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Originally Posted by Bill Nichols
I found this interesting little tidbit on a site about the Navy's ARCI sonar improvement program:
"Specific software improvements included passive ranging, spatial vernier processing, full spectrum processing, dual towed array concurrent processing, low frequency active interference rejection, passive broadband, passive narrowband and passive detection and tracking processing, track management, on-board training, and port/starboard ambiguity resolution."
http://www.defenseindustrydaily.com/...ated/index.php |
Ah ha! So subs are toting dual towed arrays, or at least planning too. :hmm: Thanks Bill.
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Originally Posted by SeaQueen
Actually, as far as I've been able to tell, it's exactly the opposite. Computing power is probably not the big problem here. The thing is, the SURTASS ships are bigger, hence they are able to keep the twin line arrays sufficiently separated that the phase differences between corrolated signals are sufficient that one can exploit the effect
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Yeah those ships are pretty wide too, about 30meters in beam
http://www.fas.org/irp/program/collect/t19_bow.jpg
http://www.fas.org/irp/program/collect/surtass.htm
However, seeing what Bill just found seems like the projects has already been brought to subs, or at least soon will be. Intuitively, the wider the seperation, the better the resolution of the system, but the theory seems to still hold. Just cructhing some rough estimates...
...The speed of sound waves in water is roughly 1500m/s
With a distance of 10meters being the two arrays, the time delay between the two arrays intercepting the same signal should be on the order of a few hundredth to a few thousandths of a second. So if the signal processing is able to determine a 1/100th sec to 1/1000th sec time lag, in theory it shoud be able to delineate between the true and false contact vector with consistency, (perhaps not in turns as well). As far as range estimates, no idea here, as you said, range estimates are probably a bit trickier, and my recollection of advanced geometry and signal processing is too elementary/old.
So............ down with bearing ambiguity!!!
