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Originally Posted by moose1am
Here is what I have problems understanding. Why does the Nose Sonar. Spherical Sonar Array only show one contact when the Towed Array shows a true bearing and a false bearing?
Must be a difference in the sizes of the two types of arrays?
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Bow-style sonar is directional. Imagine a dome comprised of many hundreds of small transducers (pressure-sensitive thingamajigs) and the sound hitting it at one point, only registering on a few transducers. The sensor knows where the sound is coming from because it's only hitting at one point on the dome, and the computer end of the system can figure out the exact bearing from that - normally calculated from a time delay of the sound energy hitting a series of the transducers. That process is called beamforming.
A towed array is quite different. The sound travelling through the water hits one side of the array, but it also hits the
other side of the array (it's OK to imagine it as a two dimensional object here) simultaneously. The array processor is unable to tell which side the sound is actually on, which is why you get an ambiguous bearing.