ITU-T U 2-1988 STANDARDIZATION OF DIALS AND DIAL PULSE GENERATORS FOR THE INTERNATIONAL TELEX SERVICE《国际用户电报业务 互通的一般技术要求》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 5 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(G0G037)4#().%.%2!,34!.$!2$):!4)/.G0G0/amended at Arnhem, 1953 and Geneva, 1956)The CCITT,considering(a) that, when dials and dial pulse generators are used for the process of automatic selection by su

2、bscribers tothe international telex network, it is advantageous to standardize as far as possible the characteristics of such dials anddial pulse generators;(b) that the standardization of the dialling speed and lost motion periods of dials presents no technicaldifficulty;(c) that, for the satisfact

3、ory working of certain automatic systems, the time between successive pulse trainsshould not be less than 500 milliseconds, but that experience has shown that the minimum time taken by anexperienced operator to rotate the dial is of the order of 300 milliseconds;(d) that pulse ratios from 1.2:1 to 1

4、.9:1 will ensure the satisfactory working of existing automaticswitching systems;(e) that these pulse ratios can be usefully adopted with a view to simplifying direct calling betweensubscribers,unanimously declares the view(1) that in the international telex service, when dials or dial pulse generat

5、ors are used for the automaticselection of subscribers:a) the dialling speed shall be standardized at 10 pulses per second with a tolerance of 10%;b) the lost motion period of dials shall be not less than 200 milliseconds nominal value;c) the inter-digit pause of dial pulse trains generated by dial

6、pulse generators shall not be less than600 milliseconds;(2) a) that the pulse ratio must be between 1.2:1 and 1.9:1, the nominal ratio may be chosen as lyingbetween 1.5:1 or 1.6:1;b) that when the selection signals pass through a regenerative repeater it may be advantageous to use anominal ratio of 1.5:1.