Atec EXFO-FTB-5500 Series - Manual (Page 3)

Measuring PMD the Smart Way
The FTB-5500 PMD Analyzer module uses a Michelson interferometer
to accurately measure PMD delay. It performs a mean measurement
over the entire wavelength range of a broad-spectrum polarized LED
source. After fitting the Gaussian distribution curve, the analysis soft-
ware calculates and displays the fiber’s total PMD and second-order
PMD value and coefficient. Vibration-proof: The broad spectrum and short coherence time of the
LED source used in the interferometric method renders the EXFO
PMD analyzer almost immune to vibration. This characteristic is espe-
cially important when testing installed cables. Acquisition speed is also a
factor with regard to vibration immunity.
Fast results: The interferometric method also provides fast results by
automating the measurement process. The software typically completes
the test cycle in 15 seconds.
High dynamic range
Averaging PMD over the entire source wavelength range (without filter-
ing) preserves full power for PMD measurement. The standard
40 dB dynamic range remains available for testing long fiber spans.
A high dynamic range option, using EXFO’s M-2100 Broadband Light
Source, a high-power EELED source, increases the dynamic range to
more than 50 dB to measure fiber spans longer than 250 km.
Great measurement range
The interferometric method can handle high PMD values. An extended
range option increases the instrument's analysis from 0.05 to 200 ps.
The measurement range of the instrument goes from 0.1 to 115 ps, but
users can obtain calculated values down to 0.05 ps and estimated val-
ues from 115 up to 200 ps.
Second-order PMD
Second-order PMD is derived from the measured PMD value and is pro-
portional to the link length, unlike first-order PMD. This means that sec-
ond-order PMD is particularly important in long-distance links. Moreover,
second-order PMD, because it is based on the mean variation in the
slope of the first-order PMD curve, is wavelength-dependent.
EXFO's PMD software provides second-order PMD delay and coefficient
values. These figures help to characterize fibers and cables more pre-
cisely than simple PMD, which makes for better control of transmission
quality in both digital and analog high-bandwidth systems.
Field-proof advanced technology