论文部分内容阅读
概述UHF 和 VHF 频带中常用的工作方式有下述三种:(1)单频单工:发射和接收所用的频率都是相同的。因此除后面讲到的某些技术外,接收机在发射期间是不工作的。其操作基本上是“按讲”方式。(2)双频单工:使用二个频率,这二个频率有足够的频率间隔,能使因为下文讲到的场地限制而设置在一起的电台满意地工作。其操作基本上也是采用“按讲”方式。(3)双工:发射机和接收机能同时工作,能进行通常的双向对讲,无需“按讲”开关。
Overview There are three common modes of operation in the UHF and VHF bands: (1) Single-frequency simplex: The frequencies used for transmission and reception are the same. Therefore, except for some of the techniques mentioned later, the receiver does not work during launch. Its operation is basically “by stresses” approach. (2) Dual-frequency simplex: Use two frequencies, which have enough frequency spacing to work satisfactorily with stations set together due to the site constraints described below. Its operation is basically the “by stresses” approach. (3) Duplex: Transmitter and receiver can work at the same time, can carry out the usual two-way intercom, without “push to talk” switch.