Résumé du contenu de la page N° 1
Résumé du contenu de la page N° 2
Résumé du contenu de la page N° 3
FOREWORD The purpose of the Digital Radio Guide is to help engineers and managers in the radio broadcast community understand various aspects of digital radio systems that are available in 2006. The guide covers those systems used for transmission in different media, but not in the production chain. The in-depth technical descriptions of the systems are available from the proponent organisations and their websites listed in the appendices. The choice of the appropriate system remains the respo
Résumé du contenu de la page N° 4
Résumé du contenu de la page N° 5
TABLE OF CONTENTS 1 INTRODUCTION............................................................................................................................... 7 2 WHAT IS DIGITAL RADIO?........................................................................................................... 8 3 WHY DIGITAL RADIO? ................................................................................................................ 10 4 TERRESTRIAL TRANSMISSION SYSTEMS.................................
Résumé du contenu de la page N° 6
6.3 INTERNET RADIO PECULIARITIES................................................................................................ 77 6.4 INTERNET RADIO AS A COMPLEMENT TO ESTABLISHED RADIO SERVICES ................................... 78 6.5 INTERNET-ONLY STATIONS:IRPORTALS AND MUSIC PORTALS ................................................. 79 6.6 STREAMING TECHNOLOGY FOR RADIO SERVICES........................................................................ 79 6.7 INTERNET RADIO TERMINALS AND PLAY
Résumé du contenu de la page N° 7
DIGITAL RADIO GUIDE INTRODUCTION 1 Introduction Digital technology has steadily transformed the way in which programmes are made and distributed in recent years. Already many broadcasters have invested in digital systems for contribution and production and now the switch from analogue to digital is moving along the broadcasting chain into transmission. At the same time, digital developments are drawing together the broadcasting, telecommunications and computer industries in a process of conver
Résumé du contenu de la page N° 8
DIGITAL RADIO GUIDE WHAT IS DIGITAL RADIO? 2 What is Digital Radio? Since the early days of broadcasting, analogue systems have been used to carry programmes from the studios to the listeners. Now, due to the growing number of broadcasters and programme services, the frequency bands allocated to AM and FM radio in many regions of the world are full. The resulting congestion in the radio spectrum has led to a decline in reception quality and is a real constraint to further growth. Furthermore, i
Résumé du contenu de la page N° 9
DIGITAL RADIO GUIDE WHAT IS DIGITAL RADIO? Table 2.1. Digital Radio Systems AVAILABILITY SYSTEM Terrestrial in service date Satellite in service date Eureka 147 1995 --- (ITU-R Digital System A) (for the UK, Norway, Denmark and Sweden) DRM - Digital Radio Mondiale Transmissions tests --- successfully since 2000; ETSI ES 201 980 V1.2.2 (2003-4) regular broadcasting from International consortium July 2003. For use in all broadcasting bands below 30 MHz DRM - Digital Radio Mondiale 2010 DRM
Résumé du contenu de la page N° 10
DIGITAL RADIO GUIDE WHY DIGITAL RADIO? 3 Why Digital Radio? The existing AM and FM analogue systems suffer from inherent short-comings and neither can offer uniform reception quality throughout the coverage area. AM radio reception is constrained by bandwidth limitations, which restrict the audio quality and by interference from other co-channel and adjacent channel transmissions. This is particularly troublesome during the hours of darkness. The start of FM services in the 1950’s improved the a
Résumé du contenu de la page N° 11
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DRM 4 Terrestrial Transmission Systems This section provides a technical overview of the various digital radio systems available for terrestrial application: DRM, DAB, ISDB-TSB, and HD Radio. These systems operate in various frequency bands and offer different attributes and features. 4.1 DRM – Digital Radio Mondiale The DRM system encompasses a high level of flexibility in its design. These are noted in this subsection in the signal flow
Résumé du contenu de la page N° 12
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DRM The combination of these techniques results in high quality sound in a narrow channel with robust reception in an intended coverage area with relatively low transmission power. In addition, source coding schemes using lower bit rates than that used with AAC/SBR are included for lesser levels of audio quality if the AAC/SBR quality level is not desired by a broadcaster. For example, a broadcaster may want to transmit two or more “speech”
Résumé du contenu de la page N° 13
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DRM The energy dispersal provides an ordering of the bits that reduces the possibility of unwanted regularity in the transmitted signal. The channel encoder adds redundant bits as a means for error protection and correction and defines the mapping of the digitally encoded information into QAM cells, which are the basic carriers of the information supplied to the transmitter for modulation. Cell interleaving rearranges the time sequence of t
Résumé du contenu de la page N° 14
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DRM • MDI – Multiplex Distribution Interface: covers the transport of data and commands from the DRM multiplexer to the DRM Modulator. • MCI – Modulator Control Interface: covers the remote signalling of commands and setups to the modulator and transmitter equipment. • SDI – Service Distribution Interface: covers the transport of data and commands from the studio and other sources to the DRM Multiplexer. • RSCI – Receiver Status and Cont
Résumé du contenu de la page N° 15
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DRM DRM Source Decoding AAC Decoder CELP super SBR Audio bit Decoder framing Decoder output stream demux HVXC Decoder Extensive tests on these codecs at the sampling rates and resulting “bandwidths” have determined that AAC and especially AAC with SBR produce a perceived audio quality to listeners that is effectively the equivalent of monophonic FM in a 9 or 10 kHz channel. HVXC produces intelligible speech quality with bit rates of 2 to 4 k
Résumé du contenu de la page N° 16
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DRM FAC provides information on the signal bandwidth and other such parameters, and is also used to allow service selection information for fast scanning. The SDC gives information to a receiver on how to decode the MSC, how to find alternative sources of the same data, and gives attributes to the services within the multiplex. The MSC multiplex may contain up to 4 services, any one of which can be audio or data. The gross bit rate of the
Résumé du contenu de la page N° 17
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DRM QAM is used for the modulation that is impressed upon the subcarriers to convey the information. Two primary QAM constellations are used: 64-QAM and 16-QAM. The former provides the highest audio quality, but is less robust than the latter. In addition, a 4-QAM (QPSK) signal, which is very robust, is used for some of the signalling (but not for the MSC). The interleaver time span (applied to the MSC) for HF transmission is around 2.4 seco
Résumé du contenu de la page N° 18
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DRM Extensive field tests have verified these performance statements. (2) Selecting, demodulating and decoding of a DRM system signal at a receiver A receiver must be able to detect which particular DRM system mode is being transmitted to handle it properly. This is done by way of the use of many of the field entries within the FAC and SDC. Once the appropriate mode is identified (and is repeatedly verified), the demodulation process is the
Résumé du contenu de la page N° 19
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DAB 4.2 DAB – Eureka 147 1 Eureka 147 is a digital radio system developed in Europe for reception by mobile, portable and fixed receivers with a simple non directional antenna. It can be used in terrestrial, satellite, hybrid (satellite with complementary terrestrial), and cable broadcast networks and has been designed to operate at any frequency from 30 to 3000 MHz. In practice, Eureka 147 is being implemented in two spectrum bands, VHF Ban
Résumé du contenu de la page N° 20
DIGITAL RADIO GUIDE TERRESTRIAL TRANSMISSION SYSTEMS - DAB Many ancillary aspects of the Eureka 147 system, such as multimedia delivery, distribution interfaces and user interactivity are also formally defined in ETSI standards. Eureka 147 can be implemented for a range of applications such as wide area or local delivery of audio and data services for mobile, portable and fixed reception. It can be delivered terrestrially, via satellite, cable or a mixture of terrestrial and satellite. Eureka
