I think we are using different terminology here to describe the same thing.
I know on the Phalanx there are two radars - a Search radar which actively searches 360 degrees and detects incoming threats to the ship. There is also a tracking radar which the search radar hands the engagement over to if a target is detected and it fulfils the parameters for an engagement. That tracking radar tracks both the target and the rounds fired from the gun. The tracking system adjusts the fall of shot and makes the two converge by correcting the aim of the gun mount. Its why the Phalanx system has such a strange drum shaped radar housing on top. The dome part contains the search radar and the stem the tracking one. It's also why the entire radar elevates with the gun mount, to keep the tracking radar pointing towards the incoming target, in line with the gun.
Obviously an IR missile doesn't need that facility, which is why I wonder the tracking radar is still there.
What you're describing would be, I thought, part of the function of the Search radar, not the Tracking radar.
BTW, if anybody is interested, there is a 1/35 Phalanx presently being auctioned on Evil Bay -
http://www.ebay.com.au/itm/KHS-VIKING-MODELS-1-35-PHALANX-CLOSE-IN-WEAPON-SYSTEM-/141161683570?pt=Model_Kit_US&hash=item20dde45a72 - you'll have to be quick though, as it ends tomorrow!