1、CCITT RECMN*O.L53 92 4862591 0579223 37T CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CO NSU LTAT I V E COM M I TTE E 0.1 53 (1 0/92) SPECIFICATIONS OF MEASURING EQUIPMENT BASIC PARAMETERS FOR THE MEASUREMENT OF ERROR PERFORMANCE AT BIT RATES BELOW THE PRIMARY RATE I Recommendation 0.153 CCITT RE
2、CMNUO.153 92 = +862591 0579224 206 FOREWORD The CCITT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (IT). CCIT is responsible for studying technical, operating and tariff questions and issuing Recommendations on t
3、hem 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 CCITT between Plenary Ass
4、emblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988). Recommendation 0.153 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” is used fo
5、r conciseness to indicate both a telecommunication administration and a recognized private operating agency. O IT 1993 All 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 microfilm, without p
6、ermission in writing from the ITU. CCITT RECMN*O*153 92 4862591 0579225 142 Recommendation 0.153 I BASIC PARAMETERS FOR THE MEASUREMENT OF ERROR PERFORMANCE AT BIT RATES BELOW THE PRIMARY RATE (Melbourne, 1988; revised 1992) Abstract w Defines the requirements for equipment to measure error performa
7、nce at bit rates between 0.050 and 3 168 kbit/s Keywords - digital error detector; - digital pattern generator; - error performance measurement; - measurement; - tester. PREAMBLE The requirements for the characteristics of error measuring equipment which are described below must be adhered to in ord
8、er to ensure compatibility between equipment produced by different manufacturers. While requirements are given for the equipment, the realization of the equipment configuration is not covered and should be given careful consideration by the designer and user. In particular, it is not required that a
9、ll features listed below shall be provided in one piece of equipment. Administrations may select those functions which correspond best to their applications. When selecting functions, administrations may also consider other Recommendations dealing with error measuring equipment, e.g. Recommendations
10、 0.151 17 and 0.152 HI. 1 General The equipment is designed to measure the error performance on circuits operating at bit rates as defined in Q 3. The measurement is based on the direct comparison of specified test patterns which are transmitted through the circuit under test, with identical pattern
11、s generated at the receive side. Synchronous and asynchronous operation shall be possible. 2 Test patterns The following test patterns are recommended (see also Recommendation 0.150 161). Note - The use of certain test patterns may be restricted to synchronous or asynchronous operation only. It shal
12、l be possible to transmit the patterns for an unlimited time. 2.1 511-bit pseudo-random test pattern This pattern is primarily intended for error measurements at bit rates up to 14.4 kbids (see 0 3.1). i The pattern may be generated in a nine-stage shift-register whose 5th and 9th stage outputs are
13、added in a modulo-two addition stage, and the result is fed back to the input of the first stage. The pattern begins with the first ONE of 9 consecutive ONES. Recommendation 0.153 (10192) 1 CCITT RECMN*0*153 92 4862591 0579226 O89 E Number of shift-register stages Length of the pseudo-random sequenc
14、e Longest sequence of ZEROS 9 29 - I= 511 bits 8 (non-inverted signal) 2.2 2047-bit pseudo-random test pattern If provided, this pattern is primarily intended for error measurements at bit rates of 64 kbit/s and Nx 64 kbit/s (see p 3.3). The pattern may be generated in an eleven-stage shift-register
15、 whose 9th and 1 lth stage outputs are added in a modulo-two addition stage, and the result is fed back to the input of the first stage (see also Recommen- dation 0.152 is). Number of shift-register stages 11 Length of the pseudo-random sequence Longest sequence of ZEROs 211 - 1 = 2047 bits 10 (non-
16、inverted signal) 2.3 1 048 575 bits pseudo-random test pattern This pattern is primarily intended for error measurements at bit rates up to 72 kbit/s (see P 3.2 below). The pattern may be generated in a twenty-stage shift-register whose 3rd and 20th stage outputs are added in a modulo-two addition s
17、tage, and the result is fed back to the input of the first stage. Number of shift-register stages 20 Length of the pseudo-random sequence Longest sequence of ZEROS Note - This test pattern is not identical with the pattern of the same length specified in Recommen- 220 - 1 = 1 O48 575 bits 19 (non-in
18、verted signal) dation 0.151 17. 2.4 Fixed test patterns vor continuiy tests) - Permanent space; - Permanent mark; - - Alternating space/mark with a ratio of: 1 : 1,l : 3,l: 7,3 : 1,7 : 1; “Quick brown fox” - text (QBF) (see Recommendation R.52 13) (asynchronous mode only). 2.5 Programmable test patt
19、erns A freely programmable pattern with a length of at least 1024 bits is recommended. 2.6 Loss of sequence synchronization Sequence synchronization 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 evaluat
20、ion of the error pattern resulting from a bit-by-bit comparison. If the error pattern bas the same structure as the pseudo-random test pattern, the out-of- phase condition can be recognized. the bit error ratio is 2 0.20 during an integration interval of 1 second; or it can be unambiguously identifi
21、ed that the test pattern and the reference pattern are out of phase. This sub-section requires further study. 2 Recommendation 0.153 (10/92) CCITT RECMN*O*353 92 I 4862593 0579227 TL5 I 3 3.1 3.2 3.3 Bit rates The instrumentation shall provide for measurements at bit rate ranges as specified in the
22、categories below. Data transmission via telephone-type circuits using modems - See Recommendations V.5 2 and V.6 3 for details. Note - Modems operating at bit rates above 14 400 bids are not covered by CCITT Recommendations. Bit rate range 50 bids to 19 200 bids. Data transmission via group-band cir
23、cuits using wideband modems - See Recommendations V.36 4 and V.37 5 for details. Bit rate range 48 kbids to 168 kbids. Data transmission at and above 64 kbith With regard to error performance measurements at 64 kbids, and N x 64 kbids, relevant information can be found in Recommendation 0.152 18. In
24、formation on measurements at higher bit rates is contained in Recommendation 0.151 17. 3.4 Deviationfrom nominal bit rate For bit rates up to 9600 bids the maximum deviation from the nominal bit rate shall be I 0.01% if timing is not derived from the object under test. For the higher bit rates the m
25、aximum deviation shall be I 0.002% if timing is not derived from the object under test. 3.5 Clock sources Clock signals are provided through the interface, via an external synchronisation input or from an internal clock generator. 4 Interfaces Depending on the application and the bit rate, one or se
26、veral of the following interfaces shall be provided: - - - Interface according to Recommendation V.10 (X.26) 6 Interface according to Recommendation V.11 (X.27) 7 Interface according to Recommendations V.24 8 and V.28 9 - - - Interface according to Recommendation V.35 lo Interface according to Recom
27、mendation V.36 4 Interface according to Recommendations X.21 i 11 and X.24 121. 5 Modes of operation The instrumentation must fully simulate the characteristics of a DTE and/or a DCE in half duplex and/or full duplex mode. This includes the relevant software or hardware handshaking procedures. In sy
28、nchronous half duplex mode, the test pattern shall be preceded by two or more leading pads (i.e. characters with alternating mark and space bits) to enable clock recovery. These pads shall be followed by two or more block-synchronization characters. Recommendation 0.153 (10192) 3 CCITT RECMN*O-L53 9
29、2 I 4862591 0579228 951 If the mode of operation requires, it shall be possible to select the parity check conditions even, odd, mark and space. Note - The insertion of parity check bits is normaily not possible when using pseudo-random test patterns. 6 Bit of synchronization Two modes of synchroniz
30、ation shall be possible: - Synchronization by means of a timing signal derived from the object under test (e.g. from a modem operating in the synchronous mode). Synchronization from the transitions of the received test signal (e.g. when a modem is operating in the nonsynchronous mode). - 7 Codes For
31、 encoding the QBF-text (Recommendation R.52 i) or a freely programmable pattern, the following data signal code shall be provided: - CCIT Alphabet No. 5 with 7 bitskharacter (Recommendation T.50 131). For asynchronous operation 1 or 2 stop bits shall be selectable. 8 8. Error measurements and error
32、evaluation Bit error measurements The range for error ratio measurements shall be 1W2 to lW7. The measurement time shall be sufficiently long to achieve accurate results. Error ratios smaller than iW7 can be observed by providing the capability to count cumulative errors. 8.2 Block error measurement
33、s It shall be possible to perform block error measurements. The block length shall be selectable to 1000 or 10 O00 bits or shall be equal to the length of the pseudo-random sequence used for the error test. In addition, a block length of 32 768 bits shall be provided for measurements at bit rates ab
34、ove 14.4 kbit/s. The range for block error ratio measurements shall be loo to it5 with measurement times being sufficiently long to achieve accurate results. 8.3 Simultaneous measurements It shall be possible to perform bit error ratio and block error ratio measurements simultaneously. 8.4 Error per
35、formance evaluation The instrumentation shali be capable of detecting errored seconds. The number of errored and error-free time intervals in a selectable time period from 1 minute to 24 hours, or continuous, shall be counted and displayed. For this measurement the error detection circuits of the in
36、strumentation shall be controlled by an internal timer which sets intervals of equal length and which operates independently of the occurrence of errors. The measurement of other error performance parameters and the application of Recommendation G.821 14 are under study. 4 Recommendation 0.153 (10D2
37、) CCITT RECMN*0.153 92 4862591 0579229 898 9 9 Measurement of distortion If the inskentation provides for distortion measurements, the following specifications are applicable. 9.1 Measurement of individual distortion The degrees of early and late individual distortion shall be measured when the inst
38、rumentation is operating in the mode in which synchronization is derived from transitions in the received test signal. When using pseudo-random test signals, the measuring error shall be less than k 3%. 9.2 Measurement of bias distortion The instrumentation shall measure bias distortion on reversais
39、 (alternating space/mark with a ratio of 1 : 1). In this mode, the measuring error shall be less than I 2%. 10 Remote control, recording of measurement results As an option, an interface shall be provided which allows remote control of the instrumentation and further processing of the measuring resu
40、lts. If provided, the interface shall comply with the interface bus according to EC Publication 625 I51 or with Recommendation V.24 8. 11 Operating environment The electrical performance requirements shall be met when operating at climatic conditions as specified in 0 2.1 of Recommendation 0.3 19. R
41、eferences CCITT Recommendation R.52 Standardization of international texts for the measurement of the margin of start-stop equipment. CCITT Recommendation V.5 Standardization of data signalling rates for synchronous data transmission in Ehe general witched telephone network. CCITT Recommendation V.6
42、 Standardization of data signalling rates for synchronous data transmission on leased telephone-type circuits. CCITT Recommendation V.36 Modems for synchronous data transmission using 60-1 08 wlz group band circuits. CCITT Recommendation V.37 Synchronous data transmission at a data signalling rate h
43、igher than 72 kbit/s using 60-108 kHz group band circuits. CCITT Recommendation V. 1 O Electrical characteristics for unbalanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications. CCITT Recommendation V. 11 Electrical characteri
44、stics for balanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications. CCITT Recommendation V.24 List of definitions for interchange circuits between data terminal equipment and data circuit-terminating equipment. CCITT Recommend
45、ation V.28 Electrical characteristics for unbalanced double-current interchange circuits. Recommendation 0.153 (10/92) 5 CCITT RECMN*O-L53 72 486259L 0579230 50T CCITT Recommendation V.35 Data transmission at 48 kbit/s using 60-108 kHz group band circuits. CCIT Recommendation X.21 Interface between
46、data terminal equipment (DTE and data circuit- terminating equipment (DCE) for synchronous operation on public data networks. CCIT Recommendation X.24 List of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) on public data networ
47、ks, CCITT Recommendation T.50 International Alphabet No. 5. CCITT Recommendation G.821 Error performance of an international digital connection forming part of an integrated digital network. IEC Publication 625 An interface system for programmable measuring instruments (byte serial, bit parallel). C
48、CITT Recommendation O. 150 Digital test patterns for performance measurements on digital transmission equipment. CCITT Recommendation 0.151 Error performance measuring equipment operating at the primary bit rate and above. CC1- Recommendation 0.152 Error performance measuring equipment for bit rates of 64 kbit/s and N x64kbMs. CCITT Recommendation 0.3 Climatic conditions and relevant tests for measuring equipment. Recommendation 0.153 (10/92) CCITT RECMN*O=353 92 g862593 0579233 446 Printed in Switzerland Geneva, 1993
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