Filtering and equalization for digital transmission

The growth of high-density television (HDTV) systems, along with the development of peripheral devices, depends on the development of transmission systems. The authors have constructed an HDTV digital transmission system for the purpose of supporting secondary distribution of HDTV signals and developed an HDTV codec intended for application in this system. The HDTV digital transmission system is a transmission system that utilizes a single (36 MHz) channel of a Kuband transponder of a communication satellite, employs a rate 3/4 convolutional code and a (255,239) Reed-Solomon block code for forward error correction, and uses quadriphase-shift keying (QPSK) as the modulation format. The HDTV codec developed for application in this system is a coding method that is based on discrete cosine transform (DCT) and motion compensated prediction, which provides 40 Mb/s coded video signal. In this paper, the structure of the HDTV digital satellite transmission system and the HDTV codec are described. The video coding method of the HDTV codec is also described. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80 (1): 35–51, 1997

19 - Digital modulation

Home and abroad, the M/W intermediary service bandwidth is between 3 and 30 GHz. However, recently the bandwidth is getting insufficient due to the increasing number of services and the capacities. Thus FPU (Field Pick UP) Transmission System, the mobile broadcasting intermediary link, needs to be evaluated in the system capacity by means of simulation in order to estimate whether or not the number of channels and the places are changeable when the bandwidth is rearranged in the future. In this paper, we have modeled of Digital FPU link system in M/W band portable digital wireless transmission system. Also, we analyzed digital FPU system performance adopt adaptive modulation scheme in variable channel environment.

Nowadays, in order to improve the quality of signal transmission and reduce the signal attenuation and noise interference, the transmission digital baseband signal modulation become mainstream in today's signal transmission. For the digital baseband signal transmission performance of research helps us to understand the process of digital signal transmission. Firstly, using shift registers to produce m sequence, used to simulate the data signal and the pseudo random noise signal. Then, to design a low pass filter, used to simulate the channel. Data signal transmission in the channel was carried with additive random noise interference, we can measure signal interference by observing eye pattern at the receiving terminal. If to Manchester encoding of data signal, the receiver decoding output data signal can be extracted using the synchronous clock circuit to get the clock signal to synchronize, and display the eye pattern, which is used to evaluate the performance of the transmission system. And we put forward the optimization scheme of the digital baseband signal transmission performance through the research.

Results are presented of a system study on cable distribution of D2-MAC (time-multiplexed analog component) TV signals. With bit error rate as a D2-data performance parameter and visibility of disturbing signals as a performance reference for MAC-video components, system requirements are derived and related to existing concepts. The D2-MAC TV-signal is a time multiplex consisting of a duobinary D2-data part at a 10.125 Mb/s bitrate and a MAC-video part. The -time compression factor for luminance is 3/2; for both of the chrominance components the factor is 3. AM-vestigal sideband transmission on the cable is assumed with a vestigal sideband of VSB=0.75 MHz, and Nyquist filtering in the receiver, while 10% residual carrier is applied during black signal levels and 100% carrier is applied during white. The logical '1' -levels of the duobinary D2-data are specified at 19% and 91% with respect to the carrier level during white signal levels. It was found that the out-of-channel selectivity requirements are more severe than for conventional TV standards if no video-scrambling is applied. This conclusion can be extended to all time-multiplexed video systems. The performance of existing quasisynchronous demodulator concepts is insufficient for proper data recovery. Tilt is a critical parameter if no correction techniques are applied. The measuring methods as used for D2-data to investigate its sensitivity for tolerances on transmission parameters are found to be also suitable for other practical investigations on digital transmissions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Present-day digital data transmission systems should provide a high accuracy for information transmission, maintaining, at the same time, the maximal rate. The systems that apply spectral-effective signal modulation methods enabling to reasonably use the selected section of the frequency spectrum. The orthogonal frequency-division multiplexing (OFDM) is among spectral-effective. This kind of modulation uses its own signal constellation at each subcarrier when transmitting information. The system noise immunity generally depends on the signal point arrangement of a signal constellation. At low noise and interference levels, the signal point arrangement increases, which leads to an increase in the information rate. As the noise and interference level increases, the signal point arrangement decreases, which leads to the transmission rate decrease. In the digital information transmission systems, particularly interesting are asymmetric signal constellations, applying which enable generally improve the system operation quality. Therefore, studying signal constellations is a vital problem nowadays. In this paper, we address the structure and the operation principle of a generator for signal constellations, implemented in the NI LabVIEW software. Using such a generator enables to create signal constellations with an extended configuration, which provides a possibility to investigate the system noise immunity by applying symmetric and asymmetric diagrams (maps).

As an aid in evaluating technical control techniques, an emulation facility that automatically performs the status monitoring, performance assessment, and fault isolation technical control functions as they apply to a future, predominantly digital Defense Communications System (DCS) has been developed. This emulation facility is a multicomputer system which automatically monitors and isolates faults for digital transmission equipments (power generators, RF distributions, digital radios, second level multiplexers, first level multiplexers, submultiplexers, and key generator units). The status monitoring and performance assessment functions are performed by two processors, the adaptive channel estimator (ACE) and an LSI 11/03, the composite being referred to as the CPMAS-D unit. When the software residing in the CPMAS-D unit detects a monitor point transition (alarm to/from nonalarm), it transmits the monitor point information to the CPMAS emulator, a PDP 11/60 minicomputer. These messages, called exception reports, enable the CPMAS emulator to perform its prime mission: fault isolation. A unique fault isolation algorithm has been developed for test with this emulation facility. The algorithm consists of three discrete steps. First, the equipment alarms are mapped into their effect upon each transmission path (link, supergroup, group, or channel). Second, the stations with the faulty equipment are located by deleting the impact of sympathetic alarms. Third, the faulty equipment is identified using the equipment alarm status. Testing of the fault isolation algorithm is enhanced by an emulated network consisting of up to 16 stations, 2048 equipments, and two nodal control areas. Monitor point simulators and T1-4000 multiplexers, which provide simulated and real inputs to two CPMAS-D units, are also part of the emulation facility. Technical control terminals are provided to evaluate man-machine operation in an automated technical control environment. An adaptive channel estimator (ACE) field test was conducted at the Rome Air Development Center (RADC) test facilities so that the ACE development unit could be evaluated as a means of assessing performance of high-speed digital radio transmission systems. Also, the fault isolation algorithm was tested using the previously described emulation facility. The test data and subsequent technique evaluations are discussed in this paper.

This paper discusses a signal transmission method based on the existing digital hierarchical transmission system that transmits signals as defined in the network node interface (NNI) of the new CCITT synchronous digital hierarchy (SDH). The method transmits the information corresponding to two virtual containers (VC‐3s) with the capacity of 28 of 1.5 Mbit/s over existing transmission systems using the fourth digital level, which is the basic unit of operation in the existing network. The fourth digital level signal in Japan has a bandwidth of 97.728 Mbit/s as specified in Rec. G.702. If two VC‐3s are to be contained according to the basic SDH philosophy of NNI, the required transmission capacity is 103.68 Mbit/s. The method that allows two VC‐3s to be transmitted at 97.728 Mbit/s should be considered.It is shown first that the use of the pointer introduced in SDH is adequate. A pointer scheme with a fourmultiframe structure is proposed, aiming at efficient information transmission. The characteristics of the fourmultiframe‐type pointer are then discussed, and the assignment of the overhead required in the transfer of maintenance/operation information is considered. Based on those discussions, the frame structure for the 97.728 Mbit/s signal is derived, which is the fourth level of the existing digital hierarchy.

The distribution system for network television signals involves the tandem connection of many different transmission systems, all of which presently operate using analog techniques. During the 1980's, the common carriers will install many digital transmission systems so as to realize the maximum economic benefit from digital switching machines. As a consequence it is virtually certain that by 1990 some, if not most, of the distribution system for network television signals will involve the use of digital transmission techniques. — The present situation regarding digital transmission of television signals in North America is reviewed and some areas of concern are noted. There is an obvious need for close liaison between the broadcaster, the common carriers, the manufacturers and the regulatory authorities if the present quality of the distribution system is to be maintained.

In order to better understand the efficiency optimization problem of radio energy transmission systems, the author proposes a genetic algorithm based research on efficiency optimization of radio energy transmission systems. The author first addresses the issue of improving the efficiency of magnetic coupled radio energy transmission. On the basis of ensuring a certain transmission distance and voltage gain, the system is mathematically modeled using coupling circuit theory, and mathematical expressions such as transmission efficiency, transmission distance, and voltage gain are obtained as the objective functions of the algorithm. Secondly, the impact of metal obstacles on the transmission system was analyzed. Design a radio energy transmission compensation circuit, and through simulation, obtain three transmission system parameter schemes that meet the objective function and constraint conditions. Finally, the multi-objective genetic algorithm is used to optimize the system parameter design and obtain the optimal combination of transmission system parameters, with coupling coefficient k=0.1818 and mutual inductance coefficient M=23.165 × 10^(-5) H. Using multi-objective genetic algorithm, the algorithm has a fast convergence function in terms of the number of iterations, a non dominated function solution, and Pareto graphs have verified that the numerical value (3) in the text is the optimal combination design for the transmission system.

The analysis of baseband digital transmission systems is reviewed. Modifications to the standard methods are proposed, which lead to fairly simple algebraic expressions for system performance in a number of important cases. These results are used to investigate the relations between system performance and design parameters, and the conditions under which optimum performance may be obtained are investigated.

지상파 TV의 디지털 전환이 완료되었지만 지상파 라디오는 전송방식을 결정하지 못해 아날로그 방송을 유지하며 표류하고 있는 상태이다. 본 연구에서는 지상파 방송사의 종사자를 대상으로 상호지향성 모델을 토대로 디지털 라디오 전송방식을 결정하는 중요 요인에 대한 인식차이를 살펴보고 쟁점 요인을 도출하였다. 연구결과, 지상파 방송 3사는 디지털 라디오가 점유할 주파수 대역 선택에서 가장 큰 인식의 차이가 있으며 제작과 송출의 병행 여부, 주파수 이용 효율성, 방송 품질과 서비스 정도는 서로 의견의 차이가 없는 것으로 나타났다. 그리고 디지털 라디오 방송의 전환에 있어 가장 큰 쟁점 요인은 FM 라디오방송이 사용하는 주파수대역(88-108 MHz)과 지상파 DMB방송 주파수대역(VHF Ch7~13), FM 라디오방송 인접대역(76~88MHz: VHF Ch5~6) 중 어떤 주파수 대역을 디지털 라디오용으로 선택하는지의 문제, 즉 DAB+, HD-Radio, DRM+ 가운데 특정 전송방식을 선택하는 문제로 귀결되었다. 이에 본 연구에서는 제작 송출 병행이 가능하고 송 중계소 1-2개로 송신 효율을 높일 수 있고 신규 사업자 진입이 가능한 방식을 채택함으로써 라디오방송서비스의 품질과 이용자의 만족도를 높일 것을 제안하고자 한다. Though the digital transition of terrestrial TV has been completed, the transmission system for terrestrial radio has not been determined and terrestrial radio still keeps its analog transmission. This study, under coorientation model, aims to explore the cognitive difference in recognizing important factors to be considered in deciding the digital radio transmission system between the employees of terrestrial broadcasters and then crucial issues related to the factors are driven. It has been found that the most big cognitive difference among the employees of three major terrestrial broadcasters lies in selecting frequency band for digital radio transmission. But there was little difference of opinion on simultaneous production-transmission, efficiency of frequency usage, broadcast quality and standards of service. The most disputable point in transition to digital radio broadcasting is selecting the frequency band for digital radio between the frequency bands used for FM radio broadcast (88-108MHz), terrestrial DMB (VHF Ch7~13) and FM radio adjacent broadcast band (76~88MHz: VHF Ch5~6). So, the question concludes into the selection issue between DAB+, HD-Radio, and DRM+. To improve the quality of radio broadcasting service and enhance the satisfaction of listeners, it is desirable to allow to operate both production system and transmission station, to enhance high transmission efficiency with minimum transmission facility, and to permit new entrance of broadcasters.

As the core hub of the power network, the transmission system bears the responsibility of safely and efficiently converting the powerful electrical energy in the high-voltage grid into low-voltage electrical energy suitable for households, enterprises, and industrial users. To cope with the increasingly complex operating environment and constantly improving safety management requirements of the transmission system, this paper innovatively proposes a realtime evaluation system for transmission system safety that integrates artificial intelligence (AI) and 3D simulation technology. The system integrates advanced monitoring and analysis modules to capture real-time operational data of key facilities such as transmission lines and substations. It uses big data processing and machine learning (ML) algorithms for deep mining and analysis, accurately identifying potential safety hazards and fault risks. At the same time, with the help of 3D modeling technology, the system can construct a virtual simulation environment for the transmission system, achieving intuitive visualization of equipment status, operating environment, and fault scenarios. The experimental results show that the system performs well in improving the timeliness, accuracy, and emergency response capabilities of transmission system safety monitoring, laying a solid foundation for building an intelligent, digital, and visual transmission system safety management system.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation William E. Glenn, Henry Helmken; Satellite distribution of digital compressed video audio and data. AIP Conf. Proc. 25 January 1995; 325 (1): 83–89. https://doi.org/10.1063/1.47256 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

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