(一)窄带模拟传输1.前言FM方式具有宽带增益、耐噪声和干扰能力强以及构成设备容易等各种适於移动通信的优点,因此,以VHF和UHF频段的移动通信为首、已应用于各种移动通信中。出于FM需要比调制信号更宽的频带,因此必须继续致力于窄带化。SSB方式因存在振幅的变动成份,因此,它可用于衰落速度较慢的短波海上 (1) Narrow-band analog transmission 1. Introduction The FM method has various advantages such as wideband gain, noise immunity, and interference resistance, and is suitable for mobile communication such as easy-to-use equipment. Therefore, it has been applied to mobile communications in the VHF and UHF bands, In a variety of mobile communications. Since FM requires a wider frequency band than the modulated signal, it must continue to be narrowband. Because of the amplitude variation component, the SSB method can be applied to shortwave sea with slow fading rate