ITU-T S 7-1988 CONTROL OF TELEPRINTER MOTORS《电传机马达的控制》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 3 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(9!,0(!“%4)#!,G0G04%,%2!0(G0G04%2-).!,%15)0-%.4#/.42/,G0G0/ amended at Arnhem, 1953, and Geneva, 1976)The CCITT,considering(a) that, in the case of public and private point-to-point circuits, it is des

2、irable that the teleprinter motors shouldbe started with the commencement of traffic signalling and stopped with the cessation of such signalling;(b) that the general practice on such circuits is to utilize a time-delay device associated with the teleprinterwhich allows of such operation,unanimously

3、 declares the view(1) that, in the case of public and private point-to-point circuits, the terminal apparatus shall be so equipped asto allow of the starting and stopping of the teleprinter motors with the commencement and completion respectively ofthe traffic;(2) that these facilities shall normall

4、y be provided by means of a time-delay device incorporated in theteleprinter, whereby the teleprinter motor is started immediately upon commencement of the signalling of traffic and isstopped within a time not less than 45 seconds after the last traffic signal;considering(c) that more strict unifica

5、tion of the delay-time of these automatic devices might give rise to serious technicalcomplications;(d) that precautions should thus be taken lest an operator, should transmit signals while the motor of hisapparatus is still rotating, to an apparatus in which the motor has just stopped,unanimously d

6、eclares the view(3) that, in the case of a pause in transmission for a period equal to or longer than 30 seconds, operators orsubscribers are recommended to send a letter-shift (combination No. 29 in International Telegraph Alphabet No. 2) andto wait at least 2 seconds after the emission of this sig

7、nal before recommencing transmission;considering(e) that, for reasons associated with the unification of terminal apparatus and for others, certainAdministrations have expressed a preference for the utilization of a method whereby calling and clearing signals areused, as in the telex service, to eff

8、ect the starting and stopping of the teleprinter motors,unanimously declares the view(4) that, notwithstanding (2) above, Administrations can, if they find it convenient, arrange betweenthemselves to use an alternative method whereby the teleprinter motor is started by the use of a call signal, and stoppedby the use of a clearing signal. In such cases the calling and clearing signals employed should conform to thosestandardized for the telex service, namely Recommendation U.1 1.Reference1 CCITT Recommendation Signalling conditions to be applied in the international telex service, Rec. U.1.