现行的移动通信系统都是单路单载波系统,本振源是采用晶体振荡后倍频的方式。随着多频道共用移动通信系统的出现,这种方式的缺点是:其一,频率稳定度不易保证;其二,订货周期不能加快。克服这些缺点的唯一途径是采用频率合成器作为本振源。为了使一个频率合成器能适应通信频道整个带宽的要求,本文介绍一种宽频可选扫描程序分频器。它是利用预置程序编码器的输出来改变可变分频比 N,以达到变化频率的目的。这种方法无论对 VHF 频段或 UHF 频段的移动通信都是合适的。一、概述移动通信中,由于频道数不多,且对带内噪声要求不高,故大都采用了单环频率合成器。其频率关系式 The current mobile communication systems are single-carrier single-carrier system, the local oscillator is the use of crystal oscillator frequency multiplier way. With the advent of multi-channel shared mobile communications systems, the drawbacks of this approach are: first, the frequency stability is not easily guaranteed; second, the ordering cycle can not be accelerated. The only way to overcome these drawbacks is to use a frequency synthesizer as the local oscillator. In order to make a frequency synthesizer to adapt to the requirements of the entire bandwidth of the communication channel, this article describes a wide frequency optional scanner divider. It is the use of pre-programmed encoder output to change the variable frequency ratio N, in order to achieve the purpose of changing the frequency. This method is suitable for mobile communications both in the VHF band and in the UHF band. First, an overview Mobile communications, due to the small number of channels, and less demanding on the band noise, so most of the single-loop frequency synthesizer. Its frequency relationship