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Reginald Fessenden
The invention of amplitude-modulated (AM) radio, so that more than one station can send signals. On Christmas Eve 1906, Reginald Fessenden used an Alexanderson alternator and rotary spark-gap transmitter to make the first radio audio broadcast, and ships at sea heard the broadcast. -
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History of Radio
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Charles David Herrold
An electronics instructor constructed a broadcasting station. It used spark gap technology, but modulated the carrier frequency with the human voice, and later music -
Edwin Howard Armstrong
Armstrong patented three important inventions that made today's radio possible. Regeneration, the superheterodyne circuit and wide-band frequency modulation or FM. -
wireless telegraphy
System based on airborne Hertzian waves. Demonstrated application of radio in military and marine communications and started a company for the development and propagation of radio communication services and equipment. -
Coast Radio Stations
It gave communication between coast radio stations between ships at sea. This helped ships out with navigation and if there were problems on the boat they can get back in touch with them. -
Crystal sets
The most common type of receiver before vacuum tubes was the crystal set. Inventions of the triode amplifier, motor-generator, and detector enabled audio radio. -
8MK radio station
The first radio news program was broadcast by station 8MK in Detroit, Michigan, which survives today. It still exist in Detroit and is now called WWJ, and is under ownership of the CBS network. -
Mobile Telephone Service
AT&T introduced Mobile Telephone Service to one hundred towns and highway corridors. By 1948 Mobile Telephone Service was a rarity with only 5,000 customers placing about 30,000 calls each week -
Pocket Transmitter Radio
This radio was powered by a "standard 22.5 V Battery. t was small enough to fit in a vest pocket, powered by a small battery. It was durable, because it had no vacuum tubes to burn out. -
Satellite Navigation
The U.S. Navy experimented with satellite navigation, culminating in the launch of the Global Positioning System (GPS) constellation in 1987. Amateur radio experimenters began to use personal computers with audio cards to process radio signals.
