SUBSIM Radio Room Forums - View Single Post - NewBee Warning!

rodandy · 10-15-10, 11:31 AM

I think it is safe to say that there is no way to determine target AOB accurately using only sonar (or hydrophone) bearings. As was mentioned earlier the TMA techniques were developed much later (and are no doubt being refined as we speak). You can, however, make an estimate based on the radiated noise of the target. A contact with a 0 AOB will radiate little noise into the water and may not be detected until very close. As the AOB increases, the radiated noise will also increase and it's typical to make a detection when the target AOB is somewhere in the range of 20 - 30 degrees. If you plot the bearing over time you will see that the bearing rate is initially slow and increases until closest point of approach (CPA) and then tapers off. The radiated noise will taper off as well and machinery noise will be almost entirely masked by screw noises on a narrow stern AOB.

If your ship is moving slowly, say 2 or 3 knots, it will have a limited effect on the target relative motion, particularly if the target is moving much faster. If you pick up a contact at 030 degrees True bearing and it is moving to the right, you can make an initial guess that the AOB is somewhere near Starboard 30 and the contact course is approximately south. Again, this assumes that you are not moving fast enough to dramatically change the bearing rate yourself. If you decide that you need to close the track to get into firing position then you will need a course to the east. Whether you need to go north as well, to close the range, or south to control the range while you close the track will depend on how fast you can travel.

I don't know how accurately games such as SH5 model target noise, so I would be interested in hearing whether any of you have any success during the game with this technique.

10-15-10, 11:31 AM	#4
rodandy Bilge Rat Join Date: Oct 2010 Posts: 1 Downloads: 0 Uploads: 0	Determining AOB I think it is safe to say that there is no way to determine target AOB accurately using only sonar (or hydrophone) bearings. As was mentioned earlier the TMA techniques were developed much later (and are no doubt being refined as we speak). You can, however, make an estimate based on the radiated noise of the target. A contact with a 0 AOB will radiate little noise into the water and may not be detected until very close. As the AOB increases, the radiated noise will also increase and it's typical to make a detection when the target AOB is somewhere in the range of 20 - 30 degrees. If you plot the bearing over time you will see that the bearing rate is initially slow and increases until closest point of approach (CPA) and then tapers off. The radiated noise will taper off as well and machinery noise will be almost entirely masked by screw noises on a narrow stern AOB. If your ship is moving slowly, say 2 or 3 knots, it will have a limited effect on the target relative motion, particularly if the target is moving much faster. If you pick up a contact at 030 degrees True bearing and it is moving to the right, you can make an initial guess that the AOB is somewhere near Starboard 30 and the contact course is approximately south. Again, this assumes that you are not moving fast enough to dramatically change the bearing rate yourself. If you decide that you need to close the track to get into firing position then you will need a course to the east. Whether you need to go north as well, to close the range, or south to control the range while you close the track will depend on how fast you can travel. I don't know how accurately games such as SH5 model target noise, so I would be interested in hearing whether any of you have any success during the game with this technique.