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10202017, 10:04 PM  #1 
Hellas

Spiess TMA (aka Four Bearings)
Spiess TMA
Hello Subsimers, This video is showing the Spiess TMA Method (aka Four Bearings) for determining Target's Course,Speed and Range. Also,in this video, is showing the brilliant and masterful way that 'Kuikueg' discovered for locating two points of Spiess Line (therefore the Spiess Line) as he described at his second version notes. Look at the description of video for links to Kuikueg's notes. Enjoy!
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10202017, 11:35 PM  #2 
Officer
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Interesting, but I don't think you can use with real navigation. Even with simple 4 bearing in movement you should use a 45* as much because the curve the boat did gets error. Even should be better 6 min in some cases, but depend of target speed 9 or 12 min, vs half hour is a difference.
About hydro and real navigation I have a question, maybe you know. Is possible only show hydro contract in attack map? This idea some from the limitation from the hydro operator, add the needs of lack of position marks in map, but as attack map don't have coordinates, you should read direction and have and idea of which ship formation with out ear. Yes is a experience but you can't do all by your self, no enough time in game nor real life when you attack a convoy.
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10212017, 08:28 AM  #3  
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10212017, 08:41 AM  #4 
Officer
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You don't understand me, I didn't say it doesn't work. I say it will be so inaccurate by the error from ship change of course when you use real navigation. Possible with this method the result will be + 10* when with the other method with only one turning you have the half. Using periscope error become a little less become bearing at funnel is much precise.
In real navigation longer interval will compensate a bit the inaccurate turning a little before the intersecting angle is no so close.
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from the kaisermarine to the ARA Independencia yesterday: H.sie v16+Stiebler 4C+gwx3.0+merchantfleet+Real navigation+MaGui WS+caws 1.61 for gwx3 now: H.sie v16+Stiebler 4C+ NYGM & WAC5.0 mix+MFM(part)+vondos+Real navigation+MaGui WS+caws JFO Extra 
10212017, 02:54 PM  #5 
Bosun
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Spiess TMA is OK, but if someone wants to be historically correct, this method was developed long after the war. Ww2 hydrophones weren't so good, hadn't such angular resolution to be used in such a way. And of course it cost a lot of precious time.

10232017, 07:32 AM  #6  
Hellas

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when you are talking about real navigation , you mean celestial navigation or something else ? Celestial navigation is not possible in sh3 [clock times and stars positions are not matching.look here (the damn imageshark deleted the images but you will get the meaning):http://www.subsim.com/radioroom/show...&postcount=57]. Did that times problem solved and i missed it? If you are not talking for celestial navigation then how are you determining your own position on map ? is there a procedure for determining your position with great accuracy ? i am suspecting that without your boat showing on map ,you will always have inaccuracies which are more responsible for the final outputs Quote:
i didn't said that is a 'historical' method.i made the video with sh3 thats why you see it here. I explained at the description of the video why i used the hydrophone lines.Of course,there were not back then hydrophones with super accuracy ,not even today. Even today , bearings from whatever passive device (even periscope's bearings) are not super accurate.All of them have a little 'cone' and crew is following extra procedures for minimazing the errors at outputs,procedures that demands special equipment. The purpose of the video is to show the principles of Spiess TMA
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10232017, 12:38 PM  #7 
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Hi, no. I know that, I tray but is reality wrong model, in surveyor so I have made star and sun positioning by total station.
What i do, Is tracking by time and speed drawing the path. Iwhen I feel I can read star or sun position I use plotter tool to see it and make a mark, I select a zoom according to weaves and clouds. Boat is hide. All graphic calculator and tools from attack and calculation disc and paper. Sometime I have to track over one and a half week
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from the kaisermarine to the ARA Independencia yesterday: H.sie v16+Stiebler 4C+gwx3.0+merchantfleet+Real navigation+MaGui WS+caws 1.61 for gwx3 now: H.sie v16+Stiebler 4C+ NYGM & WAC5.0 mix+MFM(part)+vondos+Real navigation+MaGui WS+caws JFO Extra Last edited by Aquelarrefox; 10232017 at 12:51 PM. 
10232017, 01:41 PM  #8  
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10232017, 02:28 PM  #9 
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Yes is prety. Purse add hitman disc, which is mod useful for calculation that old attack disc reverse. I'm taking about the disc with double external ring.
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from the kaisermarine to the ARA Independencia yesterday: H.sie v16+Stiebler 4C+gwx3.0+merchantfleet+Real navigation+MaGui WS+caws 1.61 for gwx3 now: H.sie v16+Stiebler 4C+ NYGM & WAC5.0 mix+MFM(part)+vondos+Real navigation+MaGui WS+caws JFO Extra 
10242017, 06:15 AM  #10  
Bosun
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As far as Spiess method is concerned, plotted course should be paralell to the axis of symmetry of the curve which is tangent to all bearing lines. It seems to be true here. Did you study what conditions (proportions of paralell and perpendicular speed components) should be met to make all bearing lines intersect in exactly one point (what are the conditions for speed and course of both vessels to be in pure lag LOS?) Last edited by B_K; 10242017 at 08:16 AM. 

10242017, 04:52 PM  #11  
Hellas

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Anyway,thats the sense i have for the term 'history'. My wish for DW too B_K The luck of manual ploting is a really missing feature About Spiess now , in my opinion, this video is showing three great steps forward for the Spiess itself. A(most important): is the great discovery by Kuikueg for locating the Spiess Line* (part 2:05 to 3:04 of video).Fast and simple to execute. *At the original notes of Spiess,they are using two different rulers (representing two different speeds of target) and ,with correct placing, are locating the two points of Spiess Line. B: at the original notes of Spiess Method,after locating the first exact position of target,they used a fifth bearing** for locating the target course line.The video shows (part 5:27 to 7:47) that this fifth bearing is not needed and solution can be found with only,the allready drawed,four bearings.Also,fast and simple to execute. **At the original notes of Spiess,they are mentioning that ,if a fifth bearing is not availiable,they can repeat the same procedure but with bearings b2,b3 and b4 for locating one more Spiess Line for the first time observation so the intersection of this new Spiess Line with b1 will give one more exact position of target (at time of first oservation) so then they would be able to draw the target course line. C: is the beauty of the geometrical solution (using only a clean ruler and a compass) Quote:
In the other case that our course is not linear ,as in this video, the parabola is tangent to all Spiess Lines produced by the three bearings and i haven't searched if the axis of this parabola is still parallel to DRM (99,9% it is,i just haven't study it).You can't 'imagine' if this axis is parallel in the video as it is impossible to draw this parabola (only one Spiess Line is showing). Quote:
If i understand you right , you are asking to solve a problem with knowing only the first two bearings (neither target course or speed or range) and with (after the second bearing) proper own speed adjustment to have ,at the time of third observation, a third bearing which pass through the intersection point of the two previous two bearings. right ? if yes, i think that such a problem is not solvable.
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10252017, 02:53 AM  #12  
Bosun
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10252017, 12:38 PM  #13  
Hellas

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About your question: I gave a look at it and here is my conclusion: The Problem you setted has infinite solutions if you let free target's course,speed and range. It has infinite solutions if you 'lock' only the range It has infinite solutions if you 'lock' only the speed The problem has two solutions if you keep 'lock' both range and speed The problem has one unique solution if you keep 'lock' only the course (direction) All the aboves are proved (i can prepare the proves if you like to see them) So,if you are looking for a solution you must have additionally known either target's range and speed or only its course (direction)
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10252017, 01:40 PM  #14 
Bosun
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In my post I don't mean the final target solution which is achieved by locking any of those estimates. That's true ofc.
but What I mean is that: bearing lines alone intersect often in one point, which could help simplifying geometric calculations. When this is the case, only two first real bering lines are enough to use Spiess method. Instead of collecting third bearing for real, you can draw a Spiess line from the place where your uboat would be if you maintained current course and speed, and conduct the line through the common intersection point. Such a line is a Spiess line which is equivalent to assumed 3rd bearing if you didn't change course and speed, went there and collected it. But in the meantime you turn the boat and by triangulation you collect real 4th bearing, intersecting freshly made Spiess line. You have target position and continue the procedure as in normal method. However you just saved one time interval, which in turn can save your approach. The point is  how do you know, having only two real first bearings, if all future bearings and Spiess lines go through one common intersection point. It is defined by certain targetuboat geometry and Line of Sight parameters such as speed components and angles. Those conditions I would like to discover EDIT: Ok, I think I am closer to that. page 42: https://www.globalsecurity.org/milit...14308_ch10.pdf describes Lagging geometry, where simplified Spiess could be utilized. I don't know yet if it's enough if speed vectors are just opposite, or should have specific component and angles proportions. But it is a good starting point. Last edited by B_K; 10252017 at 01:55 PM. 
10262017, 07:08 AM  #15  
Hellas

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I understood what you are seeking for from your previous message.According to my point of view,without knowing anything else from target's data (speed ,course or range) don't expect for a solution. The Spiess Line is the locus of all possible positions of target at the next time interval.At the case of having three bearings ,Spiess proved that ,at the fourth time, this locus is a straight line (ok,i know you know that) but (going to your theme now) , at the case of having only two bearings (and nothing more) the locus ,at the third time, is NOT a straight line (in fact there is no locus at all).By 'demanding' the third bearing ,at the third time, cross by the intersection point of two previous bearings,you are narrowing the theme to one specific situation. Look at the following pic: the blue bearing is the bearing from where your sub will be if you maintain course and speed.(as you can see is not pointing to the correct position of target) the red bearing is from the point that your sub should have been in order to point to the correct position of target. The only one specific situation that these two bearings matches and crossing from the intersection point of two previous bearings is when both courses (yours and target's) are parallel (look at pic below). As long as both speeds are constant this is independent from speeds or ranges.
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