可视对讲系统的载波调制和频分复用技术

Research of Carrier Modulation and Frequency Division Multiplexing for a Visual-Talking System

为了解决传统可视对讲系统的视频和音频信号易受干扰、系统稳定性差和联网复杂等问题,提出用振幅平衡调制、频率调制和FSK(Frequency Shift Key)调制等方法,分别将可视对讲系统的视频、音频和数据等信号调制到不同的高频载波.并利用以专用载波滤波器为基础的频分复用网络,实现了可视对讲系统的直流电源、图像载波、语音载波、数据载波等信号在一条同轴线上远距离双向传输,提高了图像画质、语音音质和系统的可靠性,并应用于楼宇可视对讲系统产品中,运行结果表明,可视图像的画质和对讲语音的音质均优于传统可视对讲系统.

To solve the problems that the signals of video and audio for classical visual-talking system were easily interfered,and there were low stability and complex networks,it was proposed that the video,audio and digital signals of a visual-talking system were modulated on the high frequency carriers,separately in the ways of amplitude modulating, frequency modulating and frequency shift key modulating. And the networks of frequency division multiplexing based on professional filters were used. It was realized that DC power,picture carrier,sound carrier and data carrier are transmitted in one coaxial wire with double-directions for a long distance. The qualities of picture and sound,and the reliability of system,were also improved. That was actually applied in the visual-talking system of building,and the results showed that the qualities of visual image and talking voice were better than the traditional visual-talking system.