Design of integrated services digital broadcasting systems usingmultirate optical fiber code-division multiplexing

This paper presents the design of a new type of integrated services digital broadcasting (ISDB) systems which use a multirate optical fiber code-division multiplexing (OF-CDM) technique. The proposed system can efficiently multiplex various kinds of digital signals with multiple bit rates. This is feasibly achieved by using strict optical orthogonal codes of both auto- and cross-correlation constraints being “1” in multirate OF-CDM systems. Moreover, the low-cost design of OF-CDM transmitters is presented, and experimental demonstrations are also carried out. The measured results show that a transmission distance up to 13 km can be feasibly accomplished by using the proposed transmitter design and the external optical injection-locking scheme. It is expected that the proposed ISDB systems can be employed to cost-effectively transmit fast ethernet (125 Mbit/s), FDDI (125 Mbit/s), ATM (155 Mbit/s), and ESCON (200 Mbit/s) protocol data. Their potential applications include Internet services and multimedia broadcasting, such as videoconferencing, video on demand, HDTV, distance learning, and World Wide Web     

A 20-channel optical communication system using subcarriermultiplexing for the transmission of digital video signals

Microwave subcarriers have been used to demonstrate an optical communication system suitable for the distribution of digital video channels. The design, performance, and optical link requirements are discussed for a 2-Gb/s subcarrier-multiplexed (SCM) system with 20 microwave subcarriers modulated at 100 Mb/s and using a frequency-shift-keyed format. The system uses the 2-6-GHz bandwidth and represents the first example of an SCM system using more than one octave of bandwidth. The bit error rate was measured for all 20 channels; results for five typical channels are shown and discussed. The performance results show that a digital SCM approach is attractive in an optical link for a multichannel wide bandwidth video distribution system made from standard microwave components     

高清晰度电视视频解码器码流分配电路实时实现技术

我国自行研制的第一代高清晰度电视功能样机视频编、解码器中,采用十字划分方案,以便使用标准清晰度电视视频编、解码芯片实现高清晰度电视视频编、解码器。文中在介绍高清晰度电视视频码流结构的基础上,提出了高清晰度电视视频解码器中码流分配电路的实现方法,并给出了实现结果。实验表明,使用该方法可以实现码流中头信息的修改、码字划分及不定长视频包的有序传输及控制。     

Optical digital transmission of HDTV signals for `contribution' use

The key technologies for a 1.2 Gb/s HDTV optical digital transmission system for contribution service use are addressed. A wide-dynamic-range optical receiver is described. Attained average received optical power for an error rate of 10^-9 was from -6 dBm to -38 dBm, with an optical dynamic range of 32 dB. This system provides for transmission lengths from a few meters to up to 80 km. It was confirmed that the system developed is available for interconnecting HDTV equipment within a studio and for dispatching HDTV programs from a production site to a postproduction studio. Scrambled-8B1C NRZ line coding was used to keep clock recovery reliable in the receiver. The line-coding circuit satisfies the BSI (bit sequence independent) property and can be easily implemented using commercial high speed ECL devices     

Performance evaluation of MPEG-2 video coding for HDTV

We examine the subjective and objective performance of HDTV coded using the MPEG-2 video coding standard. Tests were conducted on seven HDTV sequences selected to cover a broad range of program materials in terms of scene content, complexity, motion speed and direction. The selected material was digitized in a 4:2:2 format with HDTV resolution and coded using the MPEG-2 main profile/high level syntax. Formal subjective assessment was performed by non-expert viewers on the sequences coded at a bit rate of 18 Mbits/s. Since MPEG-2 allows a great flexibility at the encoding end, we also examined the impact of various MPEG-2 encoding parameters on the quality of the reconstructed HDTV video sequences. The parameters include bit rate, the structure of picture organization, as well as temporal processing     

Real-time video decoding scheme for HDTV set-top boxes

We present a scheme for real-time digital HDTV video decoding suitable for DVB or ATSC set-top boxes. Our technique is based on a dual decoding datapath controlled in two fixed-scheduling combinations with an efficient memory interface scheme for anchor pictures. Unlike other decoding approaches such as the slice bar decoding method and the crossing-divided method, our scheme reduces memory access contention problem to achieve real-time HDTV decoding without a high cost in overall decoder buffers, architecture, and bus. Our simulation shows that with a relatively low rate 81 MHz clock, our decoder can decode MPEG-2 MP@HL HDTV in real-time, based on a video format of 1920 /spl times/ 1080 pixels/frame at 30 frames/s, at a bit rate of 18-22 Mbps.     

The coding of image sequences by wavelets, wavelet packets andother subband coding schemes

For the terrestrial broadcasting of high-definition television (HDTV) in North America the discrete cosine transform (DCT), Huffman (lossless) coding and motion detection, estimation and compensation have been used to compress raw HDTV rates of 1.0-1.2 Gbps. Compressed and compacted video bit rates range from 12.59 Mbps to 13.60 Mbps for 16-QAM transmission and from 17.47 to 18.88 for 32-QAM transmission. MPEG source coding schemes, are used in a proposed HDTV system and in the Grand Alliance proposal. They share features in common with other source coding schemes which have been employed. It seems likely that compression and compaction to an HDTV video bit rate below 10 Mbps should be attainable. The methods discussed in this paper provide hope for realizing this goal     

Flexible and robust packet transport for digital HDTV

The packet-oriented transport approach used in the advanced digital television (ADTV) system for terrestrial HDTV broadcast is described. ADTV achieves robust HDTV delivery on terrestrial simulcast channels via MPEG video compression, prioritization of MPEG data, and `cell-relay' type packet transport in conjunction with a two-tier physical transmission scheme. General design issues relevant to the development of the proposed transport protocol are discussed. ADTV's prioritization algorithm for partitioning MPEG-encoded video into high-priority (HP) and standard-priority (SP) bit streams is outlined. The data transport format supporting these prioritized compressed video bit streams is described. The three principal sublayers of the ADTV transport protocol are discussed in terms of specific functions, impact of system performance, and hardware implementation factors. A proof-of-concept simulation model that incorporates transport encoding and decoding functionality is outlined, and performance evaluation results are given for illustrative transmission scenarios     

全数字化HDTV传输系统图像信源编码的研究

本文研究了一种全数字化HDTV传输系统图像信源编码方案。将运动补偿帧间预测,离散余弦变换编码和二维熵编码技术结合起来,通过对码率的自适应调节,实现HDTV图像信号的压缩编玛。在14.38Mb/s和20Mb/s码率,取得了良好的图像质量。应用数字调制技术,如16-QAM,能够实现在一个基带8MHz射频信道中传输全数字化HDTV。     

A Real-Time Video Decoder for Digital HDTV

In this paper, an architecture for real-time digital HDTV video decoding is presented. Our architecture is based on a dual decoding datapath controlled in a fixed schedule with an efficient write-back scheme for anchor pictures. The decoding datapath is synchronized at the block (8 × 8 pixels) level. Unlike other decoding approaches such as the slice bar decoding method and the cross-divide method, our scheme reduces memory access contention problem to achieve real-time HDTV decoding without a high cost in overall decoder buffers, architecture, and bus. In comparison to data-flow approaches, our method eliminates the complexity associated with tagged data operations. Our anchor picture storage is organized to minimize page-breaks during memory accesses. Simulation shows that with a relatively low rate 81 MHz clock, our decoder can decode MPEG-2 MP@HL HDTV in real-time, based on an ATSC video format of 1,920 × 1,080 pixels/frame at 30 frames/s, at a bit rate of 18 to 20 Mbps.     

Digital HDTV broadcasting over the CATV distribution system

This contribution deals with the digital broadcasting of HDTV channels over the cable television (CATV) distribution system, using either single-carrier QAM or an orthogonal frequency division multiplex (OFDM) of many QAM carriers to represent an HDTV channel. Assuming that no error-correcting codes are used, we investigate two distinct cases: in the first case, a few HDTV channels are transmitted among many analog TV channels, whereas in the second case all transmitted channels are HDTV channels. We show that in the first case the transmit power of an HDTV channel can be substantially reduced (by about 10 dB or more) as compared to the transmit power of an analog TV channel, while still maintaining a satisfactory bit error rate (BER). In the second case, not only a considerable reduction of the total transmit power but also a reduction of amplifier cost and an increase of the number of TV channels can be achieved. Single-carrier QAM is found to perform slightly better (at most about 1 or 2 dB) than a multi-carrier QAM.     

高清晰度电视芯片中视频和音频同步的异步实现

高清晰度电视的传输流采用了MPEG－2系统层标准ISO／IEC 13818－1。阐述了高清晰度电视（HDTV）传送流中时间信息码在视频和音频同步中的作用，分析了信源解码器中视频和音频同步的原理。就实际芯片中系统时钟的恢复，视频和音频的跳帧等机制进行了讨论，并提出了一种非锁相异步全数字视音同步实现方案。该方案采用了直接置数法恢复系统时钟,滞后跳帧法实现视频与系统时钟的同步，数字锁相法控制音频与系统时钟同步，最后，对视频帧率和音频PCM时钟的偏差等问题作了进一步的探讨。     

Packet video

The 1990s will see a large increase in the use of video for many purposes, made possible through the use of new optical storage and transmission methods, as well as radio and satellite communication. HDTV, new broadcast services and 64 kbit/s ISDN video are all at an advanced stage of development. Digital methods of transmission and storage feature prominently in future scenarios of video usage. To avoid long delays in transmission, packet video techniques for storage of high-quality material on optical discs are being considered. Coded video signals can be transmitted in packet form at variable bit rate. The author discusses the principles of packet video. Packet loss, queueing delay and layered coding are discussed. The future developments are also discussed     

Digital transmission of high bit rate signals using 16DAPSK-OFDMmodulation scheme

Radio transmission signals are distorted by multipath propagation and signal level fading in the channel. In the case of digital transmission systems, the distortion of signals causes a degradation of bit error performance. It is an especially severe problem with digital outside-broadcasting-link (OBL) which has to transmit, for example, digital HDTV signals at more than about 45 Mbps. The OFDM modulation scheme can mitigate the adverse effects of multipath fading. An experimental OFDM modem has been developed to enable stable transmission of digital HDTV sources in an OBL. The experimental modem distributes transmitting digital data to 688 carriers in a bandwidth of about 13.5 MHz using the 16DAPSK for each OFDM carrier. A combination of 8DPSK and 2DASK is adopted as the 16DAPSK and another combination of 8DPSK and coherent 2ASK instead of 2DASK is also considered. Indoor transmission experiments confirmed that the 16DAPSK-OFDM is feasible for transmitting high bit rate signals, even under severe propagation conditions     

Theoretical model of optical fiber secure communication system with chaotic multiple-quantum-well lasers

Chaotic synchronization of injected multiple-quantum-well lasers of optical fiber system and a theoretical model of optical fiber chaotic secure communication system are presented by coupling a chaotic multiple-quantum-well laser synchroniza- tion system and a fiber channel. A new chaotic encoding method of chaos phase shift keying On/Off is proposed for optical fiber secure communications. Chaotic synchronization is achieved numerically in long-haul fiber system at wavelength 1.55 μm. The effect of the nonlinear-phase of fiber is analyzed on chaotic signal and synchronization. A sinusoidal signal of 0.2 GHz frequency is simulated numerically with chaos masking in long-haul fiber analog communication at wavelength 1.55 μm while a digital signal of 0.5 Gbit/s bit rate is simulated numerically with c1haos masking and a rate of 0.05 Gbit/s are also simulated numerically with chaos shift keying and chaos phase shift keying On/Off in long-haul fiber digital communica- tions at wavelength 1.55 μm     

Low-complexity subband encoding for HDTV images

The transmission of high-definition television (HDTV) signals on available digital networks and satellites requires the adoption of sophisticated compression techniques to limit the bit rate requirements and to provide high-quality and reliable service to customers. For processing and transmission of image signals, a low-complexity codec without visible degradation is desired. A low-complexity intraframe subband image coding algorithm is developed. The low band is DPCM encoded and the high bands are PCM encoded. An efficient entropy coder is designed which reduces the overall bit rate significantly. It is shown that high-quality HDTV images can be obtained at as low a bit rate as 45 Mb/s or less with a very low-complexity encoder. For dividing the image into subbands, a new class of quadrature mirror filters (QMFs) called generalized quadrature mirror filters (GQMFs) is used for filtering. Performance is also evaluated by using short kernel filters (SKFs), which are easy to implement and require very few computations     

光纤多种业务传输系统

本文给出了一种实用的光纤多种业务传输系统设计。在此系统中,彩电用0～6MHz基带传输,语音用频率调制,其中心频率为6.5MHz。数据采用高频FSK调制,数据速率f_(?)≤19.2kb/s,副载频率为10.7MHz。     

Signal processing for future home-use digital VTR's

The author considers, mainly from the viewpoint of signal processing technologies, the current efforts for future home-use digital videotape recorders (VTRs). Recording technologies for future home-use digital VTRs are reviewed with respect to both current TV and HDTV systems. High-density recording and bit rate reduction are the major technologies needed for digital video recording with small cassettes. Recent experiments show that the technical problems, except those of equipment size and cost, have almost been solved     

Implementation of HDTV PES combiner based on horizontal six-block segmentation

We present the hardware design of the packetized elementary stream (PES) combiner in the third generation HDTV encoder in China, which is a key part in the HDTV encoding system. In our design, the input HDTV video signal is divided into six sub-images, and a horizontal six-block segmentation method is implemented in the HDTV encoder. Each of the sub-images is coded by one MP@ML encoding ASIC, which works at a different bitrate. The PES combiner combines all the output bit streams into one HDTV PES. The coding parameters and timing stamps are modified according to the requirements of MPEG-2 MP@HL. All these PES combiner functions are implemented by one complex programmable logic device (CPLD), which makes the whole encoding system compact and stable. The detailed discussions of hardware design are also presented in this paper. Experimental results show that the quality of decoded image is improved over the past two generation encoders, and constant bitrate can be maintained at the same time.     

VQ Digital Video Transmission through Coaxial Cable using OFDM

Transmission of high definition digital video (HDTV) by satellite, cable (CATV), and optical networks is an area of intense activity, specially in Europe and North America, where the main challenge is to increase the number of TV channels in the assigned spectrum. In this paper, OFDM modulation is studied for HDTV transmission on a 6 MHz bandwidth channel by using coaxial cable as a transmission medium. Attenuation, phase shift and propagation time are considered, as well as the prevailing degradations on CATV: thermal noise and crosstalk. We compress the video source information in terms of the Vector Quantization (VQ) technique, which is found to be very robust against channel errors. According to our results, we give some recommendations about the design of the filters required in the system and the minimum frequency guard bands between adjacent channels.