本标准定义了各种类型的HAD，并描述了测量其性能的程序 特点。这些程序有助于比较不同系统的性能特征 各种各样的地狱。本标准涉及HAD输出特性的测量 不管传播方式如何。当设备/系统能够传输信号时 使用两种或两种以上的传输方法，本标准要求设备/系统的输出 使用每种传输方法进行测量。

This standard defines various types of HADS and describes procedures for measuring their performance characteristics. These procedures are useful for comparing the performance characteristics among various HADS. This standard addresses the measurement of the output characteristics of HADS regardless of the method of transmission. Whenever the device/system is capable of transmitting signals using two or more transmission methods, this standard requires that the output of the device/system be measured using each transmission method.