2013年1月6日星期日

The History of Two-Way Radios

The Beginning
Besides the electric telegraph, which was mainly used to send Morse code messages, the first advances in 2 way radios are widely credited to Hertz. In 1885, Hertz conducted experiments proving that electricity can be transmitted as electromagnetic waves, which he concluded could be sent and received, though saw no real potential in them. Though, in 1891, the first radios, or what we would consider wireless telegraphs today, began to appear commercially on ships. By 1893, Nikola Tesla had successfully demonstrated the transfer of electromagnetic energy wirelessly. Quite simply, he made a radio.
Broadcasting
In 1896, Guglielmo Marconi patented his radio apparatus and established his own company distributing them by the next year. By 1901, Marconi had sent the first trans-Atlantic signal from Ireland to Canada. By 1902, an amateur known as “Ham” published an article on “How to Construct an Efficient Wireless Telegraphy Apparatus at Small Cost,” in “Scientific American.” Since there was no regulation on ham radio broadcasts until 1912, amateur broadcasting flourished. The U.S. government shut down all amateur radio stations in 1017 as the nation entered WWI.
Advances
In 1891, experiments into the alternator-transmitter, or “continuous-wave” transmitters, began. Over a 20-year period this transmitter was refined and gave way to another model known as the arc-transmitter, and though less refined, it was more compact. This period also introduced vacuum-tube technology, which would give way to the resurgence of civilian radio broadcasts with a significantly longer range. During the first World War, these advancements in radio transmissions would allow communications with pilots as well as military broadcasts, which previously required the pilot to land to deliver a message or for messages to literally be dropped from the plane.
Uses
The first practical use of the two-way radio was set forth in 1890, replacing carrier pigeons and flags as a form of communication, on ocean ships. This increased both ease of communication, and safety, though it was still fairly limited. In 1921 Victorian police were the first to implement the use of wireless communication in patrol cars, which initially took up the entire back seat. Previous to this, police transmissions were made on public telephones. By 1933, the Beyonne, New Jersey, police department implemented a two-way radio system between police cars and a central station for better response in emergencies. This technology was also used during World War II for air and ground troops alike.
Today they are used in nearly every industry from aviation to commercial transport, military, retail, rehabilitation, public safety, security, and fire and emergency services, just to name a few.
Modern 2 Way Radios
The original two-way radios were only able to broadcast one signal at a time, called “simplex” mode, thus you could only send or receive a signal at a time. It wasn’t until “full duplex” was available that transmitters could be tuned to different frequencies that signals could be easily broadcast in two-way form used in personal, commercial and military facets alike.
This technology has progressed to the point of being so user friendly that nearly any individual can learn how to use a two-way radio easily, professionals and children alike. The modern two-way radio is so common that many cell phone companies have been incorporating them into their products for years, and many consider cell phones to be an extension of the inventions tested and created by the Marconi company and Bell Labs back in the 1920s, mainly their car telephone system, a voice-based radio telephone.

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