United States RBDS Standard Specification of the Radio Broadcast Data System (RBDS) April, 2005
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NRSC STANDARD NATIONAL RADIO SYSTEMS COMMITTEE NRSC-4-A United States RBDS Standard Specification of the radio broadcast data system (RBDS) April, 2005 Part II - Annexes NAB: 1771 N Street, N.W. CEA: 1919 South Eads Street Washington, DC 20036 Arlington, VA 22202 Tel: (202) 429-5356 Fax: (202) 775-4981 Tel: (703) 907-7660 Fax: (703) 907-8113 Co-sponsored by the Consumer Electronics Association and the National Association of Broadcasters http://www.nrscstandards.org NOTICE NRSC Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. 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This document is distributed free of charge via the NRSC website at: http://www.nrscstandards.org Page ii Page 5 U.S. RBDS Standard ANNEXES A - Offset words to be used for group and block synchronization (normative) ........................................................... 72 B - Theory and implementation of the modified shortened cyclic code (informative)................................................. 73 C - Implementation of group and block synchronization using the modified shortened cyclic code (informative) ............................................................................................................................... 79 D - Program identification codes and Extended country codes (normative) ................................................................ 82 E - Character definition for Program Service name, Program Type Name, Radiotext and alphanumeric Radio paging (normative)........................................................................................................ 93 F - Program Type codes (normative) ........................................................................................................................... 97 G - Conversion between time and date conventions (informative) ............................................................................ 105 H - Specification of the ARI system (informative) ................................................................................................... 107 J - Language identification (normative).................................................................................................................... 108 K - RDS logo (informative) ...................................................................................................................................... 110 L - Open data registration (informative) ................................................................................................................... 111 M - Coding of Radio Paging (normative) .................................................................................................................. 118 N - Country codes and Extended country codes for countries outside the European Broadcasting Area (normative)................................................................................................... 154 P - Coding of MMBS Radio Paging, Data and In-House Application (informative)................................................. 159 Q - Emergency Alert System Open Data Application (informative).......................................................................... 180 R - In-Receiver Database System (I-RDS) File Structure (informative).................................................................... 186 S - List of Abbreviations (normative)......................................................................................................................... 205 T - Bibliography (informative)................................................................................................................................... 206 U - Open Data Application for Program Associated Data (normative)...................................................................... 207 Page 72 U.S. RBDS Standard ANNEX A (normative) Offset words to be used for group and block synchronization The offset words are chosen in such a way that the content in the offset register will not be interpreted as a burst of errors equal to or shorter than five bits when rotated in the polynomial shift register (see annex B). Only eight bits (i.e. d9 to d2) are used for identifying the offset words. The remaining two bits (i.e. d1 and d0 ) are set to logical level zero. The six offset words (A, B, C, C', D, E) of the table below are used for all applications. For MMBS applications an additional offset word E is used to maintain synchronization. Table A.1 Binary value Offset word d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 A 0011111100 B 0110011000 C 0101101000 C' 1101010000 D 0110110100 E 1) 0000000000 The offset words are added (modulo-two) to the checkword c9 - c0 to generate the modified check-bits: c'9 - c'0 (see 2.3, Error protection). 1) Attention is drawn to the fact that, in the USA (see [15] of annex Q), offset word E (binary value = 0) is used in multiples of four blocks, when RDS and MMBS are simultaneously implemented. Offset word E must not be used in RDS implementations corresponding to this specification. Page 73 U.S. RBDS Standard ANNEX B (informative) Theory and implementation of the modified shortened cyclic code The data format described in this document uses a shortened cyclic block code, which is given the capability of detecting block-synchronization-slip by the addition (modulo-two) of chosen binary sequences (offset words, see annex A) to the check bits of each codeword [4, 6, 7]. B.1 Encoding procedure B.1.1 Theory A definitive description of the encoding of the information is given in 3.2. The code used is an optimum burst-error-correcting shortened cyclic code [5] and has the generator polynomial: g(x) = x10 + x8 + x7 + x5 + x4 + x3 + 1 Each block consists of 16 information bits and 10 check bits. Thus the block length is 26 bits. The 10-bit checkword of the basic shortened cyclic code may be formed in the usual way, i.e. it is the remainder after multiplication by xn-k (where n-k is the number of check bits, 10 here), and then division (modulo- two) by the generator polynomial g(x), of the message vector. 15 14 Thus if the polynomial m(x) = m15 x + m14 x + ... + m1 x + m0 (where the coefficients mn are 0 or 1), represents the 16-bit message vector, the basic code vector v(x) is given by: The transmitted code vector is then formed by the addition (modulo-two) of the 10-bit offset word, d(x) (see annex A) to the basic code vector v(x). Thus the transmitted code vector, c(x), is given by: 25 10 The code vector is transmitted m.s.b. first, i.e. information bits c25x to c10x , followed by modified 9 0 check bits c9'x to c0'x . Page 74 U.S. RBDS Standard The encoding process may alternatively be considered in terms of its generator matrix G which is derived from the generator polynomial. The 16 information bits are expressed as a 16 x 1 column matrix and multiplied by the generator matrix to give the information bits and check bits. The complete transmitted code