电子技术兴起与应用

1、电子技术的兴起与应用人、技术、经济、政治、历史、文化的综合作用1广播（broadcasting)的技术特点无线广播和电视的声音、图像、文字信号被加载在电磁波（electro-magnetic wave)上传播。只要拥有发射器、电动机和接收装置，就可以进行最简单的无线电信号的传播了。电磁波在空气中以直线向四面八方辐射：地球的地貌和动力的限度决定了无线广播只能达到有限的距离。要想向更远的距离传输信号，需要其他技术的帮助（e.g. 微波转播站，电缆，光缆，卫星）2广播（broadcasting)的技术特点直线传播的电磁波，尤其是高频电波，很容易被固体物所阻挡发射装置一般都放置在当地较高的地方。无线电

2、信号的传送需要一定频率区间的电磁波，而电磁波的容量是有限的。使用相同或相邻波段会产生干扰。对电磁波的大量需求使其成为稀缺资源，这成为许多国家对无线电使用进行立法的基础。国家一般都会规定不同部门使用电磁波的波段和合法覆盖区域，以防止干扰。国际间也需要电信协议来防止电磁波的跨境干扰。至今无线电仍旧是最普遍、最经济、最可靠的远距离传送音像信号的方式。3Invention of Telegraph: New Era of Communication1844First telegraph line between Washington, D.C., and Baltimore, Maryland1861

3、Lines ran from coast to coast1866The first transatlantic cable ran between Newfoundland and Ireland along the ocean floor.4电报的局限性不能传输人的声音（Morse Code局限于专业人员）无法解决海上船只之间，以及船只与陆地上的通讯（海上运输的发展，现代海战的需要，商业与殖民扩张）5Development of Wireless Communication19世纪殖民活动和商业的扩张推动了交通、通讯技术的迅速发展。1860sJames Maxwell (Scottish)

4、 Theorizing electromagnetic phenomenon（从理论上阐释电磁现象）1880sHeinrich Hertz (German) 实验证实了电磁波的存在6Guglielmo Marconi 1894 sending Morse codes over distance 1896 无线电报的英国专利 1897 Marconi Wireless Telegraph Company 1899 Branch opened in US (American Marconi), first wireless Morse code signal across the English

5、Channel to France.1900 First wireless signal across the Atlantic Ocean7De Forest and Radio发明三极管1901 First case of signal intervention and noise (De Forest Vs. Maconi )1902 Wireless Telephony company (De Forest), direct competition with Marconi1907&1908 Broadcasting experiment 8无线电技术发明早期美国对相关立法的态度190

6、3：first international conference on wireless communication (signal interference, wireless requirements for ships at sea)1910 US Wireless Ship ActRadio Act of 1912: licensing from the Commerce Department; definition of wireless frequencies as natural resources; formal adoption of SOS Morse-code)9战争、国

7、家战略、技术垄断1914 WWI, issue of national security raised by the navy （GE, AT&T taking advantage over Marconi)1917 美国参战，海军对无线电技术的垄断和控制1919 国家扩张战略：保证美国在无线电技术和设备的国际垄断地位（shipping, oil, and communication elements for world power President Wilson）1919 RCA成立, 美国传播技术全球扩张的工具10美国商业广播的发展Early 1920s 商业广播实验迅速发展，多数电台由

8、大公司建立，但也有许多个人、教育机构、社会组织运作的非营利性电台。1922-1924 AT&T, GE, Westinghouse, RCA之间的竞争 (telephone group Vs. radio group)1925 政府仲裁下的利益重新分配（AT&T monopoly on providing the wires; not to re-enter broadcasting for eight years (actually extended into the mid-1990)Radio Act of 1927，频率干扰制造的混乱影响了收音机的销量，新兴工业的前景受到威胁。27年法

9、案规定：电台不拥有播出频道，它们只是拥有播出执照；电波是公共财产，广播机构要从中获取商业利益就必须符合公共服务的规定（public interest, convenience, or necessity）；成立FRC作为管理广播的政府机构，广播执照不再由商务部颁发。Federal Communication Act of 1934，将FRC改为FCC，其管理权限涉及广播、电话、电报（后来包括电视、有线服务和互联网）11David Sarnoff 与NBC1926：Creation of NBC NBC-Red (telephone group), NBC-blue (radio group)

10、RCA (50)，GE (30)，Westinghouse (20%).Late 20s：System of affiliate stations gradually establishedEconomic rationales behind the network system 1932：在政府反垄断压力下重组, RCA 收购了GE、Westinghouse的收音机生产部门，以增加这个领域的竞争（mid eighties, GE bought back RCA and NBC）。1941：FCC demanding RCA to sell one of its two networks, a

11、nd NBC-blue became ABC later.Limited frequency space made it difficult for smaller networks to compete with established ones, and the market can only sustain a few national networks.12William Paley与CBS1927： NBC出现竞争者 (UIB Columbia Phonograph Company) C(P)BS1928： Paley买下CBS，为父亲公司的雪茄作宣传30s & 40s： Pione

12、er in news programs, soap operas and comedy-variety series, luring talents and stations away from NBC13The Golden Age of Radio(1920s-1950s) Radio sets the precedence for television in America.Weather forecast, farm reports and news analysisVariety shows （综艺节目）Live or recorded musicQuiz showsSoap ope

13、ra: Clara, Lu, and Em (1931)Situation comedy: Amos n Andy (1925)Drama serials （系列广播剧）: War of the Worlds（广播的形式与内容）14早期电视的发展与实验1883：Practical system for transmitting image (Paul Nipkow German)1920s： Laboratory improvement of Mechanical television (GE, AT&T, RCA, John L. Baird and Charles Francis Jenk

14、ins)1929：Fifteen experimental television stations in the US 1929: Depression and radios hostility slowed down televisions development, mechanical system not reliable15Development of Electronic Television 1939：New York Worlds Fair first appearance of television, first televised presidential address F

15、ranklin Roosevelts opening speech at the on April 301940: RCA began daily broadcasts to NY area Formation of the National Television System Committee (NTSC) under FCC 16技术标准的制定对电视发展的影响1941: 525-line picture；6MHz of spectrum space, video transmission use AM, audio FM 1942: FCC granting commercial license 1950-1952：Failure of CBS color system, an example of commercial interest blocking the development of technology1953: RCAs color system adopted by FCC to be industrial standard17彩色电视的缓慢发展1955：Color TV $500; black and white $138 1959: NBC 700 ho