click for enlargement

April 25, 1925 - Electrical World magazine published Doolittle's article, "Binaural Broadcasting." The technical paper and accompanying photographs detailed WPAJ's experimentation with the new form of broadcasting: "By this means the ears of the listener are in effect transferred to the location of the microphones, and nearly the same sound impression is produced as though he were located in the studio."

click for a 1952 article Doolittle wrote explaining binaural broadcasting

spring 1925 - WPAJ's call letters were changed to WDRC (Doolittle Radio Corporation).

1926 - The sale of radio equipment was discontinued as radio broadcasting became the Corporation's sole business.

1927 - Doolittle secured the first U.S. patents for binaural broadcasting, the forerunner of stereophonic broadcasting.

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August 4, 1931 - The U.S. Patent Office finally approved Doolittle's 1921 patent application for "Sound-Recording and Sound-Reproducing and Locating Apparatus." He assigned his rights to Radio Corporation of America on June 14, 1921.

click for enlargement; note how he pictured himself in the diagram!

1936 - Doolittle received permission to operate W1XSL, one of twelve "Apex" AM high frequency stations on an experimental basis. It was built on the west peak of Meriden Mountain and operated at 40,300kc (40.3mc) with 1kw of power.

January 16, 1939 - Major Edwin H. Armstrong, professor of electrical engineering at Columbia University, announced the invention of frequency modulated radio.

January 17, 1939 - Doolittle announced a series of experimental broadcasts "free of static and interrupting noises of any kind" would be undertaken in the spring. His station would use the frequency modulated type of transmission pioneered by Armstrong at Columbia University.

May 13, 1939 - At a cost of $20,000, Doolittle put America's first commercial FM station on the air at 2:39PM, as experimental station W1XPW. It was on the air from 3PM-12M, airing classical music, and later simulcasting WDRC.

January, 1940 - To demonstrate the capabilities of FM, music and speech are broadcast over an FM station in Yonkers, NY. Major Armstrong's W2XMN in Alpine, NJ picks it up and relays it to W1XOJ in Paxton, MA., which relays it to W1XER atop Mt. Washington, NH. From there the signal was rebroadcast by short wave to a Yankee Network outpost near Boston, and back to Yonkers.