IEC 60793-1-40:2019 is available as IEC 60793-1-40:2019 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 60793-1-40:2019 establishes uniform requirements for measuring the attenuation of optical fibre, thereby assisting in the inspection of fibres and cables for commercial purposes. Four methods are described for measuring attenuation, one being that for modelling spectral attenuation:

– method A: cut-back;

– method B: insertion loss;

– method C: backscattering;

– method D: modelling spectral attenuation.

Methods A to C apply to the measurement of attenuation for all categories of the following fibres:

– class A multimode fibres;

– class B single-mode fibres.

Method C, backscattering, also covers the location, losses and characterization of point discontinuities. Method D is applicable only to class B fibres. Information common to all four methods appears in Clauses 1 to 11, and information pertaining to each individual method appears in Annexes A, B, C, and D, respectively. This second edition cancels and replaces the first edition published in 2001. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) Improvement of the description of measurement details for B6 fibre;

b) Improvement of the calibration requirements for A4 fibre;

c) Introduction of Annex E describing examples of short cable test results on A1 multimode fibres.

Keywords: measuring the attenuation of optical fibre