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本文导出了调频电视系统静止图象受到数字调制信号干扰时的基带加权干扰噪声功率和干扰减少因子的计算公式,并参照文献[1]的精确计算方法,算出了计算干扰噪声功率需要的已预加重的彩条亮度信号的复包络功率谱。由于这种算法是从彩条亮度信号的波型函数出发,可不必忽略任何视频谱线,因而在此基础上得出的单频、PSK、ASK和FSK信号干扰时的基带干扰噪声功率是精确的,并可据以衡量只计入了主要视频谱线的近似算法的准确性。为了验证计算结果的可靠性,进行了初步的客观测量,结果与计算值基本吻合。最后,根据计算结果对不同数字调制信号干扰的特点,特别是数模兼容性进行了分析,并得出了一些有用的结论。
In this paper, we derive the formula for calculating the weighted power of the noise and the reduction factor of the interference when the still picture of the FMTV system is disturbed by the digital modulated signal. The calculation of the interference noise power has been made with reference to the accurate calculation method of [1] Complex envelope power spectrum of intensified color bars luminance signal. Since this algorithm is based on the wave function of the color bar luminance signal, it is not necessary to ignore any video line, so the baseband interference noise power at the time of single-frequency, PSK, ASK and FSK signal interference is accurate , And can be used to measure the accuracy of the approximate algorithm that counts only the main video line. In order to verify the reliability of the calculation results, a preliminary objective measurement was carried out, and the results are in good agreement with the calculated values. Finally, the characteristics of different digital modulated signals interference, especially the digital-to-analog compatibility are analyzed according to the calculation results, and some useful conclusions are drawn.