Problem when estimating target position via sonar

Antba · 10-20-09, 01:15 PM

Hello!

I am newbie on SH4 and I am having some problems. I like simulators to come as real as possible to the real situations, so I ask everyone to respect this option of mine to choose realistic options even if I have few knowledge about subs. The learning may be harder, but it's much more fun!

I will be direct here to ease the understanding and the further helping. I'll provide as many information as I can, so you guys may use what you think is necessary:

Simulator: SH4 with TMO 1.8 beta (ONLY MOD). Everything in realistic, except for external views enabled

Submarine: Tambor

Date: February 9, 1942

Mission: Sink enemy merchant shipping around Honshu

My Objective: Intercept a merchant detected by the radar at a longe range

Situation: Contact is moving away from me, so I want to get ahead of it, going parallel and maintaining a certain lateral distance, then a turn to stay at a 90º angle with the target to make the shot

Method: Use sonar to get target bearing and approximate distance, write marks on the map about its position with 10 minutes difference from one to another, then estimate its course, speed, and overtake him without visual contact to take position for the shot.

First mark (06:48)

Bearing 324, increasing speed, moving away
Estimated ranges:
-22630
-22470
-21920
-23140
-21230
Final estimated range: 22278

Second mark (06:58)

Bearing 324, constand speed, moving away
Estimated ranges:
-23330
-22130
-22470
-21010
-19370
Final estimated range: 21662

Third mark (07:08)

Bearing 325, moving slow, moving away
Estimated ranges:
-22000
-18940
-19470
-21430
-21700
Final estimated range: 20708

Fourth mark (07:18)

Bearing 325, moving away, moving slow
Estimated ranges:
-17810
-18880
-19260
-20740
-20260
Final estimated range: 19390

As you can see, his trajectory looks strange 'cause it's a curve (nothing against ships doing curves

I just think it's not the case).

So I took more data 20 and 30 minutes later, at 07:38 and 07:48

Fifth mark (07:38)

Bearing 326, moving slow, moving away
Estimated ranges:
-15690
-18290
-17030
-15800
-18520
Final estimated range: 17066

Sixth mark (07:48)

Bearing 326, moving slow, moving away
Estimated ranges:
-16120
-16570
-16760
-15910
-15250
Final estimated range: 16122

It looks like this trajectory is really offset. The estimated trajectory in sonar tutorials look so much closer to a straight line than mine, so it's difficult for me to estimate the target's future position with this 'zig-zag'.

And I couldn't demonstrate here, but I've already tried this approach a couple of times and the target always is at positions I wasn't expecting. I suppose it is making some hard turns sometimes, but it's not the problem. My problem is to estimate his present and future position even if it looks to be on a straight line and constant speed. Could the merchant know about me and is changing course/speed everytime? Or am I doing something wrong with the measurements? I just want a more-or-less-straight estimated trajectory.

Thanks!

10-20-09, 01:15 PM	#1
Antba Swabbie Join Date: Oct 2009 Location: São Paulo, Brazil Posts: 6 Downloads: 9 Uploads: 0	Problem when estimating target position via sonar Hello! I am newbie on SH4 and I am having some problems. I like simulators to come as real as possible to the real situations, so I ask everyone to respect this option of mine to choose realistic options even if I have few knowledge about subs. The learning may be harder, but it's much more fun! I will be direct here to ease the understanding and the further helping. I'll provide as many information as I can, so you guys may use what you think is necessary: Simulator: SH4 with TMO 1.8 beta (ONLY MOD). Everything in realistic, except for external views enabled Submarine: Tambor Date: February 9, 1942 Mission: Sink enemy merchant shipping around Honshu My Objective: Intercept a merchant detected by the radar at a longe range Situation: Contact is moving away from me, so I want to get ahead of it, going parallel and maintaining a certain lateral distance, then a turn to stay at a 90º angle with the target to make the shot Method: Use sonar to get target bearing and approximate distance, write marks on the map about its position with 10 minutes difference from one to another, then estimate its course, speed, and overtake him without visual contact to take position for the shot. First mark (06:48) Bearing 324, increasing speed, moving away Estimated ranges: -22630 -22470 -21920 -23140 -21230 Final estimated range: 22278 Second mark (06:58) Bearing 324, constand speed, moving away Estimated ranges: -23330 -22130 -22470 -21010 -19370 Final estimated range: 21662 Third mark (07:08) Bearing 325, moving slow, moving away Estimated ranges: -22000 -18940 -19470 -21430 -21700 Final estimated range: 20708 Fourth mark (07:18) Bearing 325, moving away, moving slow Estimated ranges: -17810 -18880 -19260 -20740 -20260 Final estimated range: 19390 As you can see, his trajectory looks strange 'cause it's a curve (nothing against ships doing curves I just think it's not the case). So I took more data 20 and 30 minutes later, at 07:38 and 07:48 Fifth mark (07:38) Bearing 326, moving slow, moving away Estimated ranges: -15690 -18290 -17030 -15800 -18520 Final estimated range: 17066 Sixth mark (07:48) Bearing 326, moving slow, moving away Estimated ranges: -16120 -16570 -16760 -15910 -15250 Final estimated range: 16122 It looks like this trajectory is really offset. The estimated trajectory in sonar tutorials look so much closer to a straight line than mine, so it's difficult for me to estimate the target's future position with this 'zig-zag'. And I couldn't demonstrate here, but I've already tried this approach a couple of times and the target always is at positions I wasn't expecting. I suppose it is making some hard turns sometimes, but it's not the problem. My problem is to estimate his present and future position even if it looks to be on a straight line and constant speed. Could the merchant know about me and is changing course/speed everytime? Or am I doing something wrong with the measurements? I just want a more-or-less-straight estimated trajectory. Thanks!