CEPT T CD 01-12 E-1983 Concerning the Specification of Engineering Requirements for Three Types of Plug-in DCE s Operating with a User Data Signalling Rate of 2 400 Bits s《有关三类在240.pdf

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1、CEQT T/CD*OL-LZ*E 3 E 232b4LL1 U0832L -tloa T/CD 01-12 E (Cm 1983) CONCERNING THE SPECIFICATION OF ENGINEERING REQUIREMENTS FOR THREE TYPES OF PLUGIN WES OPERATING WITH A USER DATA SIGNALLING RATE OF - that T/CD ha; studied the haknonization of DCEs under the auspias of Quation CD7. Recommend that t

2、he attached specitication of engineering requirements for threc types of built-in versions of DCEs as contained in the Annex to this Recommendation should apply when such equipment is being considered by CEPT Administra- tions for a particular application.“ This Recommendation is to be seen as the f

3、irst step of harmonizing the built-in NE. This Recommendation includes a number of national requimnentr, as reveral networks have already been in operation and changa could not be made to thew without conriderable penaltiea in delays and costs. A harmonization project that will take into (ux1ount fu

4、ture development ofcomponents, software, etc., is to be formed as the second step of this work. Note 1: It should be notad that this Remmmendiiiion my k miscd from time to time. Note 2: nie Annex ir rn integral pari of the Recommendation. T/CD 01-12 E Page 3 Annrx . Indrx Page 1 . scope . 5 PART I (

5、Type I) Pages 1 to 31 Section A . Common reqarements 1.Ccncrd 2. Functionil ngdmnib for bc trmddoa mit 0 3 . Functional requimacab for the coarersioa mit (CU) 4 . Testloop. 5 . Powcrcoorrsmnptioa . 6 . Combuction 7 . Environmcntdnguircmits . Section B . Network depennt reqn . 3 5 . RequiremenQforAlt

6、eniativeBZ . 3 6.Testl oops . 3 7.Powercomumption . 3 8.Colistniction 3 Y . Eavironmentalrequirements . 3 1.Gcuerd 4 2.Buc-brndDCEi 4 3. Teatingaadmeuuriagrequircmib.,. . 5 2. OptlonrlIrtcrcbaapecimilb., . 6 4. OptloarlRiodcrofopcratloa . 6 5.Testpolnb . 6 2 . ReqdremeatsforAltemadveAl . 2 Section B

7、 . Net work ?T- Figure I I. Wal, basic elements. I I 4 I I I I I dl T I (c) The TUB shall be designed to demodulate satisfactorily a line signal generated as described in item 2. I, 1 .b above, and will be recovered via an unamplified line having an insertion loss of up to 45 dB at a frequency equal

8、 to that of the carrier signal. The line will be standard local line plant and no adjustment facilities shall be required to accommodate line characteristics. 2.1.2. Scrambling The data received on the data input interconnecting circuit shall be scrambled and differentially encoded before being modu

9、lated and transmitted to line. Similarly the demodulated data shall be diflerentially decoded and descrambled before being presented on the data output interconnecting Circuit. The scrambling and descrambling process shall be as described in CCITT Recommendation V.35 Appen- dix I, .e. the generating

10、 polynomial is: The differential encoding and decoding shall bc a scrambling and descramblinp procees with generating polynomial: 1 + x- + x-O I +x- 2, I ,3, Line inrer/ace (a) In addition to the following requirementi, ihr; general rquirementr of Recommer.datian T/CD 01-01 #hall apply. (b) The TUB

11、ihtrll be capable of carrying a waiting current of mngniiudc in thc ranga 5 to 8 mA, (c) Failure of the DTE power supply ihall au# n change in direction of flow of the wotting current in ihc mond pair of the Cwire circuit (we Figure l2), (d) The UI of u line welting current shall not degrude ihc pcr

12、formuncc of the TUB. CEPT T/CD*OL-LZ*E 3 E 2326414 0003236 T = - TICD 01-12 E Part I, Page 14 2.1.4. I LINE I 1 I RLA I I I di I I I I 1 I I I I - 21 RLA - NI- E dIlw i I I I I I I Figure 12. Wetting current monitor. I - Line signal requirements (a) The requirements of Recommendation T/CD 01-01 shal

13、l apply. (b) If the level of the signal at the receive line terminals is below -48 dBm, then the TUB shall take the following action: - Clamp data on the data output interconnecting circuit to a constant binary 1, - Present a binary O condition on the Received Line Signal Detector interconnecting ci

14、rcuit. TheTUB shall not resume normal operation until the level of the signal at th.c receive line terminals is above -45 dBm. 2.1.5. Equalizaiion The shape of the Wal, modulated line spcctnim is such that it can be considered as hwing preequalization, thw a rquirement for an qualizer in the receive

15、r is not envisaged. 2.2. Alkrrutlvc C2 (Auctlan PIT) 2.2.1. Coding The coding proceis producer a raiscd cosine wudo ternary line aignal (Ist order, baac band-alternative mark invernion) Sac Figura 13, TICD o1 -1 2 t Part i, Page 16 Examole Transmit dgnrl clement timing Transmitted data aher scrambli

16、ng I i c Line sipl DCcodcd reccivcd line rimel - - SQ-window J U U U U Received data before descrambling 1 I J Receive rignal element timing Figure 13. 2.2.2. Timing All timing signals for the modulator shall be derived from the received line signal. 2.2.3. Scrambling The same scrdmbler is used as i

17、n Section A, item 2.1.4. However, the guard circuitry shown in Annex 3 is mandatory. 2.2.4. Line interface (a) The requirements of Recommendation T/CD 01-01 shall apply. (b) The TUB shall be capable of carrying a wetting current of 3 mA maximum. (c) The use of the wetting current shall not degrade t

18、he performance of the TUB. 2.2.5. Line signal requirements (a) The requirements of Recommendation T/CD 01-01 shall apply. (b) Threshold of received line signal detector. than -41 dBm circuit A “OFF”. Levels of received line signal: greater than -40 dBm circuit A “ON” less (c) Response time of circui

19、t A A fall in level of the incoming line signal to -41 dBm or lower for more than 1OI5 ms will cause circuit A to be turned OFF. An increase in level to -40 dBm or higher will, within 1OI5 rns, turn this circuit ON. Circuit DR is held in a marking condition (binary i), when circuit A is in the OFF c

20、ondition. When this condition does not exist, the clamp is removed and circuit DR can respond to the input signals of the TUB. 2.2.6. Equalization (a) In most applications, no manual adjustment of the equalizer shall be required. (b) For exceptional cases, a manual fine adjustmcnt of the equalizatio

21、n shall be possible to achievc optimum signal quality, particularly with longer subscribcr lines, The manual adjustment would alsr bc needed if, for any reason, a higher transmit level were used (3 dB is suggested in cases of seven electrical noise). (d) Clamping to binary 1 condition of circuit DR

22、(data output, received data) 2.3, Altemative C3 (Ikubrbe Bundrrpori) 2A1. Codlng Tho codlng proocri producer u ruid cosine half-baudcd pseudo-ternary line ciqnal (alternate murk invorrlon codc AMI), The wave rhaplng li depicted bclow (Figure 14). TICD 01-12 E Part I, Page 16 Clock Examplc T Dat. I 1

23、 I . Line signal Figure 14. All timing signals for the modulator shall be derived from the received line signal except for the case of a test loop 3a being activated, in which case the TUB has to maintain all necessary timing signals towards the CU with a frequency tolerance of f 0.01 % from nominal

24、 value. 2.3.3. Scrambling The same scrambler is used as described in Section A, 2.1.5. The guard circuitry shown in Annex 3 is mandatory. 2.3.4. Line interface (a) In addition to the following requirements, the general requirements of Recommendation T/CD 01-01 shall apply. (b) The nominal impedance

25、shall be jumper-selectable: either 150 ohms or 1,OOO ohms. (a) In addition to the following requirements, the general requirements of Recommendation T/CD 01-01 shall apply. (b) The peak-to-peak line signal voltage shall be 1.4 Vp-p with tolerances of + lo%/-20% measured with an 150 ohms non-inductiv

26、e load resistance. (c) If the voltage of the received signal is below 7 mVpp, than the TUB shall take the following actions: - Clamp data on interchange access point Do to a constant binary 1. - Present an OFF condition on interchange access point Ao. 2.3.2. Timing 2.3.5. Line signal requirements Th

27、e TUB shall not resume normal operation until the voltage of the received signal is above 14 mVp-p. The TUB shail be equipped with an automatic adaptive equalizer which shall cater for both the equalization of the attenuation distortion of unloaded cables and the attenuation and phase distortion of

28、loaded cables. The phase equalizer may be switched in manually. 2.3.6. Equalization 2.4. Alternative C4 (NPDN) 2.4.1. Modulation and coding (a) All timing signals for the modulator shall be derived from the received line signal. (b) The modulation system is based on differential biphasc modulation (

29、biphL .;pioc of a square wave carrier with fundamental frequency in Hz nominally equal to the dab signalling rale in bitla. The line rignal shall consist of a two-level tignal with the following traniitions: “I“ trantition at t - to “O“ trandtion at t - b+f and t - to, whcrc T tignifkr the period of

30、 one data dlcmcnt, and t. is the time at which a data clement bqhr (sec Figure 15). CEPT T/CD*OL-LZ*E 83 = 232b4l14 0003239 5 _ TICD O1 -12 E Part I, Page 17 1 I I I Line signal “prior to filtration” . Figure 15. (c) The following maintenance functions shall be included. If the received line signal

31、detector is in the OFF condition, transmission in the opposite direction shall cease either after a time delay of 2.5 seconds or alternatively controlled by the CU via the use of interchange circuit LEA. (d) The TUB shall be designed to demodulate satisfactorily a line signal generated as described

32、in item 2.4.l.c) above and transmitted via an unamplified line having an insertion loss of 40 dB at a frquency equal to that of the carrier signal. The received line signal detector shall have a hysteresis of a least 2 dB. 2.4.2. Scrambling Data scrambling is not employed. 2.4.3. Line intersace (a)

33、In addition to the following requirements the general requirements of Recommendation T/CD 01-01 shall apply. (b) The TUB shall be capable of carrying a wetting current of magnitude in the range 5-15 mA. (c) The use of a line wetting current shall not degrade the performance of the TUB. (d) When a ti

34、mer within the TUB is used to control the “transmit inhibit” function specified in item 2.4. 1.c) above this function shall be implemented in such a way that the MTBF for all the circuitry of concern for this function is at least one magnitude greater than the MTBF for the whole TUB. (e) The TUB sha

35、ll be provided with a “powersff generator with the characteristics described in Sec- tion B, item 6. The generator shall be powered from the wetting current in the receiver line. (a) In addition to the following requirements, the general requirements of Recommendation T/CD 01-01 shall apply. (b) The

36、 transmit level shall be O dEm or -6 dBm (mappable) when measured with pseudo-random (51 I-bit pattern) data against a resistive impedance of 600 ohms. Tolerance at nominal level: f 1 dB. (c) If the received line signal detector is in, the OFF condition, then the TUB shall clamp data in the data out

37、put interconnecting circuit to a constant binary I. 2 -4.5. Equalization The TUB should be preferably equipped with an adaptive equalizer in the receiver. 2.4.6. Performance (a) The receiver clock in the TUB shall maintain its phase and frequency for at least 500 ms in order to avoid resynchronizati

38、on in case of short breaks on the line. This also implies that the TUB shall not produce a bit slip when the line signal returns after a short break on the line. (b) Amplitude hits on the line of up to IO V and with a duration of up to 15-bit lengths shall not cause any bit slip in the TUB. 2.5. Alt

39、ernative CS (Italian FT) 2.5.1, Modulation and coding 2.4.4. Line signal requirements (a) All timing signals for the modulator shall be derived from the received line signal (b) The modulation system is based on differential diphase modulation of a square wwe carrier with fundamental frequency in Hz

40、 nominally equal ia the data rate in bit/s, The following relation is forecast: Digit O - No phase inversion Digit 1 - Inversion of the phase, . TICD01-12 E Part I, Poge 18 2.5.2. 2S.3. 2.5.4. 2.5.5. 2.6. 2.6.1. 2.6.2. 2.6.3. 2.6.4. 2.6.5. 2.6.6, (c) The TUB shall bc designed to demodulate satisfact

41、orily a line signal generated as described above, and will be ncovered via an unloaded line having an insertion loss of up to 40 dB at the frequency equal to the data rate. Scrambling Data scrambling is not employed, Line interface (a) In addition to the following requirements, the general requireme

42、nts of Recommendation T/CD 01-01 (b) The TUB shall be capable of carrying a wetting current of 3 mA maximum, without decreasing the Line signal requirements (a) The requirements of Recommendation T/CD 01-01 shall apply. (b) If the level of the signal at the receive line terminals is 6-12 dB below th

43、e minimum level, the TUB shall shall apply. performance of the TUB. take the following action: - Clamp data on the data output interconnecting circuits t0.a constant binary I. - Present a binary O condition on the received Line-Signal-Detector interconnecting circuit, The TUB shall not resume normal

44、 operation until the level of the signal at the receive line terminals is 6 dB above the minimum level. The minimum level is the level received at the output of an artificial line (Figures 16 and 17) having an attenuation loss of 40 dB at the frequency qual to the data rate, the transmitted signal s

45、hall be f6 dBm with a pseudo-random sequence of 51 I-bits. Equalization A simple amplitude equalizer is used without manual adjustment. Alternative D1 wt8cbc Bundespost) Alternative DI is a 2-wire duplex TUB using the echo cancellation technique. Coding The same coding is used as for alternative C3

46、(item 2.3.1.). Timing The same requirements as for alternative C3 apply (item 2.3.2.). Scrambling The scrambling and descrambling process shall be as described in CCITT Recommendation V.35, Appen- dix I, .e. the generating polynomial is: Line inteflace (a) In addition to the following requirements,

47、the general requirements of Recommeiidation T/CD 01-01 (b) The nominal impedance of the line interface shall be I50 ohms. Line signal requirements (a) In addition to the following requirements, the general requirements of Recornmendation T/CD 01-01 shall apply. (b) The peak-to-peak line signal volta

48、ge shall be 1.0 Vp-p with a tolerance of i 15%, measured with an 150 ohms non-inductive load resistance. (c) If the voltage of the received signal is below 40 mVpp, then the TUB shall take the following action: - ClamNata on interchange access point Do to constant binary I. - Present on OFF conditio

49、n on interchange access point AO. The TUB shall not tesume normal operation until the voltage of the received signal ir above 60 mVpp. Equalization The TUB rhall be equipped with an automatic adaptive equalimr capable of equalizing tho atte:iuation distortion of unloaded cables, 1 + x- + x-20 shall apply. TICD o1 -12 Part I, Pige 19 I I I I 10 alo 104 f(w 10 Figure 16. Artificial network. L1 L2 L3 47.7 mH 9.53 mH 10.1 mH lson 1m Tokrrnco of miilinca 53.5% Figure 17, Eloctric whoma, CD 01-12 E art I, Page 20 2.7. Alteraative D2 (Norway) 2.7.