1、CCITT RECMN*Oo353 92 4862593 0579208 Ob3 7 INTERNATIONAL TELECOMMUN KATION UN ION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE 0.151 (1 0/92) SPECIFICATIONS OF MEASURING EQUIPMENT ERROR PERFORMANCE MEASURING EQUIPMENT OPERATING AT THE PRIMARY RATE AND ABOVE Recommendation 0
2、.151 CCITT RECMN*O-LSL 92 48b2591 0579209 TTT N FOREWORD The CCITT (the Intemational Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (ITU). CCiT is responsible for studying technical, operating and tariff questions and issuing Recomme
3、ndations on them with a view to standardizing telecommunications on a worldwide basis. The Plenary Assembly of CCIT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCIT between
4、 Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988). Recommendation 0.151 was revised by Study Group IV and was approved under the Resolution No. 2 procedure on the 5th of October 1992. CCIT NOTE In this Recommendation, the expression “Administration
5、” is used for conciseness to indicate both a telecommunication administration and a recognized private operating agency. o ITU 1993 Ail rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfi
6、lm, without permission in writing from the ITU. CCITT RECMN*O.151 92 48b2591 0579210 711 = Recommendation 0.151 ERROR PERFORMANCE MEASURING EQUIPMENT OPERATING AT THE PRIMARY RATE AND AB OVE) (Published 1976; revised 1980, 1984,1988 and 1992) Abstract Defines the requirements for an equipment to mea
7、sure error performance of digital systems at the Keywords - digital error detector; - digital pattern generator; - error performance measurement; - measurement; - tester. hierarchical bit rates between 1.5 and 140 Mbit/s. PREAMBLE The requirements for the characteristics of bit-error performance mea
8、suring equipment which are described below must be adhered to in order to ensure compatibility between equipment produced by different manufacturers. 1 General The equipment is designed to measure the bit-error performance of digital systems2) by the direct comparison of a received pseudo-random tes
9、t pattern with a locally generated test pattern identical to the transmitted test pattern. In addition, the capability to measure errored time intervals is provided. 2 Test patterns The following patterns are recommended (see Recommendation 0.150 for further details). 2.1 Pseudo-random pattern for s
10、ystems using a 215 - 1 (32 767 bit) pattern length This pattern is primarily intended for error and jitter measurements at bit rates of 1544, 2048, 6312, 8448, This pattern may be generated in a fifteen-stage shift register whose 14th and 15th stage outputs are added in 32 O64 and 44 736 kbits. a mo
11、dulo-two addition stage, and the result is fed back to the input of the first stage. This Recommendation is the joint responsibility of Study Groups IV, XW and XWI. 2, “Digital system” is used as a generic term for paths, links, transmission systems, etc. Recommendation 0.151 (10B2) 1 CCITT RECflN*O
12、=353 92 +862593 0579233 b58 Number of shift register stages 15 Length of pseudo-random sequence 215 - 1 = 32 767 bits Longest sequence of ZEROS 15 (inverted signal) 2.2 Pseudo-random pattern for systems using a 223 - I (8 388 607 bit) pattern length This pattern is primarily intended for error and j
13、itter measurements at bit rates of 34 368 and 139 264 kbit/s. The pattern may be generated in a twenty-three-stage shift register whose 18th and 23rd stage outputs are added in a modulo-two addition stage, and the result is fed back to the input of the first stage. Number of shift register stages Le
14、ngth of pseudo-random sequence 23 223 - 1 = 8 388 607 bits Longest sequence of ZEROS 23 (inverted signal) 2.3 Pseudo-random pattern for systems using a 220 - 1 (I 048 575 bit) pattern length This pattern is primarily intended for error and jitter measurements at bit rates of 1544, 6312, 32064 and 44
15、 736 kbit/s. The pattern may be generated in a twenty-stage shift register whose 17th and 20th stage outputs are added in a modulo-two addition stage, and the result is fed back to the input of the first stage. An output bit is forced to be a ONE whenever the previous 14 bits are ail ZERO. Number of
16、 shift register stages 20 220 - 1 = 1 048 575 bits Length of pseudo-random sequence Longest sequence of ZEROS 15 (see note) Note - This test pattern is not identical with the pattern specified in Recommendation 0.153 because different feedback mechanisms are used when the patterns are produced by me
17、ans of shift registers. The pattern specified in this section suppresses consecutive sequences of more than 14 ZEROS, 2.4 Fixed patterns (optional) Fixed patterns of all ONEs (. 11 11 .) and alternating ONEs and ZEROS (. 1010 .) may be provided. 2.5 “Framed” measurements Certain measurements require
18、 that the test pattern is transmitted as “payload” within a valid frame. In this case, the transmission of the test pattern shall be stopped while framing bits are transmitted. When using pseudo-random test patterns for framed measurements, the beginning of the test pattern has no fixed relationship
19、 with the beginning of a frame. 2.6 Loss of sequence synchronization Sequence synchronization shall be considered to be lost and resynchronization shall be statted if a) b) the bit error ratio is 2 0.2 during an integration interval of 1 second; or it can be unambigously identified that the test pat
20、tern and the reference pattern are out of phase. 2 Recommendation 0.151 (10/92) CCITT RECMN*O*353 92 W 48b2593 0579232 594 W 6 312 8 448 Nute - One method to recognize the out-of-phase condition is the evaluation of the error pattern resulting from the bit-by-bit comparison. If the error pattern has
21、 the same structure as the pseudo-random test pattern, then the out-of-phase condition can be recognized. G.743 3 G.742 4, G.745 5 This sub-section requires further study. 3 Bit rate The bit rates in accordance with CCIT Recommendations are indicated in Table UO.151. TABLE U0.151 Bit rates, pertinen
22、t Recommendations and pseudo-random test patterns Bit rates Recommendations corresponding 1 (kbifs) I to multiplex system Recommendations corresponding to digital line sectiodine system Bit rate tolerance Test pattern G.911 8, G.951 9, G.955 lo f50.1W 215 - i, 220 - i G.733 i f50.10-6 215 - i G.732
23、2 I 2048 I G.921 1 i, G.952 121, G.956 131 G.912 14, G.951 9, G.955 lo f30.1W 215 - i, 220 - i G.921 111, G.952 121, G.956 13 f30.104 215 - i 2 15 - 1,220 - 1 I 32064 I G.752 6 G.913 15, G.953 16, G.955 lo f 10.1W r3;68 I G.751 7 G.921 li, G.954 17, G.956 13 f20.10-6 223 - i I- 44736 I G.752 6 f20.1
24、04 215 - i, 220 - i G.914 MI, G.953 16, G.955 lo G.921 111, G.954 171, G.956 131 I15.104 223 - i I 139264 I G.751 7 Note - Normally only the appropriate combination of bit rates - either 2048 kbifs, 8448 kbifs, etc. or 1544 kbit/s, 6312 kbifs, etc. - will be provided in a given instrumentation. 4 In
25、terfaces The interface characteristics (impedances, levels, codes, etc.) should be in accordance with Recommenda- tion G.703 191. In addition to providing for terminated measurements, the instrumentation shall also be capable of monitoring at protected test points on digitai equipment. Therefore, a
26、high impedance and/or additional gain should be provided to compensate for the loss at monitoring points already provided on some equipment. 5 Error-ratio measuring range The receiving equipment of the instrumentation should be capable of measuring bit-error ratios in the range 10-3 to 10-8. In addi
27、tion, it should be possible to measure bit-error ratios of 10-9 and 10-10; this can be achieved by providing the capability to count cumulative errors. Recommendation 0.151 (10192) 3 CCITT RECNN*O-LSL 92 = 4862533 0577233 420 6 Mode of operation The mode of operation should be such that the signal t
28、o be tested is first converted into a unipolar (binary) signal in the error measuring instrument and subsequently the bit comparison is made also with a reference signal in binary form. Facilities may optionally be provided to ailow the direct comparison at line code (e.g. AMI or HDB3) with correspo
29、ndingly coded reference signals. In the case of such measurements polarity distinction is possible, so that errors caused by the injection or omission of positive or negative pulses can be determined separately. 7 Measurement of errored time intervais The instrument shall be capable of detecting err
30、ored seconds and other errored or error-free time intervals as defined in $ 1.4 of Recommendation G.821 20 and of deriving error performance reduced to 64 kbits in accordance with Annex D to Recommendation G.821 2OI3). The number of errored or error-free time intervals in a selectable observation pe
31、riod from 1 minute to 24 hours, or continuous, shall be counted and displayed. For this measurement, the error detection circuits of the instrument shall be controlled by an internal timer which sets intervals of equal length and which operates independently of the occurrence of errors. 8 Operating
32、environment in $2.1 of Recommendation 0.3. The electrical performance requirements shall be met when operating at the climatic conditions as specified References CCITT Recommendation G.733 Characteristics of primary PCM multiplex equipment operating at 1544 kbids. CCIT Recommendation G.732 Character
33、istics of primary PCM multiplex equipment operating at 2048 kbids. CCIT Recommendation G.743 Second-order digital multiplex equipment operating at 6312 kbith and using positive justification. CCIT Recommendation G.742 Secon-order digital multiplex equipment operating at 8448 kbitls and using positiv
34、e justification. CCITT Recommendation G.745 Secon-order digital multiplex equipment operating at 8448 kbith and using positivekerohegative justification. CCITT Recommendation G.752 Characteristics of digital multiplex equipment based on a second-order bit rate of 6312 kbitls and using positive justi
35、fication. CCITT Recomendation G.751 Digital multiplex equipment operating at the third-order bit rate of 34 368 kbids ana the fourth-order bit rate of 139 264 kbit/s and using positive justification. 3, kor performance evaluation at bit rates other than 64 kbit/s is under study. 4 Recommendation 0.1
36、51 (10192) CCITT RECMNUO-151 92 m 4862593 0579214 367 m 81 91 1171 CCITT Recommendation G.911 Digital line sections at I544 kbids. CCITT Recommendation G.951 Digital line systems based on the 1544 kbi/s hierarchy on symmetric pair cables. CCITT Recommendation G.955 Digital line systems based on the
37、1544 kbit/s hierarchy on optical fibre cables. CCI“ Recommendation G.921 Digital sections bused on the 2048 kbith hierarchy. CCITT Recommendation G.952 Digital line systems based on the 2048 kbith hierarchy on symmetric pair cables. CCITT Recommendation G.956 Digital line systems based on the 2048 k
38、bit/s hierarchy on optical fibre cables. CCIT Recommendation G.9 12 Digital line sections at 6312 kbith. CCIT Recommendation G.913 Digital line sections at 32 064 kbit/s. CCITT Recommendation G.953 Digital line systems based on the I544 kbith hierarchy on coaxial pair cables. CCITT Recommendation G.
39、954 Digital line systems based on the 2048 kbith hierarchy on coaxial pair cables. CCITT Recommendation G.914 Digital line sections at 44 736 kbifh. CCITT Recommendation G.703 Physicallelectrical characteristics of hierarchical digital interfaces. CCITT Recommendation G.821 Error performance on an international digital connection forming part of an integrated services digital network. CCITT Recommendation O. 150 Digital test patterns for performance measurements on digital transmission equipment. CCITT RECMN*OoL53 92 48b2593 0579235 2T3 Printed in Switzerland Geneva, 1993
