WPCL 2BJ|x ` H   x|@  @8'@8' 5.HProposed additions and revisions to Recommendation M.580 2SETTING UP AND LINING UP OF AN ,INTERNATIONAL CIRCUIT FOR PUBLIC TELEPHONY   HAdd the following text as a new subparagraph to 1 of M.580:  X  "As an alternative to the procedures given in 7 to 14 which require testing personnel to be present at both ends of the circuit, 15 gives a procedure involving the use of the CCITT Automatic Transmission Measuring and Signalling Testing Equipment (ATME) No.2 (RecommendationO.22) (with typea responding equipment) which may be used subject to the agreement of the administrations involved." HTo 7 add a footnote to the heading of this paragraph consisting of the following: "The procedure given in 15 may be followed as an alternative to those given in 7 to 14 if agreement has been reached with the distant administration to use ATME No.2 for lining up, measurement of circuit noise and functional tests. It should be noted that this procedure does not include the tests in 12. The administrations involved should consider scheduling such tests, if applicable, when cooperative effort can be arranged." HReplace the existing note to Table4/M.580 by the following one: "Note At the present time the section of a circuit provided by a satellite employing FDM techniques with an earth station at its receiving end of INTELSAT Standard A (Figure of merit40.7dB/k) or StandardC (Figure of merit39.0dB/k) contributes approximately 10,000pWOp (50dBmOp) of noise. The noise contributed by earth stations with revised figures of merit are for further study. Therefore, for the purpose of determining maintenance limits for noise measurements on international public telephony circuits, the length of this section may be considered to be equivalent to a terrestrial length of 2,500km. The section of a circuit provided by a satellite employing FDM techniques with an earth station at its receiving end of INTELSAT StandardB contributes approximately 80,000pWOp (41dBmOp) of noise for FM companded circuits. The methods of determining total distortion and/or noise objectives for such a circuit are given in RecommendationM.590. The contribution to noise of a circuit section provided by a satellite employing TDM techniques remains a subject for further study." HParagraph 8 HInsert new subparagraph 8.1: "8.1HWhere a circuit is routed via a circuit multiplication system employing digital speech interpolation techniques it may not be possible to make a reliable noise test using the method described in this paragraph. In this case, a total distortion measurement should be made instead, as described in  9.3." HAll existing subparagraphs in  8 should be renumbered accordingly. HInsert a new  9 as follows: "9.HMeasurement of total distortion 9.1HGeneral HThis measurement is required for composite (i.e. mixed analogue/digital) circuits only. The measurement of total distortion should be made for both directions of transmission. HThe measuring equipment should be as specified in Recommendation 0.132. [6]. HThe measuring equipment should be applied at the circuit access points. HA test frequency of 1 020 Hz should be used. HIt is assumed that the measurements and adjustments outlined in  7.2.2 and 7.2.3 above have already been carried out. 9.2HMeasurement of total distortion using a test signal level of 10 dBm0 9.2.1HThe results of the total distortion measurement should be compared with the total distortion objectives shown in Table 5/M.580 according to the number of Quantizing Distortion Units (QDUs) in the circuit and the total length of the analogue circuit sections. 9.2.2HIf these objectives are exceeded by a circuit which has satisfied the noise objectives described in  8, then a fault on a digital equipment causing excessive quantizing distortion should be suspected. 9.3HMeasurement of total distortion using a test signal level of 25 dBmo 9.3.1HOn circuits routed via a circuit multiplication system employing digital speech interpolation, this measurement may be regarded as a substitute for a measurement of circuit noise. The results of the measurement should be compared with the objectives shown in Table 6/M.580. 9.3.2HIf the measured total distortion is higher by 5 dB or more than the appropriate value from Table 6/M.580 or is higher than 37 dBm0p, whichever is the more stringent requirement, on a circuit which has satisfied the test in 9.2 above, then a fault on an analogue circuit section causing excessive noise should be suspected. 9.3.3HFor maintenance purposes a measurement of total distortion using a 25dBm0 signal level can be useful on all composite circuits. In conjunction with a measurement using a 10 dBm0 signal level it may be possible to identify whether a fault lies in an analogue or digital circuit section from endtoend measurements using the same instrument.* If the circuit satisfies the objectives of Table 5/M.580 but exceeds the objectives of Table 6/M.580, a faulty analogue circuit section should be suspected. Conversely, if the objectives of Table6/M.580 are satisfied but those of Table 5/M.580 are not, faulty digital equipment is likely. * Note If the number of QDUs is 4 and the analogue noise level is 55 dBm0p, this procedure will produce less accurate results. In this case, a 30dBmO test tone will be appropriate to check the analogue section, when a circuit is not fitted with an echocanceller or the echo canceller can be disabled." HExisting 9 to 11 should be renumbered 10 to 12. The note under existing 9 should be deleted. HIn 12.3 (old 11.3): H replace the word "suppressors" with "control devices"; HH© add the following:  `    HX "In addition, a check of the echo control device with the corresponding tester as specified in RecommendationsO.22 and O.25 should be made if available."  w.ԌHIntroduce the following new 13: "13.HEcho canceller test capability HWhen echo cancellers are fitted to a circuit, tests by other administrations using test facilities specified in Recommendation O.22, can successfully be carried out only if the canceller stages and echo path delay characteristic are programmed into the test sequence. Therefore, the administration placing echo cancellers in their international switching centre should so apprise the other administration(s). This may be done by a specific communication, for example a telex message, or by including such information with the exchange of routine maintenance schedules (Recommendation M.605)." HRenumber the existing 12 to 14, Record of results. HAdd the following new paragraph after 14: "15.HSettingup and liningup an international circuit using ATME   15.1HThe following procedure should be followed when it has been agreed between the administrations concerned that ATMENo.2 can be used. Generally, it is suitable only when there are no intermediate circuit subcontrol stations and for circuits which do not have particular measurement requirements (see 9). 15.2HSettingup the circuit   HThe circuit control and subcontrol stations in conjunction with their testing points should ensure that all associated signalling, switching and other terminal equipment has been connected, is free from faults and is operating satisfactorily. This should include the check of signalling level specified in 10. The subcontrol station should advise the control station that these checks have been made. 15.3HLiningup the circuit HOn receiving the advice from the subcontrol station, the control station should test the circuit using ATMENo.2. The time at which the tests are performed should take into account the availability schedules of the ATMENo.2 responding equipments and the period of peak traffic at the distant terminal exchange (see RecommendationM.150, 3). The ATMENo.2 should be programmed to perform the full range of transmission measurements and signalling tests. HIf the transmission level in the receive direction at the control station is not within 1dB of its nominal level, the level should be adjusted to within 0.3dB of its nominal level, and the circuit should then be retested. HIf the transmission level in the receive direction at the subcontrol station distant end is not within 1dB of its nominal level or if any of the other limits specified in the Recommendation are not met in either direction of transmission, then the procedures given in  7 to 12 should be followed. HWhen the ATMENo.2 tests have been successfully completed, the control station informs the subcontrol station of the results. 15.4HRecording of results HThe control station should record all results given by ATMENo.2 for both directions of transmission." HInclude the following two new Tables5/M.580 and 6/M.580 in the Recommendation and renumber existing Tables5/M.580 to Table7/M.580. Existing references should be amended. 15.5HOther tests HWhen the lineup procedure, as described above, has been completed, a check should be made of the functioning of the compandors, where appropriate, in accordance with RecommendationM.590. This should be followed by a speaking test including a check of the satisfactory operation of echo suppressors and echo cancellers.