Spinning Mango of Death

In "Spinning Mango of Death" from 2011, Bill Sweetman looks at the problem of trying to find a submarine periscope that only does a short pop-up to take imagery.

This was interesting, since at one time the Navy had said in budget documents that it was going to leave the Automatic Radar Periscope Detection and Discrimination (ARPDD) mode off the P-8A radar, and concentrate on developing that capability for the MH-60R helicopter's Telephonics APS-147 and the mast-mounted Northrop Grumman SPS-74(V) radar for Nimitz-class carriers (logically, since those are the tallest masts in the group).

ARPDD is the result of a very long development program involving the Navy-oriented Johns Hopkins Applied Physics Laboratory as well as Raytheon (previously Texas Instruments).

The challenge is to pick out a small, stealth-treated, slow-moving object out of sea clutter - and moreover, one that is transient. Now that periscopes have high-definition TV sensors that equal the acuity of direct optics, the submarine can pop up the mast, make one scan and drop it back into the water. The crew can then review the scene at leisure and zoom in digitally on potential targets.