1、BRITISH STANDARD BS EN 60835-1-3:1997 BS 7573-1.3: 1993 IEC 835-1-3: 1992 Incorporating Amendment No. 1 to BS 7573-1.3:1993 (renumbers BS as BSEN 60835-1-3: 1997) and Amendment No. 1 toBS EN 60835-1-3: 1997 Methods of measurement for equipment used in digital microwave radio transmission systems Par
2、t 1: Measurements common to terrestrial radio-relay systems and satellite earth stations Section 1.3 Transmission characteristics The European Standard EN 60835-1-3:1995, together with its amendmentA1:1995, has the status of a British Standard ICS 33.060.30BSEN60835-1-3:1997 This British Standard, h
3、aving been prepared under the directionof the Electronic Equipment Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 15 April 1993 BSI 03-2000 The following BSI references relate to the work on this standard: Committee reference EEL/25 Draft
4、for comment 90/33695 DC ISBN 0 580 21733 7 Committees responsible for this BritishStandard The preparation of this British Standard was entrusted by the Electronic Equipment Standards Policy Committee (EEL/-) to Technical Committee EEL/25, upon which the following bodies were represented: British Br
5、oadcasting Corporation British Radio and Electronic Equipment Manufacturers Association British Telecommunications plc Institution of Electrical Engineers Radio, Electrical and Television Retailers Association Radiocommunications Agency The following body was also represented in the drafting of the
6、standard, through subcommittees and panels: ERA Technology Ltd. Amendments issued since publication Amd. No. Date Comments 9599 September 1997 Indicated by a sideline in the marginBSEN60835-1-3:1997 BSI 03-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2
7、 Introduction 3 1 Scope 3 2 Amplitude/frequency characteristic 3 3 Group-delay/frequency characteristic 4 4 A.M.-to-p.m. conversion and a.m. compression 5 5 Differential gain and phase 8 6 Delay difference between two transmission paths 8 Annex A (informative) Bibliography 18 Figure 1 Simplified arr
8、angement for measuring the i.f. amplitude/frequency characteristic, the group delay/frequency characteristic and a.m.-to-p.m. conversion 10 Figure 2 Example of oscilloscope display of an amplitude/frequency characteristic 11 Figure 3 Example of an oscilloscope display of a group/delay frequency char
9、acteristic 11 Figure 4 Arrangement for measuring a.m.-to-p.m. conversion factor andamplitude compression 12 Figure 5 Example of spectrum analyser display when measuring a.m.-to-p.m. conversion 12 Figure 6 Curves for determining the a.m.-to-p.m. conversion factor K p 13 Figure 7 Curves for determinin
10、g the amplitude compression coefficient C 14 Figure 8 Example of space diversity receiving system where delay difference could be a problem 15 Figure 9 Arrangement for measuring delay difference between two branches of a diversity system 15 Figure 10 Delay difference measurement: CRT display for a s
11、ynchronized switch 15 Figure 11 Delay difference measurement: CRT display for a non-synchronized switch 15 Figure 12 Arrangement for measuring the switch-over characteristic as a function of delay difference 16 Figure 13 Measurement of absolute delay of an i.f. component or sub-assembly 17BSEN60835-
12、1-3:1997 ii BSI 03-2000 National foreword This Section of BS EN 60835 has been prepared by Technical Committee EPL/102 (formerly EEL/25), and is the English language version of EN 60835-1-3:1995, Methods of measurement for equipment used in digital microwave radio transmission systems Part 1: Measur
13、ements common to terrestrial radio-relay systems and satellite earth stations Section 3: Transmission characteristics, including amendment A1:1995, published by the European Committee forElectrotechnical Standardization (CENELEC). It is identical with IEC 835-1-3:1992, including amendment No. 1:1995
14、, published by the International Electrotechnical Committee (IEC). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunit
15、y from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theENtitle page, page 2 to 18 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendme
16、nt table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 60835-1-3 February 1995 + A1 May 1995 ICS 33.060.30 Descriptors: Radiocommunications, telecommunications, satellite broadcasting, communication equipment, earth stations, radio-relay systems, microwave frequencie
17、s, characteristics, measurements English version Methods of measurement for equipment used in digital microwave radio transmission systems Part1:Measurements common to terrestrial radio-relay systems and satellite earth stations Section 3: Transmission characteristics (includes amendment A1:1995) (I
18、EC 835-1-3:1992 + A1:1995) Mthodes de mesure applicables au matriel utilis pour les systmes de transmission numrique en hyperfrquence Partie 1: Mesures communes aux faisceaux hertziens terrestres et aux stations terriennes de tlcommunications par satellite Section 3: Caractristiques de transmission
19、(inclut lamendement A1:1995) (CEI 835-1-3:1992 + A1:1995) Meverfahren for Gerte in digitalen Mikrowellen-Funkbertragungssystemen Teil1: Messungen an terrestrischen Richtfunksystemen und Satelliten-Erdfunkstellen Hauptabschnitt 3: bertragungseigenschaften enthlt nderung A1:1995) (IEC 835-1-3:1992 + A
20、1:1995) This European Standard was approved by CENELEC on 1994-03-08. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliogr
21、aphical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility o
22、f 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 electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands
23、, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1995 Copyright
24、reserved to CENELEC members Ref. No. EN 60835-1-3:1995 + A1:1995 EEN60835-1-3:1995 2 BSI 03-2000 Foreword The text of the International Standard IEC 835-1-3:1992, prepared by SC 12E, Radio-relay and fixed satellite communications systems, of IECTC 12, Radiocommunications, was submitted tothe formal
25、vote and was approved by CENELEC as EN 60835-1-3 on 1994-03-08 without any modification. The following dates were fixed: Foreword to amendment A1 The text of document 12E(CO)167, future amendment 1 to IEC 835-1-3:1992, prepared bySC12E, Radio relay and fixed satellite communication systems, of IEC T
26、C 12, Radiocommunications, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as amendment A1 to EN 60835-1-3:1992 on 1995-05-15. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standa
27、rd or by endorsement (dop)1995-12-15 latest date by which the national standards conflicting with the EN have to be withdrawn (dow)1995-12-15 latest date by which the amendment has to be implemented at national level by publication of an identical national standard or by endorsement (dop)1996-02-15
28、latest date by which the national standards conflicting with the amendment have to be withdrawn (dow)1996-02-15EN60835-1-3:1995 BSI 03-2000 3 Introduction In the following clauses, the equipment under test is any carrier-frequency part of the digital microwave transmission system such as an i.f. or
29、r.f. amplifier, a filter or a transmit-receive section between the output port of the digital modulator and the input port of the following digital demodulator. The methods described are applicable to complete systems or to sub-systems. No restrictions are made with respect to intermediate or radio
30、frequency ranges so that measurements between terminals of the same frequency range (i.f. or r.f.) or different ranges (i.f. to r.f. or r.f. to i.f.) are possible using the methods of measurement described. When adaptive equalizers are employed they shouldbe rendered inoperative, if possible, before
31、 carrying out any of the measurements described in this section. Methods of measurement for adaptive equalizers are described in IEC 835-2-8 (under consideration). 1 Scope This section of IEC 835-1 deals with methods of measurement of the characteristics which may be of importance for the transmissi
32、on performance of microwave systems with digital modulation. The need to carry out any particular measurement and the limits to be met depend, for example, on the bit rate and the method of modulation. 2 Amplitude/frequency characteristic 2.1 Definition and general considerations The amplitude/frequ
33、ency characteristic is given by the curve representing the difference, expressed in decibels, between the output level and a nominal level, as a function of frequency for a constant input level. The significance of the measurement made on linear equipment differs from that made on equipment incorpor
34、ating non-linear devices. For example, when the equipment incorporates a limiter or an amplifier with automatic gain control (a.g.c.), the amplitude/frequency characteristic of the stages preceding these devices will appear to be compressed; therefore the a.g.c. should be disconnected before making
35、the measurement. 2.2 Methods of measurement Measurements may be made using either point-by-point or swept-frequency methods. For the latter case, an example of the measurement arrangement is shown in Figure 1. When using the sweep-frequency method, the repetition rate of the sweep-frequency within t
36、he generator is normally in the range of 10 Hz to 100 Hz with a sinusoidal wave-form. The centre frequency and sweep deviation should be adjusted to the nominal values. The test arrangement in Figure 1 may also be used for end-to-end measurements, and the sweep voltageforthe X-deflection of the disp
37、lay can be obtained from the receiver part. The i.f. bandwidth of the i.f. envelope detector should be at least 50 to 100 times the chosen sweep rate. The Y-axis should be calibrated in decibels in different ranges from only a few decibels for measurements in the pass-band, up to some tens of decibe
38、ls for filter measurements in the stop-band. These features are normally to be found in test equipment of the link analyser type. With a constant input level, the output level is determined as a function of the frequency. Themeasurements may be repeated for a restricted number of different input lev
39、els within the normalrange of input levels specified for the equipment under test. The measurement may be extended to include frequencies on either side of the pass-band. In such cases, the signal will be appreciably attenuated and it will be necessary therefore to use a selective voltmeter or selec
40、tive level-meter to avoid errors caused by harmonics. 2.3 Presentation of results 2.3.1 Amplitude/frequency characteristic The results of the measurements should be presented, preferably, as an XY-record or photograph of the oscilloscope display as shown in Figure 2. Both the horizontal and the vert
41、ical scales of the oscilloscope display should be calibrated.EN60835-1-3:1995 4 BSI 03-2000 When the results of the measurements are not presented graphically, they should be given as in the following example for an i.f. sub-system: Amplitude/frequency characteristic is within 0,2 dB to + 0,1 dB wit
42、h reference to 70 MHz, from 60 MHz to80 MHz. 2.3.2 Ripple components When ripple components are easily identifiable from the measured characteristic, they should be expressed in decibels, peak-to-peak and the ripple frequency should be stated. 2.4 Details to be specified The following items should b
43、e included as required in the detailed equipment specification: a) permitted limits of amplitude variation; b) frequency limits; c) reference frequency; d) input levels; e) peak-to-peak amplitude and frequency of ripple components, if applicable. 3 Group-delay/frequency characteristic 3.1 Definition
44、 and general considerations The group-delay/frequency characteristic of a network is the first derivative of the phase/angular frequency characteristic and is expressed in seconds. It is usual to measure group-delay variation, which is the difference between the group-delay as stated above and the g
45、roup-delay at a reference frequency. The significance of the measurement when made on linear equipment is different from that made on equipment incorporating non-linear devices. When the equipment incorporates a limiter exhibiting amplitude modulation/phase modulation conversion effects, “coupled” o
46、r “indirect” distortion will be introduced: for example amplitude/frequency variation prior to such a limiter will result in an apparent change of group-delay. 3.2 Method of measurement In the preferred method shown in Figure 1, a sweep-signal having a frequency f sbetween 10 Hz and 100 Hz and abase
47、band test-signal having a frequency f t(below 1 MHz but higher than f s ), are fed to the baseband input(s) of a high-quality (test) modulator which generates a frequency-modulated i.f. signal at a high modulation index by the sweep-signal, and at a low modulation index by the baseband test signal.
48、The modulated i.f. signal is fed to the equipment under test and is then demodulated by a high-quality (test) demodulator which recovers the baseband test-signal (f t ). As the i.f. signal is swept over the i.f.bandwidth, the demodulated baseband test signal undergoes amplitude and phase variations.
49、 Thesignal from the phase detector is proportional to the i.f. group-delay. For testing r.f. equipment, up-and-down convertors with negligible inherent distortion are used between the i.f. ports of the measuring equipment and the r.f. port of the equipment under test. The following conditions should apply: a) The modulation index and test signal frequency (f t ) should be small enough to ensure that the corresponding spectrum occupies a bandwidth within which the group-delay characteristics of the network under t
