Using TA+hull sonar for triangulation

NFunky · 10-03-09, 09:42 PM

Hey again,

I've been playing with the 688(i) again and just had a very strange experience vis-a-vis triangulation using two arrays. I picked up a Han class sub pretty strongly on my towed array (3 frequency lines) and so I thought I might look at my other two arrays to see if I could get him on either. Sphere was blank in NB, but I had a line in the lower window in BB. Unfortunately, DW wouldn't let me mark that line no matter how many times I clicked the designate button on and around its bearing. I then looked on hull NB and bingo, I had the second frequency line coming in feintly. I designated it and merged the contacts in TMA.

Here's where it started to get weird. After a few LOBs appeared, I tried to use the bearing cross from the two arrays to triangulate the target, but the solution I got using the crosspoints was vastly different from what my solution using DEMON said it sould be. I made a new TMA leg, waited for more bearings and again, the triangulation was way off from the solution I got by using just the TA and DEMON.

I got to what I thought was in range and fired two fish, but they didn't seem to lock onto anything and eventually ran out of gas. I was frustrated, so I quit the scenario and viewed the replay and you know what I found? The target was actually way further out than my triangulation suggested. He was at around the exact position my solution using just the TA and DEMON had given me, but I'd thought that the triangulated solution would be more accurate.

Any ideas why this happened? I seem to remember having luck with triangulation before, but I think that was most commonly using the sphere and TA, not the hull. Does the hull array give somewhat inaccurate bearings? Also, why was I able to see an intermediate timescale contact on sphere BB, but was unable to mark it for the life of me?

10-03-09, 09:42 PM	#1
NFunky Machinist's Mate Join Date: Dec 2007 Posts: 127 Downloads: 3 Uploads: 0	Using TA+hull sonar for triangulation Hey again, I've been playing with the 688(i) again and just had a very strange experience vis-a-vis triangulation using two arrays. I picked up a Han class sub pretty strongly on my towed array (3 frequency lines) and so I thought I might look at my other two arrays to see if I could get him on either. Sphere was blank in NB, but I had a line in the lower window in BB. Unfortunately, DW wouldn't let me mark that line no matter how many times I clicked the designate button on and around its bearing. I then looked on hull NB and bingo, I had the second frequency line coming in feintly. I designated it and merged the contacts in TMA. Here's where it started to get weird. After a few LOBs appeared, I tried to use the bearing cross from the two arrays to triangulate the target, but the solution I got using the crosspoints was vastly different from what my solution using DEMON said it sould be. I made a new TMA leg, waited for more bearings and again, the triangulation was way off from the solution I got by using just the TA and DEMON. I got to what I thought was in range and fired two fish, but they didn't seem to lock onto anything and eventually ran out of gas. I was frustrated, so I quit the scenario and viewed the replay and you know what I found? The target was actually way further out than my triangulation suggested. He was at around the exact position my solution using just the TA and DEMON had given me, but I'd thought that the triangulated solution would be more accurate. Any ideas why this happened? I seem to remember having luck with triangulation before, but I think that was most commonly using the sphere and TA, not the hull. Does the hull array give somewhat inaccurate bearings? Also, why was I able to see an intermediate timescale contact on sphere BB, but was unable to mark it for the life of me?