SIST EN 60835-3-13:2002

SLOVENSKI STANDARD
01-oktober-2002
Methods of measurement for equipment used in digital microwave radio
transmission systems - Part 3: Measurements on satellite earth stations - Section
13: VSAT systems (IEC 60835-3-13:1996)
Methods of measurement for equipment used in digital microwave radio transmission
systems -- Part 3: Measurements on satellite earth stations -- Section 13: VSAT systems
Meßverfahren für Geräte in digitalen Mikrowellen-Funkübertragungssystemen -- Teil 3:
Messungen an Satelliten-Erdfunkstellen -- Hauptabschnitt 13: VSAT-Systeme
Méthodes de mesure applicables au matériel utilisé pour les systèmes de transmission
numérique en hyperfréquence -- Partie 3: Mesures applicables aux stations terriennes de
télécommunications par satellite -- Section 13: Systèmes VSAT
Ta slovenski standard je istoveten z: EN 60835-3-13:1996
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
INTERNATIONAL 60835-3-13
Première édition
STAN
DARD
First edition
1996-04
Méthodes de mesure applicables au matériel
utilisé pour les systèmes de transmission
numérique en hyperfréquence
Partie 3:
Mesures applicables aux stations terriennes
de télécommunications par satellite
Section 13: Systèmes VSAT
Methods of measurement for equipment used in
digital microwave radio transmission systems
Part 3:
Measurements on satellite earth stations
Section 13: VSAT systems
© IEC 1996
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 forme
quelque que ce soit et par aucun any form or by any means, electronic or mechanical,
procédé, électronique ou mécanique,
y compris la photo- including photocopying and microfilm, without permission in
copie et les
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
PRICE CODE
International Electrotechnical Commission
IEC
MeniityiepomaR 3J1014TpoTexHH4eCHafl KOMHCCHA
Pour prix, voir catalogue en vigueur
• •
For price, see current catalogue

835-3-13 ©
IEC:1996 – 3 –
CONTENTS
Page
FOREWORD 5
Clause
1 General 7
1.1 Scope 7
1.2 Normative references 7
2 General description 9
3 Methods of measurement 11
3.1 General considerations 11
3.2 Antenna 11
3.3 RF characteristics 13
3.3.1 Transmit carrier frequency range, accuracy and stability 13
3.3.2 Transmitter output power 13
3.3.3 Spurious emissions 15
3.3.4 Output on/off ratio 17
3.3.5 Receive carrier frequency and tolerance 19
3.3.6 Equivalent noise temperature 19
3.3.7 Figure of merit (G/T) 19
3.3.8 On-axis EIRP 19
3.3.9 Off-axis EIRP density 21
3.4 Modulator/demodulator pe rf 21
ormance
3.4.1 Spectrum of the modulated output signal 21
3.4.2 Phase and amplitude unbalance of the modulator output signal 23
3.4.3 Bit-error-ratio performance 23
3.5 End-to-end connection test 29
3.5.1 General considerations 29
3.5.2 Method of measurement 29
3.5.3 Presentation of results 31
3.5.4 Details to be specified 31
3.6 Monitor and control 31
3.6.1 General considerations 31
3.6.2 Presentation of results 33
3.6.3 Details to be specified 33
Figures 35
Annex A – Bibliography 41
835-3-13 © IEC:1996 - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
METHODS OF MEASUREMENT
FOR EQUIPMENT USED IN DIGITAL MICROWAVE
RADIO TRANSMISSION SYSTEMS —
Part 3: Measurements on satellite earth stations —
Section 13: VSAT systems
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
ational Organization for Standardization (ISO) in accordance with
collaborates closely with the Inte rn
conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of the IEC on technical matters, express as nearly as possible an
international consensus of opinion on the relevant subjects since each technical committee has
representation from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are 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.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the
subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 835-3-13 has been prepared by sub-committee 12E: Radio
relay and satellite communication systems, of IEC technical committee 12: Radio-
communications.
The text of this standard is based on the following documents:
FDIS Report on voting
12E/237/FDIS 12E/267/RVD
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.

835-3-13 ©
IEC:1996 - 7 -
METHODS OF MEASUREMENT
FOR EQUIPMENT USED IN DIGITAL MICROWAVE
RADIO TRANSMISSION SYSTEMS —
Part 3: Measurements on satellite earth stations —
Section 13: VSAT systems
1 General
1.1
Scope
This section of IEC 835-3 deals with the methods of measurements applicable to very
small ape rt
ure terminals (VSATs) of data transmit/receive type both in the star network
(many VSATs controlled by the hub earth station) and in the point-to-point network. Some
clauses may also be applicable to the receive-only type VSATs. This section does not
handle the measurements of the hub earth stations' equipment.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this section of IEC 835-3. At the time of publication, the editions indi-
cated were valid. All normative documents are subject to revision, and part
ies to agreements
based on this section of IEC 835-3 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 - Pa
rt 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 - Pa
rt 1: Measurements common to terrestrial radio-relay
systems and satellite earth stations - Section 4: Transmission performance
835-3-2: 1995,
Methods of measurement for equipment used in digital microwave radio
transmission systems - Part 3: Measurements on satellite earth stations - Section 2:
Antenna
IEC 835-3-7: 1995, Methods of measurement for equipment used in digital microwave
radio transmission systems - Part
3: Measurements on satellite earth stations - Section 7:
Figure-of-merit of receiving system
IEC CISPR 22: 1985,
Limits and methods of measurement of radio interference charac-
teristics of information technology equipment
ITU-R" Recommendation S 725: 1992,
Technical characteristics for very small aperture
terminals (VSATs)
Formerly CCIR.
835-3-13 © IEC:1996 – 9 –
ITU-R Recommendation S 729: 1992, Control and monitoring function of very small
aperture terminals (VSATs)
ITU-T• Recommendation X 24: List of definitions for interchange circuits between
1988,
data terminal equipment (DTE) and data circuit-terminating equipment (DCE) on public
data circuit-terminating equipment (DCE) on public data networks
ITU-T Recommendation X 25: 1993, Interface between data terminal equipment (DTE) and
data circuit-terminating equipment (DCE) for terminals operating in the packet mode and
connected to public data networks by dedicated circuit
Radio Regulations, Appendix 8: 1990, Table of maximum permitted spurious emission
power levels
2 General description
VSATs are small, low-cost satellite earth stations which are equipped with small antennas
(typically 1 m to 2 m), with low power RF transmitters (typically 0,5 W to 2 W), and with
compact modem and signal processing units. They can be installed very easily on roof
tops, on a wall, or in the car park of the user's office building, where the user data
terminals are located. They can be used very conveniently and economically to connect
the user terminals to the central host computer located at a distant processing centre. The
VSATs are usually used for digital data communications. However, it is possible to use
them for voice and/or video communications by adding appropriate voice/video
coder/decoders or by adding TV receivers to demodulate analog FM TV signals.
VSATs are often used in the star type network as shown in figure 1 a). VSATs com-
municate with a relatively large central earth station, called the hub earth station. In this
case, the type of modulation, the bit rates, the coding and access techniques of the
outbound (hub to VSAT) channel and the inbound (VSAT to hub) channel are usually
different in order to use the satellite channels effectively by multiple access schemes. In
this type of VSAT networks the user data are usually processed by the VSAT and hub to
support the various computer network protocols effectively.
Point-to-point connections between VSATs as shown in figure lb) are also used. In this
case, the modulation rate and format of the transmitting and receiving signals of the VSAT
are usually the same, and the user data are usually passed through the VSAT network
transparently without the protocol processing.
Usually a network control and monitoring computer is provided to control and monitor the
network configuration and operation.
Formerly CCIR.
835-3-13 ©IEC:1996 -11 -
A typical configuration of a VSAT is shown in figure 2. It consists of an antenna, an
outdoor unit (ODU) and an indoor unit (IDU). Offset parabolic type antennas are widely
used and often the feed horn is integrated with the ODU, which contains a low noise
amplifier, a high power amplifier and up/down converters in a weatherproof housing and
installed behind the antenna focal point. The IDU contains an i.f. circuit, a modem and a
baseband signal processor, and is installed near the user data terminals. The ODU and
the IDU are connected by inter-facility link (IFL) cable(s).
The ITU-R has established recommendations for technical characteristics of VSATs
(see ITU-R Recommendations S 725 and 729).
3 Methods of measurement
3.1 General considerations
The RF po rt of the ODU is often directly fitted with the antenna feed horn. In this case,
it is necessary to separate the antenna and feed horn from the remaining pa rt of the ODU
by manufacturer's instructions, to enable the measurement of the antenna parameters
and the RF parameters at this inte rface point. Sometimes it may be necessary to use
appropriate waveguide adapters and/or transducers to connect the measuring equipment
with this interface point. In such a case, the performance of such adapters and/or
transducers should be calibrated. When the antenna feed horn is connected to the ODU
through a feeder circuit, the feeder circuit may be included either in the antenna sub-
system or in the ODU sub-system in the measurements, or its performance (e.g. loss) may
be measured separately, as appropriate. Where the loss of the feeder circuit is measured
separately, that loss should be subtracted when calculating the equivalent isotropically
radiated power (EIRP) of the VSAT (see 3.3.3, 3.3.8 and 3.3.9).
Since the control function inside the VSAT usually inhibits emission of the output RF sig-
nal when the VSAT in the star type network does not receive the appropriate control signal
from the hub station, it may be necessary to follow the manufacturer's instructions to force
the VSAT to emit the signal by disabling such control function or by using the hub
simulator with network control and monitoring computer or its emulator which generates
the control signal (see 3.5).
Most of the measurements described in this standard are performed as type tests.
3.2 Antenna
See IEC 835-3-2. Ideally, the following items should be measured:
a) on-axis gain;
b) radiation pattern;
c) cross-polarization discrimination.

835-3-13 © IEC:1996 -13 -
3.3 RF characteristics
3.3.1
Transmit carrier frequency range, accuracy and stability
3.3.1.1 Method of measurement
See IEC 835-1-2. Enable transmission of a continuous wave carrier (preferably
unmodulated) by appropriate local setting or remote control. Connect a frequency counter
to the RF port of the ODU and measure and record the carrier frequency. Change the
frequency by appropriate local and/or remote control and verify that the carrier frequency
changes as controlled. The accuracy and stability should be measured at several carrier
frequencies, if required.
3.3.1.2 Presentation of results
The result of the frequency control test should be presented in pass/fail format. The result
of the frequency stability measurement should be recorded as a function of the time. The
accuracy can be expressed as an absolute value, e.g. 50 Hz, or as a fractional value, e.g.
one part in 10-6.
3.3.1.3 Details to be specified
The following items should be included, as required, in the detailed equipment
specification:
a) nominal frequencies, and control range and steps, if applicable;
b)
port at which the frequency shall be measured;
c) permissible frequency tolerance.
3.3.2 Transmitter output power
3.3.2.1 Method of measurement
See IEC 835-1-2. Enable transmission of a continuous wave carrier (preferably modulated
by a pseudo-random bit sequence since the output power may be modulation dependent)
by appropriate local setting or remote control. Connect a power meter to the RF port of
the ODU, and measure and record the output power at several carrier frequencies, if
required. If applicable, change the output power by appropriate local and/or remote control
and repeat the measurement.
3.3.2.2 Presentation of results
The results should be presented as a function of the carrier frequency, preferably
graphically.
3.3.2.3 Details to be specified
The following items should be included, as required, in the detailed equipment specifi-
cation:
a)
nominal output power, and its control range and step, if applicable;
b) measuring frequencies or range;

835-3-13 © IEC:1996 -
15 -
c)
port at which the output power shall be measured;
d)
permissible power tolerance.
3.3.3 Spurious emissions
3.3.3.1 General considerations
Traditionally, the absolute power of the spurious components or its ratio to the carrier
power at the antenna feeder input port
is specified to be measured (see Radioregulations,
Appendix 8). Also, ITU-R Recommendation S 726 sets the limits of the spurious emissions
for the VSATs. In this recommendation, the radiated field strength around the VSAT is
specified referring to CISPR 22 for frequency ranges below about 1 GHz, while off-axis
spurious EIRP values within a specified measuring bandwidth are specified for frequency
ranges above about 1 GHz. The direct measurement of the off-axis spurious EIRP is often
impossible because its level may be too low if one wants to measure it at a distance
outside the near-field region of the antenna.
3.3.3.2
Method of measurement for the frequency range below about 1 GHz
Refer to IEC CISPR 22.
3.3.3.3
Method of measurement for the frequency range above about 1 GHz
See IEC 835-1-2. Disconnect the antenna feeder line and connect a spectrum analyzer to
the RF po rt
of the ODU through a suitable attenuator, and measure the spurious output
power or its density. The output carrier shall be enabled (on) and/or disabled (off) by
applying appropriate control signals to the VSAT, if required. The resolution bandwidth of
the spectrum analyzer shall be set as close as possible to the specified measuring
bandwidth. If the resolution bandwidth is different from the specified measuring bandwidth,
bandwidth correction should be performed for the noise-like wide-band spurious
emissions. The spurious EIRP can then be calculated by adding the measured values in
decibels to the maximum off-axis gain of the antenna over the specified off-axis angle
range measured according to clause 3.2 (radiation pattern), or its worst case value as-
sumed (e.g. 8 dBi at off-axis angles greater than 7° (see ITU-R Recommendation S 726).
Where the loss of the feeder circuit between the ODU and the antenna is measured
separately, that loss shall be subtracted (see 3.1).
3.3.3.4 Presentation of results
The results should be presented preferably in a graphical form with the frequency as the
x-axis and the spurious field strength in dB(p.V/m) for below about 1 GHz or the spurious
EIRP in dBW or dBpW for above about 1 GHz as the y-axis. The absolute spurious power
or its ratio (in decibels) to the carrier power at the antenna feed horn input po rt shall be
stated, if required.
835-3-13 © IEC:1996 –17 –
3.3.3.5 Details to be specified
The following items should be included, as required, in the detailed equipment specifi-
cation:
– for below about 1 GHz:
a) maximum permissible spurious field strength in the specified bandwidth at the
specified measuring distance, etc. as per IEC CISPR 22.
– for above about 1 GHz:
a) maximum permissible off-axis spurious EIRP over the specified off-axis angle
range, or maximum permissible absolute spurious power or its ratio to the carrier
power at the antenna feeder input port, as required;
b) specified measuring bandwidth;
c)
frequency range;
d) port at which the measurement shall be carried out;
e) maximum off-axis antenna gain to be assumed for EIRP calculation, if
applicable.
3.3.4 Output on/off ratio
3.3.4.1
Method of measurement
Disconnect the antenna feeder line and connect a spectrum analyzer to the RF port of the
ODU, through a suitable attenuator, and measure the outpu
...