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无线电广播已有五十多年的历史,二十年代初期,各国先后发展调幅(AM)广播,从长、中波段到短波段。由于各类电台的迅速增加,造成电台密集,致使AM广播频段的电台频率分布日益拥挤,加上音质不佳,迫切需要研究开辟一条新的广播领域。1922年Rarson等人发表了FM理论,开始只限于窄带FM的研究,由于信噪比不佳,而不能实用。1935年后对宽带FM的研究证明了在有限带宽的条件下,FM比AM确能大幅度地改善信噪比。1941年5月美国首先实现超短波FM广播,由于信噪比高,抗干扰能力强,动态范围大,重放频带宽,
Radio broadcasting has been in existence for more than 50 years. In the early 1920s, various countries have successively developed AM broadcasting, ranging from long and medium bands to short bands. Due to the rapid increase of various types of radio stations and the high frequency of radio stations, the increasingly frequent radio frequency distribution in the AM radio band coupled with the poor sound quality urgently needs to be studied in order to open up a new area of broadcasting. In 1922, Rarson et al. Published the theory of FM, which was only limited to the research of narrow-band FM. Due to poor signal-to-noise ratio, it was not practical. Studies of broadband FM after 1935 demonstrated that FM is significantly better than AM in terms of limited bandwidth. In May 1941, the United States first realized FM radio with ultra-shortwave. Due to its high signal-to-noise ratio, strong anti-interference ability, large dynamic range,