Four Bearing method into a formula/equation?

Dignan · 03-01-13, 10:49 AM

So I need some advice from the trig/geometry brains here.

I have been practicing the 4 bearings method a lot lately and want to develop a quick tool to use to calculate course of a target. I love the Hydrophone tracker tool by Gutted but it isn't available in an app and I don't want to alt-tab out of the game to use it.

So my next option is to use a trig/geo app that allows me to build a formula for the 4 bearings method that I can just plug in values. Do any of the "10 pound brains" on this forum know what the equation for the four bearings method would look like? For example, if your values are as follows;

A= bearing 1
B= bearing 2
C= bearing 3
T= time intervals between bearing readings

What would the formula/equation look like on paper that would spit out a target's course? I realize I still need to take the 4th bearing from a different location to triangulate a location but 3 bearings into a formula would be a good start.

Beardmoresam · 03-01-13, 11:33 AM

Are you basically trying to do TMA?
As in you take a line of bearing at regular intervals (say 2 mins), and use that to calc range, course and speed?

Dignan · 03-01-13, 11:54 AM

Quote:

Originally Posted by Beardmoresam

Are you basically trying to do TMA?
As in you take a line of bearing at regular intervals (say 2 mins), and use that to calc range, course and speed?

That's pretty much it. The first 3 bearings are taken at regular timed intervals from a stationary position. From this you can get a target's course, but not exact position or range. You need to move and then take a 4th bearing to triangulate.

I'm trying to figure out what the equation/formula would be on paper for estimating teh coruse based on the first three bearings.

Pisces · 03-01-13, 02:27 PM

I used the formulas on the first 4 or so pages:

http://www.gamefront.com/files/23015...s_Only_TMA.rar

to calculate the AOB at the first bearing (of 3) to make this slideruler/disk:

http://www.subsim.com/radioroom/showthread.php?t=147719

The DRM or Direction of Relative Movement, aka target course IF you yourself are not moving, is then just a matter of adding/subtracting some angles.

I think your best bet is to construct everything with vector-magic.

BigWalleye · 03-01-13, 02:52 PM

Pisces, I am very interested in exporing this method. Unfortunately, both of the links you posted lead to dead ends. Do you know of any working download sites for these?

Pisces · 03-01-13, 03:14 PM

I just uploaded the first one. Maybe it needs some time to settle in. Sailor Steve also had some problems with a different upload through Gamefront, but eventually was able to get it.

The second link is just a thread here on subsim. If you can't open it, but can read this one, then I don't know what's wrong. It works for both on my end. And I'm using Opera as a browser, so that might make things different also.

[EDIT]But I'll try to find a hosting place of my own that I can trust, in the near future.

03-01-13, 10:49 AM	#1
Dignan Seasoned Skipper Join Date: Mar 2008 Posts: 698 Downloads: 262 Uploads: 0	Four Bearing method into a formula/equation? So I need some advice from the trig/geometry brains here. I have been practicing the 4 bearings method a lot lately and want to develop a quick tool to use to calculate course of a target. I love the Hydrophone tracker tool by Gutted but it isn't available in an app and I don't want to alt-tab out of the game to use it. So my next option is to use a trig/geo app that allows me to build a formula for the 4 bearings method that I can just plug in values. Do any of the "10 pound brains" on this forum know what the equation for the four bearings method would look like? For example, if your values are as follows; A= bearing 1 B= bearing 2 C= bearing 3 T= time intervals between bearing readings What would the formula/equation look like on paper that would spit out a target's course? I realize I still need to take the 4th bearing from a different location to triangulate a location but 3 bearings into a formula would be a good start. __________________

03-01-13, 02:27 PM	#4
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,892 Downloads: 303 Uploads: 0	I used the formulas on the first 4 or so pages: http://www.gamefront.com/files/23015...s_Only_TMA.rar to calculate the AOB at the first bearing (of 3) to make this slideruler/disk: http://www.subsim.com/radioroom/showthread.php?t=147719 The DRM or Direction of Relative Movement, aka target course IF you yourself are not moving, is then just a matter of adding/subtracting some angles. I think your best bet is to construct everything with vector-magic. Last edited by Pisces; 03-01-13 at 02:58 PM.

03-01-13, 03:14 PM	#6
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,892 Downloads: 303 Uploads: 0	I just uploaded the first one. Maybe it needs some time to settle in. Sailor Steve also had some problems with a different upload through Gamefront, but eventually was able to get it. The second link is just a thread here on subsim. If you can't open it, but can read this one, then I don't know what's wrong. It works for both on my end. And I'm using Opera as a browser, so that might make things different also. [EDIT]But I'll try to find a hosting place of my own that I can trust, in the near future. Last edited by Pisces; 03-01-13 at 03:33 PM.

03-01-13, 11:33 AM	#2
Beardmoresam A-ganger Join Date: Oct 2011 Posts: 71 Downloads: 412 Uploads: 0	Are you basically trying to do TMA? As in you take a line of bearing at regular intervals (say 2 mins), and use that to calc range, course and speed?

03-01-13, 02:52 PM	#5
BigWalleye Sea Lord Join Date: Jul 2012 Location: On the Eye-lond, mon! Posts: 1,987 Downloads: 465 Uploads: 0	Pisces, I am very interested in exporing this method. Unfortunately, both of the links you posted lead to dead ends. Do you know of any working download sites for these?