page_title: Birth of public radio broadcasting
section_title: Significance
hierarchical_section_title: Birth of public radio broadcasting / Significance
caption_attribution_description: English: Entertainers performing over the New Jersey Telephone Herald in Newark
context_page_description: The birth of public radio broadcasting is credited to Lee de Forest who transmitted the world’s first public broadcast in New York City on January 13, 1910. This broadcast featured the voices of Enrico Caruso and other Metropolitan Opera stars. Members of the public and the press used earphones to listen to the broadcast in several locations throughout the city. This marked the beginning of what would become nearly universal wireless radio communication.
context_section_description: The birth of public radio broadcasting had an immediate impact on radio broadcasting as it stimulated the idea of having additional musical programs. The next month on February 24th the Manhattan Opera Company's new opera singer Mariette Mazarin sang "Love is a rebellious bird" from Carmen over a transmitter located in DeForest's laboratory. This radio concert was heard by a group of scientists, diplomats, newspaper reporters and the public within 20 miles (32 km).
  The New Jersey Telephone Herald did evening musical shows after their regular daily newscasts starting on March 15, 1911. The various musical programs consisted of instrumental music from a regular orchestra in attendance, individual recitals, and group singers. In addition they had theatrical performances, opera and organ playing at their new location on the second floor of the Essex Building in Newark, New Jersey.
  DeForest in 1912 put together an amplifying technology from his 1906 Audion vacuum tube invention. He figured out how to take a weak signal and increase it many times (amplification) through a feedback circuit. He had learned through experimentation that his Audion would increase the strength of a weak signal to some degree if a small wire mesh was placed inside the vacuum tube between the heated electron emitting element at the bottom of the tube and the pick up plate on top that had a high voltage opposite charge. He took this electronic idea one step further by taking part of that amplified electrical signal and sending it back through the Audion again. That increased the signal strength even further. That idea was further developed by Edwin Armstrong and Alexander Meissner and the technology of the vacuum tube feedback oscillator was perfected in 1912 by them. 
  This continuous feedback loop idea became a source of continuous waves through repeated feedback and amplification over and over again. The continuous waves of a particular frequency could be altered to a small degree by another signal introduced into it. This is called amplitude modulation. This was further advanced to the idea of having very high frequency continuous waves (tens-of-thousands of cycles-per-second (kHz) modulated (slightly altered) with another signal (e.g. voice, music) from a microphone. From that concept developed the amplitude modulated transmitter, which lead to AM radio broadcast entertainment.
caption: New Jersey Telephone Herald entertainers
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