1、 International Telecommunication Union ITU-T P.10/G.100TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2006) SERIES P: TELEPHONE TRANSMISSION QUALITY, TELEPHONE INSTALLATIONS, LOCAL LINE NETWORKS Vocabulary and effects of transmission parameters on customer opinion of transmission quality SERIES
2、 G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS International telephone connections and circuits General definitions Vocabulary for performance and quality of service ITU-T Recommendation P.10/G.100 ITU-T P-SERIES RECOMMENDATIONS TELEPHONE TRANSMISSION QUALITY, TELEPHONE INSTALLATIO
3、NS, LOCAL LINE NETWORKS Vocabulary and effects of transmission parameters on customer opinion of transmission quality Series P.10 Subscribers lines and sets Series P.30 P.300 Transmission standards Series P.40 Objective measuring apparatus Series P.50 P.500 Objective electro-acoustical measurements
4、Series P.60 Measurements related to speech loudness Series P.70 Methods for objective and subjective assessment of quality Series P.80 P.800Audiovisual quality in multimedia services Series P.900 Transmission performance and QoS aspects of IP end-points Series P.1000 For further details, please refe
5、r to the list of ITU-T Recommendations. ITU-T Rec. P.10/G.100 (07/2006) i ITU-T Recommendation P.10/G.100 Vocabulary for performance and quality of service Summary This Recommendation gives the definitions which have been found to be useful for the work of ITU-T Study Group 12 in the study of Perfor
6、mance and Quality of Service. It is based on the contents of ITU-T Recs P.10 (1998) and G.100 (2001) with additional amendments and corrections. Source ITU-T Recommendation P.10/G.100 was approved on 14 July 2006 by ITU-T Study Group 12 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii IT
7、U-T Rec. P.10/G.100 (07/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, opera
8、ting and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, pr
9、oduce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In t
10、his Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. in
11、teroperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest
12、 that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidenc
13、e, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may
14、be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2006 All rights reserved. No part of this publication may be r
15、eproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. P.10/G.100 (07/2006) iii CONTENTS Page 1 Introduction 1 2 Terms and definitions . 1 ITU-T Rec. P.10/G.100 (07/2006) 1 ITU-T Recommendation P.10/G.100 Vocabulary for performance and quality of service 1 Introd
16、uction This Recommendation contains terms and definitions appropriate to the work of Study Group 12. It is based on the contents of ITU-T Recs P.10 (1998) and G.100 (2001) with additional amendments and corrections. 2 Terms and definitions This Recommendation defines the following terms in alphabeti
17、c order: 0-1 3.1 kHz handset telephony A real-time two-way speech communication within the frequency range approximately from 300 to 3400 Hz using one or more telecommunication networks with suitable terminal equipment connected to the network termination points, characterized by: presentation of an
18、 acoustical speech signal to the mouthpiece of a traditionally shaped handset: either analogue transport of said speech signal under real-time conditions through and by telecommunication networks: said networks being intended for telephony applications between network termination points; or filterin
19、g of said speech signal to the frequency range approximately from 300 to 3400 Hz; transformation of said speech signal either by waveform or by non-waveform (speech analysis) encoder; transport and processing of said speech signal under real-time conditions through and by telecommunication networks:
20、 said networks being intended for telephony applications between network termination points; back transformation (speech synthesis) of said speech signal by the respective decoder; acoustical presentation of said speech signal in the frequency range approximately from 300 to 3400 Hz by the earpiece
21、of a traditionally shaped handset. 0-2 4-wire chain The 4-wire chain denotes the whole unbroken chain of 4-wire national and international circuits in a complete telephone connection, including possible 4-wire circuits between the primary centre and the local exchange and on the subscriber line, e.g
22、., ISDN access and 4-wire or digitally connected PBXs. A-1 Absolute Category Rating (ACR) (see ITU-T Rec. P.800) Test method in which subjects are asked to express opinion judgements using absolute quality scales (excellent, good, .). A-2 acceptance scale (see ITU-T Rec. P.85) Opinion scale for meas
23、uring the overall quality of the message on a service point of view. Acceptance requires a Yes/No answer. A-3 acceptance test A contractual test to prove to the customer that the device meets certain conditions of its specification. 2 ITU-T Rec. P.10/G.100 (07/2006) A-4 acoustic artificial voice Aco
24、ustic signal at the Mouth Reference Point (MRP) of the artificial mouth. It complies with the same time and spectral specifications as the electrical artificial voice. A-5 acoustic coupler (in telephonometry) A cavity of defined shape and volume used for the testing of telephone earphones or telepho
25、ne transmitters in conjunction with a calibrated microphone adapted to measure the pressure developed within the cavity. A-6 acoustic hood A hood lined with sound-absorbing material to facilitate the use of a telephone station by reducing the ambient noise level. A-7 Acoustic Reference Level (ARL) (
26、see ITU-T Recs P.310, P.311, P.341 and P.342) The acoustic level at MRP which results in a 10 dBm0 output at the digital interface. A-8 acoustic shock suppressor (in telephony) A device associated with a telephone station and intended to prevent acoustic shocks, by setting an upper limit to the abso
27、lute values of the instantaneous electrical voltage that can be applied to the telephone earphone. A-9 Acoustic startle A psychological effect caused by acoustic stimulation that may cause disturbance to some users. A-10 acoustical telephony gain (telephonic transfer function) (see ITU-T Rec. P.58)
28、Ratio of the pressure at the ear reference point of a listener to the pressure at the mouth reference point of a talker connected by a telephone channel. A-11 acoustically closed earphones (nominally sealed) (see ITU-T Rec. P.57) Earphones which are intended to prevent any acoustic coupling between
29、the external environment and the ear canal. A-12 acoustically open earphones (nominally unsealed) (see ITU-T Rec. P.57) Earphones which intentionally provide an acoustic path between the external environment and the ear canal. A-13 active speech level (see ITU-T Rec. P.56) A quantity, expressed in d
30、ecibels relative to a stated reference, e.g., volts or pascals, formed by averaging the speech-signals power over the active time, according to ITU-T Rec. P.56, method B. A-14 active time Aggregate of all intervals of time when speech is deemed to be present according to the criterion adopted by ITU
31、-T (see ITU-T Rec. P.56) for the purpose of measurement. A-15 activity factor Ratio of the active time to total time elapsed during a measurement, usually expressed as a percentage. A-16 advantage factor A scalar number (normally positive) representing the advantage of access certain systems (e.g.,
32、mobile) have over wirebound handset telephony. Expressed in units of the transmission rating factor R. ITU-T Rec. P.10/G.100 (07/2006) 3 A-17 analogue network A network in which the access interface and all network elements are considered analogue. A-18 articulation index Definition generally used i
33、n psychoacoustics A measure of the intelligibility of voice signals, expressed as a percentage of speech units that are understood by the listener when heard out of context. The articulation index is based on partially empirical, partially theoretical principles to predict the speech intelligibility
34、 under known signal-to-noise conditions. A-19 articulation scale (see ITU-T Rec. P.85) Opinion scale for measuring the impression of clarity felt by a listener. How distinguishable are the words composing the message? A-20 artificial conversational speech (see ITU-T Rec. P.59) A signal which reprodu
35、ces the on-off characteristics of human conversational speech, especially useful for characterizing speech processing systems which have speech detectors, such as speakerphones, echo control devices and Digital Circuit Multiplication Equipment (DCME). A-21 artificial ear A device for the calibration
36、 of earphones incorporating an acoustic coupler and a calibrated microphone for the measurement of sound pressure and having an overall acoustic impedance similar to that of the average human ear over a given frequency band. A-22 artificial mouth A device consisting of a loudspeaker mounted in an en
37、closure and having a directivity and radiation pattern similar to those of the average human mouth. A-23 artificial mouth excitation signal A signal applied to the artificial mouth in order to produce the acoustic artificial voice. It is obtained by equalizing the electrical artificial voice for com
38、pensating the sensitivity/frequency characteristic of the mouth. A-24 artificial voice A mathematically defined signal which reproduces human speech characteristics, relevant to the characterization of linear and non-linear telecommunication systems. It is intended to give a satisfactory correlation
39、 between objective measurements and tests with real speech. A-25 ASR system An implementation in hardware or software that accepts natural speech signal as input and provides, at the output, a coded version of what has been said (word, command, expression, sentence, etc.). A-26 Automatic Speech Reco
40、gnition (ASR) A process or a technology which accepts natural speech signal as input and provides, at the output, a coded version of what has been said (word, command, expression, sentence, etc.). 4 ITU-T Rec. P.10/G.100 (07/2006) B-1 balance return loss At a 4-wire terminating set (“hybrid“), that
41、portion of the semi-loop loss which is attributable to the degree of match between the impedance, Z2, connected to the 2-wire line terminals, and the balance impedance, ZB. It is given approximately by the expression: dBlog202210BBBRZZZZL+= NOTE Under most circumstances the expression given is suffi
42、ciently accurate. However, for some worst case evaluations, the exact expression must be used. The exact expression is: dB2log202020010BBBRZZZZZZZL+= where Z0 is the 2-wire input impedance. (If Z0 = ZB, the two expressions become identical.) B-2 band sensation level Difference, expressed in decibels
43、, between the sound integrated over a frequency band and the sound pressure level in that band at the threshold of audibility, there being no other disturbing sound. B-3 block Group of pels. For example, a block of 8 8 pels is the smallest coding block used in MPEG-1 algorithms. There are 1320 block
44、s in a SIF image, 44 in the horizontal direction (352 pels/8) and 30 in the vertical direction (240 lines/8). B-4 block distortion Distortion of the image characterized by the appearance of an underlying block encoding structure. Also called tiling. B-5 blurring A global distortion over the entire i
45、mage, characterized by reduced sharpness of edges and spatial detail. C-1 call The establishment and use of a complete connection following a call attempt. C-2 call attempt (by a user) A sequence of operations made by a user of a telecommunication network trying to obtain the desired user or service
46、. Associated term: to call. C-3 circuit access point The circuit access points have been defined as “4-wire access points so located that as much as possible of the international circuit is included between corresponding pairs of these access points at the two centres concerned“ (see ITU-T Rec. M.56
47、5). These points, and their relative level (with reference to the transmission reference point), are determined in each case by the Administration concerned. They are taken as the basic reference points of known relative level to which other transmission measurements will be related. In other words,
48、 for measurement and lining-up purposes, the relative level at the appropriate circuit access point is the relative level with respect to which other levels are adjusted. ITU-T Rec. P.10/G.100 (07/2006) 5 C-4 circuit loudness rating (CLR) (see ITU-T Rec. G.111) The loudness loss between two electric
49、al interfaces in a connection or circuit, each interface terminated by its nominal impedance which may be complex. C-5 circuit, telecommunication circuit A combination of two transmission channels permitting bidirectional transmission of signals between two points, to support a single communication. NOTE 1 If the telecommunication is by nature unidirectional (for example: long distance television transmission), the term “circuit“ is sometimes used to designate the single channel providing the facility. NOTE 2 In a telecommunication network, the use of the term “cir
