IEC 60487-2-5-1984 Methods of measurement for equipment used in terrestrial radio-relay systems Part 2 Measurements for sub-systems Section Five - Frequency de.pdf

1、NORME INTERNATIONALE INTERNATIONAL STANDARD CE1 IEC 60487-2-5 Premire dition First edition 1984-01 Mthodes de mesure applicables au matriel utilis dans les faisceaux hertziens terrestres Deuxime partie: Mesures sur les sous-ensembles Section cinq - Dmodulateurs de frquence Methods of measurement for

2、 equipment used in terrestrial radio-relay systems Part 2: Measurements for sub-systems Section Five - Frequency demodulators Numro de rfrence Reference number CEI/IEC 60487-2-5: 1984 Numros des publications Depuis le ler janvier 1997, les publications de la CE1 sont numrotes partir de 60000. Public

3、ations consolides Les versions consolides de certaines publications de la CE1 incorporant les amendements sont disponibles. Par exemple, les numros ddition 1.0, 1.1 et 1.2 indiquent respectivement la publication de base, la publication de base incorporant lamendement 1, et la publication de base inc

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9、al committee which has prepared this publication, as well as the list of publications issued, is to be found at the following IEC sources: IEC web site* Catalogue of IEC publications Published yearly with regular updates (On-line catalogue)* Available both at the IEC web site and as a printed period

10、ical IEC Bulletin Terminology, graphical and letter symbols For general terminology, readers are referred to I EC 60050: International Electrotechnical Vocabulary (IEV). For graphical symbols, and letter symbols and signs approved by the IEC for general use, readers are referred to publications IEC

11、60027: Letter symbols to be used in electrical technology, I EC 6041 7: Graphical symbols for use on equipment. Index, survey and compilation of the single sheets and IEC 60617: Graphical symbols for diagrams. * See web site address on title page. NORME INTERNATIONALE INTERNATIONAL STANDARD CE1 IEC

12、60487-2-5 Premire dition First edition 1984-01 Mthodes de mesure applicables au matriel utilis dans les faisceaux hertziens terrestres Deuxime partie: Mesures sur les sous-ensembles Section cinq - Dmodulateurs de frquence Methods of measurement for equipment used in terrestrial radio-relay systems P

13、art 2: Measurements for sub-systems Section Five - Frequency demodulators O IEC 1984 Droits de reproduction rservs -Copyright - all rights reserved Aucune partie de cette publication ne peut tre reproduite ni No part of this publication may be reproduced or utilized in utilise sous quelque forme que

14、 ce soit et par aucun any form or by any means, electronic or mechanical, procd, lectronique ou mcanique, y compris la photo- including photocopying and microfilm, without permission in copie et les microfilms, sans laccord crit de Iditeur. writing from the publisher. International Electrotechnical

15、Commission Telefax: +41 22 919 0300 3, rue de Varemb Geneva, Switzerland IEC web site http: /w.iec.ch e-mail: inmailiec.ch N CODE PRIX PRICE CODE Pour prix, voir catalogue en vigueur For price, see current catalogue Commission Electrotechnique Internationale International Electrotechnical Commission

16、 MeMnYHapOnHaR 3IleKTPOTeXHHBCHaR HOMHCCHR O 487-2-5 0 IEC 1984 -3- CONTENTS FOREWORD . PREFACE SECTION FIVE . FREQUENCY DEMODULATORS Clause 1 . Scope . 2 . Definition . 3 . General 4. I.F. input return-loss 5 . 6 . Deviation sensitivity 7 . Sense of demodulation . 8 . Differential gain/non-linearit

17、y and differential phase/group-delay . 9 . Baseband amplitude/frequency characteristic Baseband output-impedance and return-loss 10 . F.D.M.-telephony measurements . I 1 . Television measurements FIG URES Page 5 5 7 7 9 9 9 11 15 17 21 23 23 26 -4- 487-2-5 0 CE1 1984 COMMISSION LECTROTECHNIQUE INTER

18、NATIONALE MTHODES DE MESURE APPLICABLES AU MATRIEL UTILIS DANS LES FAISCEAUX HERTZIENS TERRESTRES Deuxime partie : Mesures sur les sous-ensembles Section cinq - Dmodulateurs de frquence PRAMBULE 1) Les dcisions ou accords officiels de la C E I en ce qui concerne les questions techniques, prpars par

19、des Comits - une section frquence intermdiaire bande de base (par exemple discriminateur); - une section bande de base. 487-2-5 0 I EC 1984 -7- METHODS OF MEASUREMENT FOR EQUIPMENT USED IN TERRESTRIAL RADIO-RELAY SYSTEMS Part 2: Measurements for sub-systems SECTION FIVE - FREQUENCY DEMODULATORS 1. S

20、cope Methods are given in this section for the measurement of the electrical characteristics of frequency demodulators. Threshold aspects are not included as these are not normally required for line-of-sight radio-relay systems. Furthermore, where possible, only measurements involving the basic demo

21、dulator are considered, excluding the equipment comprising the de-emphasis network and the networks associated with sound sub-carrier signals, pilot signals and auxiliary signals. Methods of measurement for frequency modulators are given in Section Four. Measurements between the baseband terminals o

22、f modulator/demodulator assemblies are covered by various sections of Part 3 of this publication. i 2. Definition For the purpose of this standard a frequency demodulator is a sub-system which, by analogue means, demodulates an intermediate frequency (i.f.) carrier which has been frequency modulated

23、 by a baseband signal. This may be a multi-channel telephony or television signal with associated sound sub-carrier signals, pilot signals and auxiliary signals. Such baseband signals are normally analogue but digital signals are not excluded. However, the methods of measurement described in this se

24、ction are intended for assessing the performance of the demodulator when analogue signals are transmitted. A demodulator sub-system usually comprises the following three main sections : - an i.f. section; - an i.f. to baseband section (discriminator); - a baseband section. -8- 487-2-5 0 CE1 1984 3.

25、Gnralits Un diagramme dun dmodulateur type pour les faisceaux hertziens terrestres est donn Les caractristiques mesurer peuvent tre rparties en trois catgories principales: la figure 1, page 26. - Caractristiques non impliques dans le transfert de f.i. bande de base. - Caractristiques f.i. bande de

26、base. - Certaines caractristiques de transmission de bande de base bande de base en conjonction La premire catgorie concerne les mesures lentre f.i. ou la sortie en bande de base. Elles sont dcrites dans les articles 4 et 5 de cette section. La deuxime catgorie forme la partie essentielle de cette s

27、ection par la nature mme du dispositif lessai (transfert de fi. bande de base). Pour valuer linfluence du niveau f.i. lentre, certains essais spcifis doivent tre effectus au niveau nominal, un niveau minimal spcifi et un niveau maximal spcifi lentre f.i. Note. - La mesure de sensibilit la modulation

28、 damplitude nest pas incluse dans cette norme, car on suppose que le niveau dentre est, dans tous les cas, situ lintrieur du domaine de fonctionnement du limiteur, et que le coefficient de conversion amplitude/phase de ce dernier est ngligeable. avec un modulateur de mesure. La troisime catgorie com

29、prend les mesures effectuer sur lensemble modulateur/dmo- dulateur complet (modem) avec cette diffrence que le modulateur utilis en pratique est remplac par un modulateur de mesure. I1 est trs souhaitable de connatre la contribution propre dun dmodulateur aux dviations permises par rapport aux carac

30、tristiques idales de qualit, car, en pratique, des dmodulateurs dune conception ou dun fabricant dtermins doivent fonctionner avec des modulateurs de conception ou de ralisation diffrentes. Les effets de compensation entre modulateur et dmodulateur sont donc indsirables et chaque dmodulateur devrait

31、 satisfaire la spcification prescrite lorsquon lassocie un modulateur de mesure. Cette procdure exige que le modulateur de mesure soit dune qualit suprieure celle spcifie pour le dmodulateur lessai. 4. Affaiblissement dadaptation lentre f.i. Voir la premire partie, section trois de cette publication

32、: Mesures effectues dans la bande Des mesures aux frquences harmoniques de la fi peuvent galement tre exiges. des frquences intermdiaires. 5. Impdance de sortie en bande de base et affaiblissement dadaptation Voir la premire partie, section quatre de cette publication: Mesures effectues dans la band

33、e de base. 487-2-5 0 IEC 1984 -9- 3. General A block diagram for a typical demodulator as used in terrestrial radio-relay systems is The characteristics to be measured can be divided into three principal categories : shown in Figure 1, page 26. - Non-transfer characteristics. - I.F. to baseband char

34、acteristics. - Certain baseband-to-baseband transmission characteristics in conjunction with a The first category of measurements applies to i.f. input measurements (Clause 4) and baseband output measurements (Clause 5). The second category of measurements forms the essential part of this section be

35、cause of the nature of the device under test-transfer from i.f. to baseband. In order to assess the influence of the i.f. input level, some specified tests should be made at nominal, minimum and maximum specified i.f. input levels. Note. - Measurement of the influence of amplitude modulation is not

36、included in the present standard since the input level is assumed to be entirely within the operating range of the limiter, the amplitude/phase conversion of the latter being assumed to be negligible. measurement modulator. The third category of measurements includes those to be carried out on the c

37、omplete modulator/demodulator (modem) assembly except that the actual or system modulator is replaced by a measurement modulator. It is very desirable to know the separate contribution of a demodulator to the total permitted tolerances of performance characteristics because, in an operational situat

38、ion, demodulators of one design or manufacturer may have to work with modulators of another. Compensation effects between modulator and demodulator are therefore undesirable and each demodulator should fulfil the prescribed specification in association with a measurement modulator. This procedure re

39、quires that the measurement modulator has a better performance than that specified for the demodulator under test. 4. I.F. input return-loss See Part 1, Section Three of this publication : Measurements in the Intermediate-frequency Range. Measurements at harmonics of the intermediate frequency may also be required. 5. Baseband output-impedance and return-loss See Part 1, Section Four of this publication: Measurements in the Baseband.