Out in the no-mans land of the international waters are the only means of communication with the submarines to use radio in the vlf or elf range.
在茫茫大洋深处，唯一可用的通信手段就是甚低频或者极低频无线电。
2
The range consists of three different types of regulation systems: a wireless system based on radiocommunication technology, a hard-wired system, and a self-acting system.
主要的三种标准的产品包括：基于无线控制技术的无线控制系统、线电缆系统以及自立式系统。
3
HF radiocommunication has a significant communication blind zone in the range of 200 kilometers usually. This disadvantage restricts its application in the near range tactical mobile communication.