IEC TR 61282-14:2024

IEC TR 61282-14 ®
Edition 3.0 2024-04
REDLINE VERSION
TECHNICAL
REPORT
colour
inside
Fibre optic communication system design guidelines –
Part 14: Determination of the uncertainties of attenuation measurements in fibre
plants
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IEC TR 61282-14 ®
Edition 3.0 2024-04
REDLINE VERSION
TECHNICAL
REPORT
colour
inside
Fibre optic communication system design guidelines –
Part 14: Determination of the uncertainties of attenuation measurements in fibre
plants
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.180.01 ISBN 978-2-8322-8867-2

– 2 – IEC TR 61282-14:2024 RLV © IEC 2024
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms . 10
4 Overview of uncertainty . 11
4.1 What is uncertainty? . 11
4.2 Origin of uncertainties . 11
4.3 What may could not be considered as uncertainty? . 11
5 Fibre cabling attenuation measurement . 11
5.1 Test methods . 11
5.2 Sources of uncertainty to be considered . 12
5.2.1 Analysis . 12
5.2.2 Uncertainties due to the environment . 16
5.2.3 Uncertainties due to operator skills . 16
5.2.4 Uncertainties due to test methods . 16
5.2.5 Uncertainties due to measuring instruments . 16
5.2.6 Uncertainties due to the setup . 18
5.2.7 Uncertainties due to cabling. 18
6 Uncertainties estimation . 19
6.1 Light source power meter measurement methods . 19
6.1.1 Measurement model . 19
6.1.2 Accumulation of uncertainties . 22
6.2 OTDR methods . 23
6.2.1 Measurement model for unidirectional methods . 23
6.2.2 OTDR bidirectional measurements . 24
7 General representation of the formula using sensitivity coefficients . 27
8 Calculation . 32
8.1 Combined standard uncertainty . 32
8.2 Expanded uncertainty . 32
8.3 Determination of the coverage factor k . 32
8.3.1 General approach . 32
8.3.2 Discussion . 32
8.3.3 Typical values of degree of freedom . 33
Annex A (informative) Mathematical basis. 35
A.1 General . 35
A.2 Type A evaluation of uncertainty . 35
A.3 Type B evaluation of uncertainty . 36
A.4 Determining the combined standard uncertainty . 36
A.5 Reporting . 37
Annex B (informative) Test methods . 38
B.1 LSPM test methods as per IEC 61280-4-1 and 61280-4-2 . 38
B.1.1 General . 38
B.1.2 Measurement configuration . 38

B.1.3 One-cord reference configuration . 38
B.1.4 Two-cord reference configuration . 39
B.1.5 Three-cord reference configuration . 39
B.1.6 Equipment cord reference configuration . 39
B.2 OTDR Test methods as per IEC 61280-4-2 and 61280-4-3 . 39
B.2.1 Unidirectional measurement . 39
B.2.2 Bi-directional measurement . 40
B.2.3 OTDR test method on PON . 40
B.2.4 Filtered OTDR on PON . 41
B.3 Test methods defined in ISO/IEC 14763-3:2014 . 42
B.3.1 General . 42
B.3.2 Channels . 43
B.3.3 Links. 44
Annex C (informative) Evaluation of uncertainties . 45
C.1 Type A uncertainties . 45
C.1.1 General . 45
C.1.2 Evaluation of optical source instability and associated uncertainties . 45
C.2 Type B uncertainties . 45
C.2.1 General . 45
C.2.2 Evaluation of the power meter noise . 46
C.2.3 Elements to be considered for power meter stability analysis . 46
C.2.4 Evaluation of the centre wavelength dependence (LS or OTDR) . 46
C.2.5 Spectral width dependence . 49
C.2.6 Evaluation of the uncertainties due to MM launch conditions . 49
C.2.7 Evaluation of the PDL . 50
C.2.8 Uncertainty of absolute power measurement of power meters . 51
C.2.9 Relative uncertainty arising from non-linearity of the OTDR . 51
C.2.10 Uncertainty arising from OTDR noise . 52
C.2.11 Practical determination of uncertainty arising from OTDR noise . 54
C.2.12 Relative uncertainty arising from OTDR cursor placement . 57
C.2.13 Considerations on backscatter coefficient . 58
Annex D (informative) Typical values of uncertainties . 59
Annex E (informative) Linear to dB scale conversion of uncertainties . 63
E.1 Definition of decibel . 63
E.2 Conversion of relative uncertainties . 63
Bibliography . 65

Figure 1 – Fishbone analysis . 15
Figure 2 – Measurement model for light source and power meter . 19
Figure 3 – Measurement model for OTDRs . 23
Figure B.1 – Measurement configuration . 38
Figure B.2 – One-cord reference measurement . 38
Figure B.3 – Two-cord reference measurement . 39
Figure B.4 – Three-cord reference measurement . 39
Figure B.5 – Equipment cord reference measurement . 39
Figure B.6 – Location of the cabling under test ports . 40
Figure B.7 – Graphic determination of F and F . 41
1 2
– 4 – IEC TR 61282-14:2024 RLV © IEC 2024
Figure B.8 – Graphic determination of F and F . 42
1 2
Figure B.9 – Measurement on channel Channel measurement configuration . 43
Figure B.10 – Channel reference measurement . 43
Figure B.11 – Link measurement configuration . 44
Figure B.12 – Link reference measurement . 44
Figure C.1 – Typical spectral response of a fibre . 47
Figure C.2 – Observed PLC splitter waveleng
...