1、BRITISH STANDARD Methods of measurement for equipment used in digital microwave radio transmission systems Part 2. Measurements on terrestrial radio-relay systems Section 2.8 Adaptive equalizer * 01 * The European Standard EN 60835243 : 1993, together with its amendment Al : 1996 has the status of a
2、 British Standard ICs 33.060.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPRIGH LAW BS EN BS 7573 : Section 2.8 : 1996 1993 60835-2-8 1996 IEC 835-2-8 : Incorpomtes Amendment No. 1 to BS EN 60835-2-8 : 1996 BS EN 60835-2-8 : 1996 Issue 2, September 1997 September 1 1997 Committees r
3、esponsible for this British Standard Indicated by a sideline in the margin The preparation of this British Standard was entrusted to Technical Committee EPU12, Radio communication, upon which the foliowing bodies were represented: British Broadcasting Corporation British Radio and Electronic Equipme
4、nt Manufacturers Association British Telecommunications plc ERA Technology Ltd. Institution of Electrical Engineerc Radio, Electrical and Television Retailers Association Radiocommunications Agency This British Standard. having been prepared under the direction of the Elect,rot,echnical Sector Board
5、, was published under the authority of the Standards Board and comes into effect on 15 February 1996 O BSI 1997 Amendments issued since publication Amd.No. /Date 1 Text affected 9598 The following BSI references relate to the work on this standard: Committee reference EPMB Draft for comment 91E9837
6、DC ISBN O 580 25173 X Issue 1, September 1997 BS EN 60835-2-8 : 1996 Summary of pages The foliowing table identifies the current issue of each page. issue 1 indicates that a page has been introduced for the first time by amendment. Subsequent issue numbers indicate an updated page. Vertical sidelini
7、ng on replacement pages indicates the most recent changes (amendment, addition, deletion). Page Front cover Inside front cover a b ii EN front cover 2 3 4 5 6 7 8 9 1 Issue 2 2 1 blank 2 2 2 original original original original original original original original Page 9a 9b 10 11 12 13 14 15 16 16a 1
8、6b 17 18 Inside back cover Back cover Issue 1 1 2 Original original original Ongial original 2 1 1 original blank original Original O ES1 1997 a STD-BSI BS EN b0835-Z-A-ENGL 299b = LbZ4bb9 ObY00bL 429 BS EN 60835-2-8 : 1996 Contents Committees responsible National foreword page Inside front cover ii
9、 Foreword Text of EN 608352-8 2 3 BS EN 60835-2-8 : 1996 Issue 2, September 1997 National foreword This British Standard has been prepared by Technical Committee EPU102 (formerly EPU12) and is the English language version of EN 608352-8 : 1993 Methods of measurement for equipment used in digital mic
10、rowave mdw transmission systems Pari 2: Measurements on terratrial radw-relay systems Section 8: Adaptive equalizer, including amendment Al : 1996, published by the European Committee for Electrotechnid Standardization (CENELEC). It is identical with IEC 8335-2-8 : 1993, including amendment No. 1 :
11、1996, published by the International Electrotechnical Commission (IEC) and is part of a series. BS EN 60835 is published in three Parts. The other Parts are: Part 1 Part 3 Measurements common to terrestrial radio-why systems and satellite earth stations Measurements on satellite earth, stations This
12、 Section of BS EN 608352 covers measurements pertaining to the adaptive equalizers used in digital microwave radio-relay systems. These measurements are intended to characterize the system equalizer in the presence of selective fading and may also be performed on systems without adaptive equalizers.
13、 To take account of those properties of the system which are especially influenced by the use of frequency andor time domain equalizers, the results of measurements performed on the system are presented by so-called signatures. Additional measurements provide further means to characterize the perfor
14、mance of the system. It is expected that other Sections of the iEC Publication 835 will be published as identical British Standards, subject to their harmonization by CENELEC. Some Sections of this British Standard have already been published as Sections of BS 7573. Compliance with a British Standar
15、d does not of itself confer immunity from legal obligations. O BSI 1997 * Kn * EUROPEAN STANDARD NO= EUROPENNE EUROP NORM EN 60835-2-8 + Al July 1993 March 1996 UDC 621.396.7 : 621.317.083 Descriptors: Radiocommunications, telecommunications, communication equipment, earth stations, raic-relay syste
16、ms, microwave frequencies, measurements, characteristics English version Methods of measurement for equipment used in digital microwave radio traylsmission systems Part 2: Measurements on terrestrial radio-relay systems Section 8: Adaptive equalizer (includes amendment Al : 1996) (EC 8352-8 : 1993 +
17、 Al : 1996) Mthodes de mesure applicables au matriel utilis pour les systmes de transmission numrique en hyperfrquence Partie 2: Mesures applicables aux faisceaux hertziens terrestres Section 8: Egaliseur auto-adaptif Mefiverfahen fr Gerte in digitaien Mihowellen- Funkubertragungss ystemen Teil 2: M
18、essungen an terrestrischen Richtfunksystemen Hauptabschnitt 8: Adaptive Entzerrer (enthlt nderung Al : 1996) (inclut lamendement Al : 1996) (CE1 8352-8 : 1993 + Al : 19%) (IEC 8352-8 : 2233 + Al : 1996) This European Standard was approved by CENELEC on 1993-07-06. CENELEC members are bound to comply
19、 with the CENKENELEC 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 bibliographical references concerning such national standards may be obtained on application to the Centrai Secret
20、ariat or to any CENELEC member. This European Standard exiss in 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
21、 official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrote
22、chnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee r Elektrotechnicche Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels O 1993 Copyright reserved to CENELEC members Ref. No. EN 60835244 : 1993 + Al : 1996 E Page 2 EN 60835-2-8 : 1993 he 2, Sep
23、tember 1997 Foreword The text of document 12E(C0)146, as prepared by subcommittee 12E, Radio relay and fixed satellite 4.4 5 5.1 5.2 6.3 5.4 6 6.1 - latest date of publication of 6.2 an identical national 6.3 standard (dop) 199407-01 6.4 7 7.1 latest date of withdrawal of 7.2 communication systems,
24、of IEC technical committee 12, Radiocommunications, was submitted to the IEC-CENELEC parailel vote in November 1991. The reference document was approved by CENELEC The following dates were fixed as EN 60835243 on 6 July 1993. - conflicting national standards (dow) 199407-01 Details to be specified M
25、easurements of dynamic fading effects Definition and general considerations Method of measurement Presentation of results Details to be specified Recovery time Defintion and general considerations Measurement method Presentation of results Details to be specified Additional measurements Outage signa
26、ture with flat fading Outage signature with interfering adjacent channels Foreword to amendment A2 Figures I The text of 12E/255/FDIS, future amendment 1 to iEC 835-2-8 : 1993, prepared by SC 12E, Radio-relay and fixed satellite communication systems, of IEC TC 12, Radiocommunications, was submitted
27、 to the IEGCENELEC parallel vote and was approved by CENELEC as amendment Al to EN 60835243 : 1993 on 1996-03-05. The following dates were fixed - latest date by which the amendment has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 19961
28、241 latest date by which the national standards conflicting with the amendment have to be - withdrawn (dow) 1996-12-01 I 2 3 4 5 6 7 8 9 10 Linear distortion and crosstalk in a QAM system caused by multipage fading Block diagram of a linear baseband equalizer Basic arrangement for the measurement of
29、 signatures Example of an outage signature Example of an outage signature with possible unusual signature values Presentation of the signature, minimum phase and non-minimum phase, on the SaMe ordinate scale Example of the return signature Arrangement for the measurement of recovery time a) Bit sequ
30、ence iilustmthg the definition of recovery time b) Designation of n0rnut.i and alarm conditions Schematic for the measurement of dynamic fading effects Contents lia niustsation of Sweep waveform for the 1 2 2.1 2.2 2.3 3 3.1 3.2 3.3 3.4 4 4.1 4.2 4.3 Scope General Frequency domain equalizer Time dom
31、ain equalizer Evaluation of system parameters influenced by the equalizers Outage signature Definition and general considerations Measurement method Presentation of results Details to be specified Return signature Definition and general considerations Measurement method Presentation of results page
32、3 3 4 4 5 6 6 7 8 8 8 8 9 9 measurement of the system sensitivity to dynamic fading: sweep of the notch effect frequency relative system sensitivity to dynamic fading: sweep of the notch offset frequency 12a Illustration of sweep waveform for the measurement of the system sensitivity to dynamic fadi
33、ng: sweep of the relative echo amplitude relative system sensitivity to dynamic fading: sweep of the relative echo amplitude llb Graphical representation of the 12b Graphical representation of the Annex A - Bibliography Page 9 10 9a 9a 9b 9b 10 10 10 11 11 11 11 11 12 12 13 13 14 14 15 15 16 16 16 1
34、6a 16a 16b 16b 17 O BSI 1997 Page 3 EN 60835-2-8 : 1993 METHODS OF MEASUREMENT FOR EQUIPMENT USED IN DIGITAL MICROWAVE RADIO TRANSMISSIONS SYSTEMS Part 2: Measurements on terrestrial radio-relay systems Section 8: Adaptive equalizer 1 Scope This section of IEC 835-2 deals with measurements pertainin
35、g to the adaptive equalizers used in digital microwave radio-relay systems. These measurements are intended to characterize the system equalizer in the presence of selective fading and may also be performed on systems without adaptive equalizers. To take account of those properties of the system whi
36、ch are especially influenced by the use of frequency and/or time domain equalizers, the results of measurements performed on the system are presented by so-called signatures. Additional measurements provide further means to characterize the performance of the system. 2 General The performance of a d
37、igital radio-relay link may be influenced by multipath pro- pagation i. This is especially true in the case of high capacity multi-state QAM systems. In addition to reducing the received signal level, .e. “flat fading“, multipath propagation results in linear distortion, .e. “dispersive fading“, pro
38、ducing amplitude and phase distortion. Multistate modulation systems are especially vulnerable to this form of fading (see 835-2-4: Part 2: Measurements on terrestrial radio-relay systems - Section 4: Transmitterlreceiver (in preparation). For a system operating under multipath propagation condition
39、s the vulnerability of the time-variant channel to linear distortion is of utmost importance. In the majority of high-capacity line-of-sight digital radio-relay systems, adaptive equalizers are used to counteract “dispersive fading“ in order to decrease outages. The following types of equalizers are
40、 generally in use: - frequency-domain equalizers, which are mainly, but not necessarily, implemented at i.f, and - time-domain equalizers, which are mainly, but not necessarily, implemented at baseband. The figures in square brackets refer to annex A. Page 4 EN 60835-2-8 : 1993 2.1 Frequency domain
41、equalizer It is the purpose of a frequency domain equalizer to correct the power density spectrum of the received signal, which, for example, can be analyzed with the aid of a bank of band- pass filters. Since there is usually no major redundant information in the transmitted signal, it is not possi
42、ble to gain any information about the phase or group delay distortion of the channel; only the attenuation distortion can be recognized properly. In some cases, the equalization network is of the minimum-phase type where the phase and magnitude responses are linked to each other via the Hilbert tran
43、sform. If the channel distortion is also of the minimum-phase type, then by equalizing the magnitude response the phase response is equalized as well. If the channel distortion is of the non-minimum phase type, for example in the case of two- path propagation where the weaker signal arrives before t
44、he stronger signal at the receiver site, the phase distortion may be increased and in some cases even doubled when the attenuation is equalized. This is the basic shortcoming of such a frequency domain equalizer. Its main advantage, however, is that it will operate correctly, with certain limitation
45、s, with- out any need for a recovered carrier signal (for synchronous demodulation), or for a recov- ered timing signal (for making correct timing decisions). Therefore, in contrast to time domain equalization systems, lock-in/lock-out properties need not be investigated. 2.2 Time domain equalizer I
46、t is the purpose of a time domain equalizer to achieve an intersymbol-interference-free (SI-free) pulse shape at the input of the decision circuitry, although the channel itself may cause a considerable amount of IS1 due to multipath propagation. Basically, time domain equalizers optimize the eye-op
47、ening either in the worst-case sense, .e. by using the zero-forcing algorithm, or in the minimum-mean-square-error (MMSE) sense, .e. using the MMSE algorithm 2. For proper operation, they require at least a correctly recovered timing signal. On the other hand, it is possible for the carrier- and tim
48、ing-recovery circuits to take advantage of the operation of the equalizer by using the already equalized signal for the control of these loops. By looking at the pulse response of the channel, time domain equalizers are usually capable of counteracting both minimum and non-minimum phase channel dist
49、ortion. In general, multipath propagation causes not only distortion in the 1-1 path and in the Q-Q path but also cross-talk contamination between the quadrature signals in a QAM system, (see figure 1). Therefore the time domain equalizer, if realized at baseband, shall have equalizing circuits not only in the 1-1 and Q-Q path, but also in the I-Q and Q-I path (see figure 2). If this equalizer is realized at .f., only two equalization networks may be used and it may be possible to have only two independent controls. Page 5 EN 60835-2-8 : 1993 2.3 Evaluati
