1、CCITT RECMN*0-22 92 48b2593 0577433 423 INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE 0.22 SPECIFICATIONS OF MEASURING EQUIPMENT (1 0/92) CCITT AUTOMATIC TRANSMISSION MEASURING AND SIGNALLING TESTING EQUIPMENT ATME No. 2 I Recommendation
2、 0.22 CCITT RECMN*0*22 72 4862573 0577432 3bT FOREWORD The CCIT (the International Telegraph and Telephone Consultative Committee) is a permanent organ of the International Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommen
3、dations 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 CCITT between
4、 Plenary Assemblies is covered by the procedure laid down in CCIn Resolution No. 2 (Melbourne, 1988). Recommendation 0.22 was revised by Study Group IV and was approved under the Resolution No. 2 procedure on the 5th of October 1992. CC NOTE In this Recommendation, the expression “Administration” is
5、 used for conciseness to indicate both a telecommunication administration and a recognized private operating agency. O ITU 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,
6、without permission in writing from the ITU. CCITT RECMN*0-22 92 m 4db259L 0577433 2Tb m Recommendation 0.ZZ1) CCIT AUTOMATIC TRANSMISSION MEASURING AND SIGNALLING TESTING EQUIPMENT ATME No. 2 (published 1972; revised 1980, 1984, I988 and 1992) Abstract Specifies the requirements for ATME No. 2 for a
7、utomatic testing of transmission performance, echo Keywords - ATMENo.2; - automatic testing; - echo canceller testing; - signailing testing; - transmission testing. cancellers, and signalling systems on international circuits terminating in exchanges with 4-wire switching. 1 General The CCITT automa
8、tic transmissiori measuring and signalling testing equipment (ATME No. 2) is intended to make transmission measurements, echo canceller tests and signalling system functional tests2) on all categories of international circuits terminating in exchanges with 4-wire switching. The ATME No. 2 will consi
9、st of two parts, namely: 1) 2) The responding equipment will be available in the following forms: a) b) It is not possible for the signalling system functional testing devices as found in Types a and b to check the busy flash signal. For this purpose, a separate test call must be established using a
10、n appropriate test code. Arrangements will therefore be provided to force the transmission of the busy flash signal over the circuit under test by the incoming international exchange equipment. This may be carried out by examination of the test code in the exchange equipment or by the provision of a
11、 separate responding equipment. The busy flash signal should be transmitted as the result of a simulation of exchange or circuit congestion. For the purposes of this specification, the equipment providing this busy test ,mangement shall be referred to as responding equipment Type c. directing equipm
12、ent at the outgoing end; and responding equipment at the incoming end. a signalling system functional testing and transmission measuring device (Type a); a signalling system functional testing device (Type b)3). The text uf this Recommendation has been established under the responsibility of Study G
13、roups IV and XI. Any modifcation to this Recommendation must be submitted for approval to these Study Groups. 2, The concept of functional text$ excludes marginal testing 3, The CCIIT directs the attention of Administrations to the advantages of providing sufficient signalling system functional test
14、ing devices (Type b) to permt several signalling system functional tests to be conucted simultaneously and to permit signalling system functional tests to he conducted more frequently than transmission tests. For the application of ATME No. 2, see Recommendation M.605 I. Recommendation 0.22 (10/92)
15、1 CCITT RECMN+0.22 92 M 4862531 0577434 132 M Responding equipment Type a is always required. Type b is optional. When used in addition to Type a, it is expected to provide an economical means for making more frequent signalling tests without occupying the transmission measuring equipment. Type c re
16、sponding equipment is required in cases when the signalling system used on the circuits to be tested provides a busy flash line signal. For bth-way circuits, directing and responding equipment are required at both ends for making signalling system functional tests. For transmission measurements over
17、 both-way circuits, the outgoing end is normally that which is the responsibility of the control station, and the incoming end is that which is the responsibility of the sub-control station. However, these may be interchanged by mutual agreement. The equipment shall be of modular construction in ord
18、er that only those features desired by the using Administrations need to be included. This Recommendation already takes account of operating over circuits using CCIT Signalling Systems Nos. 3,4,5,6,7, RI and R2. Results of measurements shall be recorded only at the outgoing end, that is by the direc
19、ting equipment. However, arrangements can be made by the Administrations or operating agencies involved to send the results of the measurements to the Administrations in charge of the incoming end and other points as desired, by mutually acceptable means. ATME No. 2 can be used on circuits incorpora
20、ting circuit multiplication systems (CMSs) if the CMS concerned is so designed that a 2800 Hz can be used to bold the circuits during absence of the normally transmitted signals. TAS1 is an example of a CMS which accepts 2800 Hz as the holding tone. 2 Kinds of measurements and tests Transmission mea
21、surements of the following kinds will be made in both directions of transmission with Type a responders: absolute power level measurement at 1020 Hz4); absolute power level measurement at 400,1020 and 2800 Hz (loss/frequency distortion); noise measurements; signal-to-totai-distortion (including quan
22、tizing distortion) ratio measurements at values of holding tone (i.e. -10 and -25 dBmO); an in-circuit echo canceller testing system (ECTS) sequence, intended to test both near-end and far-end cancellers on a circuit under test. The ECTS is suitable for testing echo cancellers complying with Recomme
23、ndation G. 165 2; on wholly digital circuits between digital exchanges, measurements by the director of a director generated digital test pattern looped back by a Type a responder. In addition to tests of the normal signalling functions required in the process of setting up the test call, line - cle
24、ar back: - forward transfer; - signals such as the following will also be tested: busy flash (this requires a separate test call to a separate test line, see Recommendation 0.1 1 lo). 4, For further information about the choice of the test signal frequency, refer to Recommendation 0.6 9. 2 Recommend
25、ation 0.22 (10/92) CCITT RECMN*Om22 92 m 4862.593 0577435 079 m In addition to the transmission measurements made between directors and responders, it shall also be possible to make measurements from a director to a digital loopback test line as described in Recommen- dation 0.11 lo. The equipment w
26、ill be designed in such a way that further measurements and tests can be incorporated at a later date. 3 Equipment for making transmission measurements and processing the results The directing and responding equipment shall each be provided with features for making absolute power level, digital test
27、 pattern tests, echo canceller tests, signal-to-total-distortion ratio and noise measurements, as described below. In addition, the directing equipment shall have the capability, where required, of receiving the results of the measurements made by both the directing and responding equipment, making
28、the necessary adjustments to these results, as discussed below, and converting the results to the proper form for transmission to the output device. The output device is also considered to be part of the directing equipment. 3.1 Absolute power level measurements 3.1.1 Sending end At the access point
29、 at the input to the path to be measured, there will be connected a sending equipment which will send a tone of the appropriate frequency and level as specified in $4 6.3 and 9.1. 3.1.2 Measuring end At the access point at the output from the path to be measured, there will be connected a measuring
30、device whose specifications are given in #6.3 and 9.1. The measuring device shall provide results in the form of a deviation, expressed in dB, from the nominal absolute power level of the circuit at the virtual switching point at the receiving end. This assumes that for the responding equipment (see
31、 4 3.6), the relative level at the receiving end virtual switching point is -4 dBr. A level higher than nominal shall be indicated as positive “ + “ and a level lower than nominal shall be indicated as nega- tive “ - “. For the total distortion measurements, the results should give the signal-to-toi
32、al-distortion ratio in decibel. The transmission parameters of the switched access path between the virtual switching point and the measuring device shail be allowed for (see Recommendation M.560 3). If the equipment is capable of detecting an interruption or a condition of instability experienced d
33、uring a measurement (see 4 10.5), the result shall be indicated as shown in Table 3/0.22. 3.2 Noise measurements Note - When ATME No. 2 is implemented using digital signal processing techniques, noise measurement is inherently limited to 4 kHz when using an 8 kHz sampling frequency. 3.2.1 Sending en
34、d At the access point at the input to the path to be measured, there will be connected a 600-ohms terminating resistance or a CMS holding tone in accordance with 5s 6.4.19 or 6.4.20 and 9.3. 3.2.2 Measuring end At the access point at the output from the path to be measured, there will be connected a
35、 noise measuring device whose specifications are given in $ 9.2. The noise measuring evice shall provide results in terms of absolute power level with psophometric weighting referred to O level (dBmOp), assuming for the responding equipment that the relative level at the receiving end virtual switch
36、ing point is -4.0 dBr (see 4 3.6). The transmission parameters of the switched access path between the virtual switching point and the noise measuring device shall be allowed for (see Recommendation M.560 3). Recommendation 0.22 (10/92) 3 3.3 Signal-to-total-distortion ratio measurements 3.3.1 Sendi
37、ng end At the access point at the input to the path to be measured, there will be connected a sending equipment which will send tones at two different levels (-10 and -25 dBmO) as specified in Q 9.1. 3.3.2 Measuring end The signal-to-total-distortion ratio measurements will be carried out in two ste
38、ps. Step 1 At the access point at the output from the path to be measured, there will be connected a noise measurhig device connected with a loo0 to 1025 Hz signal rejection filter. The noise measuring device and the signal rejection filter are specified in 9 9.2. Step 2 At the access point at the o
39、utput from the path to be measured, there will be connected a measuring device whose specifications are given in $0 6.3 and 9.1. The measuring device shall provide results in the form of the signal-to-total-distortion ratio in decibel. A bandwidth correction for the loss of effective noise bandwidth
40、 due to the rejection fdter must be incorporated. 3.4 Echo canceller testing system (ECTS) As part of the ECTS, the directing and responding equipment shaii each be provided with features for making absolute power level, echo performance ratio and noise measurements, as described below. In addition,
41、 the directing equipment shall have the capability of receiving the results of the measurements made by both the directing and responding equipment, making the necessary adjusmients to these results, as discussed below, and converting the results to the proper form. 3.4.1 Absolute power level measur
42、ements 3.4.1.1 Sending end At the access point at the input to the path to be measured, there will be connected a sending equipment which will send a tone of the appropriate frequency and level as specified in QQ 5.2 and 9.4. 3.4.1.2 Measuring end At the access point at the output from the path to b
43、e measured, there will be connected a measuring device whose specifications are given in $9 6.7 and 9.1. The measuring device shall provide results in the form of a deviation, expressed in decibel, from the nominal absolute power level of the circuit at the virtual switching point at the receiving e
44、nd. This assumes that for the responding equipment (see 9 3.6), the relative level at the receiving end virtual switching point is -4.0 dBr. A level higher than nominal shall be indicated as positive “+“ and a level lower than nominal shall be indicated as nega- tive“-“. The transmission parameters
45、of the switched access path between the virtual switching point and the measuring device shall be allowed for (see Recommendation M.560 3). If the equipment is capable of detecting an interruption or a condition of instability experienced during a measurement (see Q 1 13, the result shall be indicat
46、ed as described in 0 3.6. 3.4.2 Noise measurements To determine echo noise floor in step 1 of echo performance test. 3.4.2.1 Sending end At the access point at the input to path to be measured, there will be connected a 600-ohms terminating resistance in accordance with Qb 6.7 and 9.4.3. 4 Recommend
47、ation 0.22 (10/92) 3.4.2.2 Measuring end At the access point at the output from the path to be measured, there will be connected a noise measuring device whose specifications are given in $ 9.5.1. The noise measuring device shall provide results as noise ratios which are the relative power level wit
48、h psophometric weighting referred to the -10 (dBmOp) sending level, assuming for the responding equipment that the relative level at the receiving end virtual switching point is -4.0 dBr (see $ 3.6). Note - This noise level is referred to -10 dBmOp rather than O dBmOp to make it represent the minimu
49、m measurable noise ratio in steps 2 and 3 of the echo performance tests in $ 3.4.3. The transmission parameters of the switched access path between the virtual switching point and the noise measuring device shall be allowed for (see Recommendation M.560 3). 3.4.3 Echo performance ratio measurements Steps 2 and 3 of echo performance tests. 3.4.3.1 Sending end At the access point at the input to the path to be measured, there will be connected a sending equipment which will send a -10 dBmO noise test signal as specified in $9.4.1 e). 3.4.3.2 Measuring end At the ac
