噪声功率比(NPR)这个概念自频分多路复用(FDM)电话系统诞生之初即已出现。简单而

言，NPR用于衡量多通道系统中当其他通道上存在随机活动时，某个闲置通道的“安静”程

度。噪声和交调失真产物进入该闲置通道，从而降低性能。该概念最初用来检查FDM链

路中的4 kHz宽语音通道，如今，在确定多通道宽带通信系统的特性时也是有用的——但在

现代测量技术方面，存在一些重要的区别。-The concept of the noise power ratio (NPR) from the frequency division multiplexing (FDM) had emerged at the beginning of the birth of the telephone system. Nutshell, NPR used to measure multi-channel system when random events on the other channel, a the idle channel' s " quiet"　level. Noise and intermodulation distortion products into the idle channel, thereby reducing performance. The concept was originally used to check the FDM link 4 kHz wide voice channel, now, in determining the characteristics of multi-channel broadband communication system is useful- but in modern measurement techniques, there are some important differences.