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电视信号由以下三部分组成:调幅的亮度分量、由彩色信息另行调制的边带以及由伴音信号调频的另一个载波。彩色(色度)边带的副载波比亮度载波高3.58MHz,伴音载波比亮度载波高4.5MHz。 同任何调幅信号一样,低频调制信号(亮度沿屏幕横向渐变)所产生的边带频谱分量与载波比较接近,而陡峭的垂直细节所产生的边带能量则离载波比较远。
The television signal consists of three components: the luminance component of the amplitude modulation, the sideband modulated separately by color information, and another carrier frequency-modulated by the accompanying signal. The subcarriers of the color (chroma) sideband are 3.58 MHz higher than the luminance carrier and the sound carrier is 4.5 MHz higher than the luminance carrier. As with any amplitude modulated signal, the sideband spectral components produced by the low frequency modulated signal (luminance horizontally along the screen) are closer to the carrier, while the steeper vertical detail produces sideband energy far from the carrier.