Design concept of compact antenna for SDARS applications

A design concept to reduce the overall dimensions of a microstrip antenna using a wrapped radiating structure and embedded slits is proposed. A compact microstrip antenna for SDARS (satellite digital audio radio services) systems is designed and manufactured with light weight and compact size. Comparison between simulations by Ansoft HFSS software and measurement is provided.     

Novel slot spiral antenna designs for dual-band/multiband operation

New applications for wireless communications are typically accompanied by a need for antennas that integrate several frequencies and functionalities under a single aperture. Different requirements for pattern, gain, and polarization at each operating frequency further complicate the design of such antennas. Novel slot spiral antenna designs for dual-band/multiband operation are introduced. Typically excited to operate in the first mode, the proposed two-arm slot spiral is redesigned to operate efficiently in the second mode and in a hybrid first/second mode for better functionality. Several key features are introduced to achieve requirements for impedance matching, pattern, and gain suitable for a specific automotive dual-band DAB/SDARS (digital audio broadcasting/satellite digital audio radio services) antenna system. Among these features are new feeding systems, a suitable mix of spiral growth rates, and a low-loss spiral arm termination. The design is accomplished using full-wave finite-element boundary integral simulations and is verified with measurements.     

Broadcasting

Three major allocation issues involving the broadcasting and broadcasting-satellite services that will be discussed at the 1992 World Administrative Radio Conference (WARC-92) are examined. They are expansion of frequencies for conventional high-frequency (shortwave) broadcasting, new frequencies for both satellite and terrestrial digital audio (radio) broadcasting to handheld and automobile receivers, and new frequencies for studio-quality high-definition television broadcasting from satellites. The bands that are viable candidates for these services are discussed     

Joint encoding and decoding methods for digital audio broadcasting of multiple programs

We introduce new methods for increasing the performance of multiprogram digital audio broadcast systems, e.g., satellite digital audio broadcasting. Joint multiprogram encoding is an attractive possibility for parallel broadcasting of a large number of programs. Joint coding extended over multiple audio frames in time give further improvements. The benefits of this kind of statistical multiplexing yield improved audio quality and/or higher capacity in terms of number of programs. We describe the new Joint Multiple Program Encoding Technique in the context of the perceptual audio coding (PAC) type of algorithms. We also describe methods for multi-program transmission including Equal Error Protection (EEP) as well as Unequal Error Protection (UEP) and improved error concealment for multiple program transmission. Some of the techniques described in this paper, are currently being used in satellite digital audio broadcasting in the United States.     

CD by radio-digital radio broadcasting

Engineers have been looking at ways of broadcasting a digital radio service to the general public, which would ideally have the following features: sound quality comparable with that of the CD; reliable reception to all listeners in the coverage area; capability of offering coverage of all listeners; capability of fixed, mobile and portable reception using simple low grains antennas; simple push-button programme selection-no tuning; frequency efficiency, so that many services can be provided in any spectrum available; and capability of operation from terrestrial transmitters and/or satellite. The author describes the requirements of a digital audio broadcasting system regarding intersymbol interference and then discusses COFDM, coded-orthogonal frequency division multiplex. The author also discusses low-bit-rate sound, terrestrial transmission, satellite broadcasting, receivers, frequency allocation and system testing     

Summary of conclusions of the 1992 World Administrative RadioConference

The major decisions made at the conference are briefly described. Additional frequency bands for shortwave (HF) radio broadcasting were agreed upon. Frequency allocations were made to support a number of US proposals, to provide advanced mobile radio services using low Earth orbit satellites. Allocations for land based mobile services adopted at WARC '92, in the range 1700 to 2600 MHz, are meant to foster improved mobile services that can be used worldwide. An allocation was also made to support commercial telephone service between passengers flying on aircraft and individuals on the ground. Allocations were made for sound broadcasting from satellites, as well as for providing a means to accommodate a complementary terrestrial-based digital audio broadcasting service. New frequency allocations to support space activities were agreed upon, and an allocation was made to the fixed satellite service in the band 13.75 to 14.0 GHz     

广播电视工程中数字音频技术的应用分析

广播电视工程中数字音频技术的应用十分重要,它能够有效提升广播电视节目传播水平。在音频处理中,必须与时俱进,追求对数字音频嵌入技术的合理运用,提升音频处理与传输效率,追求对多元化音频内容的合理利用。重点分析数字音频嵌入技术的应用优势,并对多元化应用内容进行分析。     

创新的中国数字调频广播技术方案——CDRadio与HD Radio的简介与比较

数字化正对中国广播电视行业产生着深刻的影响,传统的FM音频广播也面临着数字化改造.在DAB,HD Radio,DRM及CDRadio几种先进数字音频广播技术方案中重点比较了HD Radio与CDRadio.中国数字调频广播技术方案CDRadio实现了真正的带内数模混叠同播,并通过使用非规则频谱分配、LDPC纠错编码、时...     

Digital audio broadcasting: High-grade service quality through on-board processing techniques

A digital audio broadcasting (DAB) satellite system is presented here which provides a high-grade quality of service for some hundreds of channels. This, with minimum cost of the radio set and of the broadcasting station, greatly improves the radio broadcasting service throughout the world, especially in areas where deployment of conventional relay infrastructure is difficult and not yet cost-effective. Potential broadcasters located in the visible hemisphere can directly up-link their programming to the DAB satellites. Broadcasters can also copy each up-link channel and steer flexibility to any beam or combination of satellite beams. The paper illustrates the advantages and the feasibility of a DAB system based on geostationary satellites with on-board processing generating signals of MCPC (multiple channel per carrier) type. This multiplexing technique allows large system margins. This solution allows the satellite L-band TWTA amplifiers to be operated in saturation and eliminates the intermodulation noise associated with the transmission of FDMA channels. A powerful coding scheme has been selected to create a ‘robust’ down-link. In this way several high-power DAB channels of radio programming, with selectable data rate, are directly delivered to the users.     

无线广播发展探索

随着电子科学技术不断地更新换代,无线电调幅广播正在逐步向数字中短波音频广播(DRM)和数字音频广播(DAB)直播卫星发展。     

Analysis of an advanced satellite digital audio broadcasting systemand complementary terrestrial gap-filler single frequency network

Digital audio broadcasting (DAB) to mobile and fixed users exploiting the latest advances in compression coding, and transmission techniques represents an appealing application for future satellite systems. This paper introduces coded quasi-orthogonal code division multiplexing (CQO-CDM) as a transmission technique for digital audio broadcasting. The proposed technique performs well over both the L-band satellite fading channel and the terrestrial gap-filler type of transmission. Preliminary link budgets based on extensive computer simulation results are provided. Numerical results show that remarkable overall capacity can be achieved by using a constellation of satellites in highly elliptical orbit (HEO) complemented by a terrestrial gap-filler network. A variety of transmission rates and hence broadcasting services can be realized with the proposed transmission technique. It is shown that a geostationary orbit (GEO) satellite can provide limited service availability to the mobile user, but can also be used for experimental purposes     

广播电视有线网络频谱资源及优化分析

首先分析了广电运营商完成前期双向网络整转后,包括模拟音频广播、模拟电视节目、数字音频广播、高标清电视节目、双向互动及宽带数据业务在内的频率规划方案;其次分析了网络传输、用户接入、视频编解码等关键技术和业务承载的发展方向;最后提出全数字化后广播电视网络频率划分建议.     

Technical advances in digital audio radio broadcasting

The move to digital is a natural progression taking place in all aspects of broadcast media applications from document processing in newspapers to video processing in television distribution. This is no less true for audio broadcasting which has taken a unique development path in the United States. This path has been heavily influenced by a combination of regulatory and migratory requirements specific to the U.S. market. In addition, competition between proposed terrestrial and satellite systems combined with increasing consumer expectations have set ambitious, and often changing, requirements for the systems. The result has been a unique set of evolving requirements on source coding, channel coding, and modulation technologies to make these systems a reality. This paper outlines the technical development of the terrestrial wireless and satellite audio broadcasting systems in the U.S., providing details on specific source and channel coding designs and adding perspective on why specific designs were selected in the final systems. These systems are also compared to other systems such as Eureka-147, DRM, and Worldspace, developed under different requirements.     

DAB Ensemble Planning – Problems and Techniques

The paper is about the planning of ensembles and block assignments for DAB (Digital Audio Broadcasting) networks. Besides offering superior audio quality and multimedia data services, DAB has the potential to use the available frequency resources much more efficiently than other (analog or digital) audio broadcast systems, since it has the capability to transmit an ensemble of radio programs and data services over large regions using just a single frequency. However, to fully exploit this feature new planning methods are needed. The paper discusses a possible solution approach which leads to a combined bin packing/graph coloring problem. It is shown how this problem can be solved using heuristics, how to obtain lower bounds to estimate the quality of computed solutions, and which generalizations of the problem statement arise in practical planning scenarios. The same methods also apply to other digital broadcast systems based on similar technology like, e.g., digital video broadcasting (DVB-T).     

ASTRA Digital Radio: high‐quality digital audio transmissions via satellite

ASTRA Digital Radio (ADR) is a satellite audio transmission technology which has been designed to be compatible with analogue radio and television transmissions via satellite. It uses QPSK modulated subcarriers above the video spectrum. For source coding, the internationally standardized MPEG 1 Layer II digital audio compression has been selected. Owing to its backward compatibility with the existing analogue audio transmission technology, ADR provides a maximum operational flexibility for both the broadcasters and the satellite operator. For the consumer this technology allows for a very high number of near CD quality radio programmes which may be received with a low‐cost receiver connected to a standard 60 cm satellite reception antenna. ADR was officially launched in August 1995 during the Internationale Funkausstellung in Berlin and currently allows for the reception of over 85 radio programmes in digital quality. Copyright © 2000 John Wiley & Sons, Ltd.     

Satellite DAB

Service requirements for digital audio broadcasting (DAB) from satellites are presented, and plans for implementing such systems in various countries are surveyed. Technical and economic constraints, including satellite transmitter power, frequencies of operation, transmission bandwidth, service interference and user receiver design are discussed particularly for DAB systems employing mobile receiving terminals where transmission outage from blockage and multipath fading must be addressed. Transmission performance improvement techniques such as spatial diversity, modulation, coding and interleaving are described. An illustration of a specific satellite DAB system design is presented to show the technical and economic feasibility of such new services.     

Performance of an in-band adjacent-channel DAB system forfrequency-selective Rayleigh and Ricean slow fading channels underanalog FM interference

In support of the 1995-1997 DAB (digital audio broadcasting) testing conducted by the NRSC (National Radio Systems Committee), an IBAC (in-band adjacent-channel) scheme was developed by AT&T. Although not for use in the United States, bit error rate (BER) system performance under both fading environments and the existing analog FM broadcasting is important to quantify. This is because there may still exist other countries and environments where an IBAC approach to DAB is feasible and economical. Given this situation, an IBAC simulation model has been developed to allow for a performance analysis study within the mobile reception environment, which is dominated by Rayleigh and Ricean fading statistics. This paper presents the simulation results for coherent quadrature phase-shift-keying (QPSK) with nonlinear equalization for both frequency-selective Rayleigh and Ricean slow fading channel environments, along with co-channel, 1st-adjacent and 2nd-adjacent analog FM interference. The results indicate that for a country where spectrum availability dictates an IBAC solution, this approach may perform well under various fading and interference environments     

HD Radio传输系统实验室性能测试

HD Radio是美国AM与FM波段的数字广播标准,为了了解其信号的传输性能及其在我国实际播出环境及广播频道规划条件下,与邻频道广播电台之间相互干扰的情况,需要对其传输性能进行实验室测试和场地测试,为我国调频频段广播数字化提供技术参考依据。本文主要探讨实验室性能测试的相关技术和方法。     

数模同播FM发射机的设计与实现

设计了一种基于数模同播结构的新型FM发射机,该结构可以实现在现有模拟FM广播频段上同时传输数字音频广播信号。该结构由FPGA和两路ADC组成,基于NiosⅡ软核CPU搭建控制平台,利用DDS和IFFT的原理分别实现模拟FM调制和数字OFDM调制,最后合路实现数模同播。通过实验证明,该结构具有实现简单、不需要申请新的频谱资源和拓展高音质数字广播业务的特点,可以实现模拟/数字调频同播运行,为FM广播由模拟向数字平滑过渡提供了实验验证。     

数字化中波同步广播单频网的音频时延分析

随着广播电视技术的高速发展,广播电视信号的传输已经全部实现了数字化,数字化的音频在数字化传输途径中所产生的音频时延有很大的不同.介绍了组成中波同步广播单频网要素,针对单频网中同步发射台音频信号的各种传输途径,阐述数字化音频的各种传输方式,并具体分析每种传输方式所引起的音频信号时延.