SIST EN 60835-3-7:2002
(Main)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
- Abstract
Describes several methods of measuring the figure-of-merit (G/T) of the receiving systems of earth stations.
- Status
- Published
- Publication Date
- 30-Sep-2002
- Technical Committee
- OMS - Equipment used in mobile services and satelite comunication systems
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Oct-2002
- Due Date
- 01-Oct-2002
- Completion Date
- 01-Oct-2002
SIST EN 60835-3-7:2002 is a Slovenian standard that adopts EN 60835-3-7:1995, based on IEC 60835-3-7:1995, for satellite earth station receiving systems. It specifies methods for measuring the figure-of-merit, or G/T, so engineers can assess how well an earth station antenna and receiver perform together.
What does SIST EN 60835-3-7:2002 specify?
SIST EN 60835-3-7:2002 specifies several methods for measuring the G/T of the receiving systems of earth stations used in digital microwave radio transmission systems. The document is aimed at satellite earth stations, where the result is used to characterize receiving performance in practical testing.
The standard is organized into six clauses and two annexes.
| Annex | What it covers |
|---|---|
| Annex A | Radio star data and atmospheric loss data |
| Annex B | Bibliography |
The main clauses cover the scope, normative references, definition and general considerations, an indirect method, a direct method using a radio star, and a direct method using a remote source. In practice, that structure lets the reader choose a measurement approach, follow the right test setup, and apply the needed corrections.
What are the key requirements of SIST EN 60835-3-7:2002?
SIST EN 60835-3-7:2002 treats G/T as a logarithmic quantity related to antenna gain and absolute temperature. That matters because the measured result combines antenna and receiver performance into one figure that is widely used for satellite earth station receiving systems.
Choose the measurement method to match the earth station
Clause 3 and the introduction distinguish between indirect and direct measurement. The indirect method measures antenna gain and system noise temperature separately, then calculates G/T from those values. The direct method measures the combined receiving performance and is presented as the preferred approach for large antenna systems, while the indirect method is described as generally usable and often more feasible for small and medium-size antennas.
In practice, this means a test engineer has to decide whether accuracy, equipment size, pointing capability, and source availability favor a direct or indirect approach.
Keep the test conditions suitable for receiving measurements
Clause 3 states that measurements should be made under clear sky conditions to avoid the influence of rain, snow, cloud, and fog. The same clause also notes that the choice of method depends on the type of earth station under test.
For the reader, this means environmental conditions are part of the measurement setup, not just background information. If weather affects the path, the result may not represent the receiving system alone.
Use the indirect method by combining antenna gain and noise temperature
Clause 4 defines the indirect method as separate measurements of antenna gain G and system noise temperature T. It points the reader to IEC 835-3-2 for antenna gain and to IEC 835-1-2 for noise temperature.
In practice, the user measures the two quantities with the companion methods and then calculates G/T. This is simpler to organize when a direct signal source is not practical.
Use the direct radio star method with Y-factor and corrections
Clause 5 describes the direct method using a radio star. The measurement is based on the Y-factor, which is the ratio between received noise power when the antenna points at the radio star and when it points at the background sky at the same elevation angle.
The standard identifies three typical arrangements:
- i.f. precision variable attenuator
- r.f. precision variable attenuator
- test down-converter
This matters because each arrangement includes different parts of the receiving chain, so the test has to match the equipment contribution being assessed. Clause 5 also requires correction factors for atmospheric attenuation, radio-star angular extension, time variation of radio-star flux density, frequency dependence of the flux density, and polarization effects where relevant.
Apply the correction factors that affect the radio star measurement
Clause 5.3 extends the G/T calculation by adding correction factors C1 to C4. C1 accounts for atmospheric attenuation and depends on elevation angle, receiving frequency, humidity, and temperature. C2 accounts for the angular extension of the radio star relative to the antenna beamwidth. C3 corrects for changes in flux density with time, and C4 corrects for frequency dependence using the spectral index.
In practice, this is where the method becomes more than a simple power measurement. The user has to know the test frequency, the star data from Annex A, the antenna beamwidth, and the elevation angle to get a usable result.
Report the result with the estimated accuracy and the specified details
Clause 5.4 requires the calculated G/T to be reported together with the estimated accuracy. Clause 5.5 then lists the details to be specified, including minimum G/T, receiving frequency or frequencies, antenna polarization, beamwidth, elevation angle, earth station location, the radio star used, and the correction factors applied.
For a buyer, test lab, or quality manager, this is important because the report must show not only the number but also the test conditions behind it.
Use the remote source method for relatively small and simple receiving equipment
Clause 6 gives a direct method using a remote source and a reference antenna. It is intended for relatively small and simple receiving equipment where the radio star method or indirect method may not be appropriate.
The procedure compares received signal and noise levels at the output of the receiver under test and a reference receiver. Clause 6.2.1 breaks the work into three parts: measuring power flux density difference, measuring received signal ratio, and measuring noise ratios. Clause 6.2.2 then calculates G/T using the measured quantities, the reference antenna gain, the excess noise ratio of the standard noise source, and ambient temperature.
That means the user needs a controlled test geometry, careful level measurements, and attention to receiver non-linearity.
What terms does SIST EN 60835-3-7:2002 define?
- Figure-of-merit (G/T) - A logarithmic measure that combines antenna gain G and absolute temperature T for an earth station receiving system.
- Y-factor - The ratio of noise power with the antenna pointed at the radio star to noise power with the antenna pointed at the background sky.
- Low-noise amplifier (LNA) - A receiving-chain component shown in the test arrangements that amplifies weak signals with minimal added noise.
- Intermediate frequency (i.f.) - The frequency range used at the receiver output in the measurement arrangements and power-meter readings.
- Radio frequency (r.f.) - The higher-frequency part of the receiving chain where one of the variable attenuator test arrangements operates.
- Excess noise ratio (En) - A characteristic of the standard noise source used in the remote-source method.
- Spectral power flux density - The radio star flux density used in the direct method calculation at the measurement frequency and time.
Who uses SIST EN 60835-3-7:2002?
SIST EN 60835-3-7:2002 is used by engineers and technicians who measure or verify satellite earth station receiving performance. It is relevant to antenna and receiver designers, test laboratories, and operators of digital microwave radio transmission systems.
It also supports quality managers and buyers who need a common way to specify or check minimum G/T in equipment requirements. Because the document asks for test conditions and correction factors to be reported, it is useful wherever performance claims must be compared across systems or suppliers.
What changed in SIST EN 60835-3-7:2002 from the previous edition?
SIST EN 60835-3-7:2002 is identified as identical to EN 60835-3-7:1995 and IEC 60835-3-7:1995.
Which standards are used with SIST EN 60835-3-7:2002?
- IEC 835-1-2:1992 - Provides the basic characteristics section used for measuring system noise temperature.
- IEC 835-3-2 - Provides the antenna measurement section used for measuring antenna gain.
- ITU-R Recommendation 574-3:1990 - Gives the definition and use of the decibel and the neper in telecommunications, which supports the G/T expression.
What does the SIST EN 60835-3-7:2002 document contain?
The document contains three measurement approaches: an indirect method, a direct method using a radio star, and a direct method using a remote source. It also includes the practical correction factors needed for the radio star method and the equations used to calculate G/T.
Figures 1 to 4 show typical and simplified test arrangements, including the roles of the antenna, feed, LNA, receiver, attenuators, power meter, reference antenna, and standard noise source. Figure 5 shows the linearity and signal-ratio handling used in the remote-source method.
Annex A supplies radio star characteristics, atmospheric loss data, and a correction-factor figure for angular extension. Annex B lists supporting references for further background.
Relations
- Effective Date
- 03-Feb-2026
- Effective Date
- 03-Feb-2026
- Effective Date
- 03-Feb-2026
- Effective Date
- 03-Feb-2026
Get Certified
Connect with accredited certification bodies for this standard
ANCE
Mexican certification and testing association.
Intertek Slovenia
Intertek testing, inspection, and certification services in Slovenia.
LNE (Laboratoire National de Métrologie et d'Essais)
French national laboratory for metrology and testing.
Sponsored listings
Frequently Asked Questions
SIST EN 60835-3-7:2002 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "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". This standard covers: Describes several methods of measuring the figure-of-merit (G/T) of the receiving systems of earth stations.
Describes several methods of measuring the figure-of-merit (G/T) of the receiving systems of earth stations.
SIST EN 60835-3-7:2002 is classified under the following ICS (International Classification for Standards) categories: 33.060.30 - Radio relay and fixed satellite communications systems. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 60835-3-7:2002 has the following relationships with other standards: It is inter standard links to SIST EN 60835-1-2:2002, SIST EN 60835-3-2:2002, SIST EN 60835-3-13:2002, SIST EN 60835-3-14:2002. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
SIST EN 60835-3-7:2002 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
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
7: Figure-of-merit of receiving system (IEC 60835-3-7:1995)
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
Meßverfahren für Geräte in digitalen Mikrowellen-Funkübertragungssystemen -- Teil 3:
Messungen an Satelliten-Erdfunkstellen -- Hauptabschnitt 7: Gütezahl des
Empfangssystems
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 7: Facteur de qualité du système de réception
Ta slovenski standard je istoveten z: EN 60835-3-7:1995
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
60835-3-7
INTERNATIONAL
Première édition
STAN DARD
First edition
1995-03
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 7: Facteur de qualité du système
de réception
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 1995 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 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 MemgyHapogHaR 3neKTpoTexHH4eCHaR KOMHCCHA
vigueur
Pour prix, voir catalogue en
• •
For price, see current catalogue
- 3 -
835-3-7 © IEC:1995
CONTENTS
Page
FOREWORD 7
INTRODUCTION
Clause
1 Scope
2 Normative references
3 Definition and general considerations
4 Indirect method of measurement
5 Direct method of measurement using a radio star
5.1 General considerations 13
5.2 Method of measurement 15
5.3 Correction factors
17 Correction for atmospheric attenuation (C 1 ) 5.3.1
2) 17
5.3.2 Correction for the angular extension of the radio star (C
Correction for the change of radio-star flux density
5.3.3
with time (C3)
5.3.4 Correction for frequency dependence of flux density of
the radio star (C4)
5.3.5 Correction for the polarization of radio-star flux
5.4 Presentation of results
5.5 Details to be specified
5.6 Error analysis 21
6 Direct method of measurement using a remote source
6.1 General considerations
6.2 Method of measurement
6.2.1 Measurement procedures
6.2.2 Calculation of G/T 25
6.3 Presentation of results
6.4 Details to be specified
Figures
1 Typical G/T measurement arrangement using i.f. precision variable attenuator 27
2 Typical G/T measurement arrangement using r.f. precision variable attenuator 29
835-3-7 © IEC:1995 — 5 —
Figures Page
3 Typical G/T measurement arrangement using a test down-converter 31
4 Simplified arrangement for direct G/T measurement 33
5 Linearity and signal ratio 35
A.1 Correction factor for the angular extension of radio stars 39
Annexes
A Radio star and atmospheric loss data 37
B Bibliography 41
835-3-7 © IEC:1995 - 7 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
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
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 835-3-7 has been prepared by sub-committee 12E: Radio relay
and satellite communication systems, of IEC technical committee 12: Radiocommunications.
The text of this standard is based on the following documents:
DIS Report on voting
12E(CO)169 12E/253/RVD
Full information on the voting for the approval of this standard can be found in the repo rt
on voting indicated in the above table.
835-3-7 © IEC:1995 - 9 -
INTRODUCTION
The quantity G/T represents the figure-of-merit of an earth station for satellite communication
applications.
Two measurement principles may be used in the measurement of the G/T of an earth
station, using both direct and indirect measurement methods.
The direct method measures the combined characteristics of the antenna and the receiver
and can be carried out using a radio star or other remote transmitter as a suitable signal
source.
In the indirect method, the antenna gain and receiver equivalent noise temperature are
measured separately and the G/T is calculated from the two measurements.
The choice between the indirect method, which is of low accuracy, and of the higher
accuracy, but more complex, direct method, mainly depends on the type of satellite earth
station under test.
835-3-7 © IEC:1995 - 11 -
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
1 Scope
This section of IEC 835-3 describes several methods of measuring the figure-of-merit
(G/T) of the receiving systems of earth stations.
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 indicated were valid. All normative documents are subject to revision, and pa rties
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 - Part 1: Measurements common to terrestrial radio-relay
systems and satellite earth stations - Section 2: Basic characteristics
IEC 835-3-2, Methods of measurement for equipment used in digital microwave radio
transmission systems - Part 3: Measurements on satellite earth stations - Section 2:
Antenna (under consideration)
ITU-R Recommendation 574-3: 1990, Use of the decibel and the neper in telecom-
munications
3 Definition and general considerations
The figure-of-merit (G/T) of a satellite earth station is a logarithmic quantity which is
related to the antenna power gain G, given in decibels, and the absolute temperature T,
given in kelvins, by the following expression:
G/T = G - 10 log 10 (T/1 K) [dB/K] (1)
This definition is in accordance with that given in Recommendation ITU-R 574-3.
835-3-7 © IEC:1995 - 13 -
The indirect method (see clause 4) is generally usable with all receiving systems, taking
into account the lower measurement accuracy of the method, and is the most feasible
method for receiving systems with small and medium-size antennas. In these cases, the
expected G/T of the receiving systems does not result in a sufficiently large Y-factor to
enable the direct method to be used. The indirect method may also be used for earth
stations with large antenna systems, either when the tracking capability of the antenna is
limited or a suitable remote source does not exist.
The direct method using a radio star (see clause 5) is the preferred method, with
maximum accuracy for large antenna systems.
NOTE - If the higher accuracy, more complex, direct method is preferred, specialized knowledge and
experience is necessary to carry out the measurement.
The direct method using a remote source and reference antenna is also possible for
relatively small antennas (see clause 6).
The measurement should always be carried out with clear sky conditions so as to
eliminate the effects of rain, snow, cloud, fog, etc.
4 Indirect method of measurement
The indirect measurement uses separate measurements of antenna gain G and system
noise temperature T to calculate G/T.
For measurement of G, refer to IEC 835-3-2.
For measurement of T, refer to IEC 835-1-2 (future amendment 1).
5 Direct method of measurement using a radio star
5.1 General considerations
When the direct method of measurement using a radio star is carried out, the determination of
the figure-of-merit is based on the measurement of the Y-factor, using the following
calculation:
G/T = 10 log o S) (Y - 1) [dB/K] (2)
(8 nk / X2
where
k is the Boltzmann constant, 1,38 x 10 -23 [Ws/K];
X is the wavelength;
S is the spectral power flux density of the radiation from the radio star at the
frequency at the time of the measurement (Wm -2 Hz-1);
Y is the measured Y-f actor.
The Y-factor is defined as the ratio of the measured noise power when the antenna is
pointed towards the radio star to that measured when the antenna is pointed towards the
background sky at the same elevation angle.
835-3-7 © IEC:1995 -
15 -
5.2 Method of measurement
Three different test arrangements can be used depending on which equipment contributions
to the figure-of-merit have to be determined, as detailed in the following table:
Test arrangement Contributions
Figure 1, using i.f. attenuator Antenna feed, LNA, down-converter,
i.f. amplifier
Figure 2, using r.f. attenuator Antenna feed, LNA
Figure 3, using test down-converter Antenna feed, LNA
According to the test arrangements of figures 1 and 2, the measurement is carried out by
pointing the antenna first to the background sky at an elevation angle corresponding to
that of the chosen radio star and noting the reading of the power meter connected to the
i.f. output. The antenna is then pointed, at the same elevation angle, to the chosen radio
star, thereby causing the noise power to increase. The output noise power is reduced to
its original value by adjusting the r.f. or i.f. attenuator. The Y-factor is then given by the
difference in decibels between the two attenuator settings. The measurement can also be
accomplished using a scanning technique, which is capable of indicating the maximum
noise power by sweeping the antenna over the position of the radio star. When using the
scanning technique, the Y-factor is normally measured by reading two power levels with
the same attenuator setting.
According to the test arrangement of figure 3, the down-converter normally used in the earth
station, i.e. the operational down-converter, may be replaced by a test down-converter
which has a much improved gain stability. This will eliminate the effects of gain variations
during the antenna pointing or scanning procedure. The two noise powers are read from
the power meter connected to the i.f. output of the test down-converter.
The minimum elevation angles for the G/T measurement should be limited because of the
effect of refraction and atmospheric absorption at low elevation angles.
Followin
...