雙工無線語音數(shù)據(jù)傳輸系統(tǒng)外文翻譯(已修改)
2025-06-01 15:08 本頁面
【正文】 雙工無線語音數(shù)據(jù)傳輸系統(tǒng)的設(shè)計 Triple wireless voice data transmission system design Student :, Instructor :, University Every day, in our work and in our leisure time, we e in contact with and use a variety of modern munication media, the most mon being the telephone, radio, television, and the Inter. Though these media we are able to municate (nearly) instantaneously with people on diffident continents, transact our daily business, and receive information about various developments and events of note that occur all around the world. Electronic mail and facsimile transmission have made it possible to rapidly municate written message across great distances. Wireless munications. The development of wireless munications stems from the works of Oersted, Faraday, Gauss, Maxwell, and Hertz. In1820, Oersted demonstrated that an electric current produces a magic field. On August 29,1831,Michael Faraday showed that an induced current is produced by moving a mag in the vicinity of a conductor. Thus, he demonstrated that a changing magic field produces an electric field. With this early work as background, James C. Maxwell in 1864 predicted the existence of electromagic radiation and formulated the basic theory that has been in use for over a century. Maxwell’s theory was verified experimentally by Hertz in 1887. In 1894, a sensitive device that could device that could detect radio signals, called the coherer, was used by its inventor Oliver Lodge to demonstrate wireless munication over a distance of 150 yards at Oxford, England. Guglielmo Marconi is credited with the development of wireless telegraphy. Marconi demonstrated the transmission of radio signals at a distance of approximately 2 kilometers in 1895. Two years later, in 1897 , he patented a radio telegraph system and established the Wireless Telegraph and Signal Company. On December 12, 1901, Marconi received a radio signal at Signal Hill in Newfoundland, which was transmitted from Cornwall, England, a distance of about 1700 miles. The invention of the vacuum tube was especially instrumental in the development of radio munication system .The vacuum diode was invented by Fleming in 1904 and the vacuum triode amplifier was invented by De Forest in 1906, as previously indicated. The invention of the triode made radio broadcast possible in the early part of the twentieth century. Amplitude modulation (AM) broadcast was initiated in 1920 when radio station KDKA, Pittsburgh, went on the air. From that date, AM radio broadcasting grew rapidly across the country and around the world. The super heterodyne AM radio receiver, as we know it today, was invented by Edwin Armstrong during World War I. Another significant development in radio munications was the invention of Frequency modulation (FM), also by Armstrong. 雙工無線語音數(shù)據(jù)傳輸系統(tǒng)的設(shè)計 In 1933, Armstrong built and demonstrated the first FM munication system. However, the use of FM was slow to develop pared with AM broadcast. It was not until the end of World War II that FM broadcast gained in popularity and developed mercially. The first television system was built in the United States by V. K. Zworykin and demonstrated in 1929. Commercial television broadcasting began in London in 1936 by the British Broadcasting Corporation(BBC) . Five years later the Federal Communications Commission(FCC) authorized television broadcasting in the United States. ELEMENTS OF AN ELECTRICAL COMMUNICA SYSTEM Electrical munication systems are designed to send messages or information from a source that generates the message to one more destinations. In general, a munication system can be represented by the functional block diagram shown . The information generated by the source may be of the form of voice (speech source), a picture (image source), or plain text in some particular language, such as English , Japanese, German , French, etc. An essential feature of any sourc
畢業(yè)設(shè)計相關(guān)推薦
鄂ICP備17016276號-1