CISPR TR 16-4-5:2006
(Main)Specification for radio disturbance and immunity measuring apparatus and methods - Part 4-5: Uncertainties, statistics and limit modelling - Conditions for the use of alternative test methods
Specification for radio disturbance and immunity measuring apparatus and methods - Part 4-5: Uncertainties, statistics and limit modelling - Conditions for the use of alternative test methods
This Technical Report specifies a method to enable product committees to develop limits for alternative test methods, using conversions from established limits. This method is generally applicable for all kinds of disturbance measurements, but focuses on radiated disturbance measurements (i.e. field strength), for which several alternative methods are presently specified. These limits development methods are intended for use by product committees and other groups responsible for defining emissions limits in situations where it is decided to use alternative test methods and the associated limits in product standards.
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TECHNICAL CISPR
REPORT 16-4-5
First edition
2006-10
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and
immunity measuring apparatus and methods –
Part 4-5:
Uncertainties, statistics and limit modelling –
Conditions for the use of alternative test methods
Reference number
CISPR 16-4-5/TR:2006(E)
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TECHNICAL CISPR
REPORT 16-4-5
First edition
2006-10
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and
immunity measuring apparatus and methods –
Part 4-5:
Uncertainties, statistics and limit modelling –
Conditions for the use of alternative test methods
© IEC 2006 ⎯ Copyright - all rights reserved
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photocopying and microfilm, without permission in writing from the publisher.
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– 2 – TR CISPR 16-4-5 © IEC:2006(E)
CONTENTS
FOREWORD.4
1 Scope.6
2 Normative references .6
3 Terms and definitions .6
4 Symbols and abbreviated terms.7
5 Introduction .8
6 Procedure to derive limits for an alternative test method.9
6.1 Overview .9
6.2 Select the reference quantity X.12
6.3 Describe the test methods and measurands .12
6.4 Determine the deviations of the measured quantities from the reference
quantity .13
6.5 Determine the average values of the deviations .13
6.6 Estimate the standard uncertainties of the test methods .14
6.7 Estimate the expanded uncertainties of the test methods .15
6.8 Calculate the average conversion factor.16
6.9 Verify the calculated values.17
6.10 Apply the conversion .17
Annex A (informative) Remarks on EUT modelling .18
Annex B (informative) Examples of application of the test method comparison
procedure .19
Bibliography.49
Figure 1 – Overview of quantities to estimate for use in conversion procedure.10
Figure 2 – Overview of limit conversion procedure using estimated quantities.11
Figure B.1 – Example reference quantity .19
Figure B.2 – EUT and antenna set-up for fully anechoic room emission measurement .20
Figure B.3 – EUT and antenna set-up for open-area test site measurement.20
Figure B.4 – Radiation characteristics of elementary radiator (left), and scheme of
EUT-model (right) .21
Figure B.5 – Maximum average deviations for 3 m FAR (top) and 10 m OATS (bottom) .24
Figure B.6 – Sample cumulative distribution function .26
Figure B.7 – Uncertainties due to the unknown EUT characteristic for 3 m FAR (top)
and 10 m OATS (bottom) .28
Figure B.8 – Expanded uncertainties (k = 2) of alternative (3 m FAR, top) and
established (10 m OATS, bottom) test methods .32
Figure B.9 – Maximum average conversion factors for different volumes .33
Figure B.10 – Photo (left) and cut-view of simulation model (right) of the specimen EUT .35
Figure B.11 – Deviations of the specimen EUT: 3 m fully anechoic room (top) and 10 m
open area test site (bottom) .36
Figure B.12 – Sample FAR measurement .37
Figure B.13 – OATS 10 m limit line converted to FAR 3 m conditions.37
TR CISPR 16-4-5 © IEC:2006(E) – 3 –
Figure B.14 – Expanded uncertainties.37
Figure B.15 – Comparison of the measured values with the corrected converted limit .38
Figure B.16 – EUT and antenna set-up of 3 m open area test site measurement.39
Figure B.17 – Maximum average deviations for 3 m OATS.40
Figure B.18 – Uncertainties due to the unknown EUT characteristic for 3 m OATS.41
Figure B.19 – Expanded uncertainties (k = 2) of alternative test method [OATS (3 m)].43
Figure B.20 – Maximum average conversion factors .44
Figure B.21 – Deviations of the specimen EUT: Open area test site (3 m).46
Figure B.22 – Sample OATS (3 m) measurement.47
Figure B.23 – OATS (10 m) limit line converted to OATS (3 m) conditions .47
Figure B.24 – Expanded uncertainties.48
Figure B.25 – Comparison of the corrected values with the converted limit .48
Table 1 – Summary of steps in conversion procedure .9
Table 2 – Overview of quantities and defining equations for conversion process.12
Table B.1 – Instrumentation uncertainty of the 3 m fully anechoic chamber test method .25
Table B.2 – Uncertainties in dB due to the unknown EUT characteristic for 3 m FAR .30
Table B.3 – Uncertainties in dB due to the unknown EUT characteristic for 10 m OATS.31
Table B.4 – Maximum average conversion factors in dB between 10 m OATS and
3 m FAR .34
Table B.5 – Uncertainties in dB due to the unknown EUT characteristic for 3 m OATS.42
Table B.6 – Maximum average conversion factors in dB between 10 m and 3 m OATS .45
– 4 – TR CISPR 16-4-5 © IEC:2006(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SPECIFICATION FOR RADIO DISTURBANCE
AND IMMUNITY MEASURING APPARATUS AND METHODS –
Part 4-5: Uncertainties, statistics and limit modelling –
Conditions for the use of alternative test methods
FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
CISPR 16-4-5, which is a technical report, has been prepared by CISPR subcommittee A:
Radio-interference measurements and statistical methods.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
CISPR/A/665/DTR CISPR/A/685/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
TR CISPR 16-4-5 © IEC:2006(E) – 5 –
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the CISPR 16-4 series, published under the general title Specification for
radio disturbance and immunity measuring apparatus and methods – Part 4: Uncertainties,
statistics and limit modelling, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
– 6 – TR CISPR 16-4-5 © IEC:2006(E)
SPECIFICATION FOR RADIO DISTURBANCE
AND IMMUNITY MEASURING APPARATUS AND METHODS –
Part 4-5: Uncertainties, statistics and limit modelling –
Conditions for the use of alternative test methods
1 Scope
This part of CISPR 16-4 specifies a method to enable product committees to develop limits for
alternative test methods, using conversions from established limits. This method is generally
applicable for all kinds of disturbance measurements, but focuses on radiated disturbance
measurements (i.e. field strength), for which several alternative methods are presently
specified. These limits development methods are intended for use by product committees and
other groups responsible for defining emissions limits in situations where it is decided to use
alternative test methods and the associated limits in product standards.
2 Normative references
IEC 60050-161, International Electrotechnical Vocabulary (IEV) – Chapter 161:
Electromagnetic compatibility
CISPR 16-4-1:2003, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 4-1: Uncertainties, statistics and limit modelling – Uncertainty in
standardized EMC tests
CISPR 16-4-2:2003, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 4-2: Uncertainties, statistics and limit modelling – Uncertainty in EMC
measurements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161 and the
following apply.
3.1
established test method
test method described in a basic standard with established emissions limits defined in
corresponding product or generic standards. An established test method consists of a specific
test procedure, a specific test set-up, a specific test facility or site, and an established
emissions limit
NOTE The following test methods have been considered to be established test methods in CISPR:
– conducted disturbance measurements: test method defined in CISPR 16-2-1:2003, Clause 7;
– radiated disturbance measurements up to 1 GHz: the test method defined in CISPR 16-2-3, 7.2.1;
– radiated disturbance measurements up to 18 GHz: the test method defined in CISPR 16-2-3, 7.3.
3.2
alternative test method
test method described in a basic standard without established emissions limits. The
alternative test method is designed for the same purpose as the established test method. An
alternative test method consists of a specific test procedure, a specific test set-up, a specific
test facility or site, and a derived emissions limit that was determined by the application of the
proposed method stated in this document
TR CISPR 16-4-5 © IEC:2006(E) – 7 –
3.3
established limit
limit having “many years” of good protection of radio services.
NOTE An example is radiated field strength measured on OATS, developed to protect radio services as described
in CISPR 16-3.
3.4
derived limit
limit applicable for the alternative test method, derived by appropriate conversion from the
established limit and expressed in terms of the misbrands
3.5
conversion factor K
for a given EUT or type of EUT, the relation of the measured value of the established test
method to the measured value of the alternative test method
NOTE The terms measured and calculated are used interchangeably at various places in this document to
describe actual laboratory tests and computer simulations.
3.6
reference quantity X
the basic parameter which determines the interference potential to radio reception. It may be
independent of the parameters presently used in established standards
NOTE The goal for both the established and alternative test methods is to determine the reference quantity (X) for
all frequencies of interest. For both established and alternative test methods, the test results may deviate from the
reference quantity values. The specification of the reference quantity when applying methods of this document
should include applicable procedures and conditions to calculate (or measure) this quantity
3.7
inherent uncertainty
u
inherent
uncertainty caused solely by the difference in EUT characteristics and the ability of the
measurement procedure to cope with them. It is specific to each test method and remains,
even if the measurement is performed perfectly, i.e., the standards compliance uncertainty is
zero and the measurement instrumentations uncertainty is zero
3.8
intrinsic uncertainty of the measurand
u
intrinsic
minimum uncertainty that can be assigned in the description of a measured quantity. In
theory, the intrinsic uncertainty of the measurand would be obtained if the measurand was
measured using a measurement system having negligible measurement instrumentation
uncertainty.
[CISPR 16-4-1, definition 3.6]
3.9
EUT type
grouping of products with sufficient similarity in electromagnetic characteristics to allow
testing with the same test installation and the same test protocol.
4 Symbols and abbreviated terms
The following abbreviations are used in this technical report:
ATM alternative test method (e.g. subscript in D )
ATM
D deviation
ETM established test method (e.g. subscript in D )
ETM
i index of one individual (e.g., of a number of EUTs)
– 8 – TR CISPR 16-4-5 © IEC:2006(E)
K conversion factor
k coverage factor
L limit
M measurement (or calculation) result
N number of EUTs
s standard deviation
U expanded uncertainty
u standard uncertainty
v volume
X reference quantity
Δ difference of two values or quantities
x mean value of a set of values x (e.g., D )
5 Introduction
Over the years, several test procedures and test set-ups for radiated emissions testing have
been described in basic standards. One particular combination of test method and test set-up
also having defined emissions limits is the open area test site (OATS) method, which has
proven to be successful for the protection of radio services. In general limits have not been
defined for the other, alternative test methods, e.g., fully anechoic room, TEM waveguide,
reverberation chamber.
Each alternative method can be used to get measurement results related to emission of the
EUT. Although each method gives an emission level from the EUT, the different methods may
capture the EUT emission differently. For example, considering radiated emission
measurements, different methods may capture different EUT radiation pattern lobes, differing
numbers of lobes, or the test facility may alter the EUT radiation pattern producing a different
apparent emission level. Therefore the limits defined for the established test method cannot
be applied directly to the alternative test methods. Consequently, a procedure is needed for
how to derive limits to use for the results of alternative test methods.
The specification for such a procedure should consider the general goal of disturbance
measurements. The aim of the disturbance measurement is to verify whether the EUT
satisfies or violates certain compliance criteria. Past experience has shown that using the
present system of the established test method and the associated limits yields a situation
without many cases of interference due to conducted or radiated emissions. Applying the
established test method with the associated limits will fulfill the protection requirement with a
high probability. To preserve this situation, the most important requirement for the use of
alternative test methods is as follows.
– Use of an alternative test method in a normative standard shall provide the same
protection of radio services as the established test method.
This requirement can be met by developing a procedure for deriving emission limits for the
alternative test method from the existing limits of the established test method. Such a
procedure shall relate the results of the alternative test method to those of the established
test method. Using this relation the limits of the established test method can be converted into
limits for the alternative test method. The measured values of the alternative test method can
then easily be evaluated against the converted limits. Such a procedure will provide a similar
amount of protection, even though an alternative test method is used.
TR CISPR 16-4-5 © IEC:2006(E) – 9 –
The limits conversion procedure should consider the goal of emissions measurements as
described above. The results of standard emissions tests can be considered as an
approximation of the interference potential of an EUT. Depending on the characteristics of the
EUT (e.g., radiation pattern characteristics for radiated disturbance test methods), and on the
measurement set-up, the measured value differs from the actual interference potential of the
EUT. This deviation can be divided into two parts: a systematic deviation, which can be
interpreted as a bias of the test method, and a random deviation depending on the
characteristics of different EUTs, which can be interpreted as an uncertainty of the test
method. Each emissions test method contains both quantities, and consequently the
established test method does too. In the following clauses, a procedure based on these two
quantities for comparing an alternative test method with the established test method is
described. To determine these quantities, the abstract term “interference potential” needs to
be expressed in terms of a physical quantity. For the purposes of this report, this quantity is
called the “reference quantity,” X. More details about correlation of test methods using a
)
reference quantity can be found in [1] .
6 Procedure to derive limits for an alternative test method
6.1 Overview
A procedure to derive limits for an alternative test method based on the limits of an
established test method is described in the following paragraphs. Figure 1 shows a summary
of the estimated quantities needed for the correlation process. Figure 2 shows a flowchart for
the correlation process using these quantities. The nine-step conversion process below can
be accomplished using numerical simulations, measurements, or a combination of simulations
and measurements. Calculable or reference EUTs are invaluable for this conversion
procedure. In the following subclauses, as part of the conversion process the quantities
shown in Figure 1 and Figure 2 are combined into several equations. A summary of the
equations is given in Table 2. A summary of the steps in the conversion procedure is shown in
Table 1.
Table 1 – Summary of steps in conversion procedure
1 Select the reference quantity
2 Describe the test methods and measurands
3 Determine the deviations of the measured quantities from the reference quantity
4 Determine the average values of the deviations
5 Determine the standard uncertainties of the test methods
6 Verify the calculated values
7 Apply the conversion
———————
1)
Figures in square brackets refer to the Bibliography.
– 10 – TR CISPR 16-4-5 © IEC:2006(E)
Statistical consideration
set of N EUTs
Alternative test Reference Established test
method
quantity method
definition
Measurement result Reference quantity Measurement result
X
M M
ATM ETM
– –
+ +
Set of deviations Set of deviations
D D
ATM ETM
+–
Average deviation
Average deviation
D
D
ATM
ETM
Standard deviation Standard deviation
inherent uncertainty inherent uncertainty
∼ ∼
s(D ) D , s(D ) D ,
ATM ATM inherent ETM ETM inherent
Comparison
Average
of expanded
conversion
measurement
factor k
uncertainties
IEC 1694/06
Figure 1 – Overview of quantities to estimate for use in conversion procedure
TR CISPR 16-4-5 © IEC:2006(E) – 11 –
Limit for established
Average
conversion test method L
ETM
factor k
–
+
Limit for alternative
Limitf oralternative
test method L
ATM
Uncertainties of Uncertainties of
alternative test method established test method
Inherent uncertainty Inherent uncertainty
U U
ATM, inherent ETM, inherent
Instrumentation uncertainty Instrumentation uncertainty
U U
ATM, instrumentation ETM, instrumentation
Intrinsic uncertainty Intrinsic uncertainty
U U
ATM, intrinsic ETM, intrinsic
Alternative test method + Established test method
–
expanded uncertainty expanded uncertainty
U U
ATM ETM
Difference of
uncertainties
Δ
Corrected limit for alternative test method L
ATM,U
IEC 1695/06
Figure 2 – Overview of limit conversion procedure using estimated quantities
– 12 – TR CISPR 16-4-5 © IEC:2006(E)
Table 2 – Overview of quantities and defining equations for conversion process
Quantity Meaning Equation no.
the deviation from the reference quantity of the measurement result of EUT i (1)
D (f )
ATMi
as produced by the alternative test method
the deviation from the reference quantity of the measurement result of EUT i (2)
D (f )
ETMi
as produced by the established test method
the average deviation of the alternative test method (3)
D
ATM
the average deviation of the established test method (4)
D
ETM
the inherent uncertainty of the alternative test method (5)
u
ATM,inherent
the inherent uncertainty of the established test method (6)
u
ETM,inherent
combined standard uncertainty of the alternative test method (7)
u
ATM
the expanded uncertainty of the alternative test method (8)
U
ATM
combined standard uncertainty of the established test method (9)
u
ETM
the expanded uncertainty of the established test method (10)
U
ETM
frequency dependent conversion factor for EUT i (11)
K (f )
i
the average of the conversion factors (12), (13), (14)
K (f )
the limit line of the alternative test method equivalent to the limit of the (15)
L (f )
ATM
established test method, without consideration of the uncertainties
difference of expanded uncertainties (16)
Δ
the limit to be used for alternative measurements (17)
L
ATM,U
6.2 Select the reference quantity X
The first step is to select the reference quantity X. It should be selected on the basis of a
quantity that can possibly cause interference to a radio service, and selection of a reference
quantity also depends on the type of EUT.
For the types of EUTs investigated in Annex B, as an example the maximum electric field
strength determined on a sphere of a certain radius around the EUT has been selected as the
reference quantity for radiated emission measurements in the frequency range of 30 MHz to
1 GHz. In the frequency range below 30 MHz, depending on the frequency subrange and the
coupling model, the reference quantity may be the vertical component of the electric field
strength, the magnetic field strength, or the asymmetric voltage. In general, the reference
quantity and the actual measurands will not necessarily have the same units.
6.3 Describe the test methods and measurands
The measurand shall be described for both the alternative and the established test methods.
In addition, the test set-up geometry, the methods of measurement for EUT emissions, and
any analysis methods producing the final measurement results shall be described. This
description is necessary for an understanding about how the test method works and to give a
basis for comparison of the two test methods. In most cases this description is explicit or
implicit in the standards that specify the test methods.
TR CISPR 16-4-5 © IEC:2006(E) – 13 –
6.4 Determine the deviations of the measured quantities from the reference quantity
Each test method provides results, each of which deviate from the reference quantity X. The
deviation depends on the characteristics of the test set-up as well as on the characteristics of
the EUT. Considering a certain EUT i, a frequency dependent deviation can be determined for
both alternative and established test method.
For a given EUT i the deviation of the alternative test method, in a logarithmic scale, is given
as
)D (f ) = X (f ) − M (f (1)
ATMi i ATMi
where
i is the index of the EUT;
f is the frequency;
D (f ) is the deviation from the reference quantity of the measurement result of EUT i as
ATMi
produced by the alternative test method;
X (f ) is the reference quantity defined in 6.2 for the EUT i, and
i
M (f ) is the measurement result given by the alternative test method for the EUT i.
ATMi
The results of the established test method will deviate from the reference quantity as well.
The deviation of the established test method is analogously given by the equation
)D (f ) = X (f ) − M (f (2)
ETMi i ETMi
where
X (f ) , f, i are the same as in Equation (1);
i
D (f ) is the deviation from the reference quantity of the measurement result of EUT i as
ETMi
produced by the established test method;
M (f ) is the measurement result given by the established test method for the EUT i.
ETMi
6.5 Determine the average values of the deviations
The deviations given by Equations (1) and (2) will differ for different EUTs. In order to obtain
more universal results, varying characteristics of EUTs shall be considered, for example as
shown in Annex A. Considering a range of N EUTs leads to a set of N values for the deviation
D for both alternative and established test methods. From this set of D the average can be
easily determined. See Annex A for more details about EUT considerations and variations.
An estimate of the mean of the deviation of the alternative test method is given by
N
(3)
D = D
ATM ATMi
∑
N
i =1
where
D is the set of deviations of the alternative test method;
ATM
D is the average deviation of the alternative test method;
ATM
N is the number of EUTs considered, and shall be as large as possible for statistical
reasons;
i is the index of any one EUT;
D is the deviation from the reference quantity of the measurement result of EUT i, as
ATMi
produced by the alternative test method [Equation (1)].
– 14 – TR CISPR 16-4-5 © IEC:2006(E)
An estimate of the mean of the deviation of the established test method is given by
N
D = D (4)
ETM ∑ ETMi
N
i =1
where
D is the set of deviations of the established test method;
ETM
D is the average deviation of the established test method;
ETM
N, i are the same as in Equation (3);
D is the deviation from the reference quantity of the measurement result of EUT i, as
ETMi
produced by the established test method [Equation (2)].
6.6 Estimate the standard uncertainties of the test methods
The methods comparison procedure must consider uncertainties, as are associated with every
measurement result. Because the results from the established test method itself have
uncertainties, care must be taken that these uncertainties are not transferred to results from
the alternative test methods as part of the conversion procedure. Otherwise, the use of
alternative test methods would be burdened with uncertainties that are characteristics of the
established test method.
The uncertainty of emission measurements consists of several components. On one hand, the
measurement equipment contributes several uncertainties, as documented in CISPR 16-4-2.
On the other hand the test set-up combined with the radiation characteristics of the EUT
causes an inherent uncertainty, u . For example, in radiated emissions measurements,
inherent
for some types of EUT radiation patterns, an OATS test (established test method) may fail to
capture the radiated emission peak lobe. Deviations between the results of a test method and
the reference quantity depend on the radiation characteristics of the EUT, but the radiation
characteristics of an arbitrary EUT are not known a priori. The resulting uncertainty u
inherent
can be estimated only if the behaviour of EUTs with different characteristics is examined.
Analogously to as in 6.4, the deviations from the reference quantity of a set of N EUTs can be
used for estimating the standard deviation as a measure for the inherent uncertainties.
Using the formula for experimental standard deviation, the inherent uncertainty of the
alternative test method is given by:
N
(D − D )
∑ ATMi ATM
i =1
u = s(D ) = (5)
ATM,inherent ATM
N −1
where
u is the inherent uncertainty of the alternative test method;
ATM,inherent
s(D ) is the experimental standard deviation of the set D ;
ATM ATM
N, i, D , D are the same as in Equation (3).
ATM ATMi
Analogously, the inherent uncertainty of the established test method is given:
N
(D − D )
∑ ETMi ETM
i =1
u = s(D ) = (6)
ETM,inherent ETM
N −1
TR CISPR 16-4-5 © IEC:2006(E) – 15 –
where
u is the inherent uncertainty of the established test method;
ETM,inherent
s(D ) is the experimental standard deviation of the set D ;
ETM ETM
N, i, D , D are the same as in Equation (4).
ETM ETMi
6.7 Estimate the expanded uncertainties of the test methods
The expanded measurement uncertainty is obtained from the multiplication of the combined
standard uncertainties by a coverage factor k. The combined standard uncertainty of the
alternative test method u can be calculated from
ATM
2 2 2
u = u + u + u (7)
ATM ATM,m ATM,intrinsic ATM,inherent
where
u is the combined standard uncertainty of the alternative test method
ATM,m
contributed by measurement instrumentation;
u is the inherent uncertainty of the alternative test method, according to
ATM,inherent
Equation (5);
u is the intrinsic uncertainty of the alternative test method.
ATM,intrinsic
Using the coverage factor k, the expanded uncertainty of the alternative test method is
estimated:
U = k ⋅u (8)
ATM ATM
where
U is the expanded uncertainty of the alternative test method;
ATM
k is the coverage factor;
u is the combined standard uncertainty of the alternative test method
ATM
according to Equation (7).
Analogously the combined standard uncertainty of the established test method u can be
ETM
obtained,
2 2 2
u = u + u + u (9)
ETM ETM,m ETM,intrinsic ETM,inherent
where
u is the combined standard uncertainty of the established test method
ETM,m
contributed by measurement instrumentation;
u is the EUT-dependent uncertainty of the established test method, according to
ETM,inherent
Equation (6);
u is the intrinsic uncertainty of the established test method.
ETM,intrinsic
The expanded uncertainty of the established test method is given by
U = k ⋅u (10)
ETM ETM
– 16 – TR CISPR 16-4-5 © IEC:2006(E)
where
U is the expanded uncertainty of the established test method;
ETM
k is the coverage factor;
u is the combined standard uncertainty of the established test method according
ETM
to Equation (9).
6.8 Calculate the average conversion factor
For each EUT i a frequency dependent conversion factor K (f ) can be calculated using
i
K f = D f − D f (11)
)( ) ( ) (
i ATMi ETMi
where
D (f ) is the deviation from the reference quantity of the measurement result of EUT i,
ATMi
as produced by the alternative test method [Equation (1)];
D (f ) is the deviation from the reference quantity of the measurement result of EUT i,
ETMi
as produced by the established test method [Equation (2)].
The average conversion factor can be calculated from the average deviations of the
alternative and the established test methods:
K (f ) = D (f ) − D (f ) (12)
ATM ETM
where
K(f ) is the set of conversion factors;
K (f ) is the average of the conversion factors;
D (f ) is the average deviation of the alternative test method from the reference quantity,
ATM
in dB;
D (f ) is the average deviation of the established test method from the reference
ETM
quantity, in dB.
Substituting the averages by Equations (3) and (4) gives:
N N
1 1
K = D − D = D − D (13)
ATM ETM ATM i ETM i
∑∑
N N
i==11i
Using Equations (1) and (2), the average conversion factor can be expressed in terms of the
measurement results of the set of EUTs:
N N N
1 1 1
K = ( X − M ) − ( X − M ) = (M − M )
(14)
i ATM i i ETM i ETM i ATM i
∑∑ ∑
N N N
i==11i i =1
where K is the same as in Equation (12) and M and M are the same as in
ETMi ATMi
Equation (1) and Equation (2).
TR CISPR 16-4-5 © IEC:2006(E) – 17 –
6.9 Verify the calculated values
In many cases it is necessary to obtain both the deviations from the reference quantity, and
their average and standard deviation values, from numerical simulations. It is strongly
recommended to verify such calculations by measurements.
6.10 Apply the conversion
If the limit lines defined for the established test method are to be converted into limit lines for
an alternative test method, the results from Equations (8), (10), and (12) or (14), respectively,
are needed.
A limit line of an established test method can be converted into limit conditions for an
alternative test method using the average conversion factor:
L (f ) = L (f ) − K (f ) (15)
ATM ETM
where
K (f ) is the frequency-dependent average conversion factor according to Equation (12);
L (f ) is the frequency-dependent limit of the established test method;
ETM
L (f ) is the limit line of the alternative test method equivalent to the limit of the
ATM
established test method, without consideration of the uncertainties.
To complete the process, the uncertainties of both alternative and established test methods
Δ
have to be taken into account. Defining a difference, , between the uncertainty of the
alternative test method, U , and the uncertainty of the established test method U , i.e.,
ATM ETM
)Δ = U (f ) − U (f (16)
ATM ETM
implies a rule for how to handle the measurement uncertainties. If the uncertainty of the
alternative test method is larger than the uncertainty of the established test method, it shall be
used to correct the limit of the alternative test method:
L − Δ if Δ > 0
⎧
ATM
L = (17)
⎨
ATM,U
L if Δ ≤ 0
⎩ ATM
where L is the limit to be used for alternative measurements.
ATM,U
– 18 – TR CISPR 16-4-5 © IEC:2006(E)
Annex A
(informative)
Remarks on EUT modelling
As discussed in 6.5 and 6.6, the characteristics of an EUT directly influence the measurement
results, and thus influence the deviations from the reference quantity. Considering the
example of radiated emission measurements, the radiation pattern of the EUT influences the
probability of capture for a maximum emission using the peak search procedure of an open-
area test site or a fully-anechoic room measurement. To obtain more universal results, it is
necessary to consider multiple EUTs having different radiation characteristics for use in
determining conversion parameters. This annex describes general considerations about EUT
modelling for use in investigations about emission measurement methods.
A.1 Types of EUTs
Certain characteristics of EUTs typically have the most influence on the radiation behaviour. It
is useful to categorize EUTs with equivalent primary characteristics into several EUT types,
which can then be considered and investigated independently. One general classification is to
group EUTs into the following three types, based on the test set-up:
a) tabletop equipment without cables;
b) tabletop equipment with cable(s);
c) floorstanding equipment.
A.2 Application of statistics
Each EUT category of Clause A.1 consists of many different devices and operating and
performance characteristics. To best cover these widely-varying characteristics, applying
statistical methods is helpful. With a statistical approach, universally valid values for average
conversion parameters and the uncertainties can be obtained. The uncertainty resulting from
the unknown radiation characteristics of an EUT, u , can only be determined by
inherent
considering a range of different EUTs and analysing the resulting data statistically. An
example of such a statistical approach is given in Annex B.
TR CISPR 16-4-5 © IEC:2006(E) – 19 –
Annex B
(informative)
Examples of application of the test method comparison procedure
B.1 Example 1 – Measurements at 3 m-separation in fully anechoic room
compared to 10 m-separation measurements on open-area test site
In the following subclause headings, numbers in parentheses refer to subclauses in the main
body of this document.
B.1.1 Small EUTs without cables
B.1.1.1 Select the reference quantity X (see 6.2)
The protection requirement is to minimize the risk that the disturbance field strength radiated
by an EUT interferes with radio services. A measure for this interference potential of the EUT
is the electric field strength emitted by the EUT. Because the EUT final-use set-up in general
is unknown or is variable, it is necessary to search for the maximum field strength in all
directions from the EUT and for all polarisations. Therefore the reference quantity is selected
to be the maximum far-field electric field-strength emitted under free space conditions,
independent o
...
CISPR TR 16-4-5 ®
Edition 1.1 2014-07
CONSOLIDATED VERSION
TECHNICAL
REPORT
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 4-5: Uncertainties, statistics and limit modelling – Conditions for the use
of alternative test methods
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CISPR TR 16-4-5 ®
Edition 1.1 2014-07
CONSOLIDATED VERSION
TECHNICAL
REPORT
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 4-5: Uncertainties, statistics and limit modelling – Conditions for the use
of alternative test methods
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.100.10; 33.100.20 ISBN 978-2-8322-1770-2
CISPR TR 16-4-5 ®
Edition 1.1 2014-07
CONSOLIDATED VERSION
REDLINE VERSION
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 4-5: Uncertainties, statistics and limit modelling – Conditions for the use
of alternative test methods
– 2 – CISPR TR 16-4-5:2006
+AMD1:2014 CSV IEC 2014
CONTENTS
FOREWORD. 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and abbreviated terms . 8
5 Introduction . 8
6 Procedure to derive limits for an alternative test method . 9
6.1 Overview . 9
6.2 Select the reference quantity X . 12
6.3 Describe the test methods and measurands . 13
6.4 Determine the deviations of the measured quantities from the reference
quantity . 13
6.5 Determine the average values of the deviations . 13
6.6 Estimate the standard uncertainties of the test methods . 14
6.7 Estimate the expanded uncertainties of the test methods . 15
6.8 Calculate the average conversion factor . 16
6.9 Verify the calculated values . 17
6.10 Apply the conversion . 17
7 Measurement-based procedure to derive limits for an alternative test method
based on measurement results . 17
7.1 General . 17
7.2 Application of practical measurement results to determine the conversion
fac tors . 17
Annex A (informative) Remarks on EUT modelling . 21
Annex B (informative) Examples of application of the test method comparison
procedure . . 22
Annex C (informative) Example of the application of the test method comparison
procedure based on measurement results . 52
Bibliography . . 58
Figure 1 – Overview of quantities to estimate for use in conversion procedure. . 10
Figure 2 – Overview of limit conversion procedure using estimated quantities. . 11
Figure B.1 – Example reference quantity . 22
Figure B.2 – EUT and antenna set-up for fully anechoic room emission measurement . 23
Figure B.3 – EUT and antenna set-up for open-area test site measurement . 23
Figure B.4 – Radiation characteristics of elementary radiator (left), and scheme of
EUT-model (right) . 24
Figure B.5 – Maximum average deviations for 3 m FAR (top) and 10 m OATS (bottom) . 27
Figure B.6 – Sample cumulative distribution function . 29
Figure B.7 – Uncertainties due to the unknown EUT characteristic for 3 m FAR (top)
and 10 m OATS (bottom) . 31
Figure B.8 – Expanded uncertainties (k = 2) of alternative (3 m FAR, top) and
established (10 m OATS, bottom) test methods . 35
Figure B.9 – Maximum average conversion factors for different volumes . 36
Figure B.10 – Photo (left) and cut-view of simulation model (right) of the specimen EUT . 38
+AMD1:2014 CSV IEC 2014
Figure B.11 – Deviations of the specimen EUT: 3 m fully anechoic room (top) and 10 m
open area test site (bottom) . 39
Figure B.12 – Sample FAR measurement . 40
Figure B.13 – OATS 10 m limit line converted to FAR 3 m conditions . 40
Figure B.14 – Expanded uncertainties . 40
Figure B.15 – Comparison of the measured values with the corrected converted limit . 41
Figure B.16 – EUT and antenna set-up of 3 m open area test site measurement . 42
Figure B.17 – Maximum average deviations for 3 m OATS . 43
Figure B.18 – Uncertainties due to the unknown EUT characteristic for 3 m OATS . 44
Figure B.19 – Expanded uncertainties (k = 2) of alternative test method [OATS (3 m)] . 46
Figure B.20 – Maximum average conversion factors . 47
Figure B.21 – Deviations of the specimen EUT: Open area test site (3 m) . 49
Figure B.22 – Sample OATS (3 m) measurement . 50
Figure B.23 – OATS (10 m) limit line converted to OATS (3 m) conditions . 50
Figure B.24 – Expanded uncertainties . 51
Figure B.25 – Comparison of the corrected values with the converted limit . 51
Figure C.1 – EUTs used during RRT . 52
Figure C.2 – Measurement results of the asymmetrical voltage using both CDNEs . 53
Figure C.3 – Measured disturbance field strength . 54
Figure C.4 – Conversion factors of all measurements . 55
Figure C.5 – Mean conversion factors for each EUT . 55
Figure C.6 – Measured polarization . 55
Figure C.7 – Comparison with CISPR 15:2013 . 55
Figure C.8 – Deviation of the conversion factors from the average conversion factor of
each EUT . 56
Figure C.9 – Deviation of the conversion factors from the
trend line [poly (mean value K(f))] . 56
Table 1 – Summary of steps in conversion procedure . 9
Table 2 – Overview of quantities and defining equations for conversion process . 12
Table B.1 – Instrumentation uncertainty of the 3 m fully anechoic chamber test method . 28
Table B.2 – Uncertainties in dB due to the unknown EUT characteristic for 3 m FAR . 33
Table B.3 – Uncertainties in dB due to the unknown EUT characteristic for 10 m OATS . 34
Table B.4 – Maximum average conversion factors in dB between 10 m OATS and
3 m FAR . 37
Table B.5 – Uncertainties in dB due to the unknown EUT characteristic for 3 m OATS . 45
Table B.6 – Maximum average conversion factors in dB between 10 m and 3 m OATS . 48
– 4 – CISPR TR 16-4-5:2006
+AMD1:2014CSV IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SPECIFICATION FOR RADIO DISTURBANCE
AND IMMUNITY MEASURING APPARATUS AND METHODS –
Part 4-5: Uncertainties, statistics and limit modelling –
Conditions for the use of alternative test methods
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
This consolidated version of the official IEC Standard and its amendment has been
prepared for user convenience.
CISPR TR 16-4-5 edition 1.1 contains the first edition (2006-10) [documents CISPR/
A/665/DTR and CISPR/A/685/RVC] and its amendment 1 (2014-07) [documents CISPR/
A/1050/DTR and CISPR/A/1069/RVC].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendment 1. Additions are in green text, deletions are in strikethrough
red text. A separate Final version with all changes accepted is available in this
publication.
+AMD1:2014 CSV IEC 2014
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
CISPR 16-4-5, which is a technical report, has been prepared by CISPR subcommittee A:
Radio-interference measurements and statistical methods.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the CISPR 16-4 series, published under the general title Specification for
radio disturbance and immunity measuring apparatus and methods – Part 4: Uncertainties,
statistics and limit modelling, can be found on the IEC website.
The committee has decided that the contents of the base publication and its amendment will
remain unchanged until the stability date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
reconfirmed,
withdrawn,
replaced by a revised edition, or
amended.
A bilingual version of this publication may be issued at a later date.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.
– 6 – CISPR TR 16-4-5:2006
+AMD1:2014 CSV IEC 2014
SPECIFICATION FOR RADIO DISTURBANCE
AND IMMUNITY MEASURING APPARATUS AND METHODS –
Part 4-5: Uncertainties, statistics and limit modelling –
Conditions for the use of alternative test methods
1 Scope
This part of CISPR 16-4 specifies a method to enable product committees to develop limits for
alternative test methods, using conversions from established limits. This method is generally
applicable for all kinds of disturbance measurements, but focuses on radiated disturbance
measurements (i.e. field strength), for which several alternative methods are presently
specified. These limits development methods are intended for use by product committees and
other groups responsible for defining emissions limits in situations where it is decided to use
alternative test methods and the associated limits in product standards.
2 Normative references
IEC 60050-161:1990, International Electrotechnical Vocabulary (IEV) – Chapter 161:
Electromagnetic compatibility
CISPR 16-4-1:2003, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 4-1: Uncertainties, statistics and limit modelling – Uncertainty in
standardized EMC tests
CISPR 16-4-2:2003, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 4-2: Uncertainties, statistics and limit modelling – Uncertainty in EMC
measurements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161 and the
following apply.
3.1
established test method
test method described in a basic standard with established emissions limits defined in
corresponding product or generic standards. An established test method consists of a specific
test procedure, a specific test set-up, a specific test facility or site, and an established
emissions limit
NOTE The following test methods have been considered to be established test methods in CISPR:
– conducted disturbance measurements at mains ports using an AMN in the frequency range 9 kHz to 30 MHz;
test this method is defined in CISPR 16-2-1:2003, Clause 7;
– radiated disturbance measurements up in the frequency range 30 MHz to 1 GHz at 10 m distance on an OATS
or in a SAC; the test this method is defined in CISPR 16-2-3, 7.2.1;
– radiated disturbance measurements up in the frequency range 1 GHz to 18 GHz at 3 m distance on an
FSOATS; the test this method is defined in CISPR 16-2-3, 7.3.
3.2
alternative test method
test method described in a basic standard without established emissions limits. The
alternative test method is designed for the same purpose as the established test method. An
alternative test method consists of a specific test procedure, a specific test set-up, a specific
+AMD1:2014 CSV IEC 2014
test facility or site, and a derived emissions limit that was determined by the application of the
proposed method stated in this document
3.3
established limit
limit having “many years” of good protection of radio services.
NOTE An example is radiated field strength measured on OATS, developed to protect radio services as described
in CISPR 16-3.
3.4
derived limit
limit applicable for the alternative test method, derived by appropriate conversion from the
established limit and expressed in terms of the misbrands
3.5
conversion factor K
for a given EUT or type of EUT, the relation of the measured value of the established test
method to the measured value of the alternative test method
NOTE The terms measured and calculated are used interchangeably at various places in this document to
describe actual laboratory tests and computer simulations.
3.6
reference quantity X
the basic parameter which determines the interference potential to radio reception. It may be
independent of the parameters presently used in established standards
NOTE The goal for both the established and alternative test methods is to determine the reference quantity (X) for
all frequencies of interest. For both established and alternative test methods, the test results may deviate from the
reference quantity values. The specification of the reference quantity when applying methods of this document
should include applicable procedures and conditions to calculate (or measure) this quantity
3.7
inherent uncertainty
u
inherent
uncertainty caused solely by the difference in EUT characteristics and the ability of the
measurement procedure to cope with them. It is specific to each test method and remains,
even if the measurement is performed perfectly, i.e., the standards compliance uncertainty is
zero and the measurement instrumentations uncertainty is zero
3.8
intrinsic uncertainty of the measurand
u
intrinsic
minimum uncertainty that can be assigned in the description of a measured quantity. In
theory, the intrinsic uncertainty of the measurand would be obtained if the measurand was
measured using a measurement system having negligible measurement instrumentation
uncertainty.
[CISPR 16-4-1, definition 3.6]
3.9
EUT type
grouping of products with sufficient similarity in electromagnetic characteristics to allow
testing with the same test installation and the same test protocol.
– 8 – CISPR TR 16-4-5:2006
+AMD1:2014 CSV IEC 2014
3.10
standards compliance uncertainty
SCU
parameter, associated with the result of a compliance measurement as described in a
standard, that characterizes the dispersion of the values that could reasonably be attributed
to the measurand
[IEC 60050-161:1990, 311-01-02, modified, deletion of the notes]
4 Symbols and abbreviated terms
The following abbreviations are used in this technical report:
ATM alternative test method (e.g. subscript in D )
ATM
D deviation
ETM established test method (e.g. subscript in D )
ETM
f index number of an individual measured frequency
F number of measured frequencies in the considered frequency range
i index number of one an individual EUT (e.g., of a number of EUTs)
j index number of an individual test lab
K conversion factor
k coverage factor
L limit
M measurement (or calculation) result
N number of EUTs
OATS open-area test site
RRT round robin test
s standard deviation
SAC semi-anechoic chamber
T number of test labs
U expanded uncertainty
u standard uncertainty
v volume
X reference quantity
difference of two values or quantities
x mean value of a set of values x (e.g., D )
5 Introduction
Over the years, several test procedures and test set-ups for radiated emissions testing have
been described in basic standards. One particular combination of test method and test set-up
also having defined emissions limits is the open area test site (OATS) method, which has
proven to be successful for the protection of radio services. In general limits have not been
defined for the other, alternative test methods, e.g., fully anechoic room, TEM waveguide,
reverberation chamber.
Each alternative method can be used to get measurement results related to emission of the
EUT. Although each method gives an emission level from the EUT, the different methods may
capture the EUT emission differently. For example, considering radiated emission
+AMD1:2014 CSV IEC 2014
measurements, different methods may capture different EUT radiation pattern lobes, differing
numbers of lobes, or the test facility may alter the EUT radiation pattern producing a different
apparent emission level. Therefore the limits defined for the established test method cannot
be applied directly to the alternative test methods. Consequently, a procedure is needed for
how to derive limits to use for the results of alternative test methods.
The specification for such a procedure should consider the general goal of disturbance
measurements. The aim of the disturbance measurement is to verify whether the EUT
satisfies or violates certain compliance criteria. Past experience has shown that using the
present system of the established test method and the associated limits yields a situation
without many cases of interference due to conducted or radiated emissions. Applying the
established test method with the associated limits will fulfill the protection requirement with a
high probability. To preserve this situation, the most important requirement for the use of
alternative test methods is as follows.
– Use of an alternative test method in a normative standard shall provide the same
protection of radio services as the established test method.
This requirement can be met by developing a procedure for deriving emission limits for the
alternative test method from the existing limits of the established test method. Such a
procedure shall relate the results of the alternative test method to those of the established
test method. Using this relation the limits of the established test method can be converted into
limits for the alternative test method. The measured values of the alternative test method can
then easily be evaluated against the converted limits. Such a procedure will provide a similar
amount of protection, even though an alternative test method is used.
The limits conversion procedure should consider the goal of emissions measurements as
described above. The results of standard emissions tests can be considered as an
approximation of the interference potential of an EUT. Depending on the characteristics of the
EUT (e.g., radiation pattern characteristics for radiated disturbance test methods), and on the
measurement set-up, the measured value differs from the actual interference potential of the
EUT. This deviation can be divided into two parts: a systematic deviation, which can be
interpreted as a bias of the test method, and a random deviation depending on the
characteristics of different EUTs, which can be interpreted as an uncertainty of the test
method. Each emissions test method contains both quantities, and consequently the
established test method does too. In the following clauses, a procedure based on these two
quantities for comparing an alternative test method with the established test method is
described. To determine these quantities, the abstract term “interference potential” needs to
be expressed in terms of a physical quantity. For the purposes of this report, this quantity is
called the “reference quantity,” X. More details about correlation of test methods using a
)
reference quantity can be found in [1] .
6 Procedure to derive limits for an alternative test method
6.1 Overview
A procedure to derive limits for an alternative test method based on the limits of an
established test method is described in the following paragraphs. Figure 1 shows a summary
of the estimated quantities needed for the correlation process. Figure 2 shows a flowchart for
the correlation process using these quantities. The nine-step conversion process below can
be accomplished using numerical simulations, measurements, or a combination of simulations
and measurements. Calculable or reference EUTs are invaluable for this conversion
procedure. In the following subclauses, as part of the conversion process the quantities
shown in Figure 1 and Figure 2 are combined into several equations. A summary of the
equations is given in Table 2. A summary of the steps in the conversion procedure is shown in
Table 1.
———————
1)
Figures in square brackets refer to the Bibliography.
– 10 – CISPR TR 16-4-5:2006
+AMD1:2014 CSV IEC 2014
Table 1 – Summary of steps in conversion procedure
1 Select the reference quantity
2 Describe the test methods and measurands
3 Determine the deviations of the measured quantities from the reference quantity
4 Determine the average values of the deviations
5 Determine the standard uncertainties of the test methods
6 Verify the calculated values
7 Apply the conversion
Statistical consideration
set of N EUTs
Alternative test
Reference Established test
method quantity method
definition
Measurement result Reference quantity Measurement result
X
M M
ATM ETM
– –
+ +
Set of deviations Set of deviations
D D
ATM ETM
+–
Average deviation Average deviation
D D
ATM
ETM
Standard deviation Standard deviation
inherent uncertainty inherent uncertainty
s(D ) D , s(D ) D ,
ATM ATM inherent ETM ETM inherent
Comparison
Average
of expanded
conversion
measurement
factor k
uncertainties
IEC 1694/06
Figure 1 – Overview of quantities to estimate for use in conversion procedure
+AMD1:2014 CSV IEC 2014
Limit for established
Average
conversion test method L
ETM
factor k
–
+
Limit for alternative
Limitf oralternative
test method L
ATM
Uncertainties of Uncertainties of
alternative test method established test method
Inherent uncertainty Inherent uncertainty
U U
ATM, inherent ETM, inherent
Instrumentation uncertainty Instrumentation uncertainty
U U
ATM, instrumentation ETM, instrumentation
Intrinsic uncertainty Intrinsic uncertainty
U U
ATM, intrinsic ETM, intrinsic
Alternative test method + Established test method
–
expanded uncertainty expanded uncertainty
U U
ATM ETM
Difference of
uncertainties
Corrected limit for alternative test method L
ATM,U
IEC 1695/06
Figure 2 – Overview of limit conversion procedure using estimated quantities
– 12 – CISPR TR 16-4-5:2006
+AMD1:2014 CSV IEC 2014
Table 2 – Overview of quantities and defining equations for conversion process
Quantity Meaning Equation no.
the deviation from the reference quantity of the measurement result of EUT i (1)
D (f )
ATMi
as produced by the alternative test method
the deviation from the reference quantity of the measurement result of EUT i (2)
D (f )
ETMi
as produced by the established test method
the average deviation of the alternative test method (3)
D
ATM
the average deviation of the established test method (4)
D
ETM
the inherent uncertainty of the alternative test method (5)
u
ATM,inherent
the inherent uncertainty of the established test method (6)
u
ETM,inherent
combined standard uncertainty of the alternative test method (7)
u
ATM
the expanded uncertainty of the alternative test method (8)
U
ATM
combined standard uncertainty of the established test method (9)
u
ETM
the expanded uncertainty of the established test method (10)
U
ETM
frequency dependent conversion factor for EUT i (11)
K (f )
i
the average of the conversion factors (12), (13), (14)
K (f )
the limit line of the alternative test method equivalent to the limit of the (15)
L (f )
ATM
established test method, without consideration of the uncertainties
difference of expanded uncertainties (16)
the limit to be used for alternative measurements (17)
L
ATM,U
U standards compliance uncertainty for the test method X, where X is either “E” (26)
SC,XTM
for established test method or “A” for alternative test method
f,j
i
D (20), (21)
deviation of the single calculated conversion factor K ( ) from the average
K
Kf
conversion factor
f,j
i
D (24), (25)
deviation of the single measured value M ( ) from the average for the
XTM XTM,
M
measured values
XTM,i
M measured value depending on EUT, lab, and frequency (18), (23)
XTM,i(f,j)
6.2 Select the reference quantity X
The first step is to select the reference quantity X. It should be selected on the basis of a
quantity that can possibly cause interference to a radio service, and selection of a reference
quantity also depends on the type of EUT.
For the types of EUTs investigated in Annex B, as an example the maximum electric field
strength determined on a sphere of a certain radius around the EUT has been selected as the
reference quantity for radiated emission measurements in the frequency range of 30 MHz to
1 GHz. In the frequency range below 30 MHz, depending on the frequency subrange and the
coupling model, the reference quantity may be the vertical component of the electric field
strength, the magnetic field strength, or the asymmetric voltage. In general, the reference
quantity and the actual measurands will not necessarily have the same units.
︵
︶
+AMD1:2014 CSV IEC 2014
6.3 Describe the test methods and measurands
The measurand shall be described for both the alternative and the established test methods.
In addition, the test set-up geometry, the methods of measurement for EUT emissions, and
any analysis methods producing the final measurement results shall be described. This
description is necessary for an understanding about how the test method works and to give a
basis for comparison of the two test methods. In most cases this description is explicit or
implicit in the standards that specify the test methods.
6.4 Determine the deviations of the measured quantities from the reference quantity
Each test method provides results, each of which deviate from the reference quantity X. The
deviation depends on the characteristics of the test set-up as well as on the characteristics of
the EUT. Considering a certain EUT i, a frequency dependent deviation can be determined for
both alternative and established test method.
For a given EUT i the deviation of the alternative test method, in a logarithmic scale, is given
as
D (f ) X (f ) M (f ) (1)
ATMi i ATMi
where
i is the index of the EUT;
f is the frequency;
D (f ) is the deviation from the reference quantity of the measurement result of EUT i as
ATMi
produced by the alternative test method;
X (f ) is the reference quantity defined in 6.2 for the EUT i, and
i
M (f ) is the measurement result given by the alternative test method for the EUT i.
ATMi
The results of the established test method will deviate from the reference quantity as well.
The deviation of the established test method is analogously given by the equation
D (f ) X (f ) M (f ) (2)
ETMi i ETMi
where
X (f ) , f, i are the same as in Equation (1);
i
D (f ) is the deviation from the reference quantity of the measurement result of EUT i as
ETMi
produced by the established test method;
M (f ) is the measurement result given by the established test method for the EUT i.
ETMi
6.5 Determine the average values of the deviations
The deviations given by Equations (1) and (2) will differ for different EUTs. In order to obtain
more universal results, varying characteristics of EUTs shall be considered, for example as
shown in Annex A. Considering a range of N EUTs leads to a set of N values for the deviation
D for both alternative and established test methods. From this set of D the average can be
easily determined. See Annex A for more details about EUT considerations and variations.
An estimate of the mean of the deviation of the alternative test method is given by
N
D D (3)
ATM ATMi
N
i1
where
D is the set of deviations of the alternative test method;
ATM
– 14 – CISPR TR 16-4-5:2006
+AMD1:2014 CSV IEC 2014
D is the average deviation of the alternative test method;
ATM
N is the number of EUTs considered, and shall be as large as possible for statistical
reasons;
i is the index of any one EUT;
D is the deviation from the reference quantity of the measurement result of EUT i, as
ATMi
produced by the alternative test method [Equation (1)].
An estimate of the mean of the deviation of the established test method is given by
N
D D (4)
ETM ETMi
N
i1
where
D is the set of deviations of the established test method;
ETM
D is the average deviation of the established test method;
ETM
N, i are the same as in Equation (3);
D is the deviation from the reference quantity of the measurement result of EUT i, as
ETMi
produced by the established test method [Equation (2)].
6.6 Estimate the standard uncertainties of the test methods
The methods comparison procedure must consider uncertainties, as are associated with every
measurement result. Because the results from the established test method itself have
uncertainties, care must be taken that these uncertainties are not transferred to results from
the alternative test methods as part of the conversion procedure. Otherwise, the use of
alternative test methods would be burdened with uncertainties that are characteristics of the
established test method.
The uncertainty of emission measurements consists of several components. On one hand, the
measurement equipment contributes several uncertainties, as documented in CISPR 16-4-2.
On the other hand the test set-up combined with the radiation characteristics of the EUT
causes an inherent uncertainty, u . For example, in radiated emissions measurements,
inherent
for some types of EUT radiation patterns, an OATS test (established test method) may fail to
capture the radiated emission peak lobe. Deviations between the results of a test method and
the reference quantity depend on the radiation characteristics of the EUT, but the radiation
characteristics of an arbitrary EUT are not known a priori. The resulting uncertainty u
inherent
can be estimated only if the behaviour of EUTs with different characteristics is examined.
Analogously to as in 6.4, the deviations from the reference quantity of a set of N EUTs can be
used for estimating the standard deviation as a measure for the inherent uncertainties.
Using the formula for experimental standard deviation, the inherent uncertainty of the
alternative test method is given by:
N
(D D )
ATMi ATM
i1
u s(D ) (5)
ATM,inherent ATM
N1
where
u is the inherent uncertainty of the alternative test method;
ATM,inherent
s(D ) is the experimental standard deviation of the set D ;
ATM ATM
N, i, D , D are the same as in Equation (3).
ATM ATMi
+AMD1:2014 CSV IEC 2014
Analogously, the inherent uncertainty of the established test method is given:
N
(D D )
ETMi ETM
i1
u s(D ) (6)
ETM,inherent ETM
N1
where
u is the inherent uncertainty of the established test method;
ETM,inherent
s(D ) is the experimental standard deviation of the set D ;
ETM ETM
N, i, D , D are the same as in Equation (4).
ETM ETMi
6.7 Estimate the expanded uncertainties of the test methods
The expanded measurement uncertainty is obtained from the multiplication of the combined
standard uncertainties by a coverage factor k. The combined standard uncertainty of the
alternative test method u can be calculated from
ATM
2 2 2
u u u u (7)
ATM ATM,m ATM,intrinsic ATM,inherent
where
u is the combined standard uncertainty of the alternative test method
ATM,m
contributed by measurement instrumentation;
u is the inherent uncertainty of the alternative test method, according to
ATM,inherent
Equation (5);
u is the intrinsic uncertainty of the alternative test method.
ATM,intrinsic
Using the coverage factor k, the expanded uncertainty of the alternative test method is
estimated:
U ku (8)
ATM ATM
where
U is the expanded uncertainty of the alternative test method;
ATM
k is the coverage factor;
u is the combined standard uncertainty of the alternative test method
ATM
according to Equation (7).
Analogously the combined standard uncertainty of the established test method u can be
ETM
obtained,
2 2 2
u u u u (9)
ETM ETM,m ETM,intrinsic ETM,inherent
where
u is the combined standard uncertainty of the established test method
ETM,m
contributed by measurement instrumentation;
u is the EUT-dependent uncertainty of the established test method, according to
ETM,inherent
Equation (6);
u is the intrinsic uncertainty of the established test method.
ETM,intrinsic
– 16 – CISPR TR 16-4-5:2006
+AMD1:2014 CSV IEC 2014
The expanded uncertainty of the established test method is given by
U ku (10)
ETM ETM
where
U is the expanded uncertainty of the established test method;
ETM
k is the coverage factor;
u is the combined standard uncertainty of the established test method according
ETM
to Equation (9).
6.8 Calculate the average conversion factor
For each EUT i a frequency dependent conversion factor K (f ) can be calculated using
i
K (f ) D (f ) D (f ) (11)
i ATMi ETMi
where
D (f ) is the deviation from the reference quantity of the measurement result of EUT i,
ATMi
as produced by the alternative test method [Equation (1)];
D (f ) is the deviation from the reference quantity of the measurement result of EUT i,
ETMi
as produced by the established test method [Equation (2)].
The average conversion factor can be calculated from the average deviations of the
alternative and the established test methods:
K (f ) D (f ) D (f ) (12)
ATM ETM
where
K(f ) is the set of conversion factors;
K (f ) is the average of the conversion factors;
D (f ) is the average deviation of the alternative test method from the reference quantity,
ATM
in dB;
D (f )
is the average deviation of the established test method from the reference
ETM
quantity, in dB.
Substituting the averages by Equations (3) and (4) gives:
N N
1 1
K
...
CISPR TR 16-4-5 ®
Edition 1.2 2021-10
CONSOLIDATED VERSION
TECHNICAL
REPORT
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inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 4-5: Uncertainties, statistics and limit modelling – Conditions for the use of
alternative test methods
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CISPR TR 16-4-5 ®
Edition 1.2 2021-10
CONSOLIDATED VERSION
TECHNICAL
REPORT
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 4-5: Uncertainties, statistics and limit modelling – Conditions for the use of
alternative test methods
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.100.10; 33.100.20 ISBN 978-2-8322-4232-2
CISPR TR 16-4-5 ®
Edition 1.2 2021-10
CONSOLIDATED VERSION
REDLINE VERSION
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 4-5: Uncertainties, statistics and limit modelling – Conditions for the use of
alternative test methods
– 2 – CISPR TR 16-4-5:2006+AMD1:2014
+AMD2:2021 CSV IEC 2021
CONTENTS
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Symbols and abbreviated terms . 10
5 Introduction . 11
6 Procedure to derive limits for an alternative test method . 12
6.1 Overview . 12
6.2 Select the reference quantity X. 17
6.3 Describe the test methods and measurands . 18
6.4 Determine the deviations of the measured quantities from the reference
quantity . 18
6.5 Determine the average values of the deviations . 18
6.6 Estimate the standard uncertainties of the test methods . 19
6.7 Estimate the expanded uncertainties of the test methods . 20
6.8 Calculate the average conversion factor . 21
6.9 Verify the calculated values . 22
6.10 Apply the conversion . 22
7 Measurement-based procedure to derive limits for an alternative test method
based on measurement results . 22
7.1 General . 22
7.2 Application of practical measurement results to determine the conversion
factors . 23
7.2.1 The conversion factor . 23
7.2.2 Estimation of SCU by measurement . 24
7.2.3 Applying the conversion factor . 24
8 Derivation of limits for the use of reverberation chambers as ATM for radiated
disturbance measurements based on a statistical analysis of all essential factors . 26
8.1 Conversion factor . 26
8.2 Measurement uncertainty . 27
Annex A (informative) Remarks on EUT modelling . 29
A.1 Types of EUTs . 29
A.2 Application of statistics . 29
Annex B (informative) Examples of application of the test method comparison
procedure . 30
B.1 Example 1 – Measurements at 3 m-separation in fully anechoic room
compared to 10 m-separation measurements on open-area test site . 30
B.1.1 Small EUTs without cables . 30
B.1.2 Small EUTs with cables . 49
B.2 Example 2 – 3 m open-area test site measurements compared to 10 m open-
area test site measurements . 49
B.2.1 Small EUTs without cables . 49
B.2.2 Small EUTs with cables . 59
B.3 Example 3 – reverberation chamber measurement results compared to 10 m
open-area test site results . 59
Annex C (informative) Example of the application of the test method comparison
procedure based on measurement results . 60
C.1 General . 60
+AMD2:2021 CSV IEC 2021
C.2 Measurement of conducted disturbance using CDNEs . 60
C.3 Measured disturbance field strength . 61
C.4 Conversion factor for the measurement with a CDNE . 62
C.4.1 The conversion factor . 62
C.4.2 Uncertainty of the conversion factor . 63
Annex D Annex D (informative) Statistical method for conversion of disturbance limits
from radiated disturbance established test methods to the RC test method . 66
D.1 General . 66
D.2 Models for EUT directivity . 67
D.3 Results of modelling . 68
D.4 Instrumentation uncertainty for radiated disturbance measurement results in
an RC . 73
D.4.1 Measurand for radiated disturbance measurements using an RC . 73
D.4.2 Symbols of input quantities common to all disturbance measurements . 73
D.4.3 Symbols of input quantities specific to RC measurements . 73
D.4.4 Input quantities to be considered for radiated disturbance
measurements using an RC . 74
D.4.5 Uncertainty budget for radiated disturbance measurement results
using an RC . 74
D.4.6 Rationale for the estimates of input quantities for radiated
disturbance measurement results using an RC . 76
Figure 1 – Overview of quantities to estimate for use in conversion procedure . 14
Figure 2 – Overview of limit conversion procedure using estimated quantities. 16
Figure B.1 – Example reference quantity . 30
Figure B.2 – EUT and antenna set-up for fully anechoic room emission measurement . 31
Figure B.3 – EUT and antenna set-up for open-area test site measurement . 31
Figure B.4 – Radiation characteristics of elementary radiator (left), and scheme of
EUT-model (right) . 32
Figure B.5 – Maximum average deviations for 3 m FAR (top) and 10 m OATS (bottom) . 35
Figure B.6 – Sample cumulative distribution function . 37
Figure B.7 – Uncertainties due to the unknown EUT characteristic for 3 m FAR (top)
and 10 m OATS (bottom) . 39
Figure B.8 – Expanded uncertainties (k = 2) of alternative (3 m FAR, top) and
established (10 m OATS, bottom) test methods . 43
Figure B.9 – Maximum average conversion factors for different volumes . 44
Figure B.10 – Photo (left) and cut-view of simulation model (right) of the specimen EUT . 46
Figure B.11 – Deviations of the specimen EUT: 3 m fully anechoic room (top) and 10
m open area test site (bottom) . 47
Figure B.12 – Sample FAR measurement . 48
Figure B.13 – OATS 10 m limit line converted to FAR 3 m conditions . 48
Figure B.14 – Expanded uncertainties. 48
Figure B.15 – Comparison of the measured values with the corrected converted limit . 49
Figure B.16 – EUT and antenna set-up of 3 m open area test site measurement. 50
Figure B.17 – Maximum average deviations for 3 m OATS . 51
Figure B.18 – Uncertainties due to the unknown EUT characteristic for 3 m OATS . 52
Figure B.19 – Expanded uncertainties (k = 2) of alternative test method [OATS (3 m)] . 54
Figure B.20 – Maximum average conversion factors . 55
– 4 – CISPR TR 16-4-5:2006+AMD1:2014
+AMD2:2021 CSV IEC 2021
Figure B.21 – Deviations of the specimen EUT: Open area test site (3 m) . 57
Figure B.22 – Sample OATS (3 m) measurement . 58
Figure B.23 – OATS (10 m) limit line converted to OATS (3 m) conditions . 58
Figure B.24 – Expanded uncertainties. 59
Figure B.25 – Comparison of the corrected values with the converted limit . 59
Figure C.1 – EUTs used during RRT . 60
Figure C.2 – Measurement results of the asymmetrical voltage using both CDNEs . 61
Figure C.3 – Measured disturbance field strength . 62
Figure C.4 – Conversion factors of all measurements . 63
Figure C.5 – Mean conversion factors for each EUT . 63
Figure C.6 – Measured polarization . 63
Figure C.7 – Comparison with CISPR 15:2013 . 63
Figure C.8 – Deviation of the conversion factors from the average conversion factor of
each EUT. 64
Figure C.9 – Deviation of the conversion factors from the trend line [poly (mean value
K(f))] . 64
Figure D.1 – Simulated radiation pattern of an electrically large emitter (50 cm radius,
ka = 10,5 at 1 GHz) in a single plane (X-plane) (Wilson [17]) . 66
Figure D.2 ‒ Comparison of different expressions for maximum directivity of antennas
and unintentional emitters as a function of electrical size ka. µ is the polarization
mismatch factor . 68
Figure D.3 – Conversion factors (mean and quantile values) from OATS/SAC
(measurement distance of 10 m) results to RC results and different radii a of the
surrounding sphere as a function of frequency . 69
Figure D.4 – Conversion factors (mean and quantile values) from FSOATS/FAR (d = 3
m measurement distance) results to RC results and different radii a of the surrounding
sphere as a function of frequency . 71
Figure D.5 – Conversion factor (mean and quantile values) from FSOATS/FAR results
to RC results for d = 3 m measurement distance as a function of electrical EUT size ka . 72
Figure D.6 – Deviation of the QP detector level indication from the signal level at
receiver input for two cases: sine-wave signal, and impulsive signal (PRF 100 Hz) . 78
Figure D.7 – Deviation of the peak detector level indication from the signal level at
receiver input for two cases: sine-wave signal, and impulsive signal (PRF 100 Hz) . 79
Table 1 – Summary of steps in conversion procedure . 12
Table 2 – Overview of quantities and defining equations for conversion process . 17
Table B.1 – Instrumentation uncertainty of the 3 m fully anechoic chamber test method . 36
Table B.2 – Uncertainties in dB due to the unknown EUT characteristic for 3 m FAR . 41
Table B.3 – Uncertainties in dB due to the unknown EUT characteristic for 10 m OATS . 42
Table B.4 – Maximum average conversion factors in dB between 10 m OATS and
3 m FAR . 45
Table B.5 – Uncertainties in dB due to the unknown EUT characteristic for 3 m OATS . 53
Figure B.20 – Maximum average conversion factorsTable B.6 – Maximum average
conversion factors in dB between 10 m and 3 m OATS . 55
Table D.1 – Overview of EUT diameters (= 2a) at the transition from electrically small
to electrically large (from [17]) . 67
Table D.2 – Conversion factors (mean, quantile values, and standard deviation σ) for a
= 0,1 m . 69
+AMD2:2021 CSV IEC 2021
Table D.3 – Conversion factors (mean, quantile values, and standard deviation σ) for a
= 0,75 m . 70
Table D.4 – Conversion factors (mean, quantile values, and standard deviation σ) for a
= 2,5 m . 70
Table D.5 – Example of disturbance limits for a = 0,75 m (EUT diameter 1,5 m) for the
residential environment . 70
Table D.6 – Conversion factors (mean, quantile values, and standard deviation σ) for a
= 0,1 m . 71
Table D.7 – Conversion factors (mean, quantile values, and standard deviation σ) for a
= 0,75 m . 71
Table D.8 – Conversion factors (mean, quantile values, and standard deviation σ) for a
= 2,5 m . 72
Table D.9 – Example of disturbance limits for a = 0,75 m (EUT diameter 1,5 m) for the
residential environment . 72
Table D.10 ‒ Comparison of K (f) and K (f) for the conversion of
lin mean log mean
OATS/SAC (d = 10 m) results to RC results for a = 0,75 m . 73
Table D.11 ‒ Comparison of K (f) and K (f) for the conversion of
lin mean log mean
FOATS/FAR (d = 3 m) results to RC results for a = 0,75 m . 73
Table D.12 ‒ Uncertainty budget for radiated disturbance measurement results using
an RC from 80 MHz to 1 000 MHz (example) . 75
Table D.13 ‒ Uncertainty budget for radiated disturbance measurement results using
an RC from 1 GHz to 6 GHz (example) . 75
Table D.14 – Values of P for 30 MHz to 1 000 MHz (E from [20]) . 78
lim lim
Table D.15 – Values of P for 1 GHz to 6 GHz (E from [20]) . 78
lim lim
– 6 – CISPR TR 16-4-5:2006+AMD1:2014
+AMD2:2021 CSV IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SPECIFICATION FOR RADIO DISTURBANCE
AND IMMUNITY MEASURING APPARATUS AND METHODS –
Part 4-5: Uncertainties, statistics and limit modelling –
Conditions for the use of alternative test methods
FOREWORD
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This consolidated version of the official IEC Standard and its amendments has been
prepared for user convenience.
CISPR TR 16-4-5 edition 1.2 contains the first edition (2006-10) [documents
CISPR/A/665/DTR and CISPR/A/685/RVC], its amendment 1 (2014-07) [documents
CISPR/A/1050/DTR and CISPR/A/1069/RVC] and its amendment 2 (2021-10) [documents
CIS/A/1321/DTR and CIS/A/1324/RVDTR].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendments 1 and 2. Additions are in green text, deletions are in
strikethrough red text. A separate Final version with all changes accepted is available
in this publication.
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The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
CISPR 16-4-5, which is a technical report, has been prepared by CISPR subcommittee A:
Radio-interference measurements and statistical methods.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the CISPR 16-4 series, published under the general title Specification for
radio disturbance and immunity measuring apparatus and methods – Part 4: Uncertainties,
statistics and limit modelling, can be found on the IEC website.
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until the stability date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.
– 8 – CISPR TR 16-4-5:2006+AMD1:2014
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SPECIFICATION FOR RADIO DISTURBANCE
AND IMMUNITY MEASURING APPARATUS AND METHODS –
Part 4-5: Uncertainties, statistics and limit modelling –
Conditions for the use of alternative test methods
1 Scope
This part of CISPR 16-4 specifies a method to enable product committees to develop limits for
alternative test methods, using conversions from established limits. This method is generally
applicable for all kinds of disturbance measurements, but focuses on radiated disturbance
measurements (i.e. field strength and total radiated power), for which several alternative
methods are presently specified. These limits development methods are intended for use by
product committees and other groups responsible for defining emissions limits in situations
where it is decided to use alternative test methods and the associated limits in product
standards.
2 Normative references
IEC 60050-161:1990, International Electrotechnical Vocabulary (IEV) – Chapter 161:
Electromagnetic compatibility
CISPR 16-1-1:2019, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 1-1: Radio disturbance and immunity measuring apparatus – Measuring
apparatus
CISPR 16-4-1:2003, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 4-1: Uncertainties, statistics and limit modelling – Uncertainty in
standardized EMC tests
CISPR 16-4-2:20032011, Specification for radio disturbance and immunity measuring
apparatus and methods – Part 4-2: Uncertainties, statistics and limit modelling – Uncertainty
in EMC measurements Measurement instrumentation uncertainty
CISPR 16-4-2:2011/AMD1:2014
CISPR 16-4-2:2011/AMD2:2018
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161 and the
following apply.
3.1
established test method
test method described in a basic standard with established emissions limits defined in
corresponding product or generic standards. An established test method consists of a specific
test procedure, a specific test set-up, a specific test facility or site, and an established
emissions limit
NOTE The following test methods have been considered to be established test methods in CISPR:
– conducted disturbance measurements at mains ports using an AMN in the frequency range 9 kHz to 30 MHz;
test this method is defined in CISPR 16-2-1:2003, Clause 7;
– radiated disturbance measurements up in the frequency range 30 MHz to 1 GHz at 10 m distance on an OATS
or in a SAC; the test this method is defined in CISPR 16-2-3, 7.2.1;
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– radiated disturbance measurements up in the frequency range 1 GHz to 18 GHz at 3 m distance on an
FSOATS; the test this method is defined in CISPR 16-2-3, 7.3.
3.2
alternative test method
test method described in a basic standard without established emissions limits. The
alternative test method is designed for the same purpose as the established test method. An
alternative test method consists of a specific test procedure, a specific test set-up, a specific
test facility or site, and a derived emissions limit that was determined by the application of the
proposed method stated in this document
3.3
established limit
limit having “many years” of good protection of radio services.
NOTE An example is radiated field strength measured on OATS, developed to protect radio services as described
in CISPR 16-3.
3.4
derived limit
limit applicable for the alternative test method, derived by appropriate conversion from the
established limit and expressed in terms of the misbrands
3.5
conversion factor K
for a given EUT or type of EUT, the relation of the measured value of the established test
method to the measured value of the alternative test method
NOTE The terms measured and calculated are used interchangeably at various places in this document to
describe actual laboratory tests and computer simulations.
3.6
reference quantity X
the basic parameter which determines the interference potential to radio reception. It may be
independent of the parameters presently used in established standards
NOTE The goal for both the established and alternative test methods is to determine the reference quantity (X) for
all frequencies of interest. For both established and alternative test methods, the test results may deviate from the
reference quantity values. The specification of the reference quantity when applying methods of this document
should include applicable procedures and conditions to calculate (or measure) this quantity
3.7
inherent uncertainty
u
inherent
uncertainty caused solely by the difference in EUT characteristics and the ability of the
measurement procedure to cope with them. It is specific to each test method and remains,
even if the measurement is performed perfectly, i.e., the standards compliance uncertainty is
zero and the measurement instrumentations uncertainty is zero
3.8
intrinsic uncertainty of the measurand
u
intrinsic
minimum uncertainty that can be assigned in the description of a measured quantity. In
theory, the intrinsic uncertainty of the measurand would be obtained if the measurand was
measured using a measurement system having negligible measurement instrumentation
uncertainty.
[CISPR 16-4-1:2009, definition 3.6 3.1.6, modified – Deletion of notes]
3.9
EUT type
grouping of products with sufficient similarity in electromagnetic characteristics to allow
testing with the same test installation and the same test protocol.
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3.10
standards compliance uncertainty
SCU
parameter, associated with the result of a compliance measurement as described in a
standard, that characterizes the dispersion of the values that could reasonably be attributed
to the measurand
[IEC 60050-161:1990, 311-01-02, modified, deletion of the notes]
3.11
EUT volume
cylinder defined by EUT boundary diameter and height that fully encompasses all portions of
the actual EUT, including cable racks and 1,6 m of cable length (for 30 MHz to 1 GHz), or
0,3 m of cable length (for 1 GHz and above)
NOTE 1 The test volume is one of several criteria limiting the EUT volume.
NOTE 2 The EUT volume has a diameter D (boundary diameter) and a height h.
4 Symbols and abbreviated terms
The following abbreviations are used in this technical report. Note that the symbol k is used
for four different quantities.
ATM alternative test method (e.g. subscript in D )
ATM
D deviation
ETM established test method (e.g. subscript in D )
ETM
f index number of an individual measured frequency
F number of measured frequencies in the considered frequency range
FAR fully anechoic room
i index number of one an individual EUT (e.g., of a number of EUTs)
j index number of an individual test lab
K conversion factor
k coverage factor
k = 2π/λ, wave number (in this document, k is used in the electrical size ka, where a is
the EUT radius)
k(f) linear conversion factor
K(f) logarithmic conversion factor
k coverage factor
k Boltzmann’s constant
L limit
M measurement (or calculation) result
N number of EUTs
OATS open-area test site
RC reverberation chamber
RRT round robin test
s standard deviation
SAC semi-anechoic chamber
SCU standards compliance uncertainty
T number of test labs
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U expanded uncertainty
u standard uncertainty
v volume
X reference quantity
∆ difference of two values or quantities
x mean value of a set of values x (e.g., D )
5 Introduction
Over the years, several test procedures methods and test set-ups for radiated emissions
testing disturbance measurement have been described in basic standards. One particular
combination of test method and test set-up also having defined emissions disturbance limits is
the open area test site (OATS) method, which has proven to be successful for the protection
of radio services. In general Since the first edition of this document, limits have not been
defined for the other, – alternative – test methods, e.g., fully anechoic rooms, and TEM
waveguides, but not for reverberation chambers.
Each alternative method can be used to get measurement results related to emission of the
disturbance from an EUT. Although each method gives an emission a disturbance level from
the an EUT, the different methods may might capture the EUT emission disturbance
differently. For example, considering radiated emission disturbance measurements, different
methods may capture different EUT radiation pattern lobes, differing numbers a different
number of lobes, or the test facility may might alter the EUT radiation pattern producing a
different apparent emission disturbance level. Therefore the limits defined for the established
test method cannot be applied directly to the alternative test methods. Consequently, a
procedures is are needed for how to derive limits to be used for the results of alternative test
methods.
The specification for of such a procedures should considers the general goal of disturbance
measurements. The aim of the disturbance measurement, which is to verify whether the an
EUT satisfies or violates certain compliance criteria. Past experience has shown that using
the present system of the established test methods and the associated limits yields a situation
without many cases of interference due to conducted disturbance or radiated emissions
disturbance. Applying the an established test method with the its associated limits will fulfill
the protection requirement with a high probability. To preserve this situation, the most
important requirement for the use of alternative test methods is as follows the following:
– Use of an alternative test method in a normative standard shall provide the same
protection of radio services as the established test method.
This requirement can be met by developing a procedure for deriving emission procedures to
derive disturbance limits for the alternative test methods from the existing limits of the
established test methods. Such a procedures shall relate the results of the from an alternative
test method to those of the from an established test method. Using the relations derived in
this relation document, the limits of the relevant established test method can be converted
into limits for the alternative test method. The measured values of the alternative test method
can then easily be evaluated against the converted limits. Such a procedures will provide a
similar amount of protection, even though an alternative test method is used.
The limits conversion procedures should consider the preceding goal of emissions
disturbance measurements as described above. The results of standard emissions tests
disturbance measurements can be considered as an approximation of the interference
potential of an EUT. Depending on the characteristics of the an EUT (e.g., radiation pattern
characteristics for radiated disturbance test methods), and on the measurement test set-up,
the measured value differs deviates from the actual interference potential of the EUT. This
deviation can be divided into two parts: 1) a systematic deviation, which can be interpreted as
a bias of the test method,; and 2) a random deviation depending on the characteristics of
different EUTs, which can be interpreted as an uncertainty of the test method. Each emissions
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disturbance test method contains both quantities, and consequently the established test
method does too. In the following clauses, a procedure based on these two quantities for
comparing an alternative test method with the established test method is described. To
determine these quantities, the abstract term “interference potential” needs to shall be
expressed in terms of a physical quantity. For the purposes of this report document, this
physical quantity is called the “reference quantity” X. More Other details about correlation
comparison of test methods using a reference quantity can be found in [1] .
The significance of a reference quantity is under discussion (see Magdowski [16]). It is not
used in the derivation of limits for an alternative test method based on measurements (see
Clause 7 of CISPR TR 16-4-5:2006/AMD1:2014), and in the derivation of limits for
disturbance measurements using a reverberation chamber (i.e. in this document).
6 Procedure to derive limits for an alternative test method
6.1 Overview
A procedure to derive limits for an alternative test method based on the limits of an
established test method is described in the following paragraphs. Figure 1 shows a summary
of the estimated quantities needed for the correlation process. Figure 2 shows a flowchart for
the correlation process using these quantities. The nine-step conversion process below can
be accomplished using numerical simulations, measurements, or a combination of simulations
and measurements. Calculable or reference EUTs are invaluable for this conversion
procedure. In the following subclauses, as part of the conversion process the quantities
shown in Figure 1 and Figure 2 are combined into several equations. A summary of the
equations is given in Table 2. A summary of the steps in the conversion procedure is shown in
Table 1.
Table 1 – Summary of steps in conversion procedure
1 Select the reference quantity
2 Describe the test methods and measurands
3 Determine the deviations of the measured quantities from the reference quantity
4 Determine the average values of the deviations
5 Determine the standard uncertainties of the test methods
6 Verify the calculated values
7 Apply the conversion
———————
Figures in square brackets refer to the Bibliography.
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Statistical consideration
set of N EUTs
Alternative test
Reference Established test
method
quantity method
definition
Measurement result Reference quantity Measurement result
X
M M
ATM ETM
– –
+ +
Set of deviations Set of deviations
D D
ATM ETM
+ –
Average deviation
Average deviation
D
D
ATM
ETM
Standard deviation Standard deviation
inherent uncertainty inherent uncertainty
∼ ∼
s(D ) D , s(D ) D ,
ATM ATM inherent ETM ETM inherent
Comparison
Average
of expanded
conversion
measurement
factor k
uncertainties
IEC 1694/06
– 14 – CISPR TR 16-4-5:2006+AMD1:2014
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Figure 1 – Overview of quantities to estimate for use in conversion procedure
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Limit for established
Average
conversion
test method L
ETM
factor k
–
+
Limit for alternative
Limitf or alternative
test method L
ATM
Uncertainties of Uncertainties of
alternative test method established test method
Inherent uncertainty Inherent uncertainty
U U
ATM, inherent ETM, inherent
Instrumentation uncertainty Instrumentation uncertainty
U U
ATM, instrumentation ETM, instrumentation
Intrinsic uncertainty Intrinsic uncertainty
U U
ATM, intrinsic ETM, intrinsic
Alternative test method Established test method
+ –
expanded uncertainty expanded uncertainty
U U
ATM ETM
Difference of
uncertainties
∆
Corrected limit for alternative test method L
ATM,U
IEC 1695/06
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Figure 2 – Overview of limit conversion procedure using estimated quantities
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Table 2 – Overview of quantities and defining equations for conversion process
Quantity Meaning Equation no.
the deviation from the reference quantity of the measurement result of EUT i (1)
D (f )
ATMi
as produced by the alternative test method
the deviation from the reference quantity of the measurement result of EUT i (2)
D (f )
ETMi
as produced by the established test method
the average deviation of the alternative test method (3)
D
ATM
the average deviation of the established test method (4)
D
ETM
the inherent uncertainty of the alternat
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