Radio: History and Information.

Here is the Information and History of the Radio and how did it come into existence.

The first radio transmissions made in the early twentieth century were based on the concepts of amplitude modulation, or AM. Radio waves were transmitted at a fixed frequency, and the receiver would detect changes in amplitude until the signal was decoded. While low in sound quality — primarily a deliberate technological weakness for coping with the sheer volume of AM radio stations and vulnerable to interference, it remained the dominant commercial model for broadcasting until the 1970s.

 In 1933, an alternative method for producing radio broadcasts using FM frequency modulation was patented by Edwin H. Armstrong (1890-1954) The basic theory has modulated the carrier wave so that its frequency varies with the received audio signal. The main advantage of FM over AM is that it allows broadcasts to be received with minimal interference: various atmospheric conditions, such as thunderstorms, or electrical activity surrounding them, such as car ignitions, may produce AM signals that interfere with AM broadcasts, but FM is not susceptible to such problems.

In November 1935, Armstrong delivered his paper, "A Method of Reducing Radio Signaling Disturbances through a Frequency Modulation Process," to the Institute of Radio Engineers and two years later, the first FM radio station, W1ZOJ, began broadcasting. FM was the only practical way to make high-fidelity, stereo broadcasts before the introduction of digital radio in the late 1990s. FM is the most commonly used method of broadcasting worldwide and is still used in analog broadcasting.




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