ITU-T O.81 APP I SPANISH-1998 电话型电路的群延迟测量设备.附录1:快速测量振幅和电话型电路相位的信号测量(多频测试信号).系列O:测量设备的规范.测量模拟参数的设备
Group-delay measuring equipment for telephone-type circuits Appendix I: A measuring signal (multitone test signal) for fast measurement of amplitude and phase for telephone type circuits