I departed Mobile, AL in a Helo heading pretty much due south. I had carried out all preflight requirements including a call to FSS, particularly asking the status of Warning Areas W 453 & W 155. My route was down the dividing line between them. Got a "No activity and nothing planned." About 30 minutes into the flight (and 45 minutes after my FSS briefing) I saw some sort of boat or ship dead ahead about 5-7 miles. Came a little left to pass about 200 yds E at 1500' alt. Reply lite was steady on. I recalled that in previous years, reply lite came steady on just before being intercepted by US Customs Citations. You know of course, they had all been retrofitted with F-16 radars.
At about about a mile, ID'ed it as a USN Destroyer likely home ported in Mississippi. I noticed that ALL her guns were tracking me. Lite still on. She had the drop on me. I looked to the east about 2 miles and saw a plane towing a target. She let me pass. Lite went out 5 miles later.
I burned up the phone line to FSS when I returned to Mobile. I told the guy "YOU LIED TO ME!" He kinda shrugged and said that the Warning Areas could go hot on a 30 minute notice. There is no FSS remotes or ATC repeaters S of Mobile and E of the Mississippi river delta available. I had no means to get an update.
Back some decades when I was flying DustOff helos in Nam, I came across a USAF intel paper that there was a radar directed AA gun located in the Bong Song pass. The pass was a gap in the mountain range along the coast. Caught a flight up the pass 2 days later. Somebody had told me that you cold hear static cause by radar on the FM com radio. I heard some but it could have been anything.