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本文导出了调频电视系统受到射频干扰时的基带干扰噪声功率和干扰减少因子的计算公式。干扰信号可以是调频电话信号、调频电视信号或脉冲雷达信号。文中还从理论分析得出了一些有用的结论,讨论了计算干扰减少因子时引用的近似,并具体计算了一些典型的干扰指标,其中包括射频防护比与基带信噪比。 导出的公式计入了影响干扰减少因子值的全部重要变量。这些变量是载频差、预加重因子、加权因子、视频频谱分布以及标称峰-峰频偏。如果忽略掉除去标称峰-峰频偏以外的所有变量,则导出的公式化为很按近于CCIR Rep.634-1给出的客观测量结果近似表达式,这表明本文给出的公式是对该局部经验的理论发展,从而已能计算进入调频电视系统的干扰,而且和电话的干扰计算一样,计算是可靠的。可以确信,这对干扰分析与协调将是有用的。
This paper derives the formula for calculating the power of the baseband interference noise and the interference reduction factor when the FMTV system is subjected to radio frequency interference. The interference signal can be a frequency modulated telephone signal, a frequency modulated television signal, or a pulsed radar signal. In the paper, some useful conclusions are drawn from the theoretical analysis. The approximations used in calculating the interference reduction factor are discussed. Some typical interference indexes are calculated, including the RF protection ratio and the baseband signal-to-noise ratio. The derived formula incorporates all the important variables that affect the value of the interference reduction factor. These variables are carrier frequency difference, pre-emphasis factor, weighting factor, video frequency spectrum distribution and nominal peak-to-peak frequency deviation. If you omit all variables except the nominal peak-to-peak frequency deviation, the derived formulation is very close to the approximate expression of the objective measurement given by CCIR Rep.634-1, which shows that the formulas given in this article are correct The theoretical development of this local experience has enabled the calculation of interference into FMTV systems and, like the telephone interference calculation, the calculation is reliable. It is safe to believe that this will be useful for interference analysis and coordination.