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Charles David "Doc" Herrold (November 16, 1875 – July 1, 1948) was an American inventor and pioneer radio broadcaster, who began experimenting with audio radio transmissions in 1909. Beginning in 1912 he apparently became the first person to make entertainment broadcasts on a regular schedule, from his station in San Jose, California. ==Early life== Born in Fulton, Illinois, Herrold grew up in San Jose. In 1895 he enrolled in Stanford University, where he studied astronomy and physics for three years, but withdrew due to illness and never graduated. While at Stanford he was inspired by reports of Guglielmo Marconi's demonstrations that radio signals could be used for wireless communication, and began to experiment with the new technology.〔''Charles Herrold: Inventor of Radio Broadcasting'' by Gorden Greb and Mike Adams, 2003, pages 44-51.〕 After recovering from his illness, Herrold moved to San Francisco, where he developed a number of inventions for dentistry, surgery, and underwater illumination. However, the April 18, 1906 San Francisco earthquake destroyed his work site and apartment. He next took an engineering teaching position for three years, at Heald's College of Mining and Engineering in Stockton, California. While there, his various research projects included the remote detonation of mines using radio signals. During this time he received further inspiration from the novel ''Looking Backward'' by Edward Bellamy, which foresaw the transmission of entertainment programming over telephone lines to individual homes. Herrold began to speculate about the possibilities of instead using radio signals to distribute the programming more efficiently.〔''Ibid''., pages 53-56.〕 The original spark-gap transmitters used for radio signalling could only transmit Morse code messages. Even with this limitation, there was some broadcasting by early radio stations, beginning in 1905 with daily noon time signals transmitted by U.S. Naval stations.〔"The First Wireless Time Signal" (letter from Captain J. L. Jayne), ''The American Jeweler'', October, 1912, page 411.〕 Although these broadcasts generated interest among amateur radio operators,〔One prominent example was Frank Conrad, who in 1913 built a receiver to pick up time signals, and who in 1919 would go on to begin radiotelephone broadcasts over his station, 8XK, which in turn prompted Westinghouse to establish broadcasting station KDKA.〕 especially after they were expanded to include daily weather forecasts and news summaries, the need to learn Morse code greatly restricted potential audiences. To realize his idea of distributing entertainment by radio, Herrold first needed to perfect a radiotelephone transmitter. He was not unique in this endeavor. Although he would later claim that only he had conceived of entertainment broadcasting, there were actually a few others who had speculated about the possibilities. On December 21, 1906, Reginald Fessenden demonstrated an alternator-transmitter of his own design, and one reviewer noted that it was "admirably adapted to the transmission of news, music, etc. as, owing to the fact that no wires are needed, simultaneous transmission to many subscribers can be effected as easily as to a few".〔"Experiments and Results in Wireless Telephony" by John Grant, ''The American Telephone Journal'', February 2, 1907, page 80.〕 However, Fessenden would almost exclusively focus on point-to-point transmissions intended to supplement the wire telephone system.〔In 1932, Fessenden claimed to have made two demonstration entertainment broadcasts, on December 24 and 31, 1906, but did not follow up on the idea at the time.〕 Lee DeForest was even more ambitious, although Herrold would later incorrectly assert that "Certainly de Forest had no thought of a broadcast".〔Greb and Adams (1934 interview broadcast by KQW, San Jose, California), page 19.〕 As early as June, 1907, a review of DeForest's test of his version of a Poulsen arc-transmitter noted that "the inventor believes that by using four different forms of wave as many classes of music can be sent out as desired by the different subscribers".〔"Wireless Telephony by the De Forest System" by Herbert T. Wade, ''The American Monthly Review of Reviews'', June, 1907, pages 681-685.〕 DeForest made a series of musical demonstrations from 1907 to 1910,〔"Wireless 'Phone Transmits Music", ''New York Herald'', March 7, 1907, page 8.〕 〔"Grand Opera by Wireless", ''Telephony'', March 5, 1910, pages 293-294.〕〔"Radio Telephone Experiments", ''Modern Electrics'', May, 1910, page 63.〕 although he would not actually begin regular broadcasts until 1916, when vacuum-tube transmitters became available. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Charles Herrold」の詳細全文を読む スポンサード リンク
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