 Uploads: 0	Active sonar should be less effective at finding a sub in shallow water, especially when the sub is close to the bottom. This is not modelled into the game, however.

08-06-07, 07:05 AM	#3
John Channing Sea Lord Join Date: Sep 1998 Posts: 1,846 Downloads: 163 Uploads: 5	The operative word there is "reduces"... not eliminates! JCC

08-06-07, 10:17 AM	#4
SteamWake Rear Admiral Join Date: Mar 2005 Posts: 13,224 Downloads: 5 Uploads: 0	The subs of that era did not have sound absorbing materials applied to their hull. Also they had plenty of 'right angles'. Also they (subs) were typically suspended above the ocean floor. They made a much better uhhhh sound bouncer than the ocean floor.

08-06-07, 12:04 PM	#8
Peto Ace of the Deep Join Date: Jul 2007 Location: The details of my life are quite inconsequential Posts: 1,049 Downloads: 4 Uploads: 0	LOL Sailor Steve! That happened to me more than once with me banging on the dive/rise commands (which did work once in a while). I wonder why no one has incorporated some of the basic things that were in AOD--escorts doing search patterns, lying in wait for you to surface etc. AOD was a great sim in many ways. Cheers! Peto

08-06-07, 12:37 PM	#9
WernerSobe Commodore Join Date: Jul 2006 Posts: 625 Downloads: 5 Uploads: 0	well unless a sub is lying on the ground an expirienced sonar operator should be able to separete the ground echo from sub bounce. ground echo sounds different to returns from a sub and you know the first echo is the sub, the second is the ground. I think they could even setup the filters to reduce the ground echo amplitude. But anyway the ground echo is not modeled in game.

08-06-07, 02:35 PM	#13
Peto Ace of the Deep Join Date: Jul 2007 Location: The details of my life are quite inconsequential Posts: 1,049 Downloads: 4 Uploads: 0	I agree that they're there BUT!!!---I always know that they're there. In RL (and AOD) they would lie quiet. You'd think they were gone but they would catch you when you came up. In SH4 (which I love playing btw--great sim) I can evade them as long as I know where they are. This is better and they're more persistant since 1.3 patch though and I think it's a great improvement. Cheers!

08-06-07, 02:55 PM	#15
John Channing Sea Lord Join Date: Sep 1998 Posts: 1,846 Downloads: 163 Uploads: 5	Since 1.03 and TM 1.03 I often lose sonar contacts when they shut down (and even when they don't). This is one of the best features as far as I am concerned as it introduces an element on incertainty. Now if only I could resist the urge to F12 to take a peek . JCC