CEPT T CD 03-02 E-1983 Specification of Engineering Requirements for Code Independent Time Division Multiplex Equipment for Anisochronous Telegraph and Data Transmission《用于非等时同步电报和.pdf

1、CEPT T/CD*03-02*E 83 .I 2326414 0003597 9 j - T/CD 03-02 E Page 1 Recommendation T/CD 03-02 E (Cannes 1983) concerning the specification of engineering requirements for code independent Time division multiplex equipment for anisochronous telegraph and data transmission Recommendation prepared by the

2、 Working Group T/WG 10 “Data Communications” (CD) Text of the Recommendation adopted by the “Telecommunications” Commission: “The Conference of European Post and Telecommunications Administrations, Considering - that CCITT Recommendation R. 11 1 describes the standard for a code and speed independen

3、t TDM system for - that GT/CD has studied the harmonization of multiplexing equipment for data communication under the auspices anisochronous telegraph and data tranmission using transition encoding; of Question CD 1. Recommends - that the attached specification of engineering requirements for code

4、independent time division multiplex equip- ment for anisochronous telegraph and data transmission as annexed to this Recommendation should be taken into account by all CEPT Administrations when implementation of such a piece of equipment is being planned by Administrations.” a Administrations are fr

5、ee to stipulate additional requirements, and also which of the optional requirements, if any, are to be provided. Note I: It should be noted that the specication may be revised from time to time. Note 2: The Annex is an integral part of the Recommendation. Edition of March 15, 1986 CEPT T/CD*03-02*E

6、 83 I 2326434 0003598 O m, I Tributary part I 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Aggregate I I I I I interface part I Multiplexing part - T/CD 03-02 E Page 3 Annex. Contents SCOPE . 3 FUNCTION . 5 GENERALREQUIREMENTS . 6 TRIBUTARIES . 7 64 KBIT/S MULTIPLEXER UNIT 7 MULTIPLEXED INTERFACE CONVERSION UNlT

7、6 LINE TERMINATING UNIT 6 POWERSUPPLY. . 6 CONTROLS, MOMTORS AND ALARMS. 6 REFERENCES . 6 1. SCOPE 1.1. This specification details the facilities and performance required of a code and speed independent time division multiplex equipment (hereinafter referred to as the equipment) using transition enc

8、oding for anisochronous telegraph and data services. The equipment shall be capable of multiplexing in a pre-determined manner a maximum of 60, 300 baud channels (or optionally 240, 50 baud channels) onto high bit rate isochronous data streams. It shall also provide an equivalent demultiplexing faci

9、lity. The equipment shall be required to interwork with other equipments conforming to CCITT Recommendation R. 11 1. The multiplexer shall have dual 64 kbit/s aggregate ports to permit two bearer circuits to be used in “main” and “standby” operation if required. The transmission medium between Equip

10、ments may consist of two independent digital paths with space diversity, hereinafter referred to as Line 1 and Line 2. The general schematic diagram of the Equipment (Figure 1 / T/CD 03-02) shows one multiplexer (a-k) and its aggregate interface part (1-p). 1.2. a 1.3. 1.4. 1.5. The aggregate interf

11、ace part, hereinafter referred to as the Multiplexed interface conversion (MIC) part, performs the function of converting the internal aggregate interface to the form necessary for the planned digital paths (Line 1 and Line 2). Lines 1 and 2 wili be provided by any combination of either i) time slot

12、 access equipment (either directly or via baseband modems), or ii) a 2 Mbit/s Digital line system. 1 External tributary interface I I I I Internal aggregate interface I I External aggregate interface I I I I I Telegraph I or data, I customers lines I Figure 1 (T/CD 03-02). General schematic. Code in

13、dependent TDM equipment for anisochronous telegraph ) and iii) are respectively, A pair of 2,048 kbit/s units. A pair of modem units. A pair of time slot access units. Any two units may be fitted. A manufacturer may provide the facilities of i), ii) or iii) above by incorporating facilities to fit t

14、he MIC units in the multiplexer part (see paragraph 2.1.6.). 2,048 kbitls unit The unit shall be capable of accepting one or more 64 kbit/s input signals and, by a process of bit interleaving and padding, produce an aggregate output signal of 2,048 kbit/s. The unit shall be capable of performing the

15、 equivalent demultiplexing process. The output signal rate and interface code shall conform to CCITT Recommendation G.703, paragraph 5. The units may be provided in pairs to permit two digital lines (Line 1 and Line 2) to be connected to the Equipment. Each line may operate as “main” or “reserve” an

16、d will normally carry similar signals of identical rate. The propagation delay of route 1 and route 2 will not normally be equal. Modem unit The unit shall be capable of accepting a 64 kbit/s aggregate signal from a 64 kbit/s multiplexer and, by a process of scrambling and modulation, produce a base

17、band line signal in accordance with an appropriate national specification, The unit shall be capable of performing the equivalent demodulation process on a line signal from a distant Modem unit attenuated by up to 40 dB. The units may be provided in pairs so that two routes may be operated in “main”

18、 and “reserve” modes. TSA unit The unit shall be capable of accepting a 64 kbit/s aggregate signal from a 64 kbit/s multiplexer and converting this signal to a 64 kbit/s co-directional signal, conforming to CCIT Recommendations G.703 paragraph 9 and G.732 paragraph 5 for transmission (via the line t

19、erminating unit) on internal cable pairs to a PCM muldex with time slot access facilities. It shall also perform the reverse process for the opposite direction of transmission. The units may be provided in pairs, or in combination with alternative MIC units. Line terminating unit The unit (Figure 2

20、/ T/CD 03-02, n-p) shall provide terminations and test access facilities for the following types of cable pairs: i) 75 ohm unbalanced coaxial pairs (two 2 Mbit/s bearers). ii) Balanced pairs of internal cable. GENERAL REQUIREMENTS Construction The Equipment shall be constructed using an equipment pr

21、actice in compliance with the appropriate CEPT specification and shall be compatible with Type B racks in accordance with CEPT Recommenda- tion T/TR 02-01. Edition of March 15, 1986 I CEPT T/CD*03-02*E 3 232bYL4 0003b02 9 E TICD 03-02 E Page 7 3.2. Channel capacity The Equipment shall be designed to

22、 permit any number of channels, in multiples of four, to be accommo- dated on a partially equipped shelf without adversely affecting the overall performance of the equipment. 3.3. Environment The Equipment shall be capable of meeting all the performance requirements of this specification under the e

23、nvironmental conditions described in CEPT Recommendation T/TR 02-03. 3.4. Removal and interchangeability of cards Removal and/or replacement of any card unit or module shall not cause any damage to that or any other card unit or module in the Equipment when the Equipment is in the “power on” conditi

24、on. Removal and/or replacement of any card which is peculiar to an individual low rate channel or a restricted number of low rate channels, e.g. when one card contains more than one channel, shall not adversely affect the performance of channels carried by the remaining cards. The performance of the

25、 Equipment shall not fall outside the specified limits when similar cards are interchanged among Equipments. It shall not be possible to remove a common equipment card without initiating an alarm condition. Cards shall be protected from possible damage caused by being inserted into the wrong locatio

26、n, or keyed to prevent incorrect insertion. 4. TRIBUTARIES 4.1. External tributary interface Two main variants of the interface exist: i) Low level d.c., ii) Telegraph modem, CEPT Recommendation T/CD 01-09. The performance of the multiplexer dened in subsequent paragraphs for the start-stop channel

27、inputs and outputs shall be measured at the External tributary interface when using a Tributary interface conversion unit in accordance with variant i) above. It shall be possible to use either or both of the variants within the same multiplexer. If the 64 kbit/s aggregate signal received by the 64

28、kbit/s Multiplexer unit is the alarm inhibit signal (AIS) or if the 64 kbit/s aggregate signal fails, the tributary channel outputs shall revert to an individual preprogrammed state of either A or Z polarity. Elements corresponding to A or optionally Z polarity (at the distant multiplexer output) sh

29、all be inserted in the aggregate stream in the case of i) equipped but unalocated channels; ii) open circuit line conditions at the local start/stop channel input, The elements in the aggregate stream corresponding to unequipped channels shall be those normally- - signifying A polarity. The maximum

30、degree of sampling distortion at the low level d.c. output shall be directly proportional to the baud rate and shall not exceed 7% at 300 bauds. 4.2. Channel card The Channel card combines the functional elements-a-d shown in Figure 2 F/CD 03-02) for four tributary channels. The signals from the ext

31、ernal tributary interface (Section 4.1.) are converted to logic levels which appear at an internal tributary interface. The tributary channel logic provides the signal for the Multiplexer which performs the multiplexer common logic functions. The transition encoding process shall not be performed in

32、 the Channel card. The Channel card shall also perform the complementary process for the opposite direction of transmission. The four channels on each card shall be numbered consecutively. 5. 64 KBIT/S MULTIPLEXER U” 5.1. Units The 64 kbit/s Multiplexer unit shall accept up to 15 (or optionally 60)

33、channel cards plus associated common logic, monitoring, alarm and power cards. Edition of March 15, 1986 CEPT T/CD*03-02*E 3 2326434 0003603 O Code word for a transition from Z to A at the channel (Tributary) input T/CD 03-02 E Page a Code word for a transition from A to Z at the channel (Tributary)

34、 input 5.2. Multiplexing details 5.2.1. Type of multiplexing Complying with CCITT Recommendation R. 1 11, channel interleaving shall be on a bit basis. The coding method shall be the transition coding process in accordance with paragraph 5.2.2. The aggregate rate will be 64 kbit/s+ 1 bit. 5.2.2. Tra

35、nsition encoding t A Z Channel input Sampling pulses 11111111111111111111111111111111 I I I I I I I 1 I I 1 I I I I I I I I I 1 I I I 1 I I Digital channel pulses I I I I 1 I I I L Bit sequence O 1 O 1 1 1 O O 1 Bit identification P T Cl c, P P -1. Cl c2 - - Code word Code word Figure 4 (T/CD 03-02)

36、. Transition coding process. The sampling pulses are divided into groups of four and each transition of the anisochronous signal causes a code word of 3 bits to be generated at the rate of one bit for a group of 4 samples. The first T bit of this code word indicates the sense of transition while the

37、 two bits Cl and C2 translate into binary code the position of the transition in the relevant group. Table i (T/CD 03-02) lists these code words. The code words are transmitted over the digital channel at a rate of 1 bit per group of 4 sampling pulses and the subsequent bits P between the code words

38、 confirm the polarity of the anisochronous signal at the relevant instant. The number of P bits will be zero, when the channel input rate is at its maximum theoretical value. This value is 333 bauds for the 300 baud channel inputs and 83 bauds for the 50 baud channel inputs. Position of the transiti

39、on in a group of four sampling pulses First quarter Second quarter Third quarter Fourth quarter Table 1 (T/CD 03-02). 5.2.3. Frame structure The frame consists of 240 bits for information plus 16 symmetrically distributed service bits for framing and other purposes. The 16th bit of the frame is the

40、first service bit. The Frame alignment word (FAW) comprises the first 12 service bits in the sequence 1 O i O O 1 O 1 O 1 O 1. The 13th and 14th service bits are for signalling alarm status between multiplexers (Section 5.7. refers), the 15th service bit is for maintenance use. The 16th service bit

41、(last bit of the frame) shall be allocated for justification and is fixed to 1. Details of its use are the subject of further study. Table 2 shows the frame structure and channel allocation for a 60, 300 baud system. Table 3 shows the structure for a 240, 50 baud system. Edition of March I 15, 1986

42、CEPT T/CD*03-02*E 3 E 232b414 0003604 2 E TICD 03-02 E Page 9 Bit number 1-15 16 17-31 32 33-47 48 49-63 64 80 96 97-1 11 112 113-127 128 144 160 176 192 208 65-79 81-95 129-143 145-159 161- 175 177-191 193-207 209-223 224 225-239 240 256 241-255 Function Data 1st bit of FAW Data 2nd bit of FAW Data

43、 3rd bit of FAW Data 4th bit of FAW Data 5th bit of FAW Data 6th bit of FAW Data 7th bit of FAW Data 8th bit of FAW Data 9th bit of FAW Data 10th bit of FAW Data 1 lth bit of FAW Data 12th bit of FAW Data Sig bearer fail to opposite terminal Data Sig frame alignment status to opposite terminal Data

44、For maintenance use Data For justification Value Channel number 1,5,9, 13, 17,21,25,29,33,37,41, 45, 49, 53, 57 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60 As for bits 1-15

45、As for bits 17-31 As for bits 33-47 As for bits 49-63 As for bits 1-15 As for bits 17-31 As for bits 33-47 As for bits 49-63 As for bits 1-15 As for bits 17-31 As for bits 33-47 As for bits 49-63 Frame repetition rate = 250 frames per second. Frame period = 4 ms. Table 2 (T/CD 03-02). -l 1 Edition o

46、f March 15, 1986 r CEPT T/CD*03-02*E 3 W 2326434 0003605 4 E T/CD 03-02 E Page 10 Frame slot number 1-15 16 17-31 32 33-47 48 49-63 64 65-79 80 81-95 96 97-1 11 112 113-127 128 129-143 144 145-159 160 161-175 176 177-191 192 193-207 208 2 O 9 - 2 2 3 224 225-239 240 241-255 256 Function Data 1st bit

47、 of FAW Data 2nd bit of FAW Data 3rd bit of FAW Data 4th bit of FAW Data 5th bit of FAW Data 6th bit of FAW Data 7th bit of FAW Data 8th bit of FAW Data 9th bit of FAW Data 10th bit of FAW Data I Ith bit of FAW Data 12th bit of FAW Data Sig bearer fail to opposite terminal Data Sig frame alignment s

48、tatus to opposite terminal Data For maintenance use Data For justification Value Channel number 1, 5,9, 13, 17,21,25,29, 33,37,41, 45, 49, 53, 57 61, 65,69, 73,77, 81,85, 89,93, 97, 101, 105, 109, 113, 117 121, 125, 129, 133, 137, 141, 145, 149, 153, 157, 161, 165, 169, 173, 177 181, 185, 189, 193,

49、197, 201, 205, 209, 213, 217, 221, 225, 229, 233, 237 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58 62, 66, 70, 74, 78, 82,86, 90, 94,98, 102, 106, 110, 114, 118 122, 126, 130, 134, 138, 142, 146, 150, 154, 158, 162, 164, 168, 174, 178 182, 186, 190, 194, 198, 202, 206, 210, 214, 218, 222, 226, 230, 234, 238 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59 63, 67, 71,75,79, 83, 87,91, 95,99, 103, 107, 111, 115, 119 123, 127, 131, 135, 139, 143, 147, 151, 155, 159, 163, 167, 171, 175, 179 183, 187, 191, 195, 199, 203, 207, 211, 215, 219, 223, 227, 231, 2