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FM radio opens new avenues
by Carol Stokes
FM radio made U.S. mobile forces the envy of our allies and enemies alike during World War II. But it didn't come about without some major changes of attitude by the Army and the communications industry.
The military had invested a lot of resources into AM equipment. Companies like the Radio Corporation of America known today simply as RCA and Bell Laboratories were opposed to FM's development, primarily because of their heavy investment in producing AM sets.
After the Army successfully experimented with sets the small-business Fred M. Link Company built for the Connecticut state police in the 1930s, the idea arose from the military grass roots that FM radio was the wave of future communications technology. The Signal Corps began investigating FM with the possibility of adapting it to the Army's needs. Using the new phase-shift patents of Edwin Armstrong (a former signaler and major in the World War I corps), Radio Engineering Laboratories at Long Island City, N.Y., built 28 FM sets for use in the Army's 1940 summer maneuvers.
Demands from the field came quickly. The field artillery, infantry and coast artillery wanted to service-test sets. Soon the cavalry and armored force wanted them, too. Earlier an opponent of FM, Western Electric then owned by AT& T received the contract to build the Army's FM sets.
The Link police sets became the prototypes of the SCR-293 and SCR-294, the compact, short-range vehicular sets which were to go into the tanks of the 1st and 2d Armored Divisions in North Africa. They were, in fact, the Army's first FM radios actually, the first FM radios used anywhere in combat.
The SCR-293 and 294 signaled the Signal Corps and Army's commitment to FM radio. Armstrong, who spent most of his career as a civilian scientist, generously donated his equipment, time and use of his patents to speed the Signal Corps' development of FM.
The Signal Corps' short-range vehicular FM sets gave American soldiers voice-communications capabilities, free from interference, beyond anything either the enemy or other allied nations possessed. (See notes on FM's impact on the battlefield in George Raynor Thompson's overview, this edition.) By the end of the war, whole new avenues were opening for using FM.
Dr. Stokes is U.S. Army Signal Center and Fort Gordon's command historian.
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