Thanks! LORAN A sounded a lot different. It operated around 1.8 MHz. It was more of a droning, like a piston engine airpland cruising along. LORAN C operates at 100 kHz and sounds more impulse or digital to me. I was actively listening in the late 1960s and LORAN A went away in favor of LORAN C in the early 70s. Soundtrack of my youth, along with WWV