manual range estimation via sonar

ichso · 04-23-09, 05:03 AM

Hi,

the active sonar device has it's range scale only ranging to 4500 yards and the sonar guy only gives a highly false range estimation when the targeted vessel is beyond those 4500 yards.
So I took the time that it takes the range indicator to cross the 4000 yards mark and those were roughly 6 seconds. This means that every second should roughly translate into 666,7 yards.
Now, if a ship is really far away, I just send the ping and start the stopwatch at the same time and stop it when I receive the pong. Multiplied with those 666,7 yards I get at least some range estimation if the target is still very far away.

Any confirmations or hints on this methods ? Does anybody else tried something similar before ?

Vandrith · 04-23-09, 08:10 AM

That's a good idea, when I have the opportunity I'll give that a shot.

old_tex · 04-23-09, 08:58 AM

Sound travels about 4.4 times faster in water than in air. In air, it travels at about 1125 ft/sec. So, in water, that's about 4950 ft/sec. Divided by three yields 1650 yds/sec or, by 3.3 yields 1500 m/sec. A "RADAR MILE" is the time it takes for the incident wave (the ping) to travel to the target and be reflected back (the pong). Therefore, a ship at 4000 yds is effectively at an 8000 yd time-distance. So, the ping would take ~4.8 seconds to be heard. Of course, we run the risk of detection. But, I'll try it.

Old_tex

ichso · 04-23-09, 11:34 AM

Thank you for you more scientific analysis, tex

.

I checked again in a training mission. A ship is sitting at 1000 yards, another one at 2000. The range indicator of the active sonar device both time shows the 1000 and 2000 yards respectively.
I agree that the pong needs twice the sound travelling time to the target but the sonar indicator is set to include this already. If it shows 4000 yards it means that the ship is 4000 yards away but the sound had to travel of course a distance of 8000 yards.

Weird thing though, that the stadimeter was absolutely sure about the distance of 2000 and 1000 yards to the ships while the active sonar was absolutely sure that those were 1800 and 900 yards away. (Probably the stadimeter's fault because RFB fiddled with the mast heights but who knows...).

old_tex · 04-23-09, 03:40 PM

Don't forget, it is just a game. I don't know whether the algorithm for the SONAR is timed accurately enough with everything else going on to be able to detect distance based on transit time. Remember, the game engine knows distances and displays them approriately via the device being used. If I had written the game, I would adjust the SONAR device to display the distance based on the distance of the objects on the game board. It would be great if that were the case. It would be neat to be able to use all physical elements to play the game.

Old_tex

ichso · 04-23-09, 04:12 PM

Just a game ?

You know what I did to get on that aces chalk board ? :rotfl:

04-23-09, 05:03 AM	#1
ichso Ace of the Deep Join Date: Jul 2005 Location: Germany's oldest city alive Posts: 1,066 Downloads: 57 Uploads: 0	manual range estimation via sonar Hi, the active sonar device has it's range scale only ranging to 4500 yards and the sonar guy only gives a highly false range estimation when the targeted vessel is beyond those 4500 yards. So I took the time that it takes the range indicator to cross the 4000 yards mark and those were roughly 6 seconds. This means that every second should roughly translate into 666,7 yards. Now, if a ship is really far away, I just send the ping and start the stopwatch at the same time and stop it when I receive the pong. Multiplied with those 666,7 yards I get at least some range estimation if the target is still very far away. Any confirmations or hints on this methods ? Does anybody else tried something similar before ? __________________ My Subskins: http://www.subsim.com/radioroom/showthread.php?t=164169

04-23-09, 08:10 AM	#2
Vandrith A-ganger Join Date: Jan 2009 Location: Apple Valley, MN Posts: 80 Downloads: 19 Uploads: 0	That's a good idea, when I have the opportunity I'll give that a shot. __________________ Ultima Ratio Regum (The Final Argument of the Kings) Sig by Gunfighter

04-23-09, 08:58 AM	#3
old_tex Gunner Join Date: Sep 2008 Location: New Mexico Posts: 94 Downloads: 12 Uploads: 0	RADAR Mile Sound travels about 4.4 times faster in water than in air. In air, it travels at about 1125 ft/sec. So, in water, that's about 4950 ft/sec. Divided by three yields 1650 yds/sec or, by 3.3 yields 1500 m/sec. A "RADAR MILE" is the time it takes for the incident wave (the ping) to travel to the target and be reflected back (the pong). Therefore, a ship at 4000 yds is effectively at an 8000 yd time-distance. So, the ping would take ~4.8 seconds to be heard. Of course, we run the risk of detection. But, I'll try it. Old_tex

04-23-09, 11:34 AM	#4
ichso Ace of the Deep Join Date: Jul 2005 Location: Germany's oldest city alive Posts: 1,066 Downloads: 57 Uploads: 0	Thank you for you more scientific analysis, tex . I checked again in a training mission. A ship is sitting at 1000 yards, another one at 2000. The range indicator of the active sonar device both time shows the 1000 and 2000 yards respectively. I agree that the pong needs twice the sound travelling time to the target but the sonar indicator is set to include this already. If it shows 4000 yards it means that the ship is 4000 yards away but the sound had to travel of course a distance of 8000 yards. Weird thing though, that the stadimeter was absolutely sure about the distance of 2000 and 1000 yards to the ships while the active sonar was absolutely sure that those were 1800 and 900 yards away. (Probably the stadimeter's fault because RFB fiddled with the mast heights but who knows...). __________________ My Subskins: http://www.subsim.com/radioroom/showthread.php?t=164169

04-23-09, 03:40 PM	#5
old_tex Gunner Join Date: Sep 2008 Location: New Mexico Posts: 94 Downloads: 12 Uploads: 0	Don't forget Don't forget, it is just a game. I don't know whether the algorithm for the SONAR is timed accurately enough with everything else going on to be able to detect distance based on transit time. Remember, the game engine knows distances and displays them approriately via the device being used. If I had written the game, I would adjust the SONAR device to display the distance based on the distance of the objects on the game board. It would be great if that were the case. It would be neat to be able to use all physical elements to play the game. Old_tex

04-23-09, 04:12 PM	#6
ichso Ace of the Deep Join Date: Jul 2005 Location: Germany's oldest city alive Posts: 1,066 Downloads: 57 Uploads: 0	Just a game ? You know what I did to get on that aces chalk board ? :rotfl: __________________ My Subskins: http://www.subsim.com/radioroom/showthread.php?t=164169