Multimode attenuation standards compliance
For LED sources and LTS

The following recognised international standards may apply when measuring multimode attenuation:

• ISO/IEC 14763-3: Information technology -- Implementation and operation of customer premises cabling -- Part 3: Testing of optical fibre cabling. This standard also covers single-mode fiber testing.
• ANSI/TIA/EIA-526-14-A: Optical power loss measurements of installed multimode fiber cable plant, 1998.
• IEC-61280-4-1 Ed 1.0 (draft): Fiber optic communication subsystem basic test procedures - part 4.1: Procedures for cable plant and links - multimode cable plant attenuation measurement.
• TIA TSB-178 Draft Launch Condition Guidelines for Measuring Attenuation of Installed Multimode Cabling

For multimode fiber testing, these standards typically define:

1. All these standards require LED sources with specific Launched Modal Distribution (LMD) and Center Wavelength.
2. ANSI/TIA/EIA-526-14-A also requires specific Spectral Width.
3. Tests may require one or both 850 / 1300 nm wavelengths.
4. Use a two-way or bi-directional measurement procedure.
5. Use of test cords (eg 1 - 3 test cord methods) and reference planes.

Of the above 5 points, items 1 & 2 affect test instrument performance. Kingfisher instruments meet these requirements as follows:

Launched Modal Distribution

This describes the relative distribution of optical power across the fiber core, and is an important parameter in relation to loss testing.

Subsidiary terms commonly in use are as follows: For some 30 years the term Equilibrium Modal Distribution (EMD) has been used to in multimode measurement practice, and is defined in many well recognised FOTP documents. The performance of multimode components and systems is usually both specified and measured in this condition. Its is easy to achieve the condition by the use of a long length of multimode fiber. In situations where EMD has not been achieved, the modal distribution is variously called "under filled" or "over filled". Test source conformance to this parameter can greatly improve repeatability and consistency when using multiple instruments and test cords, and also enables testing against specifications.

There are various methods of measuring launched modal distribution. These are commonly: Coupled Power Ratio, Encircled Flux or Mode Transfer Function.

• Kingfisher LED sources, Loss Test Sets and Two-Way testers comply with this requirement by design.

 

Center Wavelength

This describes the mean wavelength of the test source. For loss measurements over the short distance applications covered by these standards, this is a less important parameter, (however it's very important when measuring bandwidth).

• Kingfisher LED sources, Loss Test Sets and Two-Way testers can be ordered to comply with this requirement.

 

Spectral Width

This describes the wavelength width of the test source. For loss measurements over the short distance applications covered by these standards, this is a less important parameter, (however it's very important when measuring bandwidth).

Kingfisher LED sources, Loss Test Sets and Two-Way testers can be ordered to comply with this requirement.

 

Overall Measurement Uncertainty

We have performed careful evaluation of the performance of Kingfisher compliant multimode sources and meters in real world situations. Report.
Overall, we found that in a typical installer situation, multimode loss measurement uncertainty is dominated by randomly changing the test leads. In other words, the total loss measurement uncertainty introduced by Kingfisher test equipment, is just less than the uncertainty introduced by the test leads.