SUBSIM Radio Room Forums - View Single Post - How do you determine the target's heading with passive sonar?

Pisces · 08-06-08, 03:59 PM

Most people, I think, just chase the bearing line and hope for the best. But there are smarter ways to get into visual range. My post in the following link might help. It a sort of a sliderule that needs 3 bearings taken at equal intervals. And this takes atleast halve an hour in time total. I wait until 5 or 6 degrees change has occured and take the 3rd bearing an exact interval later. If you are stationary you will get the target's AOB [Oops, not course] at the 1st bearing after correctly aligning the slideruler, ... BUT with a reasonably large error. And you'll loose a possible advantagous position ahead of him. If you are moving, ... then it's not so simple. As the 'course' will be skewed by your speed and is actually the direction of relative motion. And that is to complex to explain further here.

http://www.subsim.com/radioroom/show...260#post875260

But there is also a graphical way to determine this course from these 3 bearings. I've been thinking of writing a tutorial on this, but that will need some preparation before it is done. As a placeholder for now I would suggest downloading The Radar Navigation and Maneuvering Board Manual. (I can only download the big package, individual chapters through the pulldown list don't seem to work) Find example 25 in chapter 6 (p 298) to learn how to do it. It also explains how to correct if you are moving in between taking the bearings.

There is also a thread with video with another graphical method, made by Mittelweachter on this forum but I cannot find a link to it in my bookmarks. You may have to search the forum for that.

08-06-08, 03:59 PM	#3
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,904 Downloads: 304 Uploads: 0	Most people, I think, just chase the bearing line and hope for the best. But there are smarter ways to get into visual range. My post in the following link might help. It a sort of a sliderule that needs 3 bearings taken at equal intervals. And this takes atleast halve an hour in time total. I wait until 5 or 6 degrees change has occured and take the 3rd bearing an exact interval later. If you are stationary you will get the target's AOB [Oops, not course] at the 1st bearing after correctly aligning the slideruler, ... BUT with a reasonably large error. And you'll loose a possible advantagous position ahead of him. If you are moving, ... then it's not so simple. As the 'course' will be skewed by your speed and is actually the direction of relative motion. And that is to complex to explain further here. http://www.subsim.com/radioroom/show...260#post875260 But there is also a graphical way to determine this course from these 3 bearings. I've been thinking of writing a tutorial on this, but that will need some preparation before it is done. As a placeholder for now I would suggest downloading The Radar Navigation and Maneuvering Board Manual. (I can only download the big package, individual chapters through the pulldown list don't seem to work) Find example 25 in chapter 6 (p 298) to learn how to do it. It also explains how to correct if you are moving in between taking the bearings. There is also a thread with video with another graphical method, made by Mittelweachter on this forum but I cannot find a link to it in my bookmarks. You may have to search the forum for that. Last edited by Pisces; 08-07-08 at 04:15 AM.