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Sweigert credited his military experience for invention of the cordless telephone, citing experimentation with various antennas, signal frequencies, and types of radios.
Cordless phones became widely used in home and workplaces during the early 1980s. According to The New York Times, the number of cordless phones sold in the United States grew from 50,000 in 1980 to 1 million in 1982. They quickly became popular because of their convenience and portability, despite fears that their reliance on radio signals ...
Cordless Phones In the 1970s, the very first cordless phones were introduced, another watershed moment in the history of telephones. In 1986, the Federal Communications Commission granted the frequency range of 47 to 49 MHz for cordless phones.
Philipp Reis, 1861, constructed the first telephone, today called the Reis telephone. Alexander Graham Bell was awarded the first U.S. patent for the invention of the telephone in 1876.
In the first experimental telephones the electric current that powered the telephone circuit was generated at the transmitter, by means of an electromagnet activated by the speaker’s voice.
In the 1960s, experiments with wireless telegraphy led to the first cordless phones. These early models used mechanical relays and vacuum tubes to convert sound into electrical signals. The first commercial cordless phones were released in the 1970s by Panasonic and AT&T.
Early models of cordless phones were far from perfect: they suffered from interference of lines, a limited range, poor sound quality and a lack of security – anyone with a radio scanner could listen into calls.
Beginning in the 1980s, cordless phones operated over a pair of frequencies in the 46- and 49-megahertz bands, and in the late 1990s phones operating in the 902–928-megahertz band began to appear. These phones employed either analog modulation, digital modulation, or spread-spectrum modulation.
First, the first cordless phones operated at only one frequency with a small range of channels. This frequency was 27 MHz (megahertz), and it meant that these phones had a very limited range and generally poor sound quality.
Astronaut John Glenn had just orbited the earth and NASA was ready to launch Telstar, the first communications satellite that could both send and receive signals. When Telstar first launched,...