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自二十世纪二十年代诞生以来,中短波调幅广播一直以其覆盖范围大、传输距离远、接收机简单、价格低廉等突出优点,被世界各国作为基本的信息传播手段之一。但传统的模拟调幅广播由于存在着传输质量差、业务单一和易被干扰及频谱过度占用等缺点,随着FM调频波段的广播节目和电视的普及,卫星及英特网等新型传输手段的出现。其听众规模呈萎缩态势,处境日
Since its birth in the 1920s, AMR broadcasting has been regarded as one of the basic means of information dissemination by all countries in the world for its prominent advantages of large coverage, long transmission distance, simple receiver and low price. However, with the traditional analog AM broadcasting, there are some shortcomings such as poor transmission quality, single service and easy interference, and excessive spectrum occupation. With the advent of broadcast programs and TVs in the FM band, new transmission means such as satellite and Internet are emerging . The size of its audience was shrinking situation, the situation day