The Birth of FM Radio Transmissions

The initial radio frequency modulation (FM) system was developed by Major Edwin H. Armstrong. A veteran of the World War I, U.S. Signal Corps, Armstrong received 5 patents for his system on December 26, 1933. Shortly thereafter, he began to experiment with different megahertz (MHz) frequencies and wattage. In 1935, Armstrong sent an experimental broadcast through a transmitter located on New York’s Empire State Building and in 1938; he began broadcasting from his own station W2XMN. The station eventually broadcast several hours of Columbia Broadcasting System (CBS) programs several hours a day. Broadcasting continued until his death in 1954. 

January 4, 1940 is usually accepted as the date of the first network broadcast. On this date, a one-hour broadcast was transmitted from station W2XCR Yonkers, New York to W2XMN in Alpine, NJ. The broadcast was then received by the Meriden, CT station W1XPW and W1XOJ in Paxton, MA, before it finally terminated with the Yankee Network Weather Service station W1XOY at Mt. Washington. 

Armstrong designed the historic network broadcast, in order to test the sound quality of FM transmissions. The broadcast featured vocal and instrumental music, as well as scripted dialogue. The success of the transmission led to the development of other transmitters that differed from Armstrong’s design. Existing historical documentation indicates that Westinghouse began to experiment with FM, before Armstrong applied for his patents. 

The experimental transmissions were commercial free, but licensing was already pending for several commercial radio stations. Unfortunately, the original bandwidths of 42-50 MHz reserved for FM transmissions was challenged by National Broadcasting Company (NBC) founder and head of Radio Corporation of America (RCA), David Sarnoff. The influential Sarnoff was able to secure the bandwidths for use in his newly developed television sets. Sarnoff’s move was not entirely motivated by business acumen, as Armstrong and Sarnoff had been bitter rivals for many years and Sarnoff looked forward to crushing Major Armstrong. 

As television took over the lower frequencies, FM radio was forced to accept the more costly higher frequencies. This eventually resulted in the closing of many stations, who could not compete for listeners at the higher MHZ. Sarnoff had been correct in his assumption that the older radio models would be incapable of receiving the higher MHz broadcasts in FM. This strategy would either force the public into deciding whether they should purchase newer, more costly radio sets or stimulate them into buying the newly developed television sets. 

Nevertheless, the FCC adopted a new call letter system in anticipation of the applications they would receive for FM broadcasting licenses. The new system identified stations using a two alphabetic letters, followed by a dash and two numerals. By the end of the year, 15 stations received licensing from the FCC, while 40 more stations waited in queue. Eventually, hundreds of applications would be processed and granted. Although television increased in popularity, Sarnoff was unsuccessful in his attempt to destroy FM radio broadcast transmission.