1、CCITT RECMN*O.352 92 4862533 0579236 33T INTERNATIONAL TELECOMMUNICATION UNION I CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE 0.1 52 (1 0/92) SPECIFICATIONS OF MEASURING EQUIPMENT ERROR PERFORMANCE MEASURING EQUIPMENT FOR BIT RATES OF 64 kbis AND Nx 64 kbis Recommendation 0
2、.152 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMNtO=352 92 H 4862593 0579237 076 FOREWORD The CCIT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunica
3、tion Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and app
4、roves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988). Recommendation 0.152 was revised by Study Group IV and was approved under the Reso
5、lution No. 2 procedure on the 5th of October 1992. CCIT NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized private operating agency. O IW 1993 Ail rights reserved. No part of this publication may b
6、e reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMN*0=152 92 48625
7、91 0579218 TO2 Recommendation 0.152 ERROR PERFORMANCE MEASURING EQUIPMENT FOR BIT RATES OF 64 kbiffs AND N x 64 kbiffs (Published 1984; revised 1988,1992) Abstract Defines the requirements for an equipment to measure bit-error performance at 64 kbitls and N x 64 kbit/s. Keywords - digitai error dete
8、ctor; - digitai pattern generator; - error performance measurement; - measurement; - tester. PREAMBLE The requirements for the characteristics of a bit-error performance measuring equipment which are described below must be adhered to in order to ensure compatibility between equipment produced by di
9、fferent manufacturers. 1 General The equipment is designed to measure the bit-enor performance of digitai paths (operating at 64 kbitls and N x 64 kbitls) by the duect comparison of a pseudo-random test pattern with locally generated test pattern identical to the transmitted test pattern. 2 Test pat
10、terns The following patterns are recommended (see Recommendation 0.150 8, for further details). 2.1 Pseudo-random pattern of 211 - I (2047 bit) pattern length This pattern is primarily intended for error and jitter measurements on circuits operating at bit rates of 64 kbit/s and N x 64 kbit/s. The p
11、attern may be generated in an eleven-stage shift register whose 9th and 1 ltb 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 11 Length of pseudo-random sequence 211 - 1 = 2047 bits Longest sequence o
12、f ZEROs 10 (non-inverted signal) Note 1 - In the case of international testing where the measurement includes systems based on 1544 kbitls, it is necessary to modify the test sequence in such a way that more than seven consecutive ZEROs are avoided. This is achieved by forcing the output bit to ONE
13、whenever the previous 7 bits of the sequence are all ZEROs. Note 2 - It is recommended to use the test pattern of 2047 bit length also at other bit rates in the range of 48 kbit/s to 168 kbids. Recommendation 0.152 (10192) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLice
14、nsed by Information Handling ServicesCCITT RECMN*O-L52 92 W 4862593 0579237 749 W Note 3 - When performing measurements at a bit rate of N x 64 kbit/s, consecutive 8-bit blocks of the test pattern shali be transmitted in consecutive time slots. In this case, the beginning of the test pattern need no
15、t to be related to the beginning of a frame. Note 4 - Whether N can be any number between 1 and 3 1 requires further study. 2.2 Fixed patterns (optional) Fixed patterns of all ONES (.i 11 i.) and alternating ONES and ZEROS (.lolo.) may be provided. 2.3 Loss of sequence synchronization Sequence synch
16、ronization shall be considered to be lost and resynchronization shall be started if: a) b) Note - 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 the same structure as the pseudo-random test
17、pattern, then the out-of-phase condition can be recognized. the bit-emor ratio is 2 0.2 during an integration interval of 1 second; or it can be unambiguously identified that the test pattern and the reference pattern are out of phase. This sub-section requires further study. 3 Bit rate Bit rate in
18、accordance with Q 1 of Recommendation G.703 i and Recommendation V.36 2 of 64 kbit/s: a) b) bit rate tolerance (Recommendation G.703 i): f 100 . 10-6, bit rate tolerance (Recommendation V.36 2), optional: f 50 . 10-6. 4 Interfaces The interface characteristics (impedances, levels, codes, etc.) shoul
19、d be in accordance with Recommendations G.703 1,1.430 7 (Optional) and V. 1 1 3 (optional). In addition to providing for terminated measurements, the measuring set shall also be capable of monitoring at protected test points on digital equipment. Therefore, a high impedance and/or additional gain mu
20、st be provided to compensate for the loss at monitoring points already provided on some equipments. 4.1 Inteaces corresponding to Recommendation G.703 i Three interfaces shall be provided a) b) c) a codirectional interface in accordance with 5 1.2.1 of Recommendation G.703 11; a centralized clock in
21、terface in accordance with Q 1.2.2 of Recommendation G.703 i; a contradirectional interface in accordance with 0 1.2.3 of Recommendation G.703 i. 4.2 Method of clock synchronization The following modes of synchronization shall be selectable: a) Lock the digitai generator clock rate to that at the in
22、put of the receive side of the measuring set (for the codirectional interface). Allow the generator clock to free run within the overall allowed frequency tolerances. b) 2 Recommendation 0.152 (10/92) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Hand
23、ling ServicesCCITT RECMN*O.L52 92 m 48b259L 0579220 bbO m c) Lock the digital generator clock rate to an external clock signal. (Configuration of input for external clock in accordance with Recommendation G.703 13.) 4.3 Interface corresponding to Recommendation 1.430 7 For further study. This study
24、should include means for obtallllng access to the individual 44 kbids channels at the S and T interface points. 4.4 Interface corresponding to Recommendation KI1 3 As an option, an interface in accordance with Recommendation V. 1 1 3 shall be provided. 5 Bit-error ratio measuring range The receiving
25、 equipment of the set should be capable of measuring bit-error ratios in the range 10-2 to 10-7. The measurement time should be sufficiently long to achieve accurate measurements. In addition, it should be possible to measure bit-error ratios smaller than 10-7. This can be achieved by providing the
26、capability to count cumulative errors. 6 Block-error ratio measurements Optionally, the instrument should be capable of performing block-error measurements in addition to the bit- error measurements. If provided, it should be possible to measure block-error ratios in the range 100 to 10-5 when using
27、 the pseudo-random test pattern with a block length of 2047 bits. 7 Mode of operation The mode of operation should be such that the signal to 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 referen
28、ce signal in binary form. 8 Error evaluation 8.1 Measurement of errored time intervals The instrument shall be capable of detecting errored seconds and other errored or error-free time intervals as defined by Recommendation G.821 4. The number of errored or error-free time intervals in a selectable
29、observation period 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
30、. 8.2 Measurement of short-term mean error ratio 8.2.1 bit-error ratio is less than 1 . 10-6. It shall be possible to record the time intervals as defined in Recommendation G.821 4, during which the 8.2.2 It shall be possible to record the one-second intervals during which the bit-error ratio is les
31、s than 1 . 10-3. Recomenda tion O. 152 (1 OB2) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services9 Recording of measurement results As an option an interface shall be provided which allows connecting external equipment for further proce
32、ssing the measuring results. The interface shall comply with Recommendation V.24 5 or the interface bus according to lEC Publication 625 6. 10 Operating environment The electrical performance requirements shall be met when operating at the climatic conditions as specified in 0 2.1 of Recommendation
33、0.3 9. References CCITT Recommendation G.703 - PhysicaVelectrical characteristics of hierarchical digital integaces. CCIR Recommendation V.36 - Modems for synchronous data transmission using 60-108 kHz group band circuits. CCT Recommendation V. 11 - Electrical characteristics for balanced double-cur
34、rent interchange circuits for general use with integrated circuit equipment in thefield of data communications. CCITT Recommendation G.821 - Error peormance on an international digital connection forming part of an integrated services digital network. CCITT Recommendation V.24 - List of definitions
35、for interchange circuits between data terminal equipment and data circuit-terminating equipment. IEC Publication 625 - An Interface system for programmable measuring instruments (byte serial, bit parallel). CCITT Recommendation 1.430 - Basic user-network interface-Layer/Speccation. CCITT Recommendat
36、ion 0.150 - Digital test patterns for performance measurements on digital transmission equipment. CCIIT Recommendation 0.3 - Climatic conditions and relevant tests for measuring equipment. Recommendation 0.152 (10B2) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesCCITT RECMNt0.152 92 4862591 0579222 433 Printed in Switzerland Geneva, 1993 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services
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