Here, we briefly summarise what we consider in greater detail in Appendix C.
Field tests carried out by a number of broadcasters’ research laboratories all came to the same conclusions.
When signals of the ARI system are broadcast simultaneously with RDS, most first-generation RDS demodulators show some significant degradation of the data transmission reliability, which is due to interference from the ARI sig- nals under multipath receiving conditions. This may be overcome however, by filtering out the ARI signal by means of a notch filter at the RDS demodulator input and an appropriate RDS signal injection level of at least±2 kHz.
One of the methods used to investigate the reliability of the RDS channel for the transmission of real applications such as PI and PS, which are very important for the operation of the automated tuning function of an RDS receiver, is to measure the “waiting time” between successful acquisitions of a particular RDS message.
Relatively low RDS data injection levels, say±1 kHz, offer a reliable data system only under receiving conditions with little or no multipath effects (typi- cally towns with flat buildings and flat countryside). In a moving receiver, once multipath effects occur due to reflections of the transmitted signal caused by high-rise buildings or mountains, there is a sharp decrease in the reliability for a correct reception of the applications. It all depends on whether the data is repeated sufficiently often in the data stream. In ODA applications, additional CRC check words may also be considered to better protect the data transmis- sion application that is implemented.
Studies usually confirm the ruggedness of the fixed format PI codes com- pared, for example, with the variable addressed format of the PS codes. There- fore, consumer receivers often store the PS name, displaying the stored name once the PI code is received. Therefore, the use of the PS name to convey, for example, some limited dynamic text information composed of scrolling text or short words of a maximum of eight characters to the radio listener, is just not admissible.
In cases where Radio Paging is implemented within the RDS data stream, the small antenna used in these special paging receivers and the reliability of
RDS System and Applications Overview 35
reception required (which is often within buildings) make an RDS injection level of at least±4 kHz necessary.
Repetition of message elements transmitted within RDS is also a general requirement. This applies to, for example, RP and TMC messages, but to a lesser degree to RT where the occasional reception of a wrong character will be perceived as less annoying to the reader.
Error detection has to be applied to all messages, and error correction can only be applied to some applications; for example, RT—that is, when an error caused by the correction system is not perceived as being critical.
References
[1] Ilmonen, K., Listener preferences for Loudness balance of broadcasts with special consid- erations to listening in noise, Yleisradio (Finnish Broadcasting Corporation), Research Report no. 12/1971.
[2] van der Heide, H. J., “Possibilities for the introduction and application of a programme code in sound broadcasting,” Berichte der 4, NTG-Hửrrundfunktagung, Dỹsseldorf, Germany, Nov. 1976.
[3] Sundin, L., and A. Sanfridsson, Programme Identification in FM broadcasting, Swedish Telecommunications Administration, Report RI 4022/77, 1977.
[4] MacEwan, D., “Radio in the 80’s Broadcasting and the ideal sound receiver of the future,”
Wireless World, May 1977, pp. 36–40.
[5] Ely, S. R., VHF Radio Data: Experimental BBC transmissions, BBC Research Depart- ment Report No. BBC RD, 1981-1984.
[6] Ely, S. R., “The impact of radio-data on broadcast receivers,”The Radio and Electronic Engineer, Vol. 52, No. 5, 1982, pp. 291–296.
[7] Swedish Telecommunication Administration: Paging receiver for the Radio Data System, Doc. 1301/A694 3798 (Alternative B), 1986.
[8] CCIR: Report 900-1 Radio-paging systems-standardisation of code and format (Annex II), 1986.
[9] ITU-R Recommendation B.S.643-2 (1995), System for automatic tuning and other appli- cations in FM radio receivers for use with the pilot-tone system.
[10] Mielke, J., and K. H. Schwaiger, “Progress with the RDS system and experimental results,”EBU Review, No. 217, June 1986.
[11] Shute, S. A., “The EBU Radio Data System,”International Broadcast Engineer, May/June 1987.
[12] Kopitz, D., “Radio Data System-from specification to practical reality,”EBU Technical Review, No. 233, Feb. 1989.
36 RDS: The Radio Data System
[13] Parnall, S. J., and J. L. Riley, “RDS developments,”International Broadcasting Convention Digest, 1990, pp. 234–240.
[14] Ely, S. R., and D. Jeffrey,Traffic Information Broadcasting in Mobile Information Systems, J. Walker, Ed., Norwood, MA: Artech House, 1990, Chapter 5.
[15] Borras Amoedo, J. M.,El RDS: Una Radio Intelligente, Biblioteca Tecnica PIONEER, Ediciones Tecnicas Rede, S. A., 1991.
[16] Universal Encoder Communications Protocol UECP-EBU doc. SPB 490, version 5.1, European Broadcasting Union, 17A Ancienne Route, CH-1218 Geneva, Aug. 1997.
[17] EBU: Proposed enhancements of the EBU on CENELEC EN 50067 (RDS), Doc.
SPB 482, European Broadcasting Union, 17A Ancienne Route, CH-1218 Geneva, Switzerland, 1990.
[18] EBU SPB 485: Rev 1992-Allocation of country/area identification codes in RDS, now included in CENELEC EN 50067:1998.
[19] EN 50067:1990-Specifications of the Radio Data System RDS, European Committee for Electrical Standardisation (CENELEC), 35B rue de Stassart, B-1050 Brussels.
[20] EN 50067:1992-Specifications of the Radio Data System RDS, European Committee for Electrical Standardisation (CENELEC), 35B rue de Stassart, B-1050 Brussels.
[21] Marks, B., “The development of RDS standards,” 3rd Montreux International Radio Symposium: Engineering Symposium Record, 1996, pp. 133–142.
[22] CENELEC EN 50067:1998 - Specifications of the Radio Data System (RDS.) for VHF/FM broadcasting, European Committee for Electrical Standardisation (CENELEC), 35B rue de Stassart, B-1050 Brussels, Switzerland, April 1998.
[23] EIA/NAB, National Radio Systems Committee: United States RBDS Standard- Specification of the Radio Broadcast Data System (RBDS), Jan. 8, 1993.
[24] EIA/NAB, National Radio Systems Committee: United States RBDS Standard version 2.0, Specification of the Radio Broadcast Data System (RBDS), 1998.
[25] EBU Guidelines for the implementation of the RDS system, Doc. Tech 3260, European Broadcasting Union, 17A Ancienne Route, CH-1218 Geneva, Switzerland, Jan. 1990.
[26] NAB RDS Applications-Opportunities for Radio Broadcasters, NAB Science and Tech- nology Department, 1771 N Street, N.W., Washington D C , 1995.
[27] EBU, Specifications of the radio data system RDS for VHF/FM sound broadcasting, Doc. Tech 3244 and Supplements 1 to 4. European Broadcasting Union, 17A Ancienne Route, CH-1218 Geneva, Switzerland, 1984.
RDS System and Applications Overview 37
2
Differences Between RDS and RBDS