FM vs AM: What's the difference?
It had only been eleven years since Guglielmo Marconi sent the first "wireless" transmission with his new invention, and only five since Marconi sent signals across the Atlantic. Making use of the high-frequency alternator, Canadian-born physicist Reginald A. Fessenden made his historic Christmas Eve broadcast, in which he transmitted music as well as human speech.
Another early broadcast took place in 1910 when Lee de Forest, inventor of a type of vacuum tube called a triode, aired programs from New York's Metropolitan Opera House.
But it was not until 1916, when a Westinghouse engineer named Frank Conrad played records for his friends over the air, that the idea of radio as a public medium took shape.
An executive at Westinghouse heard about Conrad's broadcast and realized its potential. Here was a medium available to the masses -- a huge potential audience. An audience that would listen to radio broadcasts... with radios made and sold by Westinghouse.
In 1920, Westinghouse's KDKA began regular broadcasts. That same year it aired the results of the 1920 presidential election before the results could be read in the papers. This caused a sensation and is considered the beginning of professional broadcasting.
FM radio works the same way that AM radio works. The difference is in how the carrier wave is modulated, or altered. With AM radio, the amplitude, or overall strength, of the signal is varied to incorporate the sound information. With FM, the frequency (the number of times each second that the current changes direction) of the carrier signal is varied.
The Early Years of Radio
To the shipboard radio operators, it was a miracle -- a Christmas miracle. Instead of hearing the usual dots and dashes of Morse Code, these listeners heard an eerie Silent Night, played by a violin. It was Christmas Eve, 1906, and this broadcast was among the first to transmit sound.It had only been eleven years since Guglielmo Marconi sent the first "wireless" transmission with his new invention, and only five since Marconi sent signals across the Atlantic. Making use of the high-frequency alternator, Canadian-born physicist Reginald A. Fessenden made his historic Christmas Eve broadcast, in which he transmitted music as well as human speech.Another early broadcast took place in 1910 when Lee de Forest, inventor of a type of vacuum tube called a triode, aired programs from New York's Metropolitan Opera House.
But it was not until 1916, when a Westinghouse engineer named Frank Conrad played records for his friends over the air, that the idea of radio as a public medium took shape.
An executive at Westinghouse heard about Conrad's broadcast and realized its potential. Here was a medium available to the masses -- a huge potential audience. An audience that would listen to radio broadcasts... with radios made and sold by Westinghouse.
In 1920, Westinghouse's KDKA began regular broadcasts. That same year it aired the results of the 1920 presidential election before the results could be read in the papers. This caused a sensation and is considered the beginning of professional broadcasting.
