1、ETSI TR 101 758 2.1.1 (2000-11) Technical Report Digital Audio Broadcasting (DAB); Signal strengths and receiver parameters; Targets for typical operation 2 ETSI TR 1 O1 758 V2.1.1 (2000-1 1) Reference RTWJTC-DAB-24-rl Keywords audio, broadcast, broadcasting, DAB, digital, receiver ETSI 650 Route de
2、s Lucioles F-O6921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 O0 Fax: +33 4 93 65 47 16 Siret No 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-prfecture de Grasse (06) No 7803/88 Important notice Individual copies of the present document can be downloaded fr
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5、 at http:/www.etsi.oratb/status/ If you find errors in the present document, send your comment to: editor etsi.fr Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. 8 European T
6、elecommunications Standards Institute 2000. O European Broadcasting Union 2000. All rights reserved. ETSI 3 ETSI TR 1 O1 758 V2.1.1 (2000-1 1) Contents Intellectual Property Rights 4 Foreword 4 Introduction 5 1 2 3 3.1 3.2 4 5 6 7 8 9 10 11 Scope 6 References 6 Symbols and abbreviations 6 Symbols 6
7、Abbreviations 7 The desired C/N of the broadcast channel 7 Permissible noise levels 11 The level of noise in the receiver . 12 The antenna 12 Signal strength required to deliver target C/N 13 Antenna Head Amplifiers . 15 Linearity . 16 Conclusions 17 Annex A: Bibliography . 18 History . 19 ETSI 4 ET
8、SI TR 1 O1 758 V2.1.1 (2000-1 1) Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI S
9、R O00 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server -). Pursuant to the ETSI IPR Policy, no investigation, includin
10、g IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR O00 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Report (TR) has been pro
11、duced by Joint Technical Committee (JTC) Broadcast of the European Broadcasting Union (EBU, Comit Europen de Normalisation ELECtrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI)(Broadcast). The present document is identical to TS 101 758 (see annex A), only the del
12、iverable type has been changed from Technical Specification (TS) to Technical Report (TR). With the publication of the present document TS 101 758 has been withdrawn. NOTE 1: The EBUETSI JTC Broadcast was established in 1990 to Co-ordinate the drafting of standards in the specific field of broadcast
13、ing and related fields. Since 1995 the JTC Broadcast became a tripartite body by including in the Memorandum of Understanding also CENELEC, which is responsible for the standardization of radio and television receivers. The EBU is a professional association of broadcasting organizations whose work i
14、ncludes the Co-ordination of its members activities in the technical, legal, programme-making and programme-exchange domains. The EBU has active members in about 60 countries in the European broadcasting area; its headquarters is in Geneva. European Broadcasting Union CH-1218 GRAND SACONNEX (Geneva)
15、 Switzerland Tel: +41 2271721 11 Fax: +41 22 71 7 24 81 The Eureka Project 147 was established in 1987, with funding from the European Commission, to develop a system for the broadcasting of audio and data to fixed, portable or mobile receivers. Their work resulted in the publication of European Sta
16、ndard, EN 300 401 i, for DAB (note 2) which now has worldwide acceptance. The members of the Eureka Project 147 are drawn from broadcasting organizations and telecommunication providers together with companies from the professional and consumer electronics industry. NOTE 2: DAB is a registered trade
17、mark owned by one of the Eureka Project 147 partners. ETSI 5 ETSI TR 1 O1 758 V2.1.1 (2000-1 1) Introduction DAB is a system whose main purpose is to broadcast audio programme services i. The broadcaster transmits a signal, and some distance away, the listener can listen to programmes on his or her
18、receiver. To keep the listener happy, the broadcaster has to transmit a satisfactory signal strength and the receiver has to operate well when it receives a suitable signal. The important issues are: how much signal is needed to be provided by the broadcaster; and how well should the receiver perfor
19、m. The present document describes the compromises involved. The main objective is that sufficient signal is received to overcome the noise generated throughout the system. As there are many factors which affect the signal level, and a similar number which affect the noise levels, the calculation is
20、complex. For an efficient DAB system, it is desirable to avoid unnecessary waste. Experience with transmissions in Band III shows that it is possible to reach a good balance between, on the one hand, field strengths offered by the broadcaster, and the sensitivity of the receiver on the other hand. I
21、n L-Band, operation is known to be satisfactory if all parts of the system are of high specification. If all parts of the system operate to a relaxed specification, then the coverage will be unacceptably small. Broadcasters, network operators and receiver manufacturers need to be aware of the design
22、 compromises that are part of the system. The CEPT Planning Meeting at Wiesbaden adopted parameters which are difficult to implement. The broadcast signal is relatively low in power, and this requires receivers to have a sensitivity which is difficult to provide at a low price using current receiver
23、 technology. In the present document, the implications of different parameters will be discussed. Each has a target value, but the effects of departures from this value will be considered. It is not the intention of the present document to define the minimum requirements of the system. It is the int
24、ention to show how the parameters can be chosen for good reliable performance. It is recommended that these values, or values compatible with them, are used as a target whenever possible. In planning a service, broadcasters should seek wherever possible to base their coverage areas on the proposed t
25、arget field strengths, and receiver and antenna manufacturers should provide products which are compatible with the same targets. The present document provides guidance on the field strengths and receiver sensitivity that can be adopted in a DAB system. These are close to the parameters adopted by C
26、EPT for planning international Co-ordination. Individual broadcasters and receiver makers have the flexibility to adopt other values. ETSI 6 ETSI TR 1 O1 758 V2.1.1 (2000-1 1) 1 Scope The specification of the system for broadcasting digital radio i makes no reference to the implementation of the sys
27、tem. The present document establishes general principles for deriving the necessary field strength and compatible receiver sensitivity for satisfactory operation of a DAB system. 2 References For the purposes of this Technical Report (TR) the following references apply: u1 ETSI EN 300 401: “Radio br
28、oadcasting systems; Digital Audio Broadcasting (DAB) to mobile, portable and fixed receivers“. ITU-R Special Publication: “Terrestrial and satellite digital sound broadcasting to vehicular, portable and fixed receivers in the VHFLJHF bands, Geneva, 1995“. 121 3 3.1 Symbols and abbreviations Symbols
29、For the purposes of the present document, the following symbols apply: ChV f F F G G k K n N T Te To Ta V X a 4 The carrier-to-noise ratio (i.e. the ratio of the power of the received signal to that of the noise in the receiver) Frequency of operation The normal noise figure (i.e. as represented in
30、dB) The noise figure in linear form (i.e. 10 (Flo) Gain of an antenna (measured in dBi when referred to an isotropic antenna, or dBd when referred to a dipole) Effective antenna gain (include allowance for loss etc) Boltzmanns con stan t Degrees Kelvin The overall noise factor of the receiver referr
31、ed to the receiver input The noise power in the receiver Noise temperature of the DAB receiver Contribution to noise temperature from surroundings The reference temperature The noise temperature of the sky Received field strength Loss in the cable from the antenna to the radio Resistive loss in ante
32、nna cable Passive loss in antenna system Bandwidth of DAB signal (usually taken as 1 536 kHz) ETSI 7 3.2 Abbreviations ETSI TR 1 O1 758 V2.1.1 (2000-1 1) For the purposes of the present document, the following abbreviations apply: BER CEPT COST 207 DAB EMC ETSI FFT PFD QPSK Bit-error ratio European
33、Conference of Posts and Telecommunications Commission of the European Communitys Co-operation in Scientific and Technical Research Committee project, Digital land mobile radio communications Digital Audio Broadcasting Electromagnetic compatibility European Telecommunications Standards Institute Fast
34、 Fourier Transform Power Flux Density Quaternary Phase Shift Keying 4 The desired C/Nof the broadcast channel The primary aim of the DAB system is to provide audio services of adequate audio quality. At the studio, audio quality is a function of the choice of bit rate. The quality may then be degrad
35、ed by data errors on transmission. Measurements of subjective quality as a function of error rate and source coding have been made by Eureka 147 2 and these show that the threshold of audibility for errors usually occurs with a Bit Error Ratio (BER) of around 5 x Failure occurs with a BER around DAB
36、 uses a modified version of QPSK on its carriers. This has very good noise properties, but the required CAV is not directly related to the BER. It depends on the propagation conditions within the broadcast channel. The simplest of channels is one in which a perfect signal is received with the additi
37、on of a small amount of random (thermal) noise in the receiver. This is the so-called Gaussian channel. Measurements of the performance of DAB in the laboratory are close to theoretical expectations and show that the BER required for threshold of audibility and failure are about 8 dB and 6 dB respec
38、tively. Figure 1 shows typical values measured in the Eureka 147 validation trials, as reported in 2. Unfortunately the broadcast channel rarely demonstrates a Gaussian characteristic. Figure 1 also shows that there is some sensitivity of result to the level of protection used (The measurements cite
39、d here used convolutional codes with code rates of 0,5 and 0,375). In the present document, it is assumed that level 3 protection, as defined in i will be used. This is appropriate for most terrestrial broadcasts of audio signals. Different values may be more suitable for satellite or cable systems,
40、 or for the transmission of data. An edge of service target of BER of is reasonable. 10 -1 I I I I 4 - Rate 0,5 (measured) - - _ - - - - Rate 0,375 (measured) Rate 0,5 (simulated) -e- Rate 0,375 (simulated) signal-to-noise ratio, dB Figure 1 : The performance of DAB in a Gaussian channel (Mode 1) ET
41、SI 8 ETSI TR 1 O1 758 V2.1.1 (2000-1 1) If the channel is subject to multipath distortion, Doppler shift etc., then the required CAV for a given BER is different from that of the Gaussian channel. The performance depends very much on the nature of the channel. Although DAB is often quoted as being r
42、esistant to multipath, and the guard interval provides robust performance in the presence of multipath, the CAV we require for good reception varies significantly with the type of channel. It is not the intention to explain the reasons in the present document, but examples are presented and the cons
43、equences considered. There are propagation models, many developed by the COST 207 Project (see annex A), which are typical of different receiving conditions. These cover a range of different types of country, from dense urban through to rural. The models cover different types of reception, from stat
44、ionary to high-speed mobile. Eureka 147 has measured the performance of DAB for several of these models. The quality of reception varies with the frequency of operation and the choice of mode (see annex A). Representative results are shown in figures 2, 3,4,5,6 and 7. 10 -1 I I I I I I I I I I 10-6i
45、 A i A 9 1; 1; 1; 1; l 15 16 signal-to-noise ratio, dB Figure 2: The performance of DAB in a simulated Raleigh Channel, Mode 1 ,Urban environment, 15 km/h speed, Band III 10 I I I I I I I I I I Rate 0,5 - I I I I I I I I I I 6 7 8 9 10 11 12 13 14 15 16 signal-to-noise ratio, dB Figure 3: Performanc
46、e of DAB in a simulated Raleigh Channel, Mode 2,Urban environment, 15 km/h speed, L-Band ETSI 9 ETSI TR 1 O1 758 V2.1.1 (2000-1 1) 1 I I I I I I I I I I 3 - Rate 0.5 - - _ - _ Rate 0,375 - - - 5 - 6 I I I I I I I I I I 5 6 7 8 9 10 11 12 13 14 15 16 10 10 10 210: ?j d 10 4 ! P L 10 lo 10 I I I I I I
47、 I I I I I 3 - Rate 0,5 Rate 0,375 _ r - - -. -. : - 8 9 l10 l11 112 113 1; 115 116 1; 118 19 20 g 10 10 10 Figure 4: Performance of DAB in a simulated Raleigh Channel, Mode 3, Urban environment, 15 km/h speed, L-Band 10 10 g 10 d 10 I I I I I I I I I I I - Rate 0.5 Rate 0,375 - -_ _ - _ t -. 10 10
48、8 9 10 11 12 13 14 15 16 17 18 19 20 signal-to-noise ratio. dB Figure 6: Performance of DAB in a simulated Raleigh Channel, Mode 2, Rural environment, 130 km/h speed, L-Band ETSI 10 ETSI TR 1 O1 758 V2.1.1 (2000-1 1) 10 -Rate 0.5 -_ - - _ - Rate 0,375 - -. -. - - Figure 7: Performance of DAB in a si
49、mulated Raleigh Channel, Mode 3, Rural environment, 130 km/h speed, L-Band -. - : - From these results it can be seen that in some places good reception will be possible with a low CAV close to that of the Gaussian channel, but that in others, a much higher CAV is needed. For the type of channel that is both typical and extreme (the rural model) the CAV for acceptable reception is about 14 dB. There are other models which require a higher CAV perhaps up to about 20 dB, but this high CAV is often required because the sign
