INTERNATIONAL TELECOMMUNICATION UNION RADIOCOMMUNICATION BUREAU (Direct Fax No. +41 22 730 57 85) Administrative Circular CAR/14 5 May 1994 TO THE ADMINISTRATIONS OF MEMBERS OF THE ITU Proposed approval of 17 draft new and revised Questions adopted by Radiocommunication Study Group 10 (Broadcasting service - sound) at its meeting from 28 February to 3 March 1994 Radiocommunication Study Group 10 at its meeting held in Geneva from 28 February to 3 March 1994 adopted the texts of 17 draft new and revised Questions listed in Annex 1 to be considered for approval by correspondence in acccordance with the provisions of Resolution ITU-R 1, § 3.3. The Questions will be approved if: - "a simple majority of all the Member respondents are in agreement; - and at least 10 replies are received within four months after circulation". The texts of these Questions are annexed for your approval (see Annex 2). It would be appreciated if you could advise the Director of the Radiocommunication Bureau by 5 September 1994, whether you approve the adoption of these Questions for study by the Radiocommunication Study Groups. If the Questions are approved they will have the same status as Questions approved at the Radiocommunication Assembly and will become official texts attributed to Study Group 10. The Questions will then be published as an Addendum to Book 4 which contains the ITU-R Questions approved by the 1993 Radiocommunication Assembly. Richard C. Kirby Director Annexes: 2 Distribution: - Administrations of Members of the ITU ******* ANNEX 1 LIST OF DRAFT NEW AND REVISED QUESTIONS Draft new Question ITU-R [Doc. 10/87] Draft new Question [Doc.10/99] Draft new Question [Doc. 10/111] Draft revision of Question ITU-R 44-1/10 [Doc. 10/90] Draft revision of Question ITU-R 49-1/10 [Doc. 10/92] Draft revision of Question ITU-R 55/10 [Doc. 10/91] Draft revision of Question ITU-R 58/10 [Doc. 10/93] Draft revision of Question ITU-R 59/10 [Doc. 10/83] Draft revision of Question ITU-R 62/10 [Doc. 10/94] Draft revision of Question ITU-R 65/10 [Doc. 10/97(Rev.1)] Draft revision of Question ITU-R 67/10 [Doc. 10/95] Draft revision of Question ITU-R 73/10 [Doc. 10/96] Draft revision of Question ITU-R 76/10 [Doc. 10/84] Draft revision of Question ITU-R 84/10 [Doc. 10/88] Draft revision of Question ITU-R 85/10 [Doc. 10/85] Draft revision of Question ITU-R 96/10 [Doc. 10/98] Draft revision of Question ITU-R 105/10 [Doc. 10/89] ******* ANNEX 2 QUESTIONS Source: Doc. 10/87 DRAFT NEW QUESTION ITU-R [DOC. 10/87] TRANSMITTING AND RECEIVING ANTENNAS AT LF AND MF The ITU Radiocommunication Assembly, considering a) that any transmission system should permit efficient use of the available frequency bands and transmitter power, whilst maintaining reasonable receiver costs and an acceptable level of quality; b) that it is preferable to use high-efficiency antennas appropriate to the size and shape of the required coverage area especially when the size of the coverage area is limited by interference between the sky and ground waves; c) that the use of appropriate and well-designed directional antenna systems can lead to improved wanted coverage and reduced interference; d) that the radiation pattern from antennas can be seriously affected by re-radiation from nearby structures which are not part of the antenna system; e) that it is essential to verify the antenna radiation pattern by measurements; f) that the RF power density in the vicinity of transmitting antennas is significant; g) that efficient planning will need a definition of the characteristics of antennas, decides that the following Question should be studied 1. What are the radiation patterns of types of transmitting and receiving antennas commonly used at LF and MF? 2. What is the effect of imperfect and irregular ground on the radiation pattern of antennas? 3. What are the most appropriate designations for different types of LF and MF antennas? 4. What are the methods of calculation of the electric and magnetic field strengths in the vicinity of transmitting antennas? 5. What computer-based procedures can be recommended to give in a standardized form, the gain and directivity patterns of transmitting and receiving antennas in common use at LF and MF? further decides 1. that the results of the above studies should be addressed to prepare a new Recommendation on: - receiving antennas at LF and MF; - reference receiving antenna patterns for use in planning; - transmitting antennas at LF and MF; 2. that the above studies should be completed by 1998; 3. that administrations be invited to provide appropriate measurements of antenna radiation patterns. Source: Doc. 10/99 DRAFT NEW QUESTION [DOC.10/99] SYNCHRONIZED TRANSMITTERS IN LF AND MF SOUND BROADCASTING The ITU Radiocommunication Assembly, considering that the use of synchronized-frequency transmitter operation may lead to improved efficiency in the use of the spectrum, decides that the following Question should be studied 1 Under what technical conditions can synchronized transmitters (i.e. on the same frequency and modulated by the same programme) be used for sound broadcasting in band 5 (LF) and band 6 (MF)? 2 To what extent can the coverage areas of synchronized transmitters overlap in practice? 3 What combination(s) of types of antennas may be used for synchronized operations? further decides 1 that the results of the above studies should be addressed to prepare a Recommendation on synchronized operation of LF and MF sound broadcasting transmitters; 2 that the above studies should be completed by 1998. Source: Doc. 10/111 DRAFT NEW QUESTION [DOC. 10/111] UNIFIED IDENTIFICATION LABEL FOR INTERNATIONAL EXCHANGE OF SOUND RECORDINGS The ITU Radiocommunication Assembly, considering a) that Recommendation ITU-R BR.408** Previously CCIR Recommendations 265, 408, 469 and 779. specifies minimum programme information to be provided with recorded audio tapes; Recommendation ITU-R BR.469* specifies minimum information to be provided with analogue television tapes and gives an example of suitable labels; Recommendation ITU-R BR.779* specifies minimum information to be provided with digital television tapes; Recommendation ITU-R BR.265* specifies minimum information to be provided on the identification leader of films; b) that the minimum information specified for those different recordings is not always homogeneous, either in its content or in its presentation; c) that modern methods used in the production, broadcasting and storage of sound recordings increasingly rely on automatic equipment and machine-readable identification of recording content (e.g. bar-coded information); d) that at present most broadcasters operate with their own identification method for recording content, and most manufacturers of automatic broadcast equipment implement their own machine-readable identification method; e) that the specification of a unified identification method for recording content would ease international programme exchange, and, if the unified information were machine-readable, it could potentially be ported to existing in-house identification methods by means of simple computer software, decides that the following Question should be studied 1 What is the essential information on programme content to be provided with recorded sound tapes, and films intended for international programme exchange? 2 How should that information be provided (e.g. by means of: - a programme sheet placed in the recording box; - a label fixed to the recording box; - a label fixed to the tape reel or cassette; - a combination of the above)? 3 How could that information be formatted to be provided in machine-readable form? 4 Which machine-readable method should be recommended for this application? 5 How could the essential programme information provided in machine-readable form on internationally exchanged tapes and films, be correlated to similar information currently used by broadcasters for in-house automated operation and archives? further decides 1 that the results of the above studies should be included in (a) Recommendation(s); 2 that Recommendations adopted in response to this Question should preferably be aligned with those adopted in response to Question [Doc. 11/235]; 3 that the above studies should be completed by 1998. Source: Doc. 10/90 DRAFT REVISION OF QUESTION ITU-R 44-1/10** Previously CCIR Question 44-1/10. LF, MF AND HF SOUND BROADCASTING (1982-1990) The ITU Radiocommunication Assembly, considering a) that any sound broadcasting system should specify the essential emission and reception characteristics taking into account the effects of propagation; b) that the system, or systems, chosen should permit efficient use of the frequency bands available, whilst maintaining reasonable receiver costs; c) that apart from the double-sideband amplitude-modulation system, other systems may be used; d) that sky-wave and/or ground-wave reception may be required, e) that the WARC-79, in its Resolutions and Recommendations, invited the ex-CCIR to study this problem, with specific reference to: - Resolution No. 508: Convening of a World Administrative Radio Conference (HF broadcasting planning); - Recommendations: No. 8: Automatic identification of stations, No. 64: Protection ratios and minimum field strengths required in the various services, No. 69: Frequency tolerances of transmitters, No. 70: Studies of the technical characteristics of equipment, bandwidths and channel spacing, No. 501: Introduction of single-sideband techniques in the HF broadcasting bands in preparation for the WARC (HF broadcasting), No. 503: Studies of "out-of-band spectrum" in the HF bands; f) that the WARC HFBC-87 in its Recommendations invited the ex- CCIR to continue its studies on the following items: - Recommendations: No. 503(Rev.) (HFBC-87) HF broadcasting, No. 510 (HFBC-87) Planning parameters for DSB system, No. 515 (HFBC-87) Introduction of transmitters and receivers capable of DSB and SSB, No. 516 (HFBC-87) Use of synchronized transmitters in HFBC, No. 517 (HFBC-87) Relative RF-protection ratios for SSB; g) that in the broadcasting service it is necessary to provide coverage of an intended service area, taking into account the levels of the wanted signal and of any interfering signals, decides that the following Question should be studied 1 What LF, MF and HF sound broadcasting systems should be standardized? 2 What should be the characteristics of these systems with respect to: - emission (type of modulation, audio-frequency bandwidth and necessary bandwidth of emission, dynamic compression, pre- emphasis, limiting, channel spacing etc.); - reception (principle of demodulation, audio-frequency response, dynamic expansion, de-emphasis, intermediate frequency, etc.); - the transmission of supplementary information? 3 What factors should be taken into account in the selection of: - transmitter power; - type of transmitting antenna; - operating frequency band, in order to achieve satisfactory coverage of an intended service area, noting that the three items listed above are interdependent and affect the efficiency of spectrum utilization? 4 Should a system differing from the present system be chosen, what are the consequences resulting from that choice during any transition period on: - existing receivers; - receivers constructed in conformity with the new system? 5 What are the criteria for sharing between sound broadcasting and other services? Note - See Reports ITU-R BS.458, ITU-R BS.1059, ITU-R BS.1061 and Recommendations ITU-R BS.80, ITU-R BS.411, ITU-R BS.498, ITU-R BS.597, ITU-R BS.598, ITU-R BS.638, ITU-R BS.639, ITU-R BS.640, ITU- R BS.702, ITU-R BS.703, ITU-R BS.705 and ITU-R BS.706. further decides 1 that the results of the above studies should be addressed to: - update existing Recommendation(s); - prepare new Recommendation(s); 2 that the above studies should be completed by 1998. Source: Doc. 10/92 DRAFT REVISION OF QUESTION ITU-R 49-1/10** Previously CCIR Question 49-1/10. RECEIVERS FOR SOUND BROADCASTING BELOW 30 MHz (1982-1990) The ITU Radiocommunication Assembly, considering a) that efficient planning must take into account the main parameters of the receiving installations; b) the information contained in Recommendation ITU-R BS.703 may need to be complemented and/or updated; c) that Question ITU-R 59/10 and Question ITU-R 201/10 are addressing, inter alia, the studies on receiving antennas respectively for LF, MF and HF sound broadcasting, decides that the following Question should be studied 1 What are the main characteristics of receiving installations which may be useful for planning? 2 What are the minimum performance specifications for receiving installations permitting a sound quality compatible with ITU-R specifications, for the various types of sound-broadcasting systems: - double-sideband amplitude modulation; - single-sideband amplitude modulation (including the technical and economic problems concerning receivers that would arise with the introduction of this type of modulation in the HF broadcasting bands); - digital modulation? These technical characteristics should be defined for the three cases of: - individual reception; - community reception; - community listening. Note 1 - The minimum performance specifications should take account of the latest IEC work. Note 2 - This Question deals only with terrestrial sound broadcasting until such time when the system characteristics for satellite sound broadcasting are determined. further decides 1 that the results of the above studies should be addressed to: - update and complement Recommendation ITU-R BS.703; - prepare new Recommendation(s); 2 that the above studies should be completed by 1998. Source: Doc. 10/91 DRAFT REVISION OF QUESTION ITU-R 55/10** Previously CCIR Question 55/10. PROTECTION RATIOS IN LF, MF AND HF BROADCASTING (1990) The ITU Radiocommunication Assembly, considering that any sound broadcasting system should allow efficient use of the available frequency bands and transmitter power, whilst maintaining reasonable receiver costs, decides that the following Question should be studied How should the radio-frequency protection ratios be determined under conditions which take account simultaneously of the following items, which may vary independently of each other? 1 Fading (see Question ITU-R 57/10) 1.1 wanted signal and unwanted signal stable;*** Tests should also be made with several unwanted signals and additional data broadcasting.* 1.2 wanted signal stable, and unwanted signal fluctuating;** 1.3 wanted signal and unwanted signal fluctuating;** 1.4 wanted signal fluctuating and unwanted signal stable.** 2 Frequency separation from 0 to 30 kHz between the wanted and unwanted carrier 3 Broadcasting programmes 3.1 wanted and unwanted signals modulated with the same programme;** 3.2 wanted and unwanted signals modulated with different programmes.** 4 Class of emission (the characteristics should be stated in each case) 4.1 double-sideband amplitude modulation: 4.1.1 with current receivers; 4.1.2 with receivers with characteristics adapted to the defined double-sideband transmission; 4.2 single-sideband or vestigial-sideband, including compatible single-sideband modulation; 4.2.1 with current-type receivers; 4.2.2 with receivers specially adapted to the system under consideration; 4.3 any other class of emission; 4.4 coexistence of two systems as follows: TABLE 1 Wanted emission Unwanted emission Double-sideband amplitude modulation Class of emission as under § 4.2 or 4.3 Class of emission as under § 4.2 or 4.3 Double-sideband amplitude modulation - additionally for HF, the coexistence of the following systems** Recommendation Nos. 517 and 510 of WARC HFBC-87. : TABLE 2 Wanted emission Unwanted emission 1 Double sideband (DSB) Single sideband (SSB) (6 dB carrier reduction relative to p.e.p.) 2 Single sideband (SSB) (6 dB carrier reduction relative to p.e.p.) Double sideband (DSB) 3 Single sideband (SSB) (6 dB carrier reduction relative to p.e.p.) Single sideband (SSB) (6 dB carrier reduction relative to p.e.p.) 4 Single sideband (SSB) (12 dB carrier reduction relative to p.e.p.) Single sideband (SSB) (12 dB carrier reduction relative to p.e.p.) 5 Double sideband (DSB) Double sideband (DSB) - as well as the co-channel protection ratio between synchronized transmissions within the same network, and - the relative radio-frequency protection ratios; 5 frequency band (5 (LF), 6 (MF) or 7 (HF)); 6 minimum usable field strength; 7 modulation processing (compression and pre-emphasis); 8 necessary bandwidth. Note 1 - See also Recommendation ITU-R BS.560, Annex II. Note 2 - See Reports ITU-R BS.516, BS.798 and Recommendations ITU-R BS.559, BS.560, BS.597, BS.638 and BS.639. further decides 1 that the results of the above studies should be addressed to: - update existing Recommendation(s); - prepare new Recommendation(s); 2 that the above studies should be completed by 1998. Source: Doc. 10/93 DRAFT REVISION OF QUESTION ITU-R 58/10** Previously CCIR Question 58/10. COVERAGE IN LF, MF AND HF BROADCASTING (1990) The ITU Radiocommunication Assembly, considering the need to ensure efficient spectrum utilization when planning LF, MF and HF broadcasting services, decides that the following Question should be studied 1 What is the dependence of ground-wave and sky-wave sound broadcasting coverage on: - the characteristics of the system; - the radio-frequency protection ratios; - the channel spacing; - the minimum usable field strength; - the radiated power; - the geographical distribution of the transmitters; - the distribution of population density; - the use of directional transmitting antennas; - the use of groups of synchronized transmitters; for bands 5 (LF), 6 (MF) and 7 (HF)? 2 What methods are required (including the use of computers), for calculating the minimum number of channels for the coverage for broadcasting in bands 5 (LF) and 6 (MF), for each of the systems envisaged, taking into account the points listed under decides 1? Note 1 - See Recommendation ITU-R BS.598. further decides 1 that the results of the above studies should be addressed to: - update existing Recommendation(s); - prepare new Recommendation(s); 2 that the above studies should be completed by 1998. Source: Doc. 10/83 DRAFT REVISION OF QUESTION ITU-R 59/10** Previously CCIR Question 59/10. TRANSMITTING AND RECEIVING ANTENNAS AT HF (1990) The ITU Radiocommunication Assembly, considering a) that any transmission system should permit efficient use of the available frequency bands and transmitter power, whilst maintaining reasonable receiver costs and an acceptable level of quality; b) that the use of appropriate and well-designed directional antenna systems can lead to improved wanted coverage and reduced interference; c) that highly directional antenna systems can produce strong subsidiary radiation lobes, particularly when the main beam is slewed horizontally; d) that the radiation pattern from antennas can be seriously affected by re-radiation from nearby structures which are not a part of the antenna system; e) that it is essential to verify the antenna radiation pattern by measurements; f) that the RF power density in the vicinity of transmitting antennas is significant; g) the need to share frequencies wherever possible to permit the most efficient use of the broadcasting bands at HF and in the bands allocated to broadcasting in the Tropical Zone (see Nos. 2669-2671 of the Radio Regulations); h) that further studies in the design of transmitting antennas used for short-distance broadcasting, in particular in the Tropical Zone, are necessary to concentrate energy within the desired coverage area; j) Resolution Nos. 516 and 514 of the World Administrative Radio Conference for the Planning of HF Bands Allocated to the Broadcasting Service (WARC HFBC-87); k) Recommendation ITU-R BS.705*** Previously CCIR Recommendation 705.* "HF transmitting antenna characteristics and diagrams"; l) that efficient planning will need a definition of the characteristics of the receiving antennas, decides that the following Question should be studied 1. What are the radiation patterns of types of transmitting and receiving antennas commonly used at HF, and in particular in the Tropical Zone, not already covered by Radiocommunication Study Group studies? 2. What is the effect of imperfect and irregular ground on the radiation patterns of antennas? 3. What are the most appropriate designations for different types of HF antennas? 4. What are the optimum antennas for coverage up to distances of 400 km, 600 km, 800 km and 1 000 km, in particular in the Tropical Zone? 5. What are the methods of calculation of the electric and magnetic field strengths in the vicinity of transmitting antennas? 6. What computer-based procedures can be recommended to give in a standardized form the gain and directivity patterns of transmitting and receiving antennas in common use at HF, all such procedures being suitable for use with computer-based ionospheric propagation prediction programmes? further decides 1. that the results of the above studies should be addressed to update Recommendation ITU-R BS.705 to include: - receiving antennas; - reference receiving antenna patterns for use in planning; - transmitting antennas not already included; - optimum transmitting antennas for specific coverage situations; 2. that the above studies should be completed by 1998; 3. that administrations be invited to provide appropriate measurements of antenna radiation patterns. Source: Doc. 10/94 DRAFT REVISION OF QUESTION ITU-R 62/10** Previously CCIR Question 62/10. SYNCHRONIZED TRANSMITTERS IN HF SOUND BROADCASTING (1990) The ITU Radiocommunication Assembly, considering a) that the use of synchronized-frequency transmitter operation may lead to improved efficiency in the use of the spectrum; b) that the WARC HFBC-87, in its Recommendation No. 516, invites the former CCIR to accelerate its studies on the use of synchronized transmitters for broadcasting, decides that the following Question should be studied 1. Under what technical conditions can synchronized transmitters (i.e. on the same frequency and modulated by the same programme) be used for sound broadcasting in band 7 (HF)? 2. To what extent can the coverage areas of synchronized transmitters overlap in practice? 3. What combination(s) of types of antennas may be used for synchronized operation? further decides 1. that the results of the above studies should be inserted in Recommendation ITU-R BS.702 on synchronized operation of HF sound broadcasting transmitters; 2. that the above studies should be completed by 1998. Source: Doc. 10/97(Rev.1) DRAFT REVISION OF QUESTION ITU-R 65/10** Previously CCIR Question 65/10. SHORT-DISTANCE BROADCASTING IN BAND 7 (HF) IN THE TROPICAL ZONE (1990) The ITU Radiocommunication Assembly, considering a) that the evaluation of the power required for a given grade of short-distance broadcasting service in the Tropical Zone requires precise knowledge of transmission and reception characteristics including statistical variation of natural radio noise; b) that it would be helpful in the planning of new broadcasting services in the Tropical Zone to have more reliable data; c) that more reliable data using representative transmission and reception conditions in the Tropical Zone would be helpful in the organization of various services in the shared bands allocated in the Tropical Zone (see No. 2669 of the Radio Regulations), decides that the following Question should be studied 1 What should be the value of the signal-to-noise ratio and the radio-frequency wanted-to-interfering signal ratio that should be adopted as representative of an acceptable broadcasting service in the Tropical Zone? 2 Whether the power limits in Recommendation ITU-R BS.215 need to be changed to new values depending upon long period practical data to give an acceptable broadcasting service in the Tropical Zone? 3 What is the interrelationship between: - location of the transmitter; - distance from the transmitter; - radiated carrier power; - transmitting and receiving antennas***Relevant information in the texts of Radiocommunication Study Group 10 should be taken into account.* ; - radio frequency used for achieving a required quality of service? 4 How should the value of natural radio noise be taken into account in the planning of broadcasting services in the Tropical Zone for different hours of the day and if necessary for different geographical zones? further decides 1 that the results of the above studies should be presented in the form of a handbook; 2 that the above studies and handbook should be completed by 1998. Source: Doc. 10/95 DRAFT REVISION OF QUESTION ITU-R 67/10** Previously CCIR Question 67/10. This Question should be brought to the attention of Radiocommunication Study Group 9. INTERFERENCE FROM OTHER SERVICES TO SOUND BROADCASTING IN THE TROPICAL ZONE (1990) The ITU Radiocommunication Assembly, considering a) Recommendation No. 64 of the World Administrative Radio Conference (Geneva, 1979) and the studies pursued at the Plenary Assemblies of the former CCIR; b) that Recommendation ITU-R BS.216 is based on incomplete information and that further studies are necessary to determine finally a value for the radio-frequency protection ratio for sound- broadcasting services operating in the Tropical Zone in the shared bands; c) that comprehensive data could be obtained by the use of objective methods as described in Recommendation ITU-R BS.559 as well as the subjective methods used hitherto, decides that the following Question should be studied 1 What are the values of the radio-frequency protection ratio to be provided for a sound-broadcasting service, operating in the shared bands in the Tropical Zone, against interference from telegraphy (A1A/A1B and A2A/A2B) and telephony (A3E) emissions and how should they be experimentally determined when: - the interference is caused by one of these three types of emissions; - the interference is caused by two or more types of emission at the same time? Note 1 - This study should be carried out taking into account transmitter frequency variations (up to and including those equal to the sum of the permissible frequency tolerances) of the sound- broadcasting service in the Tropical Zone and other services sharing the bands as laid down in the Radio Regulations. Note 2 - Measurements should be carried out at the output of a receiver fitted with a simple filter having an audio-frequency cut- off of 5 kHz (the characteristics of the filter employed should be given). Note 3 - Measurements should be carried out for carrier frequencies separated by 0, 1, 2, ... 10 kHz. Note 4 - The results should be expressed in terms of percentage of listeners satisfied, as well as of percentage of time during which the satisfaction is achieved. 2 What is the minimum usable field strength to which a protection ratio (to be determined under different conditions as staged in decides 1 and as stipulated in § 1 of Recommendation ITU-R BS.216), should relate (taking into account the nature, intensity and distribution of noise levels in different parts of the Tropical Zone) and how should it be experimentally determined? further decides 1 that the results of the above studies related to the values of the radio-frequency protection ratio in the presence of the mentioned interfering emissions and to the minimum usable field strength should be presented in the form of a Recommendation; 2 that the procedure to experimentally determine the above parameter should be included in an Annex to the above Recommendation; 3 that the above studies should be completed by 1998. Note - See Recommendations ITU-R BS.48, ITU-R BS.216 and Report ITU- R BS.302. Source: Doc. 10/96 DRAFT REVISION OF QUESTION ITU-R 73/10** Previously CCIR Question 73/10. SOUND BROADCASTING IN BAND 8 (VHF) IN THE TROPICAL ZONE (1990) The ITU Radiocommunication Assembly, considering a) that sound broadcasting in band 8 (VHF) is providing a high- quality service in many parts of the world and that its use is steadily growing in the Tropical Zone; b) that the rate of failure of transmission systems in band 8 is extremely low; c) that domestic receivers with adequate sensitivity are readily available for operation in band 8; d) that band 6 (MF), used for good quality broadcast service is heavily congested in tropical countries and that further expansion of broadcast service in this band is limited, especially at night-time; e) that band 7 (HF) suffers from adverse effects of interference and fading and cannot provide a reliable broadcasting service of good quality in tropical countries; f) that particular propagation conditions exist in the Tropical Zone due to humid and hot climate, duct formation over sea, thick and dense forests and strong sporadic-E layers and irregularities of the spread-F layer; g) that Questions ITU-R 69/10 and ITU-R 72/10 consider some aspects related to this Question, decides that the following Question should be studied 1 What is the minimum usable field strength and protection ratio for planning of frequency-modulation services at VHF in tropical countries? 2 How could the propagation effects described in considering f) above be taken into account in planning of frequency-modulation services of VHF in tropical countries and what are the values of propagation margins to be provided for these effects to ensure a specified reliability of the service? further decides 1 that the results of the above studies should be presented in the form of a handbook; 2 that the above studies and handbook should be completed by 1998. Source: Doc. 10/84 DRAFT REVISION OF QUESTION ITU-R 76/10** Previously CCIR Question 76/10. TRANSMITTING AND RECEIVING ANTENNAS AT VHF AND UHF (1990) The ITU Radiocommunication Assembly, considering a) that transmitting and receiving antenna characteristics are required for frequency planning; b) that planning the most efficient spectrum use often requires establishing the antenna radiation patterns to a high degree of accuracy; c) that planning the most efficient spectrum use may imply using the same antenna for several emissions; d) that in establishing transmitting radiation patterns, account must be taken of the influence of the supporting structure, significant nearby structures and the electrical stability of the antenna assembly; e) that it is essential to verify the antenna radiation pattern by measurements; f) that the RF power density in the vicinity of transmitting antennas is significant; g) that the Radiocommunication Study Groups have already made significant studies on the radiation characteristics of LF, MF, HF and satellite antennas; h) that comprehensive information on the characteristics of transmitting and receiving antenna systems at VHF and UHF is not readily available in the ITU Radiocommunication Volumes, decides that the following Question should be studied 1 What are the radiation patterns of VHF and UHF transmitting and receiving antenna systems? 2 What is the influence of supporting structures and significant nearby structures on the technical characteristics of antennas in the VHF and UHF bands? 3 What differences are to be expected between theoretical and practical performance due to practical aspects of VHF and UHF antennas? 4 What are the methods of calculation of the electric and magnetic field strengths in the vicinity of transmitting antennas? 5 What computer-based procedures can be recommended to give, in a standardized form, the gain and directivity patterns of transmitting and receiving antennas in common use at VHF and UHF? further decides 1 that the results of the above studies should be addressed to prepare a new Recommendation on: - receiving antennas at VHF and UHF; - reference receiving antenna patterns for use in planning; - transmitting antennas at VHF and UHF; 2 that the above studies should be completed by 1998; 3 that administrations be invited to provide appropriate measurements of VHF and UHF antenna radiation patterns. Source: Doc. 10/88 DRAFT REVISION OF QUESTION ITU-R 84/10** Previously CCIR Question 84/10. SOUND SYSTEMS FOR THE HEARING IMPAIRED (1990) The ITU Radiocommunication Assembly, considering a) the increasing incidence and awareness in the community of hearing impairment; b) the fact that as hearing is impaired, the threshold of hearing rises, but this is not necessarily accompanied by a corresponding increase in the threshold of pain; c) that this requires automatic gain control to be used in hearing-aids to reduce the dynamic range of the sound; d) that the dynamic range and the balance of some sound programmes may therefore be inappropriate for the hearing-impaired, decides that the following Question should be studied 1. What is the most suitable dynamic range of the sound programme needed for the hearing-impaired? 2. What is the relationship between the level of dialogue, music and effects needed for the hearing-impaired? 3. How the values of the technical parameters might be chosen to benefit the hearing-impaired? 4. What efficient method of producing, distributing and transmitting sound programmes for the hearing-impaired can be recommended? 5. What technical facilities might be provided at the receiver to improve the audibility of sound programmes for the hearing- impaired? further decides 1. that the results of the above studies should be included in a Recommendation(s); 2. that the above studies should be completed by 1998. Source: Doc. 10/85 DRAFT REVISION OF QUESTION ITU-R 85/10** PREVIOUSLY CCIR QUESTION 85/10. SUBJECTIVE ASSESSMENT OF SOUND QUALITY IN BROADCASTING USING DIGITAL TECHNIQUES (1990) The ITU Radiocommunication Assembly, considering a) that the introduction of digital techniques in the studio, in transmission circuits and at the transmitter should allow an improvement in quality and more efficient operational use; b) that these techniques entail their own specific signal impairments; c) that it is desirable to ensure high quality performance throughout the broadcasting chain without unnecessary expense, decides that the following Question should be studied 1. What is the relation between subjective assessment and objective measurements for digital systems? 2. What are the tolerable values of subjective impairment in the whole broadcasting chain? 3. What is the subjective effect of the various studio processes on the digital signal (level changes, frequency response corrections, etc.)? 4. What is the maximum number of times that processing of any kind may be applied to the signal in the studio and the associated subjective effect? 5. What are the acceptable values of impairment (expressed in objective terms): - in recording equipment; - in other studio equipment; - in broadcasting emissions? Note 1 - Digital signals used in the studio may differ from those used for transmission. Note 2 - See in particular Reports ITU-R CMTT.647** and ITU-R BS.799*** Previously CCIR Reports 647 and 799.* . Note 3 - The studies should also include a comparison with the best analogue techniques. Note 4 - Close cooperation between Radiocommunication Study Group 10 and Telecommunication Standardization Study Group 9 will be required in this study. further decides 1. that the results of the above studies should be included in a Recommendation(s); 2. that the above studies should be completed by 1998. Source: Doc. 10/98 DRAFT REVISION OF QUESTION ITU-R 96/10** Previously CCIR Question 96/10. DETERMINATION OF THE EFFECTS OF ATMOSPHERIC NOISE ON THE GRADE OF RECEPTION IN THE TROPICAL ZONE (1990) The ITU Radiocommunication Assembly, considering that the determination of the transmitter power required depends in part upon the value of the signal-to-atmospheric noise ratio regarded as being the minimum for an acceptable broadcasting service in the Tropical Zone, decides that the following Question should be studied 1 What characteristics of atmospheric noise are important in determining the response of a typical broadcast receiver and the extent to which they affect the grade of reception? 2 What is the average value of signal-to-atmospheric noise ratio required to ensure satisfactory reception for at least 90% of the total time? further decides 1 that the results of the above studies should be presented in the form of a handbook; 2 that the above studies and handbook should be completed by 1998. Source: Doc. 10/89 DRAFT REVISION OF QUESTION ITU-R 105/10** Previously CCIR Question 105/10. MULTILINGUAL SERVICES IN MULTICHANNEL SOUND SYSTEMS (1993) The ITU Radiocommunication Assembly, considering a) that, wherever possible, all languages in a multilingual service should be treated with equality; b) that recorded drama programmes, particularly films, are often available in different languages, with multichannel sound; c) that for sports programmes (and some types of recorded drama) a multichannel sound signal comprising "effects" may be provided together with one or more mono "commentary" or "dialogue" signals in different languages; d) that certain "live" programmes (for example game shows) will always favour the original language in which they are performed, and that it would be unrealistic to expect interpreted sound signals to provide a service equivalent to the service in the original language, decides that the following Question should be studied 1. What reasonable number of sound services could usefully be employed in a television or in a sound-only situation. This should take into account the number of different language services to be provided, the range of programme types, and the desirability of providing special sound signals for listeners with impaired hearing and for television viewers with impaired sight? 2. What minimum number of sound signals per service might be used in a flexible manner to enable broadcasters to serve their programme and audience requirements satisfactorily? further decides 1. that the results of the above studies should be included in Recommendations; 2. that the above studies should be completed by 1998.