产生单边带信号有三种可行的方法:调相法,滤波法和所谓“第三种方法”(见图1方框图)。调相法一度很流行,现在多已被滤波法所代替,因为后者较易实现,而且在发射和接收中都能应用。在收发信机的设计中,这是一个显著的优点。所谓“第三种方法”有时被认为是前两种方法的组合;它一直没有引起人们的充分注意。 There are three possible ways to generate single sideband signals: phase modulation, filtering, and so-called “third methods” (see the block diagram in Figure 1). Phase modulation method was very popular at the moment, and now has been replaced by the filtering method, because the latter is easier to implement, and can be used in both transmitting and receiving. This is a significant advantage in the design of the transceiver. The so-called “third method” is sometimes considered as a combination of the first two methods; it has not attracted the full attention of people.