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前言本文介绍一种用在八相差分移相键控(8φ—DPSK),速率为4800b/s数传机上的反向信道电路。大家知道,一个载波话路的有限带宽为300～3400Hz。用8φ—DPSK,速率为4800b/s的数传机,经升余弦滚降后,实际占有的线路频宽为600～30000HZ。另外,从频带的经济性考虑,剩下的300～600HZ频带宽度内还可以用来传输一种低速率的数据信息。这样,我们把600～3000HZ频宽称为主信道占有的频宽,而把300～600HZ频宽称为反向信道(或叫辅助信道)占有的频宽。如不设置反向信道,只有主信道,若要进
Preface This article describes a reverse channel circuit used on a 8,800-b / s digitizer with eight-phase differential phase shift keying (8φ-DPSK). We all know that the limited bandwidth of a carrier speech channel is 300 ~ 3400Hz. With 8φ-DPSK, the rate of 4800b / s number of machines, the cosine roll-off, the actual line width of 600 to 30000HZ. In addition, from the economic point of view of the band, the remaining 300 ~ 600HZ bandwidth can also be used to transmit a low-rate data. In this way, we call the bandwidth of 600 ~ 3000HZ the bandwidth occupied by the main channel, and the bandwidth of 300 ~ 600HZ is called the bandwidth occupied by the reverse channel (or called the auxiliary channel). If you do not set the reverse channel, only the main channel, to enter