EN 60835-2-5:1995
(Main)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
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
Deals with the methods of measurement on a digital radio signal processsing subsystem.
Meßverfahren für Geräte in digitalen Mikrowellen-Funkübertragungssystemen - Teil 2: Messungen an terrestrischen Richtfunksystemen - Hauptabschnitt 5: Untersystem für digitale Signalverarbeitung
Méthodes de mesure applicables au matériel utilisé pour les sytèmes de transmission numérique en hyperfréquence - Partie 2: Mesures applicables aux faisceaux hertziens terrestres - Section 5: Sous-ensemble de traitement du signal numérique
Traite des méthodes de mesure applicables au sous-ensemble de traitement du signal numérique.
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 (IEC 60835-2-5:1993)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2002
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 (IEC 60835-2-5:1993)
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
Meßverfahren für Geräte in digitalen Mikrowellen-Funkübertragungssystemen -- Teil 2:
Messungen an terrestrischen Richtfunksystemen -- Hauptabschnitt 5: Untersystem für
digitale Signalverarbeitung
Méthodes de mesure applicables au matériel utilisé pour les sytèmes de transmission
numérique en hyperfréquence -- Partie 2: Mesures applicables aux faisceaux hertziens
terrestres -- Section 5: Sous-ensemble de traitement du signal numérique
Ta slovenski standard je istoveten z: EN 60835-2-5:1995
ICS:
33.060.30 Radiorelejni in fiksni satelitski Radio relay and fixed satellite
komunikacijski sistemi communications systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
NORME CEI
INTERNATIONALE IEC
60835-2-5
INTERNATIONAL
Première édition
STAN
DARD
First edition
1993-05
Méthodes de mesure applicables au matériel
utilisé pour les systèmes de transmission
numérique en hyperfréquence
Partie 2:
Mesures applicables aux faisceaux hertziens
terrestres
Section 5: Sous-ensemble de traitement
du signal numérique
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
© IEC 1993 Droits
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835-2-5 © IEC: 1993 — 3 —
CONTENTS
Page
FOREWORD 7
INTRODUCTION 9
Clause -
1 Scope 11
2 Normative references 13
3 Transmit-signal processor
Return loss 13
3.1
Alarm characteristics 13
3.2
3.3 Level and shape of the signal at the output of
the transmit-signal processor 17
3.4 Jitter at the output of the transmit-signal processor 19
4 Receive-signal processor 19
4.1 19
Acceptability of the input signal
4.2 Return loss 21
4.3 Alarm characteristics 21
4.4 Level and shape of the output signal 21
4.5 Output jitter in the absence of input jitter
5 Transmitter-receiver measurements
5.1 Absolute delay time
Acceptability of the signal at each input port of
5.2
the transmit-signal processor
5.3 Tolerable input jitter
5.4 Jitter transfer function between the input of the transmit-signal processor
and the output of the receive-signal processor
5.5 Acceptable interruption at the input of the transmit-signal processor
5.6 BER alarm characteristics
Figures
— Test arrangement for measuring the delay time of the loss of signal alarm
2 — Test arrangement for measuring the delay time of the overflow alarm
835-2-5 © IEC: 1993 — 5 —
3 — Comparison of the tolerable input jitter characteristics between the clock
extractor and the input of the sub-system under test
4 — Test arrangement for measuring the level and shape of the output signal of
the transmit-signal processor 35
— Example of pulse masks in the case of NRZ data and/CK (clock) signals
— Test arrangement for measuring the acceptability of the signal at the
input of the receiver signal processor 39
7a — Test arrangement for measuring the absolute delay time
Example of the pattern to be used in the evaluation of the absolute delay time 7b —
alarm characteristics 8 — Examples of curves for the evaluation of the BER
9 — Test arrangements for measuring the BER alarm characteristics
835-2-5 © IEC: 1993 — 7 —
INTERNATIONAL ELECTROTECHNICAL COMMISSION
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
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
promote international cooperation on all questions concerning standardization in the electrical and
electronic fields. To this end and in addition to other activities, the IEC publishes International Standards.
Their preparation is entrusted to technical committees; any IEC National Committee interested in
the subject dealt with may participate in this preparatory work. International, governmental and
non-governmental organizations liaising with the IEC also participate in this preparation. The IEC
collaborates closely with the International Organization for Standardization (ISO) in accordance with
conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
which all the National Committees having a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
3) They have the form of recommendations for international use published in the form of standards, technical
reports or guides and they are accepted by the National Committees in that sense.
In order to promote international unification, IEC National Committees undertake to apply IEC International
4)
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
International Standard IEC 835-2-5 has been prepared by sub-committee 12E: Radio-relay
and fixed satellite communications systems, of IEC technical committee 12:
Radiocommunications.
The text of this standard is based on the following documents:
DIS Report on Voting
12E(CO)151
12E(CO)141
Full information on the voting for the approval of this standard can be found in the report
on voting indicated in the above table.
IEC 835 consists of the following parts, under the general title: Methods of measurement
for equipment used in digital microwave radio transmission systems:
Part 1: Measurements common to terrestrial radio-relay systems and satellite earth
—
stations.
— Part 2: Measurements on terrestrial radio-relay systems.
Part 3: Measurements on satellite earth stations.
—
835-2-5 © IEC: 1993 — 9 —
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.e. the interface points are
not accessible. This is why some processing functions, such as differential
coding/decoding, series-parallel conversion etc., may be considered as part of the
modulator/demodulator. Consequently, the measurements carried out on the transmit- and
receive-signal processing sub-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 clauses, 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 and acceptance tests are grouped into three parts:
— measurements on the transmit-signal processor are presented in clause 3;
— measurements on the receive-signal processor are presented in clause 4;
measurements on the back-to-back connected transmitter-receiver systems are
—
presented in clause 5.
The measurements 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.
835-2-5 © IEC: 1993 — 11 —
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
1 Scope
This section deals with the methods of measurement on a digital radio signal 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 (see IEC 835-2-9, "Service Channels",
figure 1);
transmission quality evaluation for switching purposes and/or alarm indicating
—
signal (AIS) insertion;
coding and multiplexing of digital service channels, (see note);
-
— 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 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 (e.g. 34 Mbit/s and
140 Mbit/s with bit inse rtion for parity bits and digital service channels, 2 x 34 Mbit/s, etc).
For low bit rate systems, e.g. < 2 Mbit/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 bits are transmitted for quality control and switching
rface
purposes. However, as far as possible, the system should be tested at defined inte
points such as those considered by the CCITT Recommendation G.703.
NOTE - Digital service channels are dealt with in IEC 835-2-9.
835-2-5 © IEC: 1993 - 13 -
2 Normative references
The following normative documents contain provisions which, through reference in this
text, constitute provisions of this section of IEC 835-2. At the time of publication, the
editions indicated were valid. All normative documents are subject to revision, and pa rties
to agreements based on this section of IEC 835-2 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 International
Standards.
IEC 835-1-2: 1992, Methods of measurement for equipment used in digital microwave
radio transmission systems - Part 1: Measurements common to terrestrial radio-relay
systems and satellite earth stations - Section 2: Basic characteristics
IEC 835-1-4: 1992, Methods of measurement for equipment used in digital microwave
radio transmission systems - Part 1: Measurements common to terrestrial radio-relay
systems and satellite earth stations - Section 4: Transmission performance
IEC 835-2-9: 199X, Methods of measurement for equipment used in digital microwave
radio transmission systems - Part 2: Measurements on terrestrial radio-relay systems -
Section 9: Service channels (under consideration)
CCITT Recommendation G.703: Physical/electrical characteristics of hierarchical digital
interfaces
3 Transmit-signal processor
Return loss
3.1
See IEC 835-1-2.
3.2 Alarm characteristics
3.2.1 General considerations
The transmit-signal processor has some alarms relating to the 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. 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.
835-2-5 ©IEC: 1993 – 15 –
The equipment under test is driven, via a switch, by a pattern generator supplying a PRBS
at a nominal bit rate with a defined length pattern (see CCITT Recommendation G.703).
The alarm signal is displayed on an oscilloscope. By driving the switch with a low
frequency (I.f.) pulse generator, it is possible to 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 measurement.
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
jittered PRB
...
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