IEC 61603-7-2003 Transmission systems of audio and or video and related signals using infrared radiation - Part 7 Transmission systems for digital audio signals.pdf

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1、INTERNATIONAL STANDARD IEC 61603-7 First edition 2003-05 Transmission systems of audio and/or video and related signals using infra-red radiation Part 7: Digital audio signals for conference and similar applications Reference number IEC 61603-7:2003(E)Publication numbering As from 1 January 1997 all

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8、1 22 919 02 11 Fax: +41 22 919 03 00INTERNATIONAL STANDARD IEC 61603-7 First edition 2003-05 Transmission systems of audio and/or video and related signals using infra-red radiation Part 7: Digital audio signals for conference and similar applications IEC 2003 Copyright - all rights reserved No part

9、 of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission, 3, rue de Varemb, PO Box 131, CH-1211 Geneva 20, Switzerland Te

10、lephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmailiec.ch Web: www.iec.ch U For price, see current catalogue PRICE CODE Commission Electrotechnique Internationale International Electrotechnical Commission 2 61603-7 IEC:2003(E) CONTENTS FOREWORD 4 1 Scope 5 2 Normative references. 5 3

11、Terms and definitions 5 4 Abbreviations. 5 5 Explanation of terms and general information 6 6 System considerations. 6 7 Basic system concept 6 8 Protocol. 7 8.1 System context. 7 8.2 Physical layer . 8 8.3 Data link layer .13 8.4 Detailed overview of audio frame structures.15 9 Data protocol 17 9.1

12、 General .17 9.2 Data messages18 9.3 Data packet structure.21 Annex A (normative) Definition of prototype filter .23 Annex B (informative) Example of /f diagram in the user area conference.24 Annex C (informative) Provision for future developments .25 Bibliography26 Figure 1 System 7 Figure 2 Concep

13、tual model 7 Figure 3 Band allocation for 6 modulated sub-carriers. 8 Figure 4 (D)QPSK constellation and differential decoding algorithm 9 Figure 5 Pulse response of a raised cosine channel filter .10 Figure 6 Scrambler.11 Figure 7 Block diagram of sub-band APCM encoder.12 Figure 8 Quantization of s

14、ub-band samples13 Figure 9 Superframe structure14 Figure 10 RS frame structure .14 Figure 11 Audio block structure15 Figure 12 CRC calculation15 Figure 13 Audio block structure for medium quality 16 Figure 14 Bit-pool sample structure for medium quality 16 Figure 15 Audio block structure for high qu

15、ality16 Figure 16 Bit-pool sample structure for high quality17 Figure 17 Positioning of the data protocol 1861603-7 IEC:2003(E) 3 Figure 18 Data message build-up.18 Figure 19 Configuration message structure 19 Figure 20 Display message structure for ASCII display data.20 Figure 21 Display message st

16、ructure for bitmap display data .21 Figure 22 Segmentation of data messages.21 Figure 23 Data packets fitted on to the superframe structure22 Table 1 Sub-carrier centre frequencies 8 Table 2 Phase transitions of the differential encoding algorithm 9 Table 3 Characteristics of sub-band APCM encoder.1

17、2 Table 4 Definition of audio mode bits .15 Table 5 Audio blocks and audio quality 17 Table 6 Data message identifier definition18 Table 7 SCI definition.19 Table 8 Channel allocation table 19 Table 9 Audio quality mode (AQM) to number of audio blocks used20 Table C.1 Sub-carrier allocation.25 4 616

18、03-7 IEC:2003(E) INTERNATIONAL ELECTROTECHNICAL COMMISSION _ TRANSMISSION SYSTEMS OF AUDIO AND/OR VIDEO AND RELATED SIGNALS USING INFRA-RED RADIATION Part 7: Digital audio signals for conference and similar applications FOREWORD 1) The IEC (International Electrotechnical Commission) is a worldwide o

19、rganization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other acti

20、vities, the IEC publishes International Standards. Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC al

21、so participate in this preparation. The IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of the IEC on technical matters express, as nearly

22、 as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested National Committees. 3) The documents produced have the form of recommendations for international use and are published in the form of standards, technic

23、al specifications, technical reports or guides and they are accepted by the National Committees in that sense. 4) In order to promote international unification, IEC National Committees undertake to apply IEC International Standards transparently to the maximum extent possible in their national and r

24、egional standards. Any divergence between the IEC Standard and the corresponding national or regional standard shall be clearly indicated in the latter. 5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity

25、 with one of its standards. 6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61603-7 has been prepared

26、 by Technical Area 3, Infrared systems and applications, of IEC technical committee 100: Audio, video and multimedia systems and equipment. This first edition cancels and replaces 2.6.2 of IEC 61603-3 (1997). The text of this standard is based on the following documents: FDIS Report on voting 100/64

27、9/FDIS 100/676/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. The committee has decided that the contents of this publication

28、will remain unchanged until 2005. At this date, the publication will be reconfirmed; withdrawn; replaced by a revised edition, or amended.61603-7 IEC:2003(E) 5 TRANSMISSION SYSTEMS OF AUDIO AND/OR VIDEO AND RELATED SIGNALS USING INFRA-RED RADIATION Part 7: Digital audio signals for conference and si

29、milar applications 1 Scope This part of IEC 61603 describes the characteristics of a digital multiple channel, multiple carrier audio transmission system as an extension to conference interpretation or similar systems using the frequency ranges 45 kHz to 1 MHz and 2 MHz to 6 MHz. NOTE These frequenc

30、y ranges are also covered by analogue pulse systems used for the same applications. Interference is not expected because both transmission systems are normally not applied at the same time in the same room. 2 Normative references The following referenced documents are indispensable for the applicati

31、on of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 61603-1:1997, Transmission of audio and/or video and related signals using infrared radiation Part 1: General IEC 6

32、1603-3:1997, Transmission of audio and/or video and related signals using infrared radiation Part 3: Transmission systems for audio signals for conference and similar systems IEC 61920, Infrared transmission systems Free air applications 1 ISO/IEC 7498-1:1994, Information technology Open Systems Int

33、erconnection Basic Reference Model: The Basic Model 3 Terms and definitions For the purposes of this document, the terms and definitions given in IEC 61603-1 apply. 4 Abbreviations APCM Adaptive pulse code modulation AQM Audio quality mode CAT Channel allocation table CM Configuration message CRC Cy

34、clic redundancy check DCI Display changed identifier DM Display message DM-CRC Data message CRC _ 1To be published. For the purposes of the reference in C.1, IEC 61920:1998 is equally valid. 6 61603-7 IEC:2003(E) DMI Data message identifier DML Data message length DQPSK Differential quadrature phase

35、 shift keying HQ High quality MAXCN Maximum channel number MHQ Mono high quality MMQ Mono medium quality MQ Medium quality OSI Open systems interconnection PCM Pulse code modulation PRBS Pseudo-random binary sequence SCI Source coding identifier SEI Setting changed identifier SF Scale factor SHQ Ste

36、reo high quality SMQ Stereo medium quality SRRC Square root raised cosine XOR Exclusive OR 5 Explanation of terms and general information For the purposes of this part of IEC 61603, the explanation and information given in IEC 61603-3, Clause 2, apply. 6 System considerations For the purposes of thi

37、s part of IEC 61603, the considerations given in IEC 61603-3, Clause 3, apply. NOTE With regard to the primary band, the special caution advised in IEC 61603-3, 3.3 should be observed, especially for inductive lighting and future developments. 7 Basic system concept The basic system concept is shown

38、 in Figure 1. The system consists of a number (N) of audio sources, either analogue or digital, which are connected to a transmitter. The transmitter processes the audio signals (in accordance with the protocol described in Clause 8) into an electrical output to feed the infrared radiator. The infra

39、red signal is received by the infrared receiver that processes the signal and outputs an audio signal and/or associated data.61603-7 IEC:2003(E) 7 Transmitter Infrared radiator Infrared receiver Audio source Audio source Audio source Audio source N sources Figure 1 System 8 Protocol 8.1 System conte

40、xt In terms of the conceptual OSI reference model, the transmission protocol shall implement the following layers: Figure 2 Conceptual model Figure 2 shows the system context using the OSI reference model. Layers 1 and 2 will be part of the transmission protocol defined in this standard. Data link l

41、ayer (layer 2)IEC 61603-7 IEC 61603-7 Physical layer (layer 1) IEC 61603-1 IEC 61920 Audio streams User data (low rate, limited) Higher OSI protocol layers Higher OSI protocol layers Medium IEC 1548/03 IEC 1549/03 8 61603-7 IEC:2003(E) 8.2 Physical layer 8.2.1 General OSI layer 1 (physical layer) sh

42、all use infrared radiation as the transfer medium between radiator and receiver as specified in IEC 61920 and IEC 61603-1. 8.2.2 Carrier Optical wavelength at the optical peak intensity P : 875 nm 25 nm 8.2.3 Sub-carriers Primary frequency band (band IV): 2 MHz 6 MHz Secondary frequency band (band I

43、I): 45 kHz 1 MHz. NOTE The secondary frequency band, 45 kHz to 1 MHz, is under consideration. Figure 3 shows the wideband allocation in the primary band, with the frequencies of each sub- carrier. A guard band between the transmission bands has been included. Table 1 shows the frequencies of each su

44、b-carrier. 2,333 3 3,667 4,333 5 5,667 f MHz Guardband Figure 3 Band allocation for 6 modulated sub-carriers Table 1 Sub-carrier centre frequencies Sub-carrier Frequency kHz CC1 2333,333 CC2 3000 CC3 3666,667 CC4 4333,333 CC5 5000 CC6 5666,667 8.2.4 Occupied bandwidth The occupied bandwidth is defin

45、ed as follows. () + = 1 S occ r B where occ B is the occupied bandwidth; IEC 1550/0361603-7 IEC:2003(E) 9 S r is the symbol rate ( = 2 b rfor (D)QPSK, r b is the bit rate (see 8.3); is the roll-off factor (see 8.2.6). 8.2.5 Sub-carrier modulation The modulation method is (D)QPSK. The constellation i

46、s shown in Figure 4a. The differential decoding algorithm is shown in Figure 4b. The phase transitions for the differential encoding algorithm are also listed in Table 2. Figure 4 (D)QPSK constellation and differential decoding algorithm Table 2 Phase transitions of the differential encoding algorit

47、hm Phase change Symbol IQ0 00 90 01 180 11 90 10 8.2.6 Filter characteristics A channel filter is included. A square root raised cosine (SRRC) characteristic, as illustrated in Figure 5, is implemented in both the transmitter and the receiver resulting in a total transfer characteristic of a raised

48、cosine. The roll-off factor of the filter is = 0,4. a) 11 01 00 10 I Qb) 10 00 01 11 00 10 01 11 11 11 11 00 00 00 10 10 10 01 01 01 IEC 1551/03 10 61603-7 IEC:2003(E) 0,2 0 0,2 0,4 0,6 0,8 1 0T b2 T b 3Tb Figure 5 Pulse response of a raised cosine channel filter The combined filter characteristic from the transmitting and receiving filter shall be in accordance with the following equation: + + + = ) ) ( 2 ( 2 ) ( 2 ) ( 2 cos ) ( 2 ) ( b b b b 2 b b b r 1 0 1 1 1 4 1 r f r f r r f T r f T f P where ) ( r f P is the power transfer function; f is the frequency (Hz);