CISPR TR 16-4-4:2025

CISPR TR 16-4-4 ®
Edition 3.0 2025-10
TECHNICAL
REPORT
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE

Specification for radio disturbance and immunity measuring apparatus and
methods -
Part 4-4: The CISPR model for the calculation of limits for the protection of radio
services
ICS 33.100.10; 33.100.20 ISBN 978-2-8327-0778-4

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CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 The CISPR model for the calculation of limits . 7
4.1 General . 7
4.2 Basic disturbance coupling mechanisms . 8
4.2.1 Coupling scenarios. 8
4.2.2 Description of coupling paths . 8
4.3 Condition at the victim receiver . 9
4.4 Systematic factors . 9
4.4.1 General. 9
4.4.2 Factors conditional on the path between source and victim . 10
4.4.3 Factors conditional on standardised test . 10
4.5 Probabilistic factors . 11
4.5.1 General. 11
4.5.2 S probabilistic factor representing the effect of events that the major
Tx
lobe of the radiation is in the direction of the victim receiver . 12
4.5.3 S probabilistic factor representing the effect of directional receiving
Rx
aerials having maximum pick-up in the direction of the disturbing source . 12
4.5.4 S probabilistic factor representing the effect of events that the victim
stat
receiver is stationary . 12
4.5.5 S probabilistic factor representing the effect of equipment
freq
generating a disturbing signal on a critical frequency at which the radio
receiver is susceptible . 13
4.5.6 S probabilistic factor representing the effect of events that the
ml
disturbing signal is below E . 13
ir,corr
4.5.7 S probabilistic factor representing the effect of events that the type of
wf
disturbing signal being generated will produce a significant effect in the
receiving system . 14
4.5.8 S probabilistic factor representing the effect of coincident operation
time
of the disturbing source and the receiving system . 14
4.5.9 S probabilistic factor representing the effect of the disturbing source
loc
being within the distance at which interference is likely to occur . 15
4.5.10 S Probabilistic factor representing the effect of events that obstacles
att
(including buildings) provide attenuation . 16
4.6 Specification of a technical CISPR limit . 16
4.6.1 General. 16
4.6.2 Determination of the permissible interference field strength values . 17
4.6.3 Application of the systematic factors . 18
4.6.4 Application of the probabilistic factors . 18
4.6.5 Determination of a technical CISPR limit . 22
4.7 Documentation of the result . 23
Annex A (informative) Basic mathematical background . 24
A.1 General . 24
A.1.1 Overview . 24
A.1.2 Generation of EM disturbances . 24
A.1.3 Immunity from EM disturbances . 24
A.1.4 Planning a radio service . 24
A.2 Probability of interference . 25
A.2.1 General. 25
A.2.2 Derivation of probability of interference . 25
A.3 A mathematical basis for the calculation of CISPR limits . 27
A.3.1 General. 27
A.3.2 Generation of EM disturbances (source of disturbance) . 27
A.3.3 Immunity from EM disturbances (victim receiver) . 29
Annex B (informative) Mathematical basis for the calculation of the probability
distribution of the maximum disturbance amplitude at a receiver when surrounded by
uniformly distributed sources . 30
B.1 General . 30
B.2 Model and assumptions . 30
B.3 Probability distribution of received amplitude of a disturbance from an
arbitrary source . 31
B.4 Probability distribution of the maximum disturbance amplitude . 34
B.5 Comparison to Monte Carlo simulation results . 38
B.6 Application to some specific distributions . 39
B.6.1 General. 39
B.6.2 Binary discrete distribution . 39
B.6.3 Lognormal distribution . 40
B.6.4 Exponential distribution . 41
Annex C (informative) A simple approximation of the mean value and standard
deviation of the probabilistic factor of location coincidence . 44
Annex D (informative) Wire-line coupling. 46
D.1 Mains coupling using the mains decoupling factor . 46
D.2 Mains and telecommunication line coupling by radiation from a network . 47
D.2.1 General. 47
D.2.2 Example for the AM frequency range . 50
D.2.3 Guidance for field-strength measurements . 51
D.2.4 Example of a measurement result . 51
Annex E (informative) Cross reference for probabilistic factors . 55
Bibliography . 57

Figure 1 – Basic RFI model for source without radio module . 8
Figure 2 – Basic RFI model for source with radio module . 8
Figure 3 – tα against confidence level α . 20
Figure B.1 – Geometry of the interference model . 31
Figure B.2 – Integration ranges for conducting the integral (see Equation (B.8)) . 33
Figure B.3 – Probability densities of the maximum received disturbance amplitude . 39
Figure C.1 – Comparison of the exact and approximated values in the case of x = 1. 45
Figure D.1 – Example of conversion factors – field strength/common-mode voltage (in
dB) – at feed point, found in practice . 51
Figure D.2 – Example of conversion factors – field strength generated by differential-
mode voltage – at feed point, found in practice . 52

Figure D.3 – Example of conversion factors – field strength generated by differential-
mode voltage –outside buildings and electrical substations, found in practice . 53
Figure D.4 – Example of conversion factors – field strength generated by differential-
mode voltage – inside buildings, found in practice. 54

Table 1 – Coupling scenarios and relevant systematic/probabilistic factors . 17
Table E.1 – Cross reference of probabilistic factors in this document and CISPR
TR 16-4-4:2007, CISPR TR 16-4-4:2007/AMD1:2017 and CISPR
TR 16-4-4:2007/AMD2:2020 . 55

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Specification for radio disturbance and immunity measuring apparatus
and methods -
Part 4-4: The CISPR model for the calculation of limits for the protection
of radio services
FOREWORD
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