1、 CCITT FASCICLE 1V.L tt = 4862591 0505425 7 4 Interface requirements at digital access points 4.1 interface requirements of Q 1.2.3 of Recommendation G.703 i. 4.2 meet the interface requirements of Recommendation G.703 i. 4.3 are under study by Study Group IV. Digital access points at 64 kbit/s sho
2、uld be operated in the contradirectional mode and should meet the Digital path access points, operated at 1544 kbit/s or 2048 kbit/s (or higher hierarchical bit rates) should Interface requirements for digital access points on circuits using an encoding technique other than PCM Reference i CCIT Reco
3、mmendation, Physical electrical characteristics of hierarchical digital interfaces, Vol. III, Rec. G.703. Recommendation M.570 CONSTITUTION OF THE CIRCUIT; PRELIMINARY EXCHANGE OF INFORMATION 1 As soon as it is decided to bring a new circuit into operation, the technical services of the terminal cou
4、ntries should agree upon the circuit control station, and the technical service of each transit country should advise the other technical services concerned of the name of the sub-control station chosen for its territory. If the circuit is routed in a direct group or block crossing a transit country
5、 without demodulation or demultiplexing, no sub-control station need be provided for the transit country. When a circuit is subjected to analogue-to-digital conversion using, for example, a transmultiplexer, the location of the transmultiplexer should be designated as circuit sub-control station. Al
6、so the technical services of all the countries concerned should send to the technical service responsible for the circuit control station information which will be required for the preparation of the circuit routing form (see the Appendix I to this Recommendation) using the letter and number code on
7、 the form. The information for a circuit without audio sections will consist of the numbers of the groups or blocks used and the number of the channel in each group or block. In the case of a both-way circuit, the circuit order of selection should be stated, including the method by which the Interna
8、tional Switching Centre selects circuits (i.e., sequentially by circuit, fully randomly or sequen- tially by block of circuits but randomly within the block, etc.). When the circuit is assigned its designation (according to Recommendation M.140, 0 i), the Administra- tion with control station respon
9、sibility will assemble the necessary technical and operational information. This should be entered into the list of Related Information (as defined in Recommendation M.140, 0 2) which consists of the items shown in Annex A. 2 Exchange of information The information should preferably be sent by telex
10、 and the examples below show typical telex messages concerning the provision of Bucuresti-London 1 when the circuit is analogue, digital or mixed analogue/digital. This method using the telex services enables agreement on routing details to be obtained quickly and also enables circuit routing forms
11、to be completed by the technical services responsible for the circuit control stations as soon as a circuit is put into service or rearranged. - r _I Fascicle IV.l - Rec. M.570 347 CCITT FASCICLE IV-L * m 4862591 0505426 9 II Example I - Telex message from the technical services of the United Kingdo
12、m to the technical services of the Federal Republic of Germany, Austria, Hungary and Roumania for an analogue circuit: NETWORK CONTROL DIVISION BTI LONDON TO FTZ DARMSTADT GENTEL WIEN GENTEL BUDAPEST GENTEL BUCURESTI OUR REF. PROPOSE PROVISION OF BUCURESTI/Al - LONDON/M B1 USING FRANKFURT- LONDON 12
13、01/9 SIGNALLING 500/20 GRATEFUL FOR YOUR AGREEMENT OR COUNTER PROPOSALS. REGARDS. Example II - Telex message from the technical services of the Federal Republic of Germany in reply to telex in example I: FTZ SCHALT DMST A NETWORK CONTROL DIVISION BTI LONDON 10 APR YOUR REF. OUR REF- 2 5 = FRANKFURT/
14、MAIN A = FFT - L 1201/9 B = 840 A FEDERAL REPUBLIC OF GERMANY 3 - BUCURESTI - LONDON 1 = FFT - WIEN 1201/11 B = 740 REGARDS. COPIES TO WIEN, BUDAPEST, BUCURESTI. Similar messages could be used for a digital circuit. The channel to be used then could be, for example, Frankfurt - London 30N003/22. Exa
15、mple III - Telex message from the technical services of the United Kingdom to the technical services of the Federal Republic of Germany, Austria, Hungary, and Roumania for a mixed analogue/digital circuit using a transmultiplexer at Frankfurt: NETWORK CONTROL DIVISION BTI LONDON TO FTZ DARMSTADT GEN
16、TEL WIEN GENTEL BUDAPEST GENTEL BUCURESTI OUR REF. PROPOSE PROVISION OF BUCURESTI- LONDON 1 USING FRANKFURT- LONDON 30NC004/7 SIGNALLING SYSTEM NO, 5 GRATEFUL FOR YOUR AGREEMENT OR COUNTER PROPOSALS. REGARDS. 348 Fascicle IV.l - Rec. M.570 7. 7 CCITT FASCICLE IV-1 tt 4862591 0505427 O m Example IV -
17、 Telex message from the technical services of the Federal Republic of Germany in reply to the telex in Example III: FTZ SCHALT DMST TO NETWORK CONTROL DIVISION BTI LONDON 10 APR YOUR REF. OUR REF. 2 = FEDERAL REPUBLIC OF GERMANY 3 = BUCURESTI-LONDON 1 5 = FRANKFURT/MAIN 19 = FRANKFURT/MAIN A FFT - L
18、 30N0004/7 B 840 A = FFT - WIEN 12008/7 B 740 REGARDS. COPIES TO WIEN BUDAPEST BUCURESTI. Using the above-mentioned information and the data supplied by sub-control stations, the circuit control station makes out a circuit routing form which is used as a level diagram for voice-frequency sections (s
19、ee Appendix I to this Recommendation, which can serve as a routing form or level diagram). This routing form shows the nominal relative levels at: - - - circuit control and sub-control stations; frontier stations, if the circuit is reduced to a voice-frequency section across a frontier; stations whe
20、re the circuit is reduced io voice frequency, in those cases where the circuit passes via a series of groups or blocks. The technical service of the circuit control station sends the routing form to the technical services of the a) only at the specific request of one of the Administrations concerned
21、 when the circuits are routed on one channel of a single international group link or digital path; b) in all cases for circuits otherwise constituted. The despatches are sent in duplicate, one copy for the technical service and one for the sub-control station. sub-control stations of the internation
22、al circuii concerned: Fascicle IV.1 - Rec. M.570 349 ANNEX A (to Recommendation M.570) Designation information on international public switched circuits A.l Designation The designation is according to Recommendation M.140, 0 1. A.2 Related information The additional information on public switched ci
23、rcuits is covered by the following items: RI 1. Urgency for restoration; RI 2, Terminal countries; RI 3. Carriers names; RI 4. Control and sub-control station); RI 5. Fault report points; RI 6. Routing; RI 7. Association; RI 8. Equipment information; RI 9. Use; RI 10. Transmission medium information
24、 RI 11. Composition of transmission; RI 12. Bandwidth or bit rate; RI 13. Signalling information; The various items will be dealt with in 4 2 of Recommendation M.140. -. 350 Fascicle IV.l - Rec. M.570 7 -1 t CCITT FASCICLE IV-L tt m qBb259L 0505q29 4 m 1. 2. 3. 4. Sa. 5b. 6. 7. 8. 9a. 9b. 10. 11. 1
25、2. 13. 14. 15. 16. 17. 18. 19. 20. 21. APPENDIX I (to Recommendation M.570) Routing form for an international circuit Date of issue. . Technical service of. . Circuit designation Length . Control station Sub-control stations Date of putting into service . Type of ISC at control station end . Type of
26、 ISC at sub-control station end Echo suppressors at. . Echo cancellers at. Compandors at Signalling . Switching equipment . Special equipment at . Special concentrator . Estimated weighted noise power Special performance requirements at Hangover time of suppressors at Estimated total distorsion powe
27、r Transmultiplexer at Echo cancellation stages at . Echo path delay characteristics, per stage, at . American Telephone and Telegraph Co. New York (10) - Stockholm 1 7870 km New York London, Stockholm October 1972 Analogue Analogue New York (%), Stockholm (%) None None System No. 5 None None -48 dBm
28、O (36 dBa) None New York: 50 ms Stockholm: 50 ms Not applicable None Nominal relative level at reference Estimated group delay time at 1020 Hz (milliseconds) Stations and Length of section measurement point (dBr) constitution (in km) Direction Direction t (A) (BI (Cl (Dl (E) I -4.5 I I I New York 34
29、A-/C/-8 522 3.2 Green Hill +7.0 +7.0 1602-05-/A/-5 5813 36.5 London I f4.0 I -4.0 I I 1211/1 I 1535 I 9.5 I I Stockholm - 11.0 I I Remarks Through-group connection points Conil (Spain) Sesimbra , (Portugal) Insert CMS only, through and CMS, or none as appropriate (or equivalent). An asterisk after the relative level indicates that the nominal value of the impedance at the measuring point differs from 600 ohms. When this column is completed for loaded cables the effective bandwidth of the section will be inserted. - Fascicle IV.l - Rec. M.570 351 - 7 7
