Thanks for the kind words... I was away on vacation last week.
It works right, if you add a zero length vector (speed zero vector) to another vector, you're adding zero to it. There should be no conversion in that case; it would be true motion.
But I think I see what you mean. You're moving along and plottting on radar the relative motion; then you stop and continue to plot the true motion.
If you're plotting true motion from a stationary position then what do you think you need to convert? It's the true motion.
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