WPCM 2%.B pz W"S^11>bbu"::Dg1:11bbbbbbbbbb11gggbuuuk1Xubuukuuuk111Rb:bbXbb1bb''X'bbbb:X1bXXXX;.;g:=::m:::mmmmm::::::mm:k1mubububububXubububub11111111bbbbbbbbbuXubbkbuXmmmmumububXXXXbububububbmbbbbbb:k:k::=kmmX:uXb'b:b:b:b'bmbbbb:::uXuXuXuXk:k:k:mbbbmbuXkXkXKQmmmm^b:kbbbbmbA@mmbmmbmmmmmmm:b:mmmbbmmmmmmmmmmmmXXmmmmmmmmmmmmmmmmmmcm`m`mm`m:mmmmmm}}}mjjmmmmmmmmmmmmmmm0mm}mmmmmmmmmmmmmmmmmmmmmmm}Mmmmmmmmmmmmmjmmmtmmmmmmmmm`'mmm`mmjmlWmmmmmmmmmmmmmmmmmmmW`mmmmjmM-lvetica#|x`H1`D4PkCQMS PS Jet Plus /800 II QPJPII.PRSPl`D4PkCg2W_ qr|xHelveticaCourier@ ,`H1`D4PkCmQrrr r  @C2K ` X` hp x (#%'H   x|@  3'3'Standard@8'@8'StandardC6QMS $=R- Recommendation R.112 HReplace by the following: < TDM HYBRID SYSTEM FOR ANISOCHRONOUS TELEGRAPH < AND DATA TRANSMISSION USING BIT INTERLEAVING < <(MalagaTorremolinos, 1984; amended at Melbourne, 1988) HThe CCITT, considering  ` H H(a)  that there is a limited requirement on certain routes to provide for rates and codes not included in Table1/R.101 which may be achieved by using timedivision multiplexing (TDM) techniques; H(b)  that wherever possible the rates and codes given in Table1/R.101 should not be expanded in the future; H(c)  that administrations may be asked to provide code and speed independent channels for cryptography, for telemetry, for rates outside the Recommendation R.101 tolerance of + 1.4%, where the rate and code may be changed frequently, and for maintenance purposes; H(d)  that the aggregate bit rate may be limited to 2400 bit/s and TDM equipment may be required to pass code independent and code dependent traffic; H(e)  that the bearer may not be suitable for using the backward channel as defined by RecommendationV.26, 5 [1], or in the provision of telegraph channels above the RecommendationV.26 aggregate by the technique of subdivision of the frequency band as given in Recommendation H.34 [2], unanimously declares the view Hthat where bitinterleaved TDM systems are used for code dependent and code independent anisochronous telegraph and data transmission with an aggregate rate of 2400 bit/s, carried either by analogue telephonetype circuit or by higher order TDM system, the equipment should be constructed to comply with the following standards: 1.HSystem capacity 1.1HThe TDM system will be capable of multiplexing the rates shown in Table1/R.101 for code dependent channels to alternative B. 1.2HEach code and rate independent channel should replace three, six or twelve 50 baud code dependent channels. 1.3HThe characteristics of the code independent channels should follow the limits shown in Table 1/R.112. H!TABLE 1/R.112 H' HCharacteristics of code independent channels and system capacityă  .Ԍ 2.HChannel inputs 2.1HThe nominal modulation rate will be 50, 100 or 200 bauds; the theoretical maximum modulation rate shall be 51.06, 102.12 or 204.24 bauds. 2.2HThe transition coding process of telegraph signals is in accordance with Recommendation R.111. 2.3HEach channel provides its individual coding intervals starting within the allocated time slots: each coding interval is subdivided into 4 quarters. In that coding interval where the skipping bit occurs in the subframe, the forth quarter is shortened by one time slot length. HFor a 50 baud channel, transmission of the code character starts with the next corresponding time slot. For channels with higher modulation rates the transmission of the code characters should be delayed by the number of the allocated time slots in the subframe minus 3. 2.4HWhere applicable, spurious elements with duration of 1.6ms (=8%) or less shall be rejected and elements longer than 2ms shall be accepted at the 50baud channel input. The element lengths to be rejected or accepted at higher channel modulation rates is for further study. 3.HChannel outputs 3.1HThe maximum degree of inherent isochronous distortion due to the sampling process shall be 8.3%. Note The longterm system distortion on a tandem connection of transition encoded channels of an independent TDM system approximates in the worst case to the arithmetic summation of the individual link distortions. 3.2HAfter a TDM link failure, actions described in 3.5 and 3.6 of RecommendationR.101, should be taken on the derived channel output. 4.HMultiplexing details 4.1HThe multiplexing details are in accordance with RecommendationR.101, alternative B on a bit basis. 4.2HThe maximum transfer delay (excluding the modem) for 50, 100 and 200baud code and rate independent channels for backtoback terminals shall not exceed 50ms for the rate 50baud and 35ms for rates 100 and 200 baud. The values of delay are subject to further study. 5.HFrame structure HThis is as defined in Recommendation R.101, alternative B. 6.HSynchronizing HThis is defined in Recommendation R.101, alternative B. 7.HHAggregate signals and interface, system clock arrangements and system control and alarmsƐ$H  .ԌHThese are defined in Recommendation R.101. 8.HChannel numbering scheme of code independent channels HChannel numbers used in the given Recommendation represent two last digits of the fourdigit numbering scheme in respect to the Figure 1/R.112, first two digits are shown in Recommendation R.114. H"REFERENCESă [1] CCITT Recommendation 2400 bit per second modem standardized for use of 4wire leased telephonetype circuits, RecommendationV.26.  Hh [2]CCITT Recommendation Subdivision of the frequency band of a telephonetype circuit between telegraph and other services, RecommendationH.34. [3]CCITT Recommendation 4800 bit per second modem standardized for use of 4wire leased telephonetype circuits, RecommendationV.27.  .Ԍ Note CD code dependent channel CID code independent channel * service channel 8"FIGURE 1/R.112 8) 8Channel allocation for code independent channels ofă 850, 100 and 200 baudsă