1、BRITISH STANDARD BS EN 60510-2-6: 1996 IEC 510-2-6: 1992 Methods of Measurement for radio equipment used in satellite earth stations Part 2: Measurements for sub-systems Section 2.6 Frequency demodulators The European Standard EN60510-2-6:1994 has the status of a British Standard ICS 33.060.30BSEN60
2、510-2-6:1996 This British Standard, having beenprepared under the directionof the Electrotechnical Sector Board, was published underthe authority of the Standards Board and comes intoeffect on 15 July 1996 BSI 01-2000 The following BSI references relate to the work on this standard: Committee refere
3、nce EPL/12/5 Draft announced in BSI News, Update September 1995 ISBN 0 580 26114 X Committees responsible for this BritishStandard The preparation of this British Standard was entrusted by Technical Committee EPL/12, Radio communication, to SubcommitteeEPL/12/5, Radio communication systems, upon whi
4、ch the following bodies were represented: British Broadcasting Corporation British Radio and Electronic Equipment Manufacturers Association British Telecommunications plc ERA Technology Ltd. Institution of Electrical Engineers Radio, Electrical and Television Retailers Association Radiocommunication
5、s Agency Amendments issued since publication Amd. No. Date CommentsBSEN60510-2-6:1996 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN 60510-2-6 3 List of references Inside back coverBSEN60510-2-6:1996 ii BSI 01-2000 National foreword T
6、his Section of BSEN60510 has been prepared by SubcommitteeEPL/12/5 and is the English language version of EN60510-2-6:1994 Methods of measurement for radio equipment used in satellite earth stations Part 2: Measurements for sub-systems Section6: Frequency demodulators, published by the European Comm
7、ittee for Electrotechnical Standardization (CENELEC). It is identical with IEC510-2-6:1992, published by the International Electrotechnical Commission (IEC). This standard is published in three Parts. The other Parts are: Part 1: Methods common to sub-systems and combinations of sub-systems; Part 3:
8、 Methods of measurement for combinations of sub-systems. References in the text to IEC page numbers should be ignored. For ease of reproduction, some of the figures also include the French text. A British Standard does not purport to include all the necessary provisions of a contract. Users of Briti
9、sh Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references Publication referred to Corresponding British Standard BS EN 60510 Methods of measurement for radio equipment used in satellite e
10、arth stations EN 60510-2-5:1994 Part 2 Measurements for sub-systems Section 2.5:1996 Frequency modulators EN 60510-3 Part 3 Methods of measurement on combinations of sub-systems Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN title page, pages2 to18
11、, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN60510-2-6 June1994 UDC621.396.6:629.783:6
12、21.317.08 Descriptors: Radiocommunications, telecommunications, satellite broadcasting, radio equipment, earth stations, characteristics, measurements, frequency modulation, demodulators English version Methods of measurement for radio equipment used in satellite earth stations Part 2: Measurements
13、for sub-systems Section 6: Frequency demodulators (IEC 510-2-6:1992) Mthodes de mesure pour les quipements radiolctriques utiliss dans les stations terriennes de tlcommunication par satellites Partie 2: Mesures sur les sous-ensembles Section 6: Dmodulateurs de frquence (CEI 510-2-6:1992) Meverfahren
14、 fr Funkgert in Satelliten-Erdfunkstellen Teil 2: Messungen an Untersystemen Hauptabschnitt Sechs: Frequenzdemodulatoren (IEC510-2-6:1992) This European Standard was approved by CENELEC on1994-03-08. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the co
15、nditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in
16、 three official versions (English French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotech
17、nical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotec
18、hnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1994 Copyright reserved to CENELEC members Ref. No. EN60510-2-6:1994EEN60510-2-6:1994 BSI 01-2000 2 Foreword The CENELEC questionnaire procedure, performed for finding out whether or not
19、the International Standard IEC510-2-6:1992 could be accepted without textual changes, has shown that no common modifications were necessary for the acceptance as European Standard. The reference document was submitted to the CENELEC members for formal vote and was approved by CENELEC as EN60510-2-6
20、on8March1994. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. In this standard, Annex ZA is normative. Contents Page Foreword 2 1 Scope 3 2 Definition 3 3 General 3 4 I.F. input return loss 3 5 Baseband output impedance and return loss 3 6 Deviati
21、on sensitivity 3 7 Sense of demodulation 5 8 Differential gain/non-linearity and differential phase/group delay 5 9 Baseband amplitude/frequency characteristic 7 10 Frequency division multiplex (f.d.m) telephony measurements 8 11 Television measurements 8 12 Threshold performance 8 13 Measurement of
22、 impulsive noise in telephone channels near the threshold 10 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications 18 Figure 1 Arrangement of a typical satellite earth station demodulator sub-system 11 Figure 2 Arrange
23、ment for measuring the deviation sensitivity of a demodulator using the Bessel zero method 11 Figure 3 Arrangement for measuring the deviation sensitivity of a demodulator using the two-signal method 12 Figure 4 Arrangement for measuring the sense of demodulation 13 Figure 5 Simplified arrangement f
24、or measuring the differential gain and phase of a demodulator 14 Figure 6 Arrangement for measuring variation of output signal/noise ratio with input carrier/noise ratio 15 Figure 7 Example of variation of S/N with C/N1 for the top and bottom telephone channels 16 Figure 8 Arrangement for measuring
25、impulsive noise 17 latest date of publication ofan identical national standard (dop)1995-03-15 latest date of withdrawal ofconflicting national standards (dow)1995-03-15EN60510-2-6:1994 BSI 01-2000 3 1 Scope Methods are given in this section for the measurement of the electrical characteristics of f
26、requency demodulators. Threshold and carrier-to-noise ratio measurements are included because these are essential for satellite systems. Where possible, only measurements involving the basic demodulator are considered, excluding the equipment comprising the de-emphasis network and the networks assoc
27、iated with sound sub-carrier signals, pilot signals and auxiliary signals. Methods of measurement for frequency modulators are given in section5. Measurements between the baseband terminals of modulator/demodulator assemblies are covered by the various sections of part3 of this publication. 2 Defini
28、tion 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 by a baseband signal. This may be a multi-channel telephony or television signal with associated sound sub-c
29、arrier signals, pilot signals and auxiliary signals. Such baseband signals are normally analogue but digital signals are not excluded. However, the methods or measurement described in this section are intended for assessing the performance of the demodulator when analogue signals are transmitted. A
30、demodulator sub-system usually comprises the following three main sections: an intermediate frequency (i.f.) section; an i.f. to baseband section (e.g. discriminator); a baseband section. 3 General A block diagram for a typical demodulator as used in satellite earth stations is shown inFigure 1. Cur
31、rently, two different types of demodulator are used, namely conventional demodulators and threshold-extension demodulators. The characteristics to be measured can be divided into three principal categories: non-transfer characteristics; i.f. to baseband characteristics; certain baseband-to-baseband
32、transmission characteristics in conjunction with a measurement modulator. The first category of measurements applies toi.f. input measurements (see4) and baseband output measurements (see5). The second category of measurements forms the essential part of this section because of the nature of the dev
33、ice under test transfer fromi.f. to baseband. In order to assess the influence of thei.f. input level, some specified tests shall be made at nominal, minimum and maximum specifiedi.f. input levels. NOTEMeasurement of the influence of spurious amplitude modulation is not included in this Standard sin
34、ce 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. The third category of measurements includes those to be carried out on the complete modulator/demodulator (modem) assembly except that
35、the actual or system modulator is replaced by a measurement modulator. It is very important to know the separate contribution of a demodulator to the total permitted tolerance of performance characteristics because, in an operational situation, demodulators of one design or manufacturer may have to
36、work with modulators of another design or manufacturer. 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 requires that the measurement modulator
37、 has a better performance than that specified for the demodulator under test. 4 I.F. Input return loss See part1, section3 of this publication: Measurements in thei.f. range. Measurements at harmonics of the intermediate frequency may also be required. 5 Baseband output Impedance and return loss See
38、 part1, section 4 of this publication: Measurements in the baseband. 6 Deviation sensitivity 6.1 Definition and general considerations The deviation sensitivity (S d ) of a demodulator for a sinusoidal signal of a given frequency is expressed as the ratio of the peak value of the baseband output vol
39、tage (V b ) to the frequency deviation (%f): V band %f are both expressed in peak or r.m.s. values. (6-1)EN60510-2-6:1994 4 BSI 01-2000 The deviation sensitivity of the demodulator is usually a function of the baseband frequency because of the effect of the de-emphasis network. In some cases, howeve
40、r, it is possible to gain access to the baseband output point (Figure 1) before the de-emphasis network: in such cases, the measured deviation sensitivity of the discriminator is independent of the baseband frequency used. 6.2 Methods of measurement Two methods for obtaining the deviation sensitivit
41、y by means of a test signal of accurately known deviation may be used, namely, the Bessel zero and the two-signal methods as discussed below. In the first method, the measurement is made with a well-defined modulation Index of2,40483 at relatively low modulation frequencies,e.g. less than about2MHz,
42、 whilst in the second method a low modulation index (e.g.not exceeding about0,2) at relatively high modulation frequencies (e.g.above2MHz) is used. This latter method is therefore especially applicable to measurements at the pilot and sound sub-carrier frequencies. 6.2.1 The Bessel zero method A sui
43、table arrangement for measuring the deviation sensitivity of the demodulator and for calibrating the deviation of the measurement modulator is shown inFigure 2. The method of measurement is known as the Bessel zero method and calibration of the deviation sensitivity of the measurement modulator is b
44、ased upon the fact that, in the case of sinusoidal modulation, the carrier frequency spectral line first disappears for a modulation index (m f ) given by: where %f is the peak frequency deviation and f is the modulating frequency. The “zero” or point of first disappearance of thei.f. carrier is obs
45、erved on the spectrum analyzer, but a perfect zero may not be obtained due to residual harmonic distortion of the baseband signal generator. However, a decrease in carrier level of30dB or more is regarded as adequate. Since there are many values of the modulation index at which a carrier-zero may be
46、 obtained, the best way of ensuring that the first zero is used is by increasing the modulating voltage smoothly from zero to the point where the carrier disappears for the first time. The measurement procedure is as follows: a) the baseband generator is set to the required frequency at which the de
47、viation sensitivity is to be measured; b) the output level of the generator is set to zero and then smoothly increased until thei.f. carrier on the spectrum analyzer first disappears; c) the r.m.s. voltage (V b ) at the baseband output of the demodulator is measured; d) The demodulator deviation sen
48、sitivity (S d ) at modulation frequency f is then calculated from equation6-3: NOTEAs a modulation index of2,40483 corresponds to an occupiedi.f. bandwidth which increases linearly with modulation frequency, the use of this method is restricted to modulation frequencies which do not cause the modula
49、ted signal spectrum to exceed the system bandwidth. An alternative method is to employ a calibrated measurement demodulator in place of the spectrum analyzer. 6.2.2 The two-signal method A suitable arrangement for measuring demodulator deviation sensitivity by the two-signal method is shown inFigure 3. The method is used to calibrate the demodulator deviation sensitivity at low modulation indices, up to about0,2 and uses high modulating frequencies between2MHz and10MHz; it is therefore especially applicable at the pi
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