Quote:
Originally Posted by B_K
I think you are right, Spiess Lines are equivalent to future bearings as if your course *was* linear. So axis of the parabola surely needs to be paralell to target's course. When own course is not linear, however, the only way to make the parabola tangent to bearing lines is to achieve such a position of your u-boat, that bearing line in time of observation will be drawn exactly on previously computed Spiess line (this is called singularity).
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Exactly !

thats it !
Quote:
Originally Posted by B_K
In Dangerous Waters often all bearing lines crossed in one point, at least it looked like this on TMA screen. If we could discover speed component proportions (conditions of pure lag LOS) to achieve this, TMA could be based on two real bearings, one assumed bearing (in fact Spiess line beginning in assumed u-boat future position and crossing the common crossing point) and 4th bearing achieved by triangulation. With some aproximation and to minimize error - preferably for far distances - even not a single point but some surrounding of that point should be enough to assume all bearing lines intersect there and to conduct simplified calculations.
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Maybe this is happening becuase ,at DW, users usually 'lock' on TMA screen one (or more) of target's data.
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)