Generally the channel is both frequency selective and time selective.

一般的，信道既是频率选择性的又是时间选择性的。

youdao

The superficial layers are often frequency selective to transmission .

表层传播一般都有频率选择性。

youdao

However, for the wireless mobile communication systems, the radio channel is frequency selective and time-varying.

对于无线通信系统，无线信道不仅是频率选择性的，而且是时变的。

youdao

Firms making third-generation mobile phones want their receivers to be highly frequency selective, so they can cope with their allotted frequency band without suffering from interference.

ECONOMIST: MONITOR