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5i' PART I Series N Recommendations MAINTENANCE OF INTERNATIONAL SOUND-PROGRAMME AND TELEVISION TRANSMISSION CIRCUITS Blanc MONTAGE: PAGE 2 = PAGE BLANCHE SECTION 1 INTERNATIONAL SOUND-PROGRAMME TRANSMISSION 1.1 International sound-programme transmissions - Defini- tions Recommendation N.1 DEFINITIONS FOR APPLICATION TO INTERNATIONAL SOUND-PROGRAMME TRANSMISSIONS , The following definitions apply to the maintenance of interna- tional sound-programme transmissions. Other definitions are used _________________________ Definitions in this Recommendation apply both to analo- gue and digital systems. Annex A to this Recommendation gives definitions for units of measurements for sound-programme transmis- sions. for other purposes, e.g., an international sound-programme link and international multiple destination sound-programme link as defined in SS 11 and 12 respectively below, are within the definition of an international sound-programme circuit as defined by the CMTT. Note 1 - It is intended that the definitions given in Recommendations N.1 and N.51 should remain identical, so far as is practical, by use of only simultaneous amendments. Note 2 - A sound-programme circuit section, circuit, link or connection is considered to be permanent for maintenance purposes if it is always available for use when required, whether or not it is continuously in use. Such a circuit may be used for the purposes of occasional transmission, that is, transmissions of short dura- tion, e.g. less than 24 hours, or it may be used for a long dura- tion, i.e. one day or more. A permanent sound-programme connection between broadcasting organizations' premises may be used at any time, except only for periods of maintenance as agreed between the Administrations and broadcasting organizations concerned. A sound-programme circuit section, circuit, link or connection is considered to be temporary for maintenance purposes when it has no existence outside the period of transmission (including line-up and testing time) for which it is required. 1 international sound-programme transmission The transmission of sound signals over the international telecommunication network for the purpose of interchanging sound-programme material between broadcasting organizations in dif- ferent countries. 2 broadcasting organization A broadcasting organization is an organization which is con- cerned with either or both sound and television broadcasting. Most of the customers ordering facilities for sound-programme and telev- ision transmission are broadcasting organizations; for convenience, the term broadcasting organization is used to denote the activity of any user or customer and, where so used, it is equally applica- ble to any other customer requiring sound-programme or television transmissions. 3 broadcasting organization (send) The broadcasting organization at the sending end of an inter- national sound-programme transmission. 4 broadcasting organization (receive) The broadcasting organization at the receiving end of an international sound-programme transmission. 5 international sound-programme centre (ISPC) A centre at which at least one international sound-programme circuit (see S 9) terminates and in which international sound-programme connections (see S 13) can be made up by the inter- connection of international and national sound-programme circuits. The responsibility of an ISPC is given in Recommendation N.5. 6 national sound-programme centre (NSPC) A centre at which two or more national sound-programme cir- cuits terminate and at which national sound-programme circuits may be interconnected. 7 sound-programme circuit section The unidirectional national or international sound-programme transmission path between two stations at which the programme is accessible at audio frequencies. The transmission path may be esta- blished via terrestrial or single destination satellite routing. (See Note 2 above and Figures 1/N.1 and 3/N.1.) 8 international multiple destination sound-programme circuit section The unidirectional sound-programme transmission path from one frontier station to two or more of the frontier stations at which interconnection is made at audio frequencies. (See Note 2 above and Figure 4/N.1.) 9 international sound-programme circuit The transmission path between two ISPCs which comprises one or more sound-programme circuit sections (national or international), together with any necessary audio equipment. The transmission path may be established via terrestrial or single destination satellite routing. (See Note 2 above and Figures 1/N.1 and 3/N.1.) 10 international multiple destination sound-programme circuit The unidirectional transmission path from one ISPC to two or more other ISPCs comprising sound-programme circuit sections (national or international) one of which is an international multi- ple destination circuit section, together with any necessary audio equipment. (See Note 2 above and Figure 4/N.1.) 11 international sound-programme link The unidirectional transmission path between the ISPCs of the two terminal countries involved in an international sound-programme transmission. The international sound-programme link comprises one or more international sound-programme circuits (see Figures 1/N.1 and 3/N.1 below) interconnected at intermediate ISPCs. It can also include national sound-programme circuits in transit countries. (See Note 2 above and Figure 2/N.1.) 12 international multiple destination sound-programme link The unidirectional transmission path between the ISPCs of the terminal countries involved in an international multiple destina- tion sound-programme transmission. The international multiple des- tination sound-programme link comprises international sound-programme circuits, one of which is an international multiple destination sound-programme circuit. (See Note 2 above and Figure 5/N.1.) 13 international sound-programme connection The unidirectional transmission path between the broadcasting organization (send) and the broadcasting organization (receive) comprising the international sound-programme link extended at its two ends over national sound-programme circuits to the broadcasting organization. (See Note 2 above and Figure 2/N.1.) 14 international multiple destination sound-programme connection The unidirectional transmission path between the broadcasting organization (send) and two or more broadcasting organizations (receive) comprising the international multiple destination sound-programme link extended at its ends over national sound-programme circuits to the broadcasting organizations. (See Note 2 above and Figure 5/N.1.) 15 send reference station The transmit sub-control station of an international multiple destination sound-programme circuit section (see S 8), circuit (see S 10) or link (see S 12). (See Figures 4/N.1 and 5/N.1.) 16 effectively transmitted signals in sound-programme transmission For sound-programme transmission , a signal at a particular frequency is said to be effectively transmitted if the nominal overall loss at that frequency does not exceed the nominal overall loss at 800 Hz by more than 4.3 dB. This should not be confused with the analogous definition concerning telephone circuits given in the Recommendation cited in [1]. For sound-programme circuits , the overall loss (relative to that at 800 Hz) defining effectively transmitted frequency is 1.4 dB, i.e. about one third of the allowance. 17 types of sound-programme circuit The various types of international sound-programme circuit or sections of such circuits should be referred to by quoting the top nominal frequency, in kHz, effectively transmitted. Example: 10-kHz sound-programme circuit. Figure 1/N.1 p. Figure 2/N.1 p. Figure 3/N.1 p. Figure 4/N.1 p.3 _________________________ To reduce problems in ordering and charging for sound-programme circuits, Study Group II has a classif- ication of circuits based on their approximate bandwidth (see the Recommendation cited in [2]). Figure 5/N.1 p. ANNEX A (to Recommendation N.1) Level and loss units used for sound-programme and television transmission A.1 Use of dB units in N Recommendations This Recommendation gives the quantities and units for sound-programme transmissions used in N Recommendations and is in accordance with existing Recommendations [3], [4]. A.2 Units used A.2.1 absolute power level (dBm) As a general rule, the dBm unit applies to the absolute power level. The unit is based on the ratio between measured power and the reference power of 1 mW. Lm= 10 log fIP0 _____ dBm = 10 log U $$Ei:2:0_ /Z0) ________________ dBm = | |20 logfIU0 _____- 10 logfIZ0 _____| | dBm Absolute power level Absolute Impedance voltage correction level Absolute voltage levels, for which terminal impedance is not defined, are more rarely used. As a correction, power level may be calculated for impedances other than 600 ohms, with respect to 1 mW. The power level thus calculated would be equal to that meas- ured in a correctly terminated system. A.2.2 relative level (dBr) _________________________ It is intended that the text contained in this annex will be further studied and refined as necessary. The relative power level of a point in a transmission system is the nominal power gain at the reference frequency from a refer- ence point to the point considered. The same consideration is used for the relative voltage level in a transmission system based on voltage levels. Relative levels can be used to compare two or more points of a network with respect to power (or voltage). One point of a network is usually defined as the reference point at 0 dBr, from which other measurement points are derived. For sound-programme circuits, the zero relative level is located at the injection point, i.e. usually at the transmission point of a sound-programme circuit. A.2.3 absolute zero power level (dBm0) (load level ) In a transmission system based on power levels the absolute power level or load level (Lm\d0) with respect to 1 mW is referred to a point of zero relative level. That means that the absolute power level (Lm) minus the relative power level (Lr) will be Lm\d0= Lm- Lr This level indication is independent of the relative power level at the measurement point considered. For a given signal the load level is nominally the same along a transmission line. For this indication it is necessary to know to what extent the power at the zero relative point is greater or less than the reference power. A.2.3 absolute zero power level (dBm0) (load level ) In a transmission system based on power levels the absolute power level or load level (Lm\d0) with respect to 1 mW is referred to a point of zero relative level. That means that the absolute power level (Lm) minus the relative power level (Lr) will be Lm\d0= Lm- Lr This level indication is independent of the relative power level at the measurement point considered. For a given signal the _________________________ The term "load level" is used provisionally and is sub- ject to further consideration. The term "load level" is used provisionally and is sub- ject to further consideration. load level is nominally the same along a transmission line. For this indication it is necessary to know to what extent the power at the zero relative point is greater or less than the reference power. A.2.4 Relation between quantities and units There is a fixed relation between level quantities and units, namely: Absolute power level = relative power level + abso- lute zero power level (load level) Lm= Lr+ Lm\d0 Therefore, for the level units: a dBm = b dBr + c dBm0. When indications are given concerning the line signal, the absolute zero power level (load level) (dBm0) is given, at which, at the relative zero point, the absolute power level coincides with the relative power level. Lm= Lm\d0, for Lr= 0 In order to simplify the specification of the level of a cir- cuit or a system, it is most appropriate to specify the absolute power level which coincides with the relative zero power level. Thus this absolute power level and the absolute zero power level (load level) are the same. A.2.5 Weighted level Power level of disturbing signals are as a rule expressed in the same units as those defined above. For noise measurements made by a weighting filter (psophometric measurements), a "p" (for "pondere" = weighted) is added to the units, e.g., dbm0p, dBmp. A "q" indicates a quasi-peak value where the "m" is replaced by a "q" which, for instance, in dBm gives dBq. A.2.6 Extra indications Sound-programme transmission level units are indicated by an extra "s" (s for sound): dBrs, dBm0s, dBm0ps, dBq0pS. Extra indications for units should be used whenever they facilitate understanding so as to prevent confusion when differing measurement techniques, weighting filters or meters are used. A.3 Various measuring instruments Absolute power level (in dBm) is obtained if a measurement is made on a terminated line. Various measurement instruments provide measurements related to a (freely) preselected relative level value. The measurement will then directly express the absolute zero power level (load level). A.4 Practical problems There is a wide range of measuring instruments used at dif- ferent measurement points, so that differences are always bound to appear. A state which every Administration is prepared to define is the permitted maximum level (PML). Despite different relative power levels, depending on the systems, a direct relation can now be indicated between the value of the level to be measured and the PML in dB. If, for instance, a signal of 21 dB below the PML is transmitted as a measurement signal, it must also be received as a signal 21 dB below PML, independently of local relative levels, which may differ according to systems and Administrations. References [1] CCITT Recommendation General performance objectives applicable to all modern international circuits and national exten- sion circuits , Vol. III, Rec. G.151, Note 1, S 1. [2] CCITT Recommendation Occasional provision of circuits for International sound- and television-programme transmissions , Vol. II, Rec. D.180, S 3. [3] CCITT Recommendation Use of the decibel and neper in telecommunications , Vol. I, Rec. B.12. [4] CCIR Recommendation Use of the decibel and neper in telecommunications , Vol. XIII, Rec. 574, ITU, Geneva, 1986. Recommendation N.2 DIFFERENT TYPES OF SOUND-PROGRAMME CIRCUIT The characteristics of the various types of international sound-programme circuit defined in Recommendations J.21 [1], J.22 [2] and J.23 [3] are as follows: 15 kHz; 10 kHz; 5, 6.4 and 7 kHz. From the point of view of sound-programme transmission ordi- nary telephone circuits are generally considered to be suitable only for the transmission of speech. It should be noted that the limits of the loss/frequency distortion cannot be guaranteed to be better than the limits shown in Recommendation M.580 [4]. When a telephone circuit is used for a sound-programme transmission the terminating sets and the signalling equipment must be disconnected to avoid echo effects and false operation of the signal receiver. When a telephone circuit is used for a sound-programme transmission, a point of zero relative level of the telephone cir- cuit must coincide with a point of zero relative level on the sound-programme circuit. (However, see S 2 of Recommendation N.15 in which it is pointed out that a 6-dB loss should be introduced in order to reduce the mean power level delivered to the telephone circuit system). References [1] CCITT Recommendation Performance characteristics of 15 kHz type sound-programme circuits , Vol. III, Rec. J.21. [2] CCITT Recommendation Performance characteristics of 10 kHz type sound-programme circuits , Red Book, Vol. III, Rec. J.22, ITU, Geneva, 1984. [3] CCITT Recommendation Performance characteristics of narrow-bandwidth sound-programme circuits , Vol. III, Rec. J.23. [4] CCITT Recommendation Setting up and lining up an _________________________ This Recommendation applies also to 7 kHz and 15 kHz digital sound-programme circuits. international circuit for public telephony , Vol. IV, Rec. M.580. Recommendation N.3 CONTROL CIRCUITS 1 Definition of control circuit A control circuit is a telephone-type circuit between the point of origin of the programme and the point where it terminates (recording equipment, studio, switching centre, transmitter, etc.) used by a broadcasting organization for the supervision and coordi- nation of a sound or television transmission. More than one control circuit may be used in association with the different programme connections involved in a single transmis- sion, such as: a) the television | onnection ; b) the international sound | onnection (for supervising the programme effects circuit provided for transmit- ting, for example, the background noises of a programme); c) the commentary | onnection (for supervising the sound-programme circuit transmitting a commentary in a given language); d) the complete programme | onnection (for supervising the sound-programme circuit transmitting the whole of the sound part of a programme). 2 Provision of control circuits for sound-programme and television transmission The conditions governing the provisions and lease of control circuits for sound-programme and television transmissions are given in Recommendation D.180 [1]. _________________________ The CCITT has noted the fact that broadcasting organi- zations use a tone having a frequency of 1900 Hz _ 6 Hz and a level not exceeding -10 dBm0, for their signal- ling purposes on control circuits. Under the conditions of use specified in the CCITT Recommendations for con- trol circuits, the CCITT has no objections to the use of this tone. Reference [1] CCITT Recommendation Occasional provision of circuits for International sound- and television-programme transmissions , Vol. II, Rec. D.180. Recommendation N.4 DEFINITION AND DURATION OF THE LINE-UP PERIOD AND THE PREPARATORY PERIOD For each international sound-programme transmission a distinc- tion is made between: - line-up period The period during which the Administrations line up the international sound-programme link before handing it over to the broadcasting organizations; and - preparatory period The period during which these broadcasting organizations do their own adjustments, tests and other work before the sound-programme transmission itself commences. 1 Line-up period 1.1 Duration In principle, the duration of the line-up period should be 15 minutes. However, in the case of sound-programme transmissions involving more than two countries, the duration may be increased. On the other hand, in certain cases, by agreement between the Administrations concerned, the duration may be less than 15 minutes, provided the line-up is properly carried out. This may be possible, for example, when there are two successive interna- tional sound-programme transmissions on the same route and the second involves extending the international sound-programme link already laid up for the first. Note - In the case of multiple destination transmissions the line-up period can have a longer duration, to be fixed by agreement between the Administrations concerned, e.g., on the order of 25 to 30 minutes. At the end of the line-up period the international sound-programme link and the control circuits are handed over to the broadcasting organizations at the booked time. 2 Preparatory period 2.1 Beginning and duration When the tests during the line-up period are completed, the international sound-programme link is not made available to the broadcasting organizations at the two ends until the time fixed for the beginning of the preparatory period. The chargeable time for the sound-programme transmission commences at the beginning of the preparatory period. The duration of the preparatory period - i.e. the time between handing over the international sound-programme link to the broadcasting organizations and the moment when the pro- gramme properly begins - is chosen in each case by the broadcasting organizations so that they can carry out all the tests and adjust- ments necessary before proceeding with the sound-programme transmission. Recommendation N.5 SOUND-PROGRAMME CONTROL, SUB-CONTROL AND | SEND REFERENCE STATIONS 1 Responsibilities of control and sub-control stations 1.1 For a unidirectional international sound-programme cir- cuit, the receiving end terminal ISPC is normally the control sta- tion. The other terminal ISPC is a terminal sub-control station. The functions of the control and sub-control stations are the same as for ordinary telephone circuits. (See Recommendations M.80 [1] and M.90 [2].) Note - In the case of a reversible sound-programme circuit, setting-up reference measurements and maintenance measurements are carried out for each direction of transmission. 1.2 The international sound-programme link is in all cases the sole responsibility of the telephone Administrations. If the inter- national sound-programme link passes through one or more transit countries, an intermediate sub-control station is also designated for each transit country. 1.3 The national sound-programme circuits at the ends of the link may be the responsibility of either the Administrations or the broadcasting organizations or the two together depending on local arrangements in each particular country. 1.4 The receiving ISPC stations on multiple destination sound-programme circuits or links act as control stations for the circuit or link in accordance with Recommendations M.80 [1] and M.90 [2]. In this case the following additional responsibilities should apply: a) reporting to the appropriate send reference sta- tion (see S 2) the results of measurements made on the circuit and link and the quality assessments observed on the link; b) reporting fault conditions to the circuit or link send reference station (see S 2). 1.5 The intermediate ISPCs are intermediate sub-control sta- tions for the international sound-programme link. 1.6 The ISPC or the repeater station at the sending end (coun- try A in Figures 2/N.1 and 5/N.1) is a terminal sub-control sta- tion for the international sound-programme connection. When a send reference station (see S 2) is associated with a multiple destina- tion communications-satellite link, it has the following responsi- bilities: a) coordination of lining up the multiple-destination sound-programme circuit sections, circuits and links, respectively; b) keeping a record of the measurements made during the lining-up period of the circuit section, circuit or link, and recording the quality assessments observed at control stations dur- ing the lining-up of the link; c) relevant maintenance action for the sub-control and control stations at the request of one of these stations. However, the choice of the station nominated as the terminal sub-control station is left to the discretion of the Administration concerned. 1.7 Exchange of contact point information on sound-programme transmission should be made in accordance with Recommendation M.93 [3]. 2 Send reference stations Sound-programme transmissions provided on a multiple destina- tion basis using a communication satellite system, differ from those using only terrestrial facilities in that the common transmitting path extends through the transmitting earth station to the satellite. The receiving paths extend from the satellite through the receiving earth stations concerned to the terminal ISPC control stations. Operations on the common path of the connection affect all receiving stations, whereas on any of the other paths the opera- tions affect only the one receiving terminal station involved. These distinctive features of a multiple destination sound-programme transmission provided in the above manner require the assistance of certain stations designated as send reference stations. Send reference stations are situated along the common path of the sound-programme circuit or link and are identified as follows: a) a sub-control station located at the transmit- ting terminal of the circuit section containing the space segment; b) the terminal sub-control stations for the cir- cuit and link containing the space segment. Figure 4/N.1 shows the basic composition for a multiple desti- nation sound-programme circuit routed via a communication satellite system. The send reference stations are shown as R and R` for the multiple destination circuit section and circuit respectively. Figure 5/N.1 shows the basic composition for a multiple desti- nation sound-programme link and connection routed via a communica- tion satellite system. The send reference stations are shown as R` and R" for the multiple destination circuit and link respectively. References [1] CCITT Recommendation Control stations , Vol. IV, Rec. M.80. [2] CCITT Recommendation Sub-control stations , Vol. IV, Rec. M.90. [3] CCITT Recommendation Exchange of contact point informa- tion for the maintenance of international services and the interna- tional network , Vol. IV, Rec. M.93. 1.2 Setting-up, lining-up and monitoring the international sound-programme links and connections It is assumed that the international sound-programme connection is as shown in Figure 2/N.1. It is also assumed that the various sound-programme circuits to be interconnected to constitute the international sound-programme link are circuits established and maintained as given in Subsection 1.3 below. Recommendation N.10 LIMITS FOR THE LINING-UP OF INTERNATIONAL SOUND-PROGRAMME LINKS AND CONNECTIONS 1 General This Recommendation gives limits in Tables 1/N.10 to 5/N.10 for the lining-up of international sound-programme links as defined in Recommendation N.1. These limits correspond to those for three audio sections of the hypothetical reference circuit as defined in CCIR Recommendation 502 [1] for 5 kHz, 6.4 kHz, 7 kHz and 10 kHz type sound-programme circuits, but correspond to four audio sec- tions for 15-kHz type sound-programme circuits except for noise limits, which correspond to three audio sections [2] It is not possible at the present time to recommend limits for the sound-programme connection. However, Administrations shall endeavour to provide national sound-programme circuits to as high a standard as possible so that the performance of the sound-programme connection is not markedly different to that of the sound-programme link. Some Administrations arrange their apparatus in an ISPC so that at the point of interconnection the output impedance of every receive channel or circuit over the frequency band of interest is substantially lower than the input impedance of any send channel or circuit. This is the so-called constant-voltage technique impedance match at the point of interconnection and choose the value of this impedance to be equal to the design resistance of measuring instru- ments. This is known as the impedance-matching technique (previ- ously referred to as the constant electromotive force technique ). It should be noted that in both cases the through-level measurement results relative to the through-level at 800 Hz will be the same. Furthermore the terminated-level measurement results relative to the terminated-level at 800 Hz will also be the same value Hence the limits recommended in the following tables are _________________________ Wider tolerance limits are recommended for 15-kHz type sound-programme circuits because of performance limita- tion of commercial equipment. This depends on the almost constant ratio of the im- pedances on the send and receive sides at the various frequencies. (See S 4 of Recommendation N.11.) applicable regardless of the arrangement adopted by Administrations at their ISPCs. The test procedures are described in Recommendation N.21. The limits for 15 kHz and 7 kHz circuits are applicable both for analo- gue and digital transmissions. 2 Limits for the loss/frequency distortion of an interna- tional sound-programme link The majority of international sound-programme links are in practice established with three or less circuits in series. Many links could be established without additional equalizers but links comprising four or more circuits will probably require equalization. In this case the opportunity could again be taken to obtain as good a loss/frequency characteristic as possible. H.T. [1T1.10] TABLE 1/N.10 Limit for the lining-up of 15 kHz sound-programme links ___________________________________________________________________________________________ Item Parameter Unit Limits ___________________________________________________________________________________________ | | | { TABLE 1/N.10 (cont.) } Item Parameter Unit Limits { { | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | { 14 Intelligible crosstalk ratio A/B dB 48 } { 15 Crosstalk ratio (intermodulation) A/B dB 58 MONTAGE: Additional parameters for stereo transmission } ___________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | Table 1/N.10 [1T1.10], p. H.T. [2T1.10] TABLE 1/N.10 (cont.) _____________________________________________________________________________________________ Item Parameter Unit Limits { { | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | { 14 Intelligible crosstalk ratio A/B dB 48 } { 15 Crosstalk ratio (intermodulation) A/B dB 58 MONTAGE: Additional parameters for stereo transmission } _____________________________________________________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 1/N.10 (cont.) [2T1.10], p. H.T. [T2.10] TABLE 2/N.10 Limits for the lining-up of 10 kHz sound programme links __________________________________________________ Item Parameter Unit Limits __________________________________________________ | | | __________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 2/N.10 [T2.10], p. H.T. [T3.10] TABLE 3/N.10 Limits for the lining-up of 7 kHz sound-programme links __________________________________________________ Item Parameter Unit Limits __________________________________________________ | | | __________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 3/N.10 [T3.10], p. H.T. [T4.10] TABLE 4/N.10 Limits for the lining-up of 6.4 kHz sound-programme links __________________________________________________ Item Parameter Unit Limits __________________________________________________ | | | __________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Table 4/N.10 [T4.10], p. H.T. [T5.10] TABLE 5/N.10 Limits for the lining-up of 5 kHz sound-programme links __________________________________________________ Item Parameter Unit Limits __________________________________________________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __________________________________________________ | | | | | | | | | | | | | | | Table 5/N.10 [T5.10], p. References [1] CCIR Recommendation Hypothetical reference circuits for sound-programme transmissions , Vol. XII, Rec. 502, ITU, Geneva, 1986. [2] CCIR Recommendation Estimation of transmission perfor- mance of sound-programme circuits shorter or longer than the hypothetical reference circuit , Vol. XII, Rec. 605, ITU, Geneva, 1986. [3] CCIR Recommendation Performance characteristics of 10 kHz type sound-programme circuits , Vol. XII, Rec. 504, ITU, Geneva, 1982. Recommendation N.11 ESSENTIAL TRANSMISSION PERFORMANCE OBJECTIVES FOR INTERNATIONAL SOUND-PROGRAMME CENTRES (ISPC) 1 Transmission level at interconnection points Levels at interconnection points must be such that a signal level of 0 dBm0 on the incoming circuit gives rise to a signal level of 0 dBm0 on the outgoing circuit. A nominal relative level of +6 dBr is recommended at interconnection points (see also Figure 3/J.13 [1] and Recommendation J.14, S 1 [2]). 2 Balance with respect to earth The balance with respect to earth (measured by the method defined in [3]) of nominally balanced apparatus should be at least 60 dB in order to give an adequate suppression against longitudinal interference induced by power supplies, alarm circuits, etc. 3 Access points There should be a well-defined circuit access point associated with the input to a sound-programme circuit at which the transmis- sion test levels at all frequencies over the band are nominally the same. This access point may be the interconnection point or separated therefrom by distortion-free loss or gain. A well-defined circuit access point should also be associated with the output of a sound-programme circuit. The nominal relative level at each access point will be chosen by each Administration, bearing in mind the dynamic range of their testing and transmission apparatus. Measurements on a sound-programme circuit should be made between such circuit access points. Administrations may also find it convenient to arrange for sound-programme circuit sections to be equipped with similar access points. International sound-programme circuit sections which can be connected to a variety of other circuit sections should always be equipped with such access points. 4 Interconnection of sound-programme circuits 4.1 Constant voltage technique If the modulus of the output impedance of any source is not greater than one hundredth of the modulus of the lowest impedance that can be connected to it (bearing in mind that it is possible to connect two or more loads in parallel) then the change in level due to change of load will be negligibly small (less than 0.1 dB approximately). 4.2 Impedance matching technique If the return loss versus the nominal design resistance of the measuring instruments of the impedance presented by incoming and outgoing circuits to the points where they are interconnected is at least 26 dB over the range 50 Hz to 10 or 15 kHz, the error due to mismatch will be insignificant, assuming that the impedance of testing apparatus has at least 30-dB return loss versus the nominal design resistance, which can be, for example, 600 ohms non-reactive. 4.3 Digital technique The interconnection of digital sound-programme circuits will be made by preference with the aid of a digital interface present- ing the following characteristics: - plesiochronous or synchronous operation - bit rate of 384 kbit/s, 1544 kbit/s or 2048 kbit/s - 384 kbit/s to carry either one 15 kHz or two 7 kHz sound-programme signals. Interface for other bit rates, namely to provide for 15 kHz monophonic and stereophonic circuits with linear coding and for 7 kHz monophonic sound-programme circuits with companded coding are the subject of further study. References [1] CCITT Recommendation Definitions for international sound-programme circuits , Vol. III, Rec. J.13. [2] CCITT Recommendation Relative levels and impedances on an international sound-programme connection , Vol. III, Rec. J.14. [3] CCITT Recommendation Transmission aspects of unbalance about earth Vol. III, Rec. G.117. Recommendation N.12 MEASUREMENTS TO BE MADE DURING THE LINE-UP PERIOD THAT PRECEDES A SOUND-PROGRAMME TRANSMISSION After the connection of the various circuits to form the international sound-programme link (conforming to the level diagrams of these circuits) it is necessary to verify, by means of an automatic measuring equipment (see Recommendations O.31 [1], O.32 [2] and O.33 [3]) or by measurements at individual frequencies, that the received level at the distant incoming termi- nal ISPC is at the correct value (see Recommendation N.10) at the following frequencies: for an international sound-programme link composed entirely of 15-kHz sound-programme circuits 40, 800 and 15 | 00 Hz | 1) for an international sound-programme link composed entirely of 10-kHz sound-programme circuits 50, 800 and 10 | 00 Hz | 1) for an international sound-programme link comprising at least one 7 kHz sound-programme circuit 50, 800 and 7 | 00 Hz | 1) for an international sound-programme link comprising at least one 6.4-kHz sound-programme circuit 50, 800 and 6 | 00 Hz | 1) for an international sound-programme link comprising at least one 5 kHz sound-programme circuit 100, 800 and 5 | 00 Hz | 1) for an international sound-programme link comprising at least one ordinary telephone circuit 300, 800 and 3 | 00 Hz The send level during these measurements should be -12 dBm0. In the case of 15-kHz sound-programme links forming a stereo- phonic pair, it is necessary to verify the interchannel parameter limits specified in Table 4/N.10. A measurement of other parameters such as nonlinear distortion and noise should be measured on all links and the results recorded. At the present time the limits cannot be specified. The national sound-programme circuits should be so adjusted that, when they are connected to the international sound-programme link, the level diagrams of the international sound-programme cir- cuits are respected. In this regard, a useful and quick method which Administrations could use to verify the correct alignment of sound-programme links is given in Annex A of Recommendation N.13. Any necessary adjustments having been made, the national cir- cuits are connected to the international sound-programme link at the terminal ISPCs. This is the end of the line-up period and the beginning of the preparatory period and is the instant when the complete connection is placed at the disposal of the broadcasting organizations. The latter then proceed to measure and adjust as necessary. References [1] CCITT Recommendation Automatic measuring equipment for sound-programme circuits , Vol. IV, Rec. O.31. [2] CCITT Recommendation Automatic measuring equipment for stereophonic pairs of sound-programme circuits , Vol. IV, Rec. O.32. [3] CCITT Recommendation Automatic equipment for rapidly measuring stereophonic pairs and monophonic sound-programme cir- cuits, links and connections , Vol. IV, Rec. O.33. _________________________ Or the frequency appropriate to the telephone-type cir- cuit used.