1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 2 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(94%,%2!0(G0G042!.3-)33)/.#/$%G0G0!.$G0G030%$G0G13G0$%0%.$!.44$-G0G0 G0“)4 3G0G03934%-G0G0(b) that TDM multiplexing systems are economical for the transmission of large numbers of channels;(c) that cer
2、tain telex switches handle TDM frames in accordance with Series-R Recommendations directly andthat frame fill should be optimized;(d) that telex switches handle channels at 50 bauds and a 7.5 unit code;(e) that a facility for regenerating start-stop signals is used in new TELEX networks;(f) that the
3、 branch-line multiplexing system should be capable of accepting and regenerating all the signals ofthe TELEX signalling system;(g) that the minimum signal transfer delay through TDM systems is achieved by the transmission ofinterleaved elements,recommendsthat, where banch-line remote or low multiple
4、x capacity TDM systems are to be used for telegraphy, theequipment shall comply with the following standards:1 System capacityThe system shall be capable of multiplexing up to 8 channels at 50 bauds (7.5 bits including a stop element of1.5 units).2 Start-stop channel inputs2.1 The modulation rate to
5、lerance that shall be accepted on incoming 50 baud start-stop signals with a stop elementof 1.4 units shall be at least 1.4%.2.2 When receiving characters at 50 bauds having nominally 1.5-unit stop elements, the system shall be capable oftransmitting without error isolated incoming characters that h
6、ave a 1-unit stop element, occurring at a maximum rate ofone per second.2.3 The minimum interval between start elements of undistorted successive continuous characters that may bepresented at the channel input when the nominal modulation rate is 50 bauds shall be 145 5/6 ms.2.4 There shall be no res
7、triction on the continuous transmission of all characters (including combination No. 32 ofInternational Telegraph Alphabet No. 2) when they are presented at the maximum permitted rate.2.5 The effective net margin on all channel inputs when undistorted signals are received from a transmitter havinga
8、nominal character length and rate shall be at least 40%.2.6 At the nominal modulation rate of 50 bauds, an input character start element shall be rejected if it is less than0.4 units duration and shall be accepted if it is more than 0.6 units duration.2.7 Elements corresponding to start polarity (at
9、 the distant multiplexer output) shall be inserted in the aggregatestream if the channels are unequipped.2.8 In the case of an open-circuit line condition at the start-stop channel input, it shall be possible to choose totransmit elements corresponding to a steady start or stop polarity in the aggre
10、gate bit stream, according to theavailability polarity selected.2 Fascicle VII.1 - Rec. R.1033 Start-stop channel outputs3.1 The maximum degree of gross start-stop distortion, produced by the system on a start-stop channel, shall be 3%for all modulation rates.3.2 The maximum difference possible betw
11、een the mean modulation rate of the channel output signals and thenominal modulation rate shall be 0.2%.3.3 The minimum stop element duration released at the ouptut shall be 1.25 units, whatever the distortion, thelength of the stop element or the input rate within the range specified in 2.1 to 2.4
12、of this Recommendation of thecharacter recognized at the other end, whether this character is in accordance with this Recommendation ofRecommendations R.101, R.102 or R.112 (for a rate of 50 bands and a 7.5 unit code).3.4 Within 6 ms of the recognition of one of the failures described in 8.3 and 8.4
13、 or carrier loss signalled by themodem, the steady polarity as selected in accordance with 2.8 shall be applied to the channel outputs of the TDMsystem affected.3.5 The affected terminal shall signal its synchronization status to the distant terminal over the signalling channelprovided (control chan
14、nel).4 Multiplexing details4.1 Channel interleaving shall be on a bit-by-bit multiplexing basis.4.2 Both start and stop elements of each input character shall be transmitted through the aggregate.4.3 The transfer delay shall not exceed 60 ms.5 Frame structure5.1 A unique frame of 12 bits, of duratio
15、n 20 ms, equivalent to an aggregate signal rate of 600 bit/s shall be used,as shown in Table 1/R.103.5.2 The frame may be considered as a 600 bit/s start/stop character, time slot “12” being the start element ofpolarity A, slots 10 and 11 forming the stop element of polarity Z, as shown in Figure 1/
16、R.103.6 Aggregate signal details6.1 The aggregate signal rate shall be 600 bit/s. The tolerance on the modulation rate of the receive aggregatesignals of the TDM system shall be between +2.3% and 0.5%.6.2 The effective net margin of the aggregate signal receiver of the TDM system shall be at least 4
17、0%.6.3 The maximum degree of isochronous distortion of the send aggregate signals of the TDM system shall be 5%.Fascicle VII.1 - Rec. R.103 3TABLE 1/R.103Frame detailsRemote muldex slot Use123456789101112Data channel 1Data channel 2Data channel 3Data channel 4Data channel 5Data channel 6Data channel
18、 7Data channel 8Control channelZ synchronizationZ synchronizationA synchronisation6.4 When the TDM system is operated over an international telephone-type circuit, a modem complying with theappropriate aspects of the Series-V Recommendations (in particular Recommendation V.23) should preferably beem
19、ployed.7 Control channel encoding7.1 The 50 bit/s control channel, the position of which in the frame described in 5 is accurately known, enables allrisk of imitation to be eliminated.7.2 The structure of the control channel shall be in accordance with Figure 2/R.103. It corresponds to ananisochrono
20、us character with a recurrence of 240 ms, formed from a one unit start element of polarity Z, fiveinformation elements and a six unit stop element of polarity A.4 Fascicle VII.1 - Rec. R.1037.3 The control channel information provides for the transmission of information in accordance with Table2/R.1
21、03.TABLE 2/R.103Information transmitted by the control channel543 2 1Information elementsFunction000 0 0Without alarm or other informations (default)001 0 0Loss of synchronism000 0 1Loop “d” request(Remoteloop 2 on 600 bit/s aggregate)1 X X X X National use0 1 0 0 0 Remoteloop “f” on TG channel 1010
22、 0 1 2010 1 0 3010 1 1 4011 0 0 5011 0 1 6011 1 0 7011 1 1 8Note The least siginificant bits are sent first.Fascicle VII.1 - Rec. R.103 58 Synchronizing8.1 The maximum average synchronization time in the absence of error and imitation shall be 600 ms.8.2 Synchronism shall be considered acheived afte
23、r recognition of the frame positioning pattern (sequence of twoelements of polarity Z followed by an element of polarity A) as described in 5 and at least two successive recognitionsof the control channel (6 elements of polarity A followed by one element of polarity Z modulo 12) in compliance with7.
24、8.3 The maximum time loss of synchronization due to a steady polarity signal shall be 120 ms.8.4 The maximum time loss of synchronization for repeated error on the synchronization pattern in the controlchannel shall be 380 ms.9 Telex signalling9.1 Specifications for the signals used to establish, to
25、 clear and to control telex calls are laid down inRecommendation U.1 (types A and B), U.11 (type C) and U.12 (type D). Recommendation U.25 lists the modes ofboth-way telex signalling on a single circuit and the signalling combinations on a given aggregate that a TDM terminalshall be capable of handl
26、ing.9.2 Recommendation U.25 also lays down the tolerances on the control signals from a TDM terminal to telex andvice versa.10 MaintenanceThe branch looping facilities shall remain in accordance with Recommendation R.115.11 Numbering of channelsThe numbering of channels for the branch line telegraph
27、 muldex is given in Tables 1/R.114 and 4/R.114 inaccordance with the numbering scheme concerning Recommendations R.101 and R.102.12 Channel selectionRemote channels shall be grouped so as to provide maximum ease of use of heterogeneous frames, a time slotallocation involving little variation in the
28、sampling rate being retained.The selection of channel grouping and the method used shall be based on bilateral agreement, particularly whenthe channels of an existing system have to be branched without there being any possibility of a reconfiguration of thewhole.Tables 3/R.103 and 4/R.103 give an ex
29、ample of remote channel grouping on the basis of muldexes inconformity with Recommendation R.101 or R.102.6 Fascicle VII.1 - Rec. R.103TABLE 3/R.103Example of grouping of remote channels for an R.101 muldex.200 baud channelseliminated50 baud channels extendedRemote channel1200120040501, 0513, 0525,
30、05360504, 0516(2), 0528, 0539Remote channel2200520090505, 0529, 0517, 05400509, 0532, 0521, 0544Remote channel3200220060502, 0526, 0514, 05370506, 0530, 0518, 0541Remote channel4200320100503, 0527, 0515, 05380501, 0533, 0522, 0545Remote channel5200720110507, 0531, 0519, 05420511, 0534, 0523, 0546050
31、8, 0512, 0520, 0524, 05350543(1)Note 1 Although incomplete, a sixth remote channel could be implemented with the remaining 50 baud channels.Note 2 Channel 0516 may not be remoted when the corresponding TS is used to transmit the maintenance channel in the R.101multiplexer.TABLE 4/R.103Example of grouping of remote channels for an R.102 muldex200 baud channels eliminatedRemotechannel 122004 and 20162012 and 20203452001 and 20132005 and 20172009 and 20216782002 and 20142006 and 20182010 and 2022910112003 and 20152007 and 20192011 and 2023
