1、Rec. ITU-R V.663-1 1RECOMMENDATION ITU-R V.663-1USE OF CERTAIN TERMS LINKED WITH PHYSICAL QUANTITIES(1986-1990)*Rec. ITU-R V.663-1The ITU Radiocommunication Assembly,consideringa) that ITU technical texts contain a number of terms expressing a relationship between quantities, such asquotient, ratio,
2、 coefficient, factor, index, constant, rate, etc., and that their meaning is liable to cause confusion owing toa lack of consistency;b) that the situation is particularly confused owing to the existence of three working languages, as can be seenfrom such texts as the Provisional list of terms consti
3、tuting the ITU Terminology base (Termite) published by the ITUin 1996;c) that attempts at standardization have been made in certain countries, in vocabularies recently prepared by theInternational Electrotechnical Commission (IEC) and the ITU-IEC Joint Coordination Group on Vocabulary (JCG) andin In
4、ternational Organization for Standardization (ISO) International Standards,unanimously recommends1. that certain terms linked with physical quantities should be used by authors and translators of ITU texts,according to the guidelines annexed to this Recommendation;2. that these guidelines should be
5、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 which deviatefrom the guidelines.ANNEX 1Guidelines for the use in ITU texts of certain terms linkedwith physical quantiti
6、es in French, English and Spanish1. QuotientThe term “quotient” is used to express the result of the division of two numbers or two quantities. Forexample, when A/B = C, C is the quotient of A by B.This very general mathematical term is not used in the composition of the names of quantities, but doe
7、s 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 “A divided by B” rather than “the quotient of A by B”.Example: the pulse repetition frequency is the number of pulses in
8、a pulse train divided by the duration of thepulse train._*This Recommendation was updated in 1997 for editorial reasons only.2 Rec. ITU-R V.663-12. Coefficient and factorThe words “coefficient” and “factor” are used for expressions representing the quotient of two quantities. Theyare used to form te
9、rms expressing certain quantities.2.1 CoefficientThe word “coefficient” is used when two quantities are of different kinds. A coefficient has therefore adimension.Examples:The word “coefficient” is also used in mathematics to express a number that multiplies the value of analgebraic quantity and in
10、statistics (see ISO Standard 3534).Examples:2.2 FactorThe word “factor” is used when the two quantities are of the same kind. A factor is therefore dimensionless.Examples:EFSHall coefficienttemperature coefficientcoefficient of linear expansioncoefficient de Hallcoefficient de tempraturecoefficient
11、de dilatationliniquecoeficiente de Hallcoeficiente de temperaturacoeficiente de dilatacin linealEFScoefficient of an equationcoefficient of correlationcoefficient of variationconfidence coefficient (level)coefficient dune quationcoefficient de corrlationcoefficient de variationniveau de confiancecoe
12、ficiente de una ecuacincoeficiente de correlacincoeficiente de variacincoeficiente (nivel) deconfianzaEFSreflection factornoise factorquality factor (Q)figure of merit (M)facteur de rflexionfacteur de bruitfacteur de qualit (Q)facteur de qualit (M)factor de reflexinfactor de ruidofactor de calidad (
13、Q)factor de calidad (M)Rec. ITU-R V.663-1 33. ConstantThe term “constant” should only be used to denote an invariable number or quantity.Examples: mathematical constants such as p , universal physical constants.The word “constant” is sometimes used incorrectly, in conjunction with a qualifier, to in
14、dicate 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”.However, the term “time
15、constant” (E), “constante de temps” (F), “constante de tiempo” (S) is acceptable, as itis in common use.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 whe
16、re one of the two quantities is areference quantity.Examples:The term also designates a quantity which is not clearly defined or which is identifiable rather thanmeasurable.EFSPlancks constantelectric constantmagnetic constantconstante de Planckconstante lectriqueconstante magntiqueconstante de Plan
17、ckconstante elctricaconstante magnticaDeprecated term Correct termEFSEFSdielectricconstantpropagationconstantattenuationconstantphase constantconstantedilectriqueconstante depropagationconstantedaffaiblisse-mentconstante dephaseconstantes dusolconstantedielctricaconstante depropagacinconstante deate
18、nuacinconstante defaseconstantes delsuelopermittivitypropagationcoefficientattenuationcoefficientphasecoefficientpermittivitexposantlinique depropagationaffaiblissementliniquedphasageliniquecaractristiquesdu solpermitividadexponentelineal depropagacincoeficiente deatenuacincoeficiente defasecaracter
19、sticasdel sueloEFSrefractive indexmodulation indexindice de rfractionindice de modulationndice de refraccinndice de modulacin4 Rec. ITU-R V.663-1Example:In all the above cases extension of the usage of the term is not recommended. It should be replaced whereverpossible by the terms coefficient, fact
20、or or (in English) ratio, or by a specific term of magnitude. Thus the French term“lindice de force des sons” was replaced by “laffaiblissement pour la sonie”, “loudness rating” (E), “coeficiente desonoridad” (S).5. RatioThe term “ratio” is used to express the result of the division of two numbers o
21、r two quantities of the same kind.It may therefore be used in this case 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 exp
22、licitly indicate the fractionalexpression of the relationship between two 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 potenci
23、a/peso.In French and in Spanish the term “rapport” (F) (“relacin” (S) should not be used when the two quantitiesare not the same physical kind, or when they are of a different mathematical kind, for example, to express the quotient ofa vector or a tensor by a scalar number.The word is also used to f
24、orm terms for expressing dimensionless quantities.Examples:Note 1 Error ratio is normally expressed as a decimal fraction, e.g. 4 105.6. Rate, ratio (E); Taux, dbit (F); Tasa/proporcin/frecuencia (S)Although in English the term “rate” may be used to express the relationship between two quantities of
25、 thesame kind, it is generally used to express the relationship of quantities of a different kind (particularly a quantity per unitof time). For expressing the proportion of errors in telecommunication however, the use of this term can be confusingand is deprecated. The term “ratio” should be used f
26、or this purpose.The term “taux” in French designates a factor usually expressed as a percentage or any decimal fraction suchas a thousandth or a millionth. It does not always correspond with the English term “rate”. In particular, it should not beused to express the relationship of a quantity with a
27、 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 reliability.EFSionospheric index indice ionosphriqu
28、e ndice ionosfricoEFSstanding wave ratiosignal-to-noise ratioprotection ratioerror ratiorapport donde stationnairerapport signal sur bruitrapport de protectiontaux derreurrelacin de onda estacionariarelacin seal/ruidorelacin de proteccinproporcin de erroresRec. ITU-R V.663-1 5In Spanish, the term “t
29、asa” should not be used to express the relationship between a quantity and the unitof time. There are a number of different terms which should be used for this purpose depending on the quantitye.g. “velocidad” (S) for distance, “frecuencia” (S) for events, “caudal” (S) for volume flow, etc.In Spanis
30、h, the term “tasa” is also frequently used incorrectly to indicate a factor or index usually expressed asa percentage or in hundredths or as a smaller decimal fraction such as a thousandth or millionth. The use of this term forthis purpose in Spanish is deprecated and should be replaced by the term
31、“proporcin” (S).Examples:EFSsampling ratedigit ratefading raterain ratemodulation ratefailure rateerror ratio *harmonic factormodulation factorfrquence dchantillonnagedbit numriquecadence dvanouissementintensit de pluierapidit de modulationtaux de dfaillancetaux derreurtaux dharmoniquestaux de modul
32、ationfrecuencia de muestreovelocidad digitalritmo de desvanecimientointensidad de lluviavelocidad de modulacintasa de fallosproporcin de erroresproporcin de armnicosfactor de modulacin* In English, “error rate” is used to denote the number of errors/unit time. In this case in French“frquence des erreurs” may be used.
