ITU-T S 10-1988 TRANSMISSION AT REDUCED CHARACTER TRANSFER RATE OVER A STANDARDIZED 50-BAUD TELEGRAPH CHANNEL《在标准的50Bd电报通路上降低字符传送速率的传输》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 3 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(9!,0(!“%4)#!,G0G04%,%2!0(G0G04%2-).!,%15)0-%.442!.3-)33)/.G0G0!4G0G02%$5#%$G0G0#(!2!#4%242!.3(b) that the cost of devices to subdivide a standardized 50-baud telegraph channel for simultaneous use by

2、anumber of users is relatively high;(c) that a number of Administrations meet the demand for transmission at reduced character transfer rates byproviding a separate standardized 50-baud telegraph channel for each user and that the number of transmittedcharacters per minute is then limited by control

3、ling the operation of the telegraph machine;(d) 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 af

4、ter the emission of this signal before recommencing transmission Recommendation S.7, (3),unanimously declares the view(1) that the preferred method of providing transmission at reduced character transfer rate on standardized50-baud telegraph channels is an arrangement that employs one transmitted ch

5、aracter followed by a period of stoppolarity, the duration of which is determined in accordance with (2) and (3) below;(2) for quarter-speed operation (100 characters per minute), the duration of the period of stop polarity requiredis equivalent to 3 character periods;(3) for half-speed operation (200 characters per minute) the duration of the period of stop polarity required isequivalent to 1 character period.