1、BRITISH STANDARD BSEN 60835-2-5:1995 BS7573-2.5: 1995 IEC835-2-5: 1993 Methods of measurement for equipment used in digital microwave radiotransmission systems Part 2: Measurements on terrestrial radio-relay systems Section 2.5: Digital signal processing sub-system The European Standard EN60835-2-5:
2、1995 has the status of a British StandardBSEN60835-2-5:1995 This BritishStandard, having been prepared under the directionof the ElectrotechnicalSector Board,was published undertheauthority of the Standards Board and comesintoeffect on 15October1995 BSI01-2000 The following BSI references relate to
3、the work on this standard: Committee referenceEPL/12 Draft for comment91/29835DC ISBN 0 580 24595 0 Committees responsible for this British Standard The preparation of this BritishStandard was entrusted to Technical Committee EPL/12, Radio communication, upon which the following bodies were represen
4、ted: British Broadcasting 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 bodies were also represented in th
5、e drafting of the standard through subcommittees and panels: ERA Technology Ltd. Amendments issued since publication Amd. No. Date CommentsBSEN60835-2-5:1995 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN 60835-2-5 3 List of reference
6、s Inside back coverBSEN60835-2-5:1995 ii BSI 01-2000 National foreword This BritishStandard has been prepared by Technical CommitteeEPL/12 and is the English language version of EN60835-2-5:1995 Methods of measurement for equipment used in digital microwave radio transmission systems Part2:Measureme
7、nts on terrestrial radio-relay systems Section5 Digital signal processing sub-system, published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC835-2-5:1993 published by the International Electrotechnical Commission (IEC). BSEN60835 is published in t
8、hree Parts. The other Parts are: Part 1: Measurements common to terrestrial radio-relay systems and satellite earth stations; Part 3: Measurements on satellite earth stations. Some of the many Sections of the three Parts have appeared under the number BS7573, of the same genetic title. A British Sta
9、ndard 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 immunity from legal obligations. Cross-references Publication referred to Corresponding
10、 BritishStandard BSEN60835 Methods of measurement for equipment used in digital microwave radio transmission systems. EN60835-1-2:1992 Part 1: Measurements common to terrestrial radio-relay systems and satellite earth stations Section 2:1995 Basic characteristics EN60835-1-4:1992 Section 4:1995 aTra
11、nsmission performance a In preparation. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN title page, pages2 to14, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. Thi
12、s will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN60835-2-5 January1995 ICS33.060.30 Descriptors: Telecommunications,radiocommunications, communication equipment, radio-relay systems, microwave frequencies, digital technics, sign
13、al processing, measurements, characteristics English version Methods of measurement for equipment used in digital microwave radio transmission systems Part 2: Measurements on terrestrial radio-relay systems Section 5: Digital signal processing sub-system (IEC835-2-5:1993) Mthodes de mesure applicabl
14、es au matriel utilis pour les systmes de transmission numrique en hyperfrquence Partie 2: Mesures applicables aux faisceaux hertziens terrestres Section 5: Sous-ensemble de traitement du signal numrique (CEI835-2-5:1993) Meverfahren fr Gerte in digitalen Mikrowellen-Funkbertragungssystemen Teil2: Me
15、ssungen an terrestrischen Richtfunksystemen Hauptabschnitt 5: Untersystem for digitale Signalverarbeitung (IEC835-2-5:1993) This EuropeanStandard was approved by CENELEC on1994-12-06. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giv
16、ing this EuropeanStandard 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 EuropeanStandard exists in three official ve
17、rsions (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 electrotechnical committees
18、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 Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisch
19、es Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1995 Copyright reserved to CENELEC members Ref.No.EN60835-2-5:1995EEN60835-2-5:1995 BSI 01-2000 2 Foreword The text of the InternationalStandard IEC835-2-5:1993, prepared by SC12E, Radio-relay and fixed
20、satellite communications systems, of IECTC12, Radiocommunications, was submitted to the formal vote and was approved by CENELEC as EN60835-2-5 on1994-12-06 without any modification. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. In this standard,
21、 Annex ZA is normative. Annex ZA has been added by CENELEC. Contents Page Foreword 2 Introduction 3 1 Scope 3 2 Normative references 3 3 Transmit-signal processor 4 3.1 Return loss 4 3.2 Alarm characteristics 4 3.3 Level and shape of the signal at the output of the transmit-signal processor 4 3.4 Ji
22、tter at the output of the transmit-signalprocessor 5 4 Receive-signal processor 5 4.1 Acceptability of the input signal 5 4.2 Return loss 5 4.3 Alarm characteristics 5 4.4 Level and shape of the output signal 5 4.5 Output jitter in the absence of input jitter 5 5 Transmitter-receiver measurements 6
23、5.1 Absolute delay time 6 5.2 Acceptability of the signal at each input port of the transmit-signal processor 6 5.3 Tolerable input jitter 6 5.4 Jitter transfer function between the input of the transmit-signal processor and the output of the receive-signal processor 7 Page 5.5 Acceptable interrupti
24、on at the input of the transmit-signal processor 7 5.6 BER alarm characteristics 7 Annex ZA (normative) Other international publications quoted in this standard with thereferences of the relevant European publications 13 Figure 1 Test arrangement for measuring the delay time of the loss of signal al
25、arm 8 Figure 2 Test arrangement for measuring the delay time of the overflow alarm 9 Figure 3 Comparison of the tolerable inputjitter characteristics between the clock extractor and the input of the sub-system under test 9 Figure 4 Test arrangement for measuring the level and shape of the output sig
26、nal of the transmit-signal processor 10 Figure 5 Example of pulse masks in the case of NRZ data and/CK (clock) signals 10 Figure 6 Test arrangement for measuring the acceptability of the signal at the input of the receiver signal processor 11 Figure 7a Test arrangement for measuring the absolute del
27、ay time 11 Figure 7b Example of the pattern to be used inthe evaluation of the absolute delay time 11 Figure 8 Examples of curves for the evaluationofthe BER alarm characteristics 12 Figure 9 Test arrangements for measuring theBER alarm characteristics 12 latest date of publication of an identical n
28、ational standard (dop) 1995-12-01 latest date of withdrawal of conflicting national standards (dow) 1995-12-01EN60835-2-5:1995 BSI 01-2000 3 Introduction In most digital radio-relay systems it is not possible to separate the digital signal processing sub-systems from the modulator or demodulator, i.
29、e.theinterface points are not accessible. This is why some processing functions, such as differential coding/decoding, series-parallel conversionetc., may be considered as part of the modulator/demodulator. Consequently, the measurements carried out on the transmit- and receive-signal processing sub
30、-systems in closed loop do not take into account the performance of the individual parts of the signal processor inside the modulator and the demodulator, while the measurements carried out on the complete system take into account the performances of the radio part of the system. In the following cl
31、auses, measurements on the signal processor in its general configuration, i.e.,with multiplex facilities, are described. In the case of some types of signal processing (e.g.without multiplex facilities) performed inside the modulator/demodulator, most of the following measurements do not apply. Type
32、 and acceptance tests are grouped into three parts: measurements on the transmit-signal processor are presented in clause3; measurements on the receive-signal processor are presented in clause4; measurements on the back-to-back connected transmitter-receiver systems are presented in clause5. The mea
33、surements are normally taken at each input/output port, while the unused input ports are supplied by pseudo-random bit-stream (PRBS) signals, and the unused output ports are terminated with their nominal impedances. 1 Scope This section deals with the methods of measurement on a digital radio signal
34、 processing sub-system. The digital signal processing sub-system is, in general, able to perform the following principal functions: multiplexing of two or more bit streams (seeIEC835-2-9, “Service Channels”, Figure 1); transmission quality evaluation for switching purposes and/or alarm indicating si
35、gnal (AIS) insertion; coding and multiplexing of digital service channels, (seenote); scrambling and descrambling; series-to-parallel and parallel-to-series conversion. System configurations differ, so some of the above functions may be missing, in which case only the measurements relating to those
36、functions present should be taken into consideration. In digital radio-relay systems, many system configurations exist where non-hierarchical bit rates are used. In such cases, multiplex equipment is used in order to transmit more than one hierarchical bit stream and/or additional service channels (
37、e.g.34Mbit/s and140Mbit/s with bit insertion for parity bits and digital service channels,2 34Mbit/s,etc). For low bit rate systems, e.g.2Mbit/s it may not be practicable to perform tests at very low BERs because of the excessively long measurement times involved. Additionally, in many cases parity
38、bits are transmitted for quality control and switching purposes. However, as far as possible, the system should be tested at defined interface points such as those considered by the CCITT Recommendation G.703. NOTEDigital service channels are dealt with in IEC835-2-9. 2 Normative references The foll
39、owing normative documents contain provisions which, through reference in this text, constitute provisions of this section of IEC835-2. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this section of IE
40、C835-2 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid InternationalStandards. IEC835-1-2:1992, Methods of measurement for equipment used in digital microwave r
41、adio transmission systems Part1: Measurements common to terrestrial radio-relay systems and satellite earth stations Section2: Basic characteristics. IEC835-1-4:1992, Methods of measurement for equipment used in digital microwave radio transmission systems Part1: Measurements common to terrestrial r
42、adio-relay systems and satellite earth stations Section4: Transmission performance. IEC835-2-9:199X, Methods of measurement for equipment used in digital microwave radio transmission systems Part2: Measurements on terrestrial radio-relay systems Section9: Service channels (under consideration). EN60
43、835-2-5:1995 4 BSI 01-2000 CCITT Recommendation G.703, Physical/electrical characteristics of hierarchical digital interfaces. 3 Transmit-signal processor 3.1 Return loss SeeIEC835-1-2. 3.2 Alarm characteristics 3.2.1 General considerations The transmit-signal processor has some alarms relating to t
44、he incoming signal and to the correct working of the processor itself. The alarm signals are, in general, used by switching equipment and/or an AIS generator. The time to initiate and to restore the alarm may be of particular importance in the complete radio system. Below, two alarms are considered.
45、 One alarm is activated by the loss of the signal at the input of the sub-system. The other alarm is controlled by the elastic store of the sub-system in the justification process. 3.2.2 Method of measurement 3.2.2.1 Loss-of-signal alarm An example of a test arrangement is shown in Figure 1. The equ
46、ipment under test is driven, via a switch, by a pattern generator supplying a PRBS at a nominal bit rate with a defined length pattern (seeCCITT RecommendationG.703). The alarm signal is displayed on an oscilloscope. By driving the switch with a low frequency (l.f.) pulse generator, it is possible t
47、o drive repeatedly the sub-system into the alarm condition, and to restore the normal condition while displaying the operate and release alarm signal on an oscilloscope. When driving the switch by a single-shot signal, it may be necessary to use a storage oscilloscope to display the result of the me
48、asurement. 3.2.2.2 Overflow alarm The measurement is made by filling the elastic store as quickly as possible in order to drive the sub-system into the alarm condition, and then measuring the time interval taken to give the alarm. This can be performed by driving the transmit-signal processor with a
49、 jittered PRBS signal with greater than maximum tolerable jitter. An example of a test arrangement is given in Figure 2. The equipment under test is driven by a jitter generator. In order to use an oscilloscope without storage, it may be convenient to drive the equipment under test periodically into the alarm condition using a l.f. pulse generator. To determine the time interval needed to initiate the alarm, it is necessary to refer to the tolerable input jitter measurement of the equipment under test. Let
