1、CCITT FASCICLE VII.3 * 9 48b2573 0530283 3 Recommendation R.59 INTERFACE REQUIREMENTS FOR 50-BAUD START-STOP TELEGRAPH TRANSMISSION IN THE MARITIME MOBILE SATELLITE SERVICE (Geneva, 1980; amended at Malaga-Torremolinos, 1984) The CCITT, considering (a) that proper interworking with the international
2、 telegraph services must be ensured: (b) that the coast-earth station equipment will interface with the international terrestrial telegraph networks and will therefore need to conform to CCIT Recommendations where applicable; (c) that the ship earth station will include a local end with its terminat
3、ion consisting of start-stop equipment using International Telegraph Alphabet No. 2: (d) that corresponding requirements are given in CCIR Recommendation 553, unanimously recommends (1) that the coast earth station equipment interfacing with terrestrial telegraph channels should conform to a) for si
4、gnals from the terrestrial network entering the coast earth station, the relevant points are given in Table 1/R.59; b) for signals from the coast earth station entering the terrestrial network, the relevant points are given in Table 2/R.59; Recommendation R. 1 O1 as applicable to 50-baud services: (
5、2) that the transmission characteristics of the ship earth station start-stop equipment should conform to Recommendation S.3 as applicable to 50-baud services, TABLE 1/R.59 Parameter Recommendation R.101 Input modulation rate Isolated character stop elements Minimum interval between start elements N
6、o restrictions on the use of combinations of International Telegraph Alphabet No. 2 Effective net margin Minimum input start element duration I 2.1 5 2.2 . 0 2.3 0 2.4 5 2.5 0 2.6 60 Fascicle VII.l - Rec. R.59 *f- F - CCITT FASCICLE VII.3 tt E LI862593 0530282 3 E _. - TABLE 2/R.59 Parameter Recomme
7、ndation R.lO1 Output distortion Q 3.1 Output modulation rate Q 3.2 Minimum output stop element 5 3.3 considering fiirther (e) that in the first generation INMARSAT system, telex characters are fransmitted in synchronous channels using 6-unit frames in such a way that, due to speed differences betwee
8、n the on-board teleprinter and the satellite telex channel, periods of Z polarity equal to the duration of a telex character occasionally appear in the data stream; (f) that this may cause difficulties when the ship earth sfation is operating towards automatic terminals, store-and-forward units, etc
9、. in the international telex network, recommends (3) that, if practicable, future systems should be designed so that insertion of unnecessary periods of Z polarity is avoided when characters are to be retransmitted at cadence speed into the international telex network. Fascicle VII.l - Rec. R.59 61
