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短波无线通信的衰落现象,是引起码元错误的主要因素之一.人们已经想出了许多办法来减小其影响,其中之一就是在移频制上改进解调方式,将常用的限幅鉴频解调方式改为传号、空号频率分别独立解调,并运用自动调节门限进行判定.实践证明,频率相差数百赫的两个信号,一般是不会同时衰落的.宽带移频制无线电报的频移量一般都在200赫以上,这样,当传号衰落时空号不一定衰落;反之,空号衰落时传号依
The decline of shortwave wireless communications is one of the major causes of symbol errors.Many ways have been devised to reduce its impact, one of which is to improve demodulation on frequency shift systems, The frequency demodulation method is changed to the transmission number, the space frequency frequency is independently demodulated, and the use of automatic adjustment threshold to determine. Practice has proved that the frequency difference of several hundred hertz of the two signals are generally not fading at the same time. The frequency shift of the system radiotelegraph usually above 200 Hz, so when the sign fading time and space does not necessarily decline; the other hand,