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一、概述电视发射机是用来将全电视信号和伴音信号对载波进行调制,并放大到一定功率电平的设备.多年以来,电视图象信号的传送都是将图象信号直接调制在射频波信号上,一九三六年英国广播公司的第一部电视发射机就是采用这种直接调制方式的.直到一九五六年才由马可尼公司提出了中频调制的概念.之后,由于晶体管、固体器件和高增益电子管的成熟和完善,中频调制日益显示出比直接调制优越得多,因此在电
I. Overview TV transmitters are devices used to modulate a full-scale television signal and a sound signal to a carrier wave and amplify it to a certain power level. For many years, the transmission of television image signals has been to modulate the image signals directly into a radio frequency On the wave signal, this direct modulation was adopted by the BBC’s first television transmitter in 1936. The concept of IF modulation was not proposed by Marconi until 1956. Since then, The maturation and refinement of transistors, solid state devices, and high-gain tubes have increasingly shown that IF modulation is much superior to direct modulation,