SIST EN 60244-9:1999
(Main)Methods of measurement for radio transmitters -- Part 9: Performance characteristics for television transposers
Methods of measurement for radio transmitters -- Part 9: Performance characteristics for television transposers
Assesses the perfomance characteristics of television transposers. Enables the comparison of the results of measurements made by different observers.
Meßverfahren für Funksender -- Teil 9: Übertragungseigenschaften von Fernsehumsetzern
Méthodes de mesure applicables aux émetteurs radioélectriques -- Partie 9: Qualité de fonctionnement des réémetteurs de télévision
Décrit les méthodes de mesure pour évaluer la qualité de fonctionnement des réémetteurs de télévision. Permet de comparer les résultats de mesures réalisées par différents observateurs.
Methods of measurement for radio transmitters - Part 9: Performance characteristics for television transposers (IEC 60244-9:1993)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 60244-9:1999
01-januar-1999
Methods of measurement for radio transmitters - Part 9: Performance
characteristics for television transposers (IEC 60244-9:1993)
Methods of measurement for radio transmitters -- Part 9: Performance characteristics for
television transposers
Meßverfahren für Funksender -- Teil 9: Übertragungseigenschaften von
Fernsehumsetzern
Méthodes de mesure applicables aux émetteurs radioélectriques -- Partie 9: Qualité de
fonctionnement des réémetteurs de télévision
Ta slovenski standard je istoveten z: EN 60244-9:1994
ICS:
33.060.20 Sprejemna in oddajna Receiving and transmitting
oprema equipment
SIST EN 60244-9:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 60244-9:1999
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SIST EN 60244-9:1999
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SIST EN 60244-9:1999
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SIST EN 60244-9:1999
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SIST EN 60244-9:1999
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SIST EN 60244-9:1999
NORME
CEI
INTERNATIONALE
IEC
244-9
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
1993-03
Méthodes de mesure applicables aux émetteurs
radioélectriques
Partie 9:
Qualité de fonctionnement des réémetteurs
de télévision
Methods of measurement of radio transmitters
Part 9:
Performance characteristics for
television 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 Internationale 3, rue de Varembé Genève, Suisse
Commission Electrotechnique Internationale
CODE PRIX "
International Electrotechnical Commission
PRICE CODEPRICE CODE
IEC
MeautyHapoAHaa 3neKTpoTexHie ect{aa %renoua
• • Pour prix, voir catalogue en vigueur
For price, see current catalogue
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SIST EN 60244-9:1999
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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 13
5 General conditions of measurements 15
6 General transposer characteristics 19
7 Stability of the characteristic vision levels and output power 31
8 Linear distortion 33
9 Non-linear distortion 41
10 Wave-form distortion 45
11 Unwanted modulation 47
12 Unwanted emissions and changes in pe rf
ormance caused by feedback
from output to input 53
13 Impairments of the pe rf
ormance caused by coupling between
output and input 59
14 Special measurements for data signals in the vision signal 61
15 Method of measurement of the sound channel(s) 61
Annexes
A Input and output signal arrangements 67
B Input impedance 71
C Noise figure and signal-to-noise ratios 75
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
METHODS OF MEASUREMENT
FOR RADIO TRANSMITTERS
Part 9: Performance characteristics
of television 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.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
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 244-9 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 1982 and its amend-
ment 1 (1983) and constitutes a technical revision.
The text of this standard is based on the following documents:
DIS Repo rt on Voting
12C(CO)224 12C(CO)228
Full information on the voting for the approval of this standard can be found in the report
on voting indicated in the above table.
Annexes A and B form an integral pa rt of this standard.
Annex C is for information only.
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INTRODUCTION
International Standard IEC 244-9 is one of a series of parts of IEC 244.
A number of existing parts of IEC 244 are currently under review and several of these will
be revised or withdrawn. When this process is complete, this series of publications
will comprise one part dealing with general characteristics, with cross-references to
relevant CCIR publications and the Radio Regulations, and a number of specialized parts,
each dealing with particular types of transmitters.
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METHODS OF MEASUREMENT
FOR RADIO TRANSMITTERS
Part 9: Performance characteristics
of television transposers
1 Scope
This part of IEC 244 contains the method of measurement to assess the performance
characteristics of television transposers. To assess all other characteristics, this standard
is to be used in conjunction with the publications quoted in clause 2.
This standard is intended to be used for type tests and acceptance or factory tests.
It is not mandatory to measure all the described characteristics. Additional measurements
may be carried out by agreement between customer and manufacturer.
The performance characteristics measured in accordance with this standard makes
possible the comparison of the results of measurements made by different observers.
Limiting values for acceptable performance are not covered by this standard but, in
connection with the presentation of measured characteristics, some data are given for
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 apply-
ing the most recent editions of the normative documents indicated below. Members of IEC
and ISO maintain registers of currently valid International Standards.
IEC 215: 1987,
Safety requirements for radio transmitting equipment
Amendment 1 (1990)
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)
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 radio transmitters — Part 10: Methods of
measurement for television transmitters and transposers employing insertion test signals
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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
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 244-13: 1991, Methods of measurement for radiotransmitters - Part 13: Performance
characteristics for FM sound broadcasting
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 - Part 1: Interface standards for
systems using dedicated interconnections
Amendment 1 (1987)
CCIR Recommendation 468-4: 1986, Measurement of audio frequency noise voltage level
in sound broadcasting
CCIR Recommendation 567-1: 1986, Transmission performance of television circuits de-
signed for use in international connections
CCIR Recommendation 653: 1986, Teletext systems
CCIR Repo rt 624-3: 1986, Characteristics of television systems
CCIR Report 795-2: 1986, Transmission of two or more sound programmes or information
channels in television.
3 General terms and definitions
3.1 Television transposer
The term "television transposer" is used in this standard to refer to the equipment in a tele-
vision relay station which is connected between the feeder terminations of the receiving
aerial and the transmitting aerial and in which a frequency transposition is performed
without demodulation and modulation.
In some television relay stations, equipment is used in which no frequency transposition
takes place. Such equipment is termed an "active deflector". Most of the measurements
described in this standard also apply to active deflectors.
3.2 Description of the television system and other relevant information
See annex A of IEC 244-5.
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3.3 Definition of performance characteristics
The definitions are given in the clause describing the method of measurements, and are in
line with those given in IEC 244-12.
3.4 Standard video test signals
The video test signals are identified by a letter symbol. They are described in annex B of
IEC 244-5.
3.5 Definitions relating to the transposer output signal
3.5.1 Rated output power
The rated output power is defined as the peak envelope power of the vision signal. The
term "rated output power" is used for various measurements in this standard.
3.5.2 Reference output level
The reference output level is the level corresponding to the specified rated output power.
3.6 Definitions relating to the transposer input signal
3.6.1 Input voltage
The voltage of the vision signal at the input of a transposer with negative (or positive)
modulation of the vision carrier is the r.m.s. voltage, expressed in millivolts (dB(mV)) or
microvolts (dB(mV)), of a sinusoidal signal with an amplitude corresponding to the peak
envelope level of the vision signal.
3.6.2 Reference input level
The reference input level (100 % or 0 dB) is the level corresponding to the peak envelope
above) which produces the rated output
value of a vision signal of given voltage (see 3.6.1
power after appropriate adjustment of the transposer gain controls.
3.6.3 Input voltage range
The input voltage range of a transposer is the range of input voltages within which the
transposer's performance specification applies.
4 General conditions of operation
The transposer shall be tested under the following conditions:
a) Any device for the suppression of unwanted signals, irrespective of whether or not it
is located inside the transposer, shall be considered as a part of the transposer for the
purpose of this standard.
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b)
Unless otherwise specified, the measurements shall be made under normal operat-
ing conditions and at rated output power. If required, they shall be repeated under
extreme environmental conditions, in accordance with the equipment specification.
The power supply voltage and environmental conditions shall be stated with the
measurement results.
c) Due to practical limitations on the position of receiving and transmitting aerials,
there will be some coupling between them.
Where such coupling is specified, all the transposer tests shall be carried out with the
coupling simulated by feeding part of the output signal to the input of the transposer by
means of directional couplers inserted in the input and output connections of the
transposer. For further details, see figures A.1 to A.3 of annex A.
5 General conditions of measurements
Because a television transposer is a piece of equipment with radio-frequency input and
output, most of the measurements are based on radio-frequency input and output signals
only. Some measurements shall be carried out on video and audio signals using a
DSB (double-sideband) modulator or test transmitter and a VSB (vestigial-sideband)
demodulator.
5.1 Measuring arrangements
For the purposes of measurement, the transposer can be considered in terms of input and
output characteristics, and of transmission performance.
Depending on the particular measurements, one of the three measuring arrangements
described below may be employed.
Details of the arrangements are given in annex A.
— Arrangement A (figure A.1 of annex A)
The arrangement is built up from three (four) radio-frequency generators, each con-
nected to a passive matching and combining network. The combined output is con-
nected to the transposer input via an adjustable attenuator.
With this arrangement, the tests do not rely upon the process of modulation and de-
modulation as in B and C below.
NOTE — Before starting the measuring procedures using arrangement A, the transposer should be adjusted
in accordance with 6.2.2.
—
Arrangement B (figure A.2 of annex A)
A double-sideband vision test modulator equipped with a receiver pre-correction group
delay filter (if required) in accordance with the system concerned, and two (three) radio-
frequency generators simulating the vision and sound carriers are used. The outputs of
the modulator and the sound carrier generators are connected to a passive matching
and combining network. The combined output is connected to the transposer input via
an adjustable attenuator.
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NOTE — Before starting the measuring procedures using arrangement B, the transposer should be adjusted
in accordance with 6.2.3.
-
Arrangement C (figure A.3 of annex A)
A test transmitter is used, capable of delivering modulated vision, sound, and data
signals in accordance with the system concerned.
NOTE — Before starting the measuring procedures using arrangement C, the transposer should be adjusted
in accordance with 6.2.3.
NOTES
1 Unless otherwise stated, the VSB demodulator in arrangements B and C should be used in the
synchronous-detection mode with the sound trap in circuit.
2 As the measurements are normally made with a VSB demodulator connected to the transposer output,
the overall performance of the combination modulator-demodulator or test transmitter-demodulator, exclud-
ing the transposer, should be known and allowed for.
5.2 General requirements regarding input signal source and test load
5.2.1 Input signal source
The output impedance of the signal source measured at the input connector of the
transposer, expressed in terms of return loss relative to the nominal input impedance of
the transposer, shall be at least:
a) 26 dB at frequencies within the input channel bandwidth;
b) 16 dB at any frequency outside this bandwidth at which a measurement is to be
made.
5.2.2 Test load
The transposer shall be terminated in a test load. For measurement purposes, this will be
connected via a directional coupler (see 5.2.3) and, possibly, cables and feeders. The
impedance which this combination presents to the transposer, measured at the point of
connection to the transposer's output, and expressed in terms of return loss relative to the
nominal load impedance of the transposer, shall be at least:
a) 30 dB at frequencies within the output channel bandwidth;
b) 16 dB at any frequency outside that bandwidth at which a measurement is to be
made.
It should be noted that for ce rt
ain measurements using arrangement A, the load should be
capable of maintaining the above characteristics whilst continuously handling a power
equal to the sum of the peak envelope powers of vision and sound signals.
5.2.3 Connection of measuring equipment to the transposer
The radio-frequency test equipment is connected to the transposer output via a calibrated
directional coupler inserted in the connection between the transposer and the test load.
For low-power transposers, the preferred arrangement for the test load is an attenuator,
the output of which is used to feed the test equipment.
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Any measuring instrument used at the input of the transposer is connected to the input via
a calibrated directional coupler inserted in the connection between the input signal source
and the transposer.
The terms "connected to the input" and "connected to the output" will be used hereinafter
for test equipment connected as described above.
6 General transposer characteristics
6.1 Input impedance
For the purpose of this standard, the input impedance of the transposer is expressed in
terms of return loss.
The input impedance shall be measured within the specified input channels and range of
input levels, using any suitable measuring techniques such as those described in annex B.
6.2 Adjustment and measurement of input levels and output power
In the adjustment and measurement procedures described below, the voltages produced
by the input signal source are measured by means of the calibrated directional coupler.
The output power of the transposer may be determined by measuring the power of a
sinusoidal signal, the amplitude of which is equal to the peak amplitude of the envelope of
the vision output signal.
6.2.1 Measuring arrangement
The output power of the transposer can be set under either manual gain or automatic gain
control conditions.
Arrangement A is used when the transposer is adjusted to the rated output power with the
manually adjusted gain control.
To adjust the "output level control" of the transposer to obtain the correct output power
when the automatic gain control is in operation, either arrangement B or arrangement C
may be used.
A calibrated spectrum analyzer may be used to measure the levels at the input and output
of the transposer.
When the same instrument is used for both purposes, it will be necessary to note the two
settings of the analyzer gain control corresponding to the reference input level and the
reference output level determined in 6.2.2 below.
When a spectrum analyzer is used in arrangement B or C, ensure that it has an appro-
priate sweep rate and bandwidth to avoid errors. It is impo rtant to ensure that the
spectrum analyzer input signal level is not too high; even if the level is below the damage
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threshold, significant errors and intermodulation products can result from high-level
signals outside the displayed frequency range.
An instrument capable of measuring the mean output power of the transposer. See 6.5 of
IEC 244-5.
6.2.2
Adjustment procedure for transposer test using arrangement A
a) Connect the equipment in accordance with arrangement A and switch the automatic
gain control off.
b) With the sound carrier(s) and vision sideband signal suppressed, adjust the
attenuator at the output of the vision carrier generator to obtain an input level within
the input voltage range of the transposer.
c) Adjust the gain of the spectrum analyzer connected to the transposer input so that
the vision carrier is referenced to the 0 dB scale point. This level then becomes the
"reference input level".
d) Adjust the manual gain control of the transposer to obtain the rated output power.
For methods of measuring the output power, see IEC 244-1.
e) Adjust the gain of the spectrum analyzer connected to the transposer output so that
the vision carrier is referenced to the 0 dB scale point. This level corresponds to the
"reference output level".
f) Adjust the attenuator at the output of the sound carrier generator(s) to obtain the
appropriate level with respect to reference input level, in accordance with the television
system concerned.
g) If necessary, readjust the manual gain control of the transposer so that the vision
carrier displayed on the analyzer again corresponds to the reference output power.
h) Proceed as follows, depending on the type of transposer concerned:
-
for transposers using separate amplification of the vision and sound carrier(s),
adjust the separate gain control of the sound channel to obtain a reading on the
spectrum analyzer at the transposer output corresponding to the appropriate level
mentioned above;
- for transposers using common amplification of the vision and sound carrier(s),
record and calculate, in decibels, the difference between the level of the sound
carrier(s) and reference output level.
6.2.3 Adjustment procedure for transposer tests using arrangements B and C
a) Adjust the manual gain control and determine the reference output level in
accordance with items a) to g) of 6.2.2.
b) Replace arrangement A with arrangement B or arrangement C, whichever is appli-
cable. Use test signal Al, i.e. an "all-black picture", for negative modulation of the
vision signal, or test signal A2, i.e. an "all-white picture", for positive modulation of
the vision signal.
c) Adjust the vision signal level control of the modulator so that the peak of the wave-
form displayed on the analyzer at the transposer output corresponds to the reference
output level.
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d) Adjust the sound signal(s) level control to obtain the appropriate input level, in
accordance with the television system concerned. Repeat the two adjustments where
necessary.
e) "output level control" of the
Switch the automatic gain control on and adjust the
transposer to obtain the same level indication on the analyzer as in item c) above.
f) Adjust or record the output level of the sound carriers as in item h) of 6.2.2.
6.3 Automatic gain control (AGC)
6.3.1 Introduction
Automatic gain control is used in a transposer in order to maintain the peak envelope level
of the vision signal or vision plus sound signal(s) substantially constant for variations of
the signal level at the input. The performance characteristics of the transposer shall
remain within specification for input signal variations within the working range of the auto-
matic gain control.
The following properties shall be measured:
automatic gain control (AGC) range;
-
- automatic gain control time constants;
effect of the AGC on the wave-form of the demodulated output signal;
-
- operation of the AGC with abnormal signals at the transposer input.
6.3.2 Automatic gain control range
6.3.2.1 Definition
The automatic gain control range of a transposer is the range of input levels, expressed in
decibels, above and below a specified input level, for which the output level remains within
specified limits.
NOTE — In certain transposers, the automatic gain control range is smaller than the input voltage range.
If this is the case, a manual control is normally provided in order to centre the AGC on the desired point of
the input voltage range.
Measuring arrangement
6.3.2.2
Arrangement B shall be used with a spectrum analyzer connected to the transposer
output.
6.3.2.3 Measuring procedure
a) Adjust the transposer in accordance with 6.2.3 with the input signal level, expressed
in dB(mV), set to the arithmetic mean of the limits of the input voltage range, also
expressed in dB(mV).
If the automatic gain control system is provided with a manual adjustment it should be
centred on the input level mentioned above.
b) By means of the attenuator at the output of the signal source, increase the input
level until the amplitude displayed on the spectrum analyzer connected to the output of
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the transposer has changed by the amount allowed in the equipment specifications,
for example ±0,5 dB. Record the change of input level in decibels.
c)
Repeat item b) but in this case for a decrease of input level.
d)
If the automatic gain control range is smaller than the input voltage range and if the
transposer is provided with a manual adjustment, the measurement shall be repeated
with the transposer input level successively adjusted to the mean level of the lowest
range and to the mean level of the highest range of the automatic gain control.
6.3.2.4 Presentation of the results
The two changes in input level obtained in items b) and c) of 6.3.2.3 give the automatic
gain control range of the transposer. State those values (for each of the three levels
concerned, if applicable) and state also the specified permissible variation of output level.
6.3.3 Automatic gain control time constants
6.3.3.1 Definition
The time constant of the automatic gain control system of a transposer is the time for the
output level to reach its steady-state level within specified limits, and to remain within
those limits, after a sudden change of input level within the automatic gain control range of
the transposer.
6.3.3.2 Measuring procedure
Proceed as follows, with the transposer adjusted as described in item a) of 6.3.2.3, for the
measurement of the automatic gain control range.
a) Set the intermediate-frequency bandwidth of the spectrum analyzer connected to
the transposer output as narrow as possible and the scanwidth as low as possible,
preferably zero, and tune the instrument to the vision carrier.
By selection of an appropriate value of sweep frequency, an almost straight horizontal
line will appear on the display of the analyzer.
b)
Increase the input level of the transposer by 6 dB and adjust the analyzer so that
the steady-state value of the wave-form displayed corresponds to the 0 dB scale point.
c)
Decrease the input level to its original value, then suddenly increase the level by
6 dB. The change in input level will appear as a hump in the wave-form displayed on
the analyzer.
d)
Determine the duration of the hump by measuring, on the analyzer display, the time
elapsed between the change in input level and the instant at which the wave-form
±1
reaches its steady-state value within the specified limits (e.g.
dB) and remains
within these limits.
e)
Repeat steps b) to d) for a sudden decrease of 6 dB in input level. The change in
output level will then appear as a trough in the wave-form displayed on the analyzer.
NOTE — It is also possible to make the measurements by means of an oscilloscope connected to a VSB
demodulator. This method is preferable if the time duration cannot be determined with sufficient accuracy
by the spectrum analyzer.
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6.3.3.3 Presentation of the results
State the times so measured as the AGC time constants of the transposer.
Alternatively, present a photograph or a hard copy of the oscilloscope picture with the time
scale on the X-axis.
6.3.4 Effect on the wave-form at the transposer outpt
The automatic gain control might affect the wave-form of the video modulation of the
vision signal at the transposer output. This shall be checked by the tests described in
clauses 7 and 10 concerning wave-form stability and transient response.
6.3.5 Abnormal input signal
The operation of the automatic gain control shall also be investigated for abnormal input
signals such as incorrect vision-to-sound ratio, loss of vision or sound carriers or both,
loss of modulation, etc. The requirements of the transposer specification relevant to such
faults will determine the tests required.
6.4 Frequency
6.4.1 Introduction
This subclause concerns the measurement of frequency transposition error and frequency
transposition stability.
6.4.2 Definitions
Frequency error is the difference between the value of frequency obtained by measure-
ment and its nominal value.
Frequency stability is expressed as the difference between the highest and the lowest
value of frequency (or frequency
...
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