1、BRITISH STANDARD BS EN 60835-1-4:1997 BS 7573-1.4: 1993 IEC 835-1-4: 1992 Incorporates Amendment No. 1 to BS7573-1.4:1993 (renumbers BS as BSEN 60835-1-4: 1997) and Amendment No.1 to BSEN60835-1-4: 1997 Methods of measurement for equipment used in digital microwave radio transmission systems Part 1:
2、 Measurements common to terrestrial radio-relay systems and satellite earth stations Section 1.4 Transmission performance The European Standard EN60835-1-4:1995, together with its amendmentA1:1995, has the status of a British Standard ICS 33.060.30BSEN60835-1-4:1997 This British Standard, having bee
3、n prepared under the directionof the Electronic Equipment Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 15May1993 BSI 03-2000 The following BSI references relate to the work on this standard: Committee reference EEL/25 Draft for comment89
4、/25989 DC ISBN 0 580 21801 5 Committees responsible for this British Standard 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 Broadcasting Co
5、rporation 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 standard, thr
6、ough subcommittees and panels: ERA Technology Ltd. Amendments issued since publication Amd. No. Date Comments 9594 September 1997 Indicated by sideline in the marginBSEN60835-1-4:1997 BSI 03-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Introduction 3
7、 1 Scope 3 2 Bit error ratio 3 3 Additional parameters 4 4 Timing jitter 5 5 Acceptable input interruption 6 Annex A (informative) Bibliography Inside back cover Figure 1 Arrangement for the measurement of bit error ratio 7 Figure 2 Definition of timing jitter 8 Figure 3 Arrangement for the measurem
8、ent of timing jitter (in accordance with 5) 9 Figure 4 Examples of frequency responses showing the jitter transfer function (a) and the maximum tolerable input jitter (b), together with limit curve examples for a bit-rate of34 spacing368kbit/s (according to1) 10 Figure 5 Arrangement for measuring th
9、e response of the radio system to input signal interruptions 10BSEN60835-1-4:1997 ii BSI 03-2000 National foreword This Section of BSEN60835 has been prepared by Technical Committee EPL/102 (formerly EEL/25), and is the English language version of EN60835-1-4:1995, Methods of measurement for equipme
10、nt used in digital microwave radio transmission systems Part1: Measurements common to terrestrial radio-relay systems and satellite earth stations Section4: Transmission performance, including amendmentA1:1995, published by the European Committee for Electrotechnical Standardization (CENELEC). It is
11、 identical with IEC835-1-4:1992, including amendment No.1:1995, 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. Compli
12、ance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages 2 to 10, an inside back cover and a back cover. This standard has been updated (see copyright
13、 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 EN 60835-1-4 February 1995 + A1 March 1995 ICS 33.060.30 Descriptors: Radiocommunications, telecommunications, satellite broadcas
14、ting, communication equipment, earth stations, radio-relay systems, microwave frequencies, characteristics, measurements, transmissions, quality English version Methods of measurement for equipment used in digital microwave radio transmission systems Part1: Measurements common to terrestrial radio-r
15、elay systems and satellite earth stations Section4: Transmission performance (including amendment A1:1995) (IEC 835-1-4:1992+A1:1995) Mthodes de mesure applicables au matriel utilis pour les systmes de transmission numrique en hyperfrquence Partie1: Mesures communes aux faisceaux hertziens terrestre
16、s et aux stations terriennes de tlcommunications par satellite Section4: Qualit de transmission (inclutlamendementA1:1995) (CEI835-1-4:1992+A1:1995) Meverfahren fr Gerte in digitalen Mikrowellen-Funkbertragungssystemen Teil1: Messungen an terrestrischen Richtfunksystemen und Satelliten-Erdfunkstelle
17、n Hauptabschnitt4: bertragungsqualitt (enthlt nderungA1:1995) (IEC835-1-4:1992+A1:1995) 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 conditions for giving this European Standard the stat
18、us 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 three official versions (English, French, German).
19、 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 electrotechnical committees of Austria, Belgium, Denmark, Fin
20、land, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische N
21、ormung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1995 Copyright reserved to CENELEC members Ref. No. EN 60835-1-4:1995+A1:1995 EEN60835-1-4:1995 BSI 03-2000 2 Foreword The text of the International Standard IEC835-1-4:1992, prepared bySC12E, Radio-relay and fixed satellite communicati
22、ons systems, of IECTC12, Radiocommunications, was submitted to the formal vote and was approved by CENELEC as EN60835-1-4 on1994-03-08 without any modification. The following dates were fixed: Foreword to amendment A1 The text of document12E(CO)165, future amendment1 to IEC835-1-4:1992, prepared by
23、SC12E, Radio-relay and satellite communications systems, of IECTC12, Radiocommunications, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as amendment A1 to EN60835-1-4:1995 on 1995-03-06. The following dates were fixed: latest date by which the EN has to be implemented at
24、 national level by publication of an identical national standard 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 a
25、n identical national standard or by endorsement (dop) 1996-03-01 latest date by which the national standards conflicting with the amendment have to be withdrawn (dow) 1996-03-01EN60835-1-4:1995 BSI 03-2000 3 Introduction The transmission performance of a digital transmission system is expressed by s
26、everal parameters, such as bit-error ratio (BER), jitter and acceptable input interruption. The BER is the most important parameter related to system transmission performance. Parameters other than the BER, for example, error-free seconds, are applicable to transmission rates up to64kbit/s. Their ap
27、plication to higher bit rates is under consideration (see2 1) ). 1 Scope This section of IEC835-1 deals with the measurement of transmission performance and is applicable to simulated digital microwave transmission systems or sub-systems. The transmission parameters should normally be measured at in
28、terface points recommended by the CCITT (see1). In special cases when equipment specifications require measurements at other ports (e.g.between modulator input and demodulator output terminals), interface circuits between the measuring equipment and the equipment under test may be necessary. 2 Bit e
29、rror ratio 2.1 Definition and general considerations The bit-error-ratio, BER, is defined as follows (see3): where: The BER is measured by comparing, bit by bit, the coincidence, or non-coincidence, of the transmitted and received bit streams. The arrangement for BER measurement is shown inFigure 1.
30、 The comparison of the transmitted and received bit streams is made and the number of errored bits is counted. The preferred test signal to be applied to the equipment under test is one having a pseudo-random pattern with a pattern length of either2 15 1 or2 23 1, depending on the nominal bit-rate o
31、f the transmission system (see4), but a selectable or programmable word pattern is sometimes used for testing the effect of specific patterns on the BER characteristics. Equation(3-1) can give an estimate of the error probability. The accuracy of this estimate increases asN eincreases, but the pract
32、ical limitations of the measurement time interval usually set a limit to the value ofN e . Assuming a random distribution of errors independent of each other and with a constant probability, i.e.according to Poissons law, the minimum acceptable value ofN eis approximately10. In this case, the true e
33、rror probability is contained in a range equal to 50% aroundN e /N twith a confidence coefficient of90% (see3). Depending on the circuit configuration, for example high spectral efficiency systems, the distribution of errors may be structured. In such cases the minimum acceptable value ofN eshould b
34、e correspondingly increased. The measurement time interval of the BER needs to be long enough to obtain the required accuracy. If a BER ofn 10 pis to be measured on a bit-stream having a bit rateB, the required measuring time t ois given by: For example, assumingN e =10 and a BER of10 -7is to be mea
35、sured at6,3Mbit/s,t oshall be longer than16s. 2.2 Method of measurement The arrangement for the measurement of BER is shown inFigure 1. The measuring instrument has a transmit portion comprising a pseudo-random test-pattern generator, a receive portion comprising an identical local reference-pattern
36、 generator and a comparator for comparing the received and locally generated reference patterns. An error counter counts the errors whenever the received and locally generated bits are not identical, and the ratio of the errored bits to the total number of bits, i.e.the BER, is displayed by the erro
37、r counter. 1) References in brackets are given inAnnex A: Bibliography. (3-1) N e is the number of bit errors in a time intervalt o N t is the total number of transmitted bits in a time intervalt o B is the bit-rate of the signal at the point where the measurement is made t o is the measurement time
38、 interval in seconds (error-counting time) (3-2)EN60835-1-4:1995 4 BSI 03-2000 The bit rate of the test pattern is usually selectable to permit the generation of the hierarchical bit rates given in1. However an external clock input is also usually available for generating non-hierarchical bit rates.
39、 The receive pattern generator is normally synchronized by the clock signal extracted from the incoming bit stream. A BER measurement range of at least10 2or10 3to10 8 or10 9should be covered. The choice of the extreme values depends on the hardware configuration and on the digital rate. In making t
40、he test, the demodulator input should be connected and disconnected several times and the highest measured BER should be recorded. When there are two or more baseband channels in the equipment under test, sufficiently uncorrelated pulse streams need to be applied to the channels and the measurements
41、 made one channel at a time. The BER is measured as a function of the specified receiver input conditions as described in the appropriate sections of parts2 and3 of IEC835. 2.3 Presentation of results The BER is expressed as a function of some appropriate parameter of the equipment being measured, s
42、uch as receiver input level. 2.4 Details to be specified The following items should be included, as required, in the detailed equipment specification: a) ports between which the measurement is to be made; b) main interface conditions, e.g.bit rate, level, impedance and coding of the signal; c) speci
43、fied receiver input levels, as appropriate; d) type and length of the test pattern; e) limiting bit error ratio characteristic; f) measurement time interval or number of errors by measurement. 3 Additional parameters This clause describes residual bit-error ratio. Other additional parameters remain
44、under consideration by other international organizations. 3.1 Residual bit-error ratio 3.1.1 Definition and general considerations Residual bit-error ratio (RBER) for digital microwave radio transmission systems is an indispensable factor to guarantee the system performance. NOTEThe RBER is the erro
45、r ratio in the absence of fading and includes allowance for system-inherent errors, environmental and ageing effects and long-term interference. The RBER should be measured with the equipment under test operating under normal conditions. An integration time should be chosen using a value given by eq
46、uation(3-2) in3.2. The BER measurements are carried out repeatedly with the fixed integration time and the RBER may be defined as the highest BER not exceeded in a specified percentage of integration intervals. The BER measurement period of one day may be appropriate. 3.1.2 Method of measurement The
47、 RBER is obtained by taking BER measurements (seeclause2) over a long period,e.g.24h, using a long integration time, e.g.15min. These examples are related for systems with a capacity of about100Mbit/s and an RBER of1 10 10 . In case of terrestrial radio-relay systems, the measurements should be carr
48、ied out with long-term interference, if required, in the absence of fading (seeIEC835-2-10). In the case of satellite communication systems, a high carrier-to-noise ratio condition should be applied (see IEC835-3-12). The measuring of the BER shall be recorded in order to obtain the highest BER not
49、exceeded in a specified percentage of integration intervals. It is advisable to record the power supply voltage and room temperature, etc.,at the same time as the BER, in order to identify any causes of error and to discard incorrect measurements produced by environmental effects which would not happen in a real link. 3.1.3 Presentation of results The residual bit-error ratio shall be expressed as the highest BER not exceeded in a specified percentage of integration intervals. 3.1.4 Details to be spec
