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随着CATV系统规模的扩大,目前的主要问题是如何解决当系统的传输长度增加时仍能保证高质量的接收。由于传输电缆存在一定的损耗,所以需要在传输干线上串接一些放大器来提高信号电平。放大器属于非线性器件,当信号通过时就会产生非线性失真。本文主要讨论两种非线性失真—2次非线性失真和3次非线性失真,介绍由它们所产生的2次谐波干扰、2次差频干扰、3次谐波干扰、3次差频干扰、相互调制干扰、交扰调制干扰的原因、大小以及对系统的影响。并给出它们与信号电平、串接放大器等因素的关系。
With the expansion of CATV system, the main problem at present is how to solve the problem of ensuring high-quality reception when the system transmission length increases. Due to the loss of the transmission cable, some amplifiers need to be connected in series on the transmission line to improve the signal level. The amplifier is a non-linear device that produces non-linear distortion when the signal passes. This paper mainly discusses two nonlinear distortions, the second-order nonlinear distortion and the third-order nonlinear distortion. The second harmonic interference, the second-order difference interference, the third-order harmonic interference, the third-order difference frequency interference , Intermodulation Interference, Interference Interference Modulation Interference Causes, Size, and Impact on the System. And give them and signal level, cascade amplifier and other factors.