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由于近年来计算机网络、数字压缩编码及信号调制技术的发展,利用有线电视网开展数据广播,从几年前的逆程图文广播到目前兴起的高速多媒体数据广播实现了质的提高,后者的优越性主要有:一是传输速率大大提高,不仅可传输图片、文字,还可传输图像、声音、动画等,实现了多媒体广播;二是对信号质量的要求大大降低,经测试当用户端电平低于正常值15dB仍可接收;三是进行交互式业务成为现实,拓宽了有线电视应用范围。笔者因参与安装调试了一套采用QPSK调制的CATV多媒
Due to the development of computer network, digital compression coding and signal modulation technology in recent years, the use of cable television network to carry out data broadcasting, from a few years ago the reverse teletext broadcast to the rise of high-speed multimedia data broadcasting to achieve a qualitative improvement, the latter The main advantages are: First, greatly improve the transmission rate, not only can transfer pictures, text, but also transfer images, sounds, animations, and so on, to achieve a multimedia broadcast; Second, the signal quality requirements greatly reduced by the test when the client The level is lower than the normal 15dB can still receive; Third, to become an interactive business, broaden the range of cable television applications. I participated in the installation of a set of debugging using QPSK modulated CATV multimedia