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随着当今世界通信量的增加,更有效地利用可用频谱间隔是未来电视系统的根本需要。到目前为止,8MHz是传输1套电视节目所必需的。如今数字信号处理取得了长足的进步,允许在单一的标准VHF/UHF信道内传输数套电视或HDTV节目。只有通过各种有效的源编码技术的组合来降低所需传输的信息量,并通过频谱高效率的调制来增加信道所能传递的数据量,才能赢得这个挑战。 Thomson CSF/LER公司开发的源编码和调制设备实现了在一个标准电视信道内传输4套电视和1套HDTV节目。每套以8Mb/S编码的4套电视节目纳入1个34Mb/s信道内。第2个43Mb/s信道传递HDTV节目。本文介绍视频编码和调制这两方面的技术。所用的源编码系统以CCIR建议书723(34Mb/s节目供应电视编码解码器)为基础,为了降低比特率(4:2:2图像为8Mb/s)和增加图像尺寸(HDTV为34Mb/s),该建议书有所扩展。此文件的第1部分介绍这种以先进的DCT冗余缩减技术和利用高集成芯片组为基础的编码系统。本文的第2部分涉及调制方式。叙述了能在一个宽8MHz信道内传送2个34Mb/s数据流的设备。介绍了用此设备进行的实验室测量和现场试验。
As communications in the world increase, more efficient use of the available spectrum spacing is a fundamental requirement of future television systems. To date, 8MHz is required to transmit 1 TV show. Significant advances have now been made in digital signal processing, allowing the delivery of several television or HDTV programs within a single standard VHF / UHF channel. This challenge can only be overcome by reducing the amount of information that needs to be transmitted by combining a variety of effective source coding techniques and increasing the amount of data that can be conveyed by the channel through spectrum efficient modulation. The source coding and modulation equipment developed by Thomson CSF / LER enables the transmission of 4 TV sets and 1 HDTV program on a standard TV channel. Each set of 4 TV programs encoded in 8Mb / S is included in a 34Mb / s channel. The second 43Mb / s channel delivers HDTV programming. This article describes both video coding and modulation techniques. The source coding system used was based on CCIR Recommendation 723, a 34Mb / s program supplied TV codec. In order to reduce the bit rate (8Mb / s for 4: 2: 2 pictures) and increase the picture size (HDTV is 34Mb / s ), The proposal has been expanded. Part 1 of this document describes this encoding system based on advanced DCT redundancy reduction techniques and using highly integrated chipsets. Part 2 of this article deals with modulation. Describes a device that can deliver two 34Mb / s streams over a wide 8MHz channel. The lab measurements and field tests conducted with this equipment are presented.