麥克風(fēng)屏蔽不良功能測試:1.0 Objective 目的
The purpose of this document is to describe and setup a functional test for the USB
microphones. The ideal reason for the test is to make sure that the functional test catches
inadequate microphone shielding.
本文件描述的是如何建立一個USB 麥克風(fēng)的功能測試平臺，以檢測麥克風(fēng)是否有
屏蔽不良的問題。
1.1 Inadequate shielding description 屏蔽不良的問題
Some USB microphones have shown a 50 to 60 Hz Ground noise coupling to the center
conductor of the microphone cable. This noise is amplified on the input gain stage of the
Micronas Codec and becomes audible. If the microphone cable is shielded then the noise
coupling is reduced below audible range.
一些麥克風(fēng)的電纜芯線上有從地線藕合進來的50 到60Hz 的噪音，這個噪音經(jīng)輸
入級放大而形成可聽見的噪音。如果麥克風(fēng)電纜屏蔽完好將會將此噪音減小到聽不
到的程度。