I was able to pinpoint the Mandarin’s broadcast signal. It’s in Miami.
Tony Stark , after finding the location of The Mandarin, drives into Miami. He is traveling west on I-195 over the Julia Tuttle causeway.
Tony and Rhodes work on a plan to rescue Pepper and also warn the Vice President of the impending danger. The speedboat is heading southeast from the Puente William M. Powell Bridge.
(Iron Man 3, 2013)