EN 60244-8:1994
(Main)Methods of measurement for radio transmitters - Part 8: Performance characteristics of vestigial-sideband demodulators used for testing television transmitters and transposers
Methods of measurement for radio transmitters - Part 8: Performance characteristics of vestigial-sideband demodulators used for testing television transmitters and transposers
To be used for type tests and acceptance or factory tests or to check the characteristics of a demodulator measuring television transmitters and transposers.
Meßverfahren für Funksender - Teil 8: Übertragungseigenschaften von Restseitenband-Demodulatoren zur Prüfung von Fernsehsendern und Umsetzern
Méthodes de mesure applicables aux émetteurs radioélectriques - Partie 8: Qualité de fonctionnement des démodulateurs à bande latérale résiduelle utilisés pour les essais des émetteurs et réémetteurs de télévision
Destinées à réaliser les essais de type, ainsi que les essais de réception et les essais en usine. Peut servir à évaluer les caractéristiques d'un démodulateur utilisé pour réaliser des mesures sur les émetteurs et les réémetteurs de télévision.
Methods of measurement for radio transmitters - Part 8: Performance characteristics of vestigial-sideband demodulators used for testing (IEC 60244-8:1993)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-1999
Methods of measurement for radio transmitters - Part 8: Performance
characteristics of vestigial-sideband demodulators used for testing (IEC 60244-
8:1993)
Methods of measurement for radio transmitters -- Part 8: Performance characteristics of
vestigial-sideband demodulators used for testing television transmitters and transposers
Meßverfahren für Funksender -- Teil 8: Übertragungseigenschaften von Restseitenband-
Demodulatoren zur Prüfung von Fernsehsendern und Umsetzern
Méthodes de mesure applicables aux émetteurs radioélectriques -- Partie 8: Qualité de
fonctionnement des démodulateurs à bande latérale résiduelle utilisés pour les essais
des émetteurs et réémetteurs de télévision
Ta slovenski standard je istoveten z: EN 60244-8:1994
ICS:
33.060.20 Sprejemna in oddajna Receiving and transmitting
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
NORME
CEI
INTERNATIONALE I EC
244-8
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
1993-03
Méthodes de mesure applicables aux émetteurs
radioélectriques
Partie 8:
Qualité de fonctionnement des démodulateurs
à bande latérale résiduelle utilisés pour les essais
des émetteurs et réémetteurs de télévision
Methods of measurement for radio transmitters
Part 8:
Performance characteristics of vestigial-sideband
demodulators used for testing television transmitters
and transposers
© CEI 1993
Droits de reproduction réservés — Copyright — all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun pro- any form or by any means, electronic or mechanical,
cédé, électronique ou mécanique, y compris la photocopie et including photocopying and microfilm, without permission
les microfilms, sans l'accord écrit de l'éditeur. in writing from the publisher.
Bureau Central de la Commission Electrotechnique Intern
ationale 3, rue de Varembé Genève, Suisse
Commission Electrotechnique Internationale CODE PRIX
International Electrotechnical Commission PRICE CODE
MescayHaponHaR 3nettrpoTe%HH4ecKaR liomucCHR
IEC
• Pour prix, voir catalogue en vigueur S
For price, see current catalogue
244-8 ©IEC: 1993 - 3 -
CONTENTS
Page
FOREWORD 5
INTRODUCTION 7
Clause
1 Scope 9
2 Normative references 9
3 General terms and definitions 11
4 General conditions of operation and measurement 13
5 Measuring arrangements and standard video test signals 15
6 Demodulator input and output characteristics 15
7 Linear distortion 23
8 Non-linear distortion 31
9 Wave-form distortion 33
10 Unwanted modulation 35
11 Special measurements for data signals in the vision signal 37
12 Measurements relative to the synchronous-detection mode 37
13 Performance of the sound section 41
Annex A - Input impedance 47
244-8 © IEC: 1993 . - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
METHODS OF MEASUREMENT
FOR RADIO TRANSMITTERS
Part 8: Performance characteristics of vestigial-sideband
demodulators used for testing television transmitters
and transposers
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 244-8 has been prepared by sub-committee 12C: Transmitting
equipment, of IEC technical committee 12: Radiocommunications.
This second edition cancels and replaces the first edition published in 1980 and its amend-
ment 1 (1983) and constitutes a technical revision.
The text of this standard is based on the following documents:
DIS Report on Voting
12C(CO)223 12C(CO)227
Full information on the voting for the approval of this standard can be found in the report
on voting indicated in the above table.
Annex A is for information only.
– 7 –
244-8 © IEC: 1993
INTRODUCTION
International Standard IEC 244-8 is one of a series of parts of IEC 244.
A vestigial-sideband (VSB) demodulator is a measuring instrument for assessing the
performance characteristics of television transmitters, for which the method of measure-
ment is described in IEC 244-5. The measuring arrangement and the method of
measurement for the VSB demodulator is therefore in most cases identical with that in
IEC 244-5, with the understanding that the television transmitter is replaced by a high-
quality, double-sideband (DSB) modulator which is capable of delivering test signals
suitable for measuring an instrument which is significantly better in performance than a
television transmitter. Therefore, for most measurements, reference is made to IEC 244-5.
A number of measurements, using radio-frequency generators to simulate vision and
sound carriers and sideband signals, are fully described in this standard.
244-8©IEC:1993 - 9 -
METHODS OF MEASUREMENT
FOR RADIO TRANSMITTERS
Part 8: Performance characteristics of vestigial-sideband
demodulators used for testing television transmitters
and transposers
1 Scope
This part of IEC 244 is intended to be used for type tests and acceptance or factory tests
and may be used to check the characteristics of a demodulator used for measuring tele-
vision transmitters and transposers. It is not mandatory to measure all the described
characteristics.
Additional measurements may be carried out by agreement between customer and manu-
facturer.
Measuring performance, characteristics in accordance with this standard, makes the
comparison of the results of measurements, made by different observers, possible. Limit
values for acceptable performance are not normally specified, but, in connection with the
presentation of measured characteristics, some figures can be given for the sake of
clarity.
2 Normative references
The following normative documents contain provisions which, through reference in this
text, constitute provisions of this part of IEC 244. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and parties to agree-
ments based on this part of IEC 244 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 244-1: 1968, Methods of measurement for radio transmitters - Part 1: General
conditions of measurement, frequency, output power and power consumption (revision
under consideration)
Amendment 2, 1989
IEC 244-5: 1992, Methods of measurement for radio transmitters - Part 5: Performance
characteristics of television transmitters
IEC 244-10: 1986,
Methods of measurement for radiotransmitters. Part 10: Methods of
measurement for television transmitters and transposers employing insertion test signals
IEC 244-12-1: 1989,
Methods of measurement for radio transmitters - Part 12: Guideline
for drawing up descriptive leaflets for transmitters and transposers for sound and tele-
vision broadcasting - Characteristics to be specified
244-8 © IEC: 1993 - 11 -
IEC 244-12-2: 1989,
Methods of measurement for radio transmitters - Part
12: Guideline
for drawing up descriptive leaflets for transmitters and transposers for sound and tele-
vision broadcasting - Specification sheets
IEC 487-1: 1984,
Methods of measurement for equipment used in terrestrial radio-relay
systems - Part 1: Measurements common to sub-systems and simulated radio-relay
systems
IEC 864-1: 1986, Standardization of interconnections between broadcasting transmitters
or transmitter systems and supervisory equipment - Pa
rt 1: Interface standards for
systems using dedicated interconnections
Amendment 1, 1987
CCIR Report 404-2: 1974, Distortion of television signals due to the use of vestigial side-
band emissions
3 General terms and definitions
3.1
Vestigial-sideband demodulator
The term vestigial-sideband demodulator, sometimes referred to as a "Nyquist demodu-
lator", is used in this standard to refer to that equipment with one or more radio-frequency
inputs and with one or more demodulated video and audio outputs.
The demodulator shall include:
- a "zero carrier" reference pulse;
- true synchronous and envelope detection, switchable;
in the case of synchronous detection, a quadrature
video output;
-
a switchable "sound trap" and associated group delay correction filter (with the
sound trap switched out, the phase/frequency characteristic shall be linear);
-
independent (direct) sound demodulation, and intercarrier sound demodulation may
be used;
-
in the case of multiple sound channels, a suitable demodulator and decoder, and
analogue or digital sound outputs depending on the system concerned.
3.2
Description of the television systems and other relevant information
See annex A of IEC 244-5.
3.3 Definitions relating to the demodulator output and input signals
3.3.1 Output voltage
The peak-to-peak voltage of the video output signal.
244-8 ©IEC: 1993 - 13 -
3.3.2 Reference output level
An output voltage of 1 V between sync pulse level and white level.
3.3.3 Input voltage
The voltage of the vision signal at the input of a demodulator for negative (or positive)
modulation of the vision carrier is the r.m.s. voltage, expressed in mV or dB(mV), of a
sinusoidal signal with an amplitude corresponding to the synchronizing pulse level (or
white reference level) of that signal.
3.3.4 Input voltage range
The input voltage range of a demodulator is the range of input voltages within which the
demodulator can deliver the reference output level within its performance specifications by
adjusting the input attenuator of the demodulator.
4 General conditions of operation and measurement
The vestigial-sideband demodulator shall be tested under normal operating conditions.
A sufficient warm-up time, in accordance with the demodulator specification, shall be
allowed before commencing measurements.
The power supply and environmental conditions shall be stated with the measurement
results.
If the sources of the demodulator's input test signal have significant interaction between
their generator outputs, it is recommended that circulators be inserted between the gener-
ators and the combining network. If circulators are not available, attenuators of at least
10 dB shall be inserted at the output of each generator.
The instruments used at the input of the demodulator, are connected to the input through
a calibrated attenuator or directional coupler inserted in the connection between the input
signal source and the demodulator.
The impedance presented by the test equipment connected to the video and audio outputs
of the demodulator shall have the nominal value as specified.
Any video and audio output not used for the measurement shall be appropriately
terminated.
In both cases the return loss of the termination shall be within the tolerances specified.
If the sound trap of the demodulator is in circuit, the associated group delay precorrector
in the modulator shall also be in circuit.
244-8©IEC:1993 - 15 -
All measurements, except those specifically related to one mode of demodulation only,
shall be made in both modes, synchronous and envelope detection.
If the demodulator is fitted with both radio-frequency (RF) and intermediate frequency (IF)
inputs, the demodulator specification may require that certain tests be repeated at the
intermediate frequency input(s).
5 Measuring arrangements and standard video test signals
Figure 1 gives the measuring arrangements built up from three radio-frequency gener-
ators, simulating vision carrier, sideband signals and/or sound carrier(s).
This arrangement is used for a limited number of measurements. Most of the measure-
ments can be carried out using the arrangements described in IEC 244-5. In such cases,
the television transmitter should be replaced by the DSB test modulator.
Some measurements need modulated sound signals. In these cases, a TV test transmitter
should be used. Alternatively, one or two RF generators in combination with the DSB test
modulator may be used, with sufficient decoupling to avoid intermodulation products,
along with a switchable group delay precorrector. The precorrection should be in
accordance with the standards concerned: see clause A.3 (extract from CCIR Repo rt 624-3)
of IEC 244-5.
rformance of the input test
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.