1、 Recommendation ITU-R BS.643-3(05/2011)Radio data system for automatic tuning and other applications in FM radio receiversfor use with pilot-tone systemBS SeriesBroadcasting service (sound)ii Rec. ITU-R BS.643-3 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable,
2、 efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sect
3、or are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-
4、R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database ca
5、n also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service
6、M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectru
7、m management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2011 ITU 2011 All rights reserved.
8、No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R BS.643-3 1 RECOMMENDATION ITU-R BS.643-3*Radio data system for automatic tuning and other applications in FM radio receivers for use with the pilot-tone system (1986-1990-1995-2011)
9、Scope This Recommendation specifies the main parameters and operational requirements for the use of the radio data system (RDS) for VHF/FM broadcasting. The ITU Radiocommunication Assembly, considering a) that, in VHF/FM broadcasting, the density of transmissions in many parts of the world is increa
10、sing to the extent that tuning to a given programme service is becoming more and more difficult, particularly for listeners using FM portable or car radios; b) that, on the other hand, technologies offer the possibility of adding auxiliary data signals to the sound-programme signals which offer a wi
11、de variety of methods for identifying the transmissions, thereby facilitating the implementation of assisted and automatic tuning in radio receivers; c) that such radio-data signals can be added to existing VHF/FM broadcasts in such a way that they are inaudible, thus achieving good compatibility wi
12、th reception of the normal stereophonic or monophonic sound-programme signals; d) that inexpensive receiver technology optimized in miniaturization processes is available to implement assisted or automatic tuning using radio-data signals; e) that such a system offers the flexibility to implement a w
13、ide range of optional applications to suit the particular needs of individual broadcasting organizations; f) that many countries have implemented this system on their broadcasts, recommends 1 that broadcasters wishing to introduce the transmission of supplementary information for station and program
14、me identification in FM broadcasting and other applications, should use the radio-data system (RDS), as specified in Annex 1. 2 the following notes should be considered as part of the Recommendation. NOTE 1 Information regarding the operational characteristics of RDS is given in Annex 2. NOTE 2 The
15、most recent version of the international RDS standard is IEC 62106 Ed.2:2009. In North America although the structure and coding is identical, there are minor differences in implementation of certain features for the United States of America these are described in the US national standard version of
16、 RDS which is called RBDS, specified in US NRSC-4-A. In general, other North American countries also follow the practice of the United States of America in their implementations. *This Recommendation should be brought to the attention of the International Electrotechnical Commission (IEC). 2 Rec. IT
17、U-R BS.643-3 NOTE 3 Since RDS was first specified by the European Broadcasting Union (EBU) in 1984 more than 500 million RDS receivers were already produced worldwide and this number is continuing to increase significantly every year with retail prices held low due to RDS decoder silicon embedded in
18、 FM receiver chips costing very little in large quantities. Annex 1 Specifications of the radio data system*1 Modulation of the data channel 1.1 Sub-carrier frequency: 57 kHz, locked in phase or in quadrature to the third harmonic of the pilot tone 19 kHz (2 Hz) in the case of stereophony. (Frequenc
19、y tolerance: 6 Hz.) 1.2 Sub-carrier level: the recommended nominal deviation of the main FM carrier due to the modulated sub-carrier is 2 kHz. However in practice it can be as low as 1.2 kHz; many EBU broadcasters with wide dynamic range (e.g. classical music) services prefer this lower value to ens
20、ure best signal-to-noise performance. The decoder should, however, be designed to work with sub-carrier levels corresponding to between 1 kHz and 7.5 kHz deviation. 1.3 Method of modulation: the sub-carrier is amplitude-modulated by the shaped and biphase-coded data signal. The sub-carrier is suppre
21、ssed (see Figs 1a) to 1c). 1.4 Clock frequency and data rate: the basic clock frequency is obtained by dividing the transmitted sub-carrier frequency by 48. Consequently the basic data rate is 1 187.5 bit/s 0.125 bit/s. 1.5 Differential coding: when the input data-level from the coder at the transmi
22、tter is 0, the output remains unchanged from the previous output bit, and when an input 1 occurs, the new output bit is the complement of the previous output bit. 2 Baseband coding 2.1 Coding structure: the largest element in the structure is called a “group” of 104 bits. Each group comprises 4 bloc
23、ks of 26 bits. Each block comprises an information word and a checkword, of 16 and 10 bits respectively. 2.2 Order of bit transmission: all information words, checkwords and addresses have their most significant bit transmitted first. 2.3 Error protection: the 10-bit cyclic redundancy checkword, to
24、which a 10-bit offset word is added for synchronization purposes, is intended to enable the receiver/decoder to detect and correct errors which occur in reception. 2.4 Synchronization of blocks and groups: the data transmission is fully synchronous and there are no gaps between the groups or blocks.
25、 The beginning and end of the data blocks may be recognized in the decoder by using the fact that the error-checking decoder will, with a high level of confidence, detect block synchronization slip. The blocks within each group are identified by different offset words added to the respective 10-bit
26、checkwords. *The characteristics published here are only a summary drawn from a more detailed text which is published separately as the IEC 62106 standard. Rec. ITU-R BS.643-3 3 FIGURE 1 Spectrum and time-functions of RDS signals Modulating frequency (Hz)a) Spectrum of biphase coded radio-data signa
27、lsRelative amplitude0.5Example ofmaincarrierdeviation (kHz)c) 57 kHz radio-data signalsOne biphase symbol = one data bit period: = std11 187.5TimeRelativeamplitude0.5 0.7Symbol generated when the data bitis a logic 1Symbol generated when the data bitis a logic 0b) Time-function of a single biphase s
28、ymbol11 187.5One data clock period: = std20 2 3td4 td td2 td4td4td2td3td401 11 2 400 0 240 240 2 400 1 200 1 2004 Rec. ITU-R BS.643-3 2.5 Message format: the first five bits of the second block of every group are allocated to a five-bit code which specifies the application group type and its version
29、. The group types specified are given in Table 1. There is also the open data application feature to add applications not yet defined. Once registered, this allows applications to use specified groups on a locally regulated basis. A large part of the data-transmission capacity of the RDS system will
30、 be used for features relating to the automatic or assisted tuning functions of an FM receiver. Such messages are repeated frequently so that a short data-acquisition time for tuning or retuning may be achieved. Many of the relevant codes occupy fixed positions within every group. They can therefore
31、 be decoded without reference to any block outside the one which contains this information. FIGURE 2 Message format and addressing PI codeTrafficprog.codeFirst transmitted bit of group Last transmitted bit of groupBlock 1Block 2Block 3Block 4One group = 104 bits 87.6 msCheckwordand offset AGrouptype
32、 codeCheckwordand offset BOffset C = version AOffset C = version BCheckwordand offset C or CCheckwordand offset DMostsignificant bitLeast significant bit4-bit group type code 0 = version A1 = version BNote 1 Group type code = 4 bits.Note 3 PI code = programme identification code = 16 bits.Note 4 TP
33、= traffic programme identification code = 1 bit.Note 5 PTY = programme type code = 5 bits.Note 6 Checkword + offset “N” = 10 bits added to provide error protection and block and group synchronisa tion information.Note 2 B = version code = 1 bit.0Note 7 t t : block 1 of any particular group is transm
34、itted first and block 4 last.12A3A2A1A0B0PT4PT3PT2PT1PT0PTY PIB0TPt1t2Rec. ITU-R BS.643-3 5 TABLE 1 Example of group type codes Group type Applications Decimal value Binary code A3A2A1A0B00 0 0 0 0 X (1)Basic tuning and switching information 1 0 0 0 1 X Programme item number 2 0 0 1 0 X Radiotext 3
35、0 0 1 1 0 Open data application 4 0 1 0 0 0 Clock-time and date 5 0 1 0 1 X Transparent channels (32 channels) 6 0 1 1 0 X In-house applications 7 0 1 1 1 0 Radio paging 14 1 1 1 0 X Enhanced other networks information 15 1 1 1 1 1 Fast basic tuning and switching information (1)X indicates that valu
36、e may be “0” (version A) or “1” (version B). Table 2 explains the abbreviations used and the features to which they are relevant. TABLE 2 List of abbreviations and features Tuning functions Other functions PI: Programme identification TA: Traffic announcement flag PS: Programme service name DI: Deco
37、der identification AF: List of alternative frequencies M/S: Music/speech switch TP: Traffic programme identification PIN: Programme item number PTY: Programme type RT/RT+/eRT: Radiotext/radiotext plus/enhanced radiotext EON: Enhanced other networks information TDC: Transparent data channel IH: In-ho
38、use applications CT: Date and time RP: Radio pagingODA: Open data application TMC: Traffic message channel 2.6 Repetition rates: Table 3 indicates the appropriate repetition rates for some of the main applications, when and if they are implemented by the broadcaster. 6 Rec. ITU-R BS.643-3 TABLE 3 Ap
39、propriate repetition rates Applications Group types which contain this information Appropriate repetition rate per second Programme identification (PI) code All 11.4(1)Programme type (PTY) code All 11.4(1)Traffic programme (TP) identification code All 11.4(1)Programme service (PS) name 0A, 0B 1(2)Al
40、ternative frequency (AF) code pairs 0A 4(2)Traffic announcement (TA) code 0A, 0B, 15B 4 Decoder identification (DI) code 0A, 0B, 15B 1 Music/speech (M/S) code 0A, 0B, 15B 4 Radiotext (RT) message 2A, 2B 0,2(3)Enhanced other networks information (EON) 14A, 14B Up to 2(4)(1)Valid codes for this item w
41、ill normally be transmitted with at least this repetition rate whenever the transmitter carries a normal broadcast programme. (2)A total of four 0A groups are required to transmit the entire PS name and therefore four 0A groups will be required per second. The repetition rate of group type 0A may be
42、 reduced if more capacity is needed for other applications. A minimum of two type 0A groups per second is necessary to ensure correct functioning of PS and AF features. It should be noted that in this case transmission of the complete PS will take 2 s. However, under typical reception conditions the
43、 introduction of errors will cause the receiver to take 4 s or more to acquire the PS name for display. PS is static and must not be used for text transmission. (3)A total of 16 type 2A groups are required to transmit a 64 character radiotext message and therefore 3.2 type 2A groups will be required
44、 per second. For certain character sets composed of a 2-byte character code, the enhanced Radiotext feature is more suitable. (4)The maximum cycle time for the transmission of all data relating to all cross-referenced programme services shall be less than 2 min. Annex 2 Operational characteristics o
45、f the radio data system “RDS” 1 Compatibility with existing VHF/FM broadcasts The frequency, level and method of modulation of the sub-carrier used to convey the data signals have been carefully chosen so as to avoid interference to reception of the main stereo or mono programme signals. Because of
46、the extreme importance of these compatibility considerations, extensive and prolonged field-trials have been conducted in several countries. It has been found that over a wide variety of propagation conditions, and with a wide variety of receivers, good compatibility is achieved. However, in some lo
47、cations where the received signals are affected by severe multipath propagation, interference to the main programme signal may occur. In such circumstances, however, even in the absence of RDS signals, the quality of the received programme signal is usually poor due to distortion. Rec. ITU-R BS.643-
48、3 7 2 Reliability of reception of radio-data signals When assessing the reliability of reception of radio-data signals it is important to divide the applications of the RDS system into two categories: those using short and frequently repeated messages, for example, automatic tuning functions; and th
49、ose using longer messages which are repeated rarely, for example, radiotext (RT) messages. In the case of field-strength limited reception conditions, as might be experienced in a fixed domestic installation, and with the recommended RDS injection level of 2 kHz, adequately reliable reception of short messages is possible for an input e.m.f. to the receiver down to about 15 dB(V) (from a 50 source) whilst adequately reliable reception of the longer messages required an input e.m.f. of about 20 dB(V). It should be stressed tha
