Edwin Howard Armstrong loved heights. When he built the 425-foot radio tower on the Palisades here in the late 1930's, he would climb it and swing from its 150-foot arms in a specially rigged deck chair. From the top of the tower, he could see the far tip of Long Island.

It was from this tower, which still dominates the Palisades like the mast of a great schooner, that FM radio was launched as a broadcast medium. And though Armstrong is remembered (if only barely) as the inventor of a stunning array of radio and communications devices from the 1910's through the 40's, FM may well be the most stunning of all.

Armstrong, who loved music, had long been dissatisfied with the quality of the AM signal -- which is great for carrying voices over long distances but is easily degraded by interference from the weather and other stations. By 1933 he developed a new method of transmission, frequency modulation, and combined it with circuitry that all but eliminated background noise and interference from other signals.

He first tested the invention from a tower in his backyard in Yonkers, then from the top of the Empire State Building. By 1937 he was building the 425-foot tower atop the Palisades. And in 1939 he went on the air with station W2XMN, broadcasting to General Electric receivers he himself had designed. "The clarity knocked people's socks off," said Tom Lewis, author of "Empire of the Air: The Men Who Made Radio" (HarperCollins, 1991).