ITU-T B 16-1993 USE OF CERTAIN TERMS LINKED WITH PHYSICAL QUANTITIES《与物理量相关的特定术语使用》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 “ TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-%!.3G0G0/(b) that the situation is particularly confused owing to the existence of three working languages, as can be seenfrom such texts as the Provisional Glossary of Telecommunications Terms published by

2、the ITU in 1979;(c) that attempts at standardization have been made in certain countries, in vocabularies recently prepared bythe IEC and the JCG and in ISO International Standards,recommends(1) that certain terms linked with physical quatities should be used by authors and translators of ITU texts,

3、according to the guidelines annexed to this Recommendation;(2) that these guidelines should be used to ensure that the term chosen to denote a quantity, fully describes itsnature;(3) that these guidelines should be followed when forming new terms or reviewing existing terms whichdeviate from the gui

4、delines.ANNEX A(to Recommendation B.16)Guidelines for the use in ITU texts of certain terms linkedwith physical quantities in French, English and SpanishA.1 QuotientThe term “quotient” is used to express the result of the division of two numbers or two quantities. For example;when A/B = C, C is the

5、quotient of A by B.This very general mathematical term is not used in the composition of the names of quantities, but does formpart of the definition of some of them.In the context of definitions, quotient is a difficult word to use in English as it is often much more practical touse the expression

6、“A divided by B” rather than “the quotient of A by B”.Example: the pulse repetition frequency is the number of pulses in a pulse train divided by the duration of thepulse train.A.2 Coefficient and factorThe words ”coefficient” and “factor” are used for expressions representing the quotient of two qu

7、antities. Theyare used to form terms expressing certain quantities._1)A similar text will be submitted to the CCIR as a revision of Recommendation 663.2 Fascicle I.3 - Rec. B.16A.2.1 CoefficientThe word “coefficient” is used when two quantities are of different kinds. A coefficient has therefore adi

8、mension.Examples:EFSHall coefficienttemperature coefficientcoefficient of linear expansioncoefficient de Hallcoefficient de tempraturecoefficient de dilatationliniquecoeficiente de Hallcoeficiente de temperaturacoeficiente de dilatacin linealThe word “coefficient” is also used in mathematics to expr

9、ess a number that multiplies the value of an algebraicquantity and in statistics (see ISO Standard 3534).Examples:EF Scoefficient of an equationcoefficient of correlationcoefficient of variationconfidence coefficient (level)coefficient dune quationcoefficient de corrlationcoefficient de variationniv

10、eau de confiancecoeficiente de una ecuacincoeficiente de correlacincoeficiente de variacincoeficiente (nivel) deconfianzaA.2.2 FactorThe word “factor” is used when the two quantities are of the same kind. A factor is therefore dimensionless.Examples:EFSreflection factornoise factorquality factor (Q)

11、figure of merit (M)facteur de rflexionfacteur de bruitfacteur de qualit (Q)facteur de qualit (M)factor de reflexionfactor de ruidofactor de calidad (Q)factor de calidad (M)A.3 ConstantThe term “constant” should only be used to denote an invariable number or quantity.Examples: mathematical constants

12、such as pi, universal physical constants.EFSPlancks constantelectric constantmagnetic constantconstante de Planckconstante lectriqueconstante magntiqueconstante de Planckconstante elctricaconstante magnticaFascicle I.3 - Rec. B.16 3The word “constant” is sometimes used incorrectly, in conjunction wi

13、th a qualifier, to indicate a variablecharacteristic quantity of a system or substance. In such cases, the use of the word is deprecated, and a specific termshould be used (frequently the word “coefficient” suitably qualified) or in French, in the absence of such a term, theword “caractristique”.Dep

14、recated term Correct termEF SE F Sdielectricconstantpropagationconstantattenuationconstantphase constantconstantedilectriqueconstante depropagationconstantedaffaiblissementconstante dephaseconstantes dusolconstantedielctricaconstante depropagacinconstante deatenuacinconstante defaseconstantes delsue

15、lopermittivitypropagationcoefficientattenuationcoefficientphasecoefficientpermittivitexposant liniquede propagationaffaiblissementliniquedphasageliniquecaractristiquesdu solpermitividadexponente linealde propagacincoeficiente deatenuacincoeficiente defasecaractersticasdel sueloHowever, the term “tim

16、e constant” (E), “constante de temps” (F), “constante de tiempo” (S) is acceptable, as itis in common use.A.4 IndexIn French and Spanish the term “indice” (F), “ndice” (S) is sometimes used instead of “facteur” (F), “factor”(S). In English “index” is sometimes used instead of “ratio” in those cases

17、where one of the two quantities is areference quantity.Examples:EF Srefractive indexmodulation indexindice de rfractionindice de modulationndice de refraccinndice de modulacinThe term also designates a quantity which is not clearly defined or which is identifiable rather than measurable.Example:EF S

18、ionospheric index indice ionosphrique ndice ionosfrico4 Fascicle I.3 - Rec. B.16In all the above cases extension of the usage of the term is not recommended. It should be replaced whereverpossible by the terms coefficient, factor or (in English) ratio, or by a specific term of magnitude. Thus the Fr

19、ench term“Lindice de force des sons” was replaced by “laffaiblissement pour la sonie”, “loudness rating” (E), “coeficiente desonoridad” (S).A.5 RatioThe term “ratio” is used to express the result of the division of two numbers or two quantities of the same kind.It may therefore be used in this case

20、as an equivalent of the term “quotient”.Examples: Attenuation is defined as the ratio of two powers. Ratio of A to B. Ratio of width to height (picture).In English and in Spanish, the word “ratio” (”relacin”) is also used to explicitly indicate the fractionalexpression of the relationship between tw

21、o quantities before the division is performed, e.g. written as a fraction or arelationship as 5/21 or 5:21 rather than the resulting 0.238. The two quantities may or may not be the same, e.g.power/weight ratio, relacin potencia/peso.In French and in Spanish the term “rapport” (F) (“relacin” (S) shou

22、ld not be used when the two quantities arenot the same physical kind, or when they are of a different mathematical kind, for example, to express the quotient of avector or a tensor by a scalar number.The word is also used to form terms for expressing dimensionless quantities.Examples:EF Sstanding wa

23、ve ratiosignal-to-noise ratioprotection ratioerror ratiorapport donde stationnairerapport signal sur bruitrapport de protectiontaux derreurrelacin de onda estacionariarelacin seal/ruidorelacin de proteccinproporcin de erroresNote Error ration is normally expressed as a decimal fraction, e.g. 4 10-5.

24、A.6 Rate, ratio (E) ; Taux, dbit (F); Tasa/proporcin/frecuencia (S)The term “taux” in French designates a factor usually expressed as a percentage or any decimal fraction such asa thousandth or a millionth. It does not always correspond with the English term “rate”. In particular, it should not beus

25、ed to express the relationship of a quantity with a unit of time. In such cases, an appropriate term such as “dbit” (F),“frquence” (F), “vitesse” (F) should be used. An exception which has been established by usage is “failure rate” (E),“taux de dfaillance” (F), “tasa de fallos” (S) in the field of

26、reliability.Although in English the term “rate” may be used to express the relationship between two quantities of the samekind, it is generally used to express the relationship of quantities of a different kind (particularly a quantity per unit oftime). For expressing the proportion of errors in tel

27、ecommunication however, the use of this term can be confusing andis deprecated. The term “ratio” should be used for this purpose.In Spanish, the term “tasa” should not be used to express the relationship between a quantity and the unit oftime. There are a number of different terms which should be us

28、ed for this purpose depending on the quantity e.g.“velocidad” (S) for distance, “frecuencia” (S) for events, “caudal” (S) for volume flow, etc.Fascicle I.3 - Rec. B.16 5In Spanish, the term “tasa” is also frequently used incorrectly to indicate a factor or index usually expressed asa percentage or i

29、n hundredths or as a smaller decimal fraction such as a thousandth or millionth. The use of this erm forthis term for this purpose in Spanish is deprecated and should be replaced by the term “proporcin” (S).Examples:EF Ssampling ratedigit ratefading raterain ratemodulation ratefailure rateerror rati

30、o a)harmonic factormodulation factorfrquence dchantillonnagedbit numriquecadence dvanouissementintensit de pluierapidit de modulationtaux de dfaillacetaux derreurtaux dharmoniqestaux de modulationfrecuencia de muestreovelocidad digitalritmo de desvanecimientointensidad de lluviavelocidad de modulacintasa de fallosproporcin de erroresproporcin de armnicosfactor de modulacina)In English, “error rate” is used to denote the number of errors/unit time. In this case in French “frquencedes erreurs” may be used.