Principle Of Measurement Of Chromatic Dispersion (Cd Odm) Using Phase Shift Method - Viavi 8100 V2 Series User Manual

Chapter 1 Principles of measurement

Principle of measurement of Chromatic Dispersion (CD ODM) using phase shift method

The table below indicates the maximum permitted PMD values for various
bit rates.
Bit rate (Gbit/s)
2.5
10
40
10Gbps Ethernet
• Tables at the end of chapter gives information about the appropriate
standards and limits.
Principle of measurement of Chromatic
Dispersion (CD ODM) using phase shift
method
The Phase shift method
A modulated broadband light is sent over the Fiber Under Test. The phase
of the test signal is compared to the phase of the reference signal. The
measured value is the group delay, corresponding to a wavelength interval
between the reference phase and the test wavelength phase. It is
measured in the frequency domain, by detecting, recording and processing
the phase shift of The modulated signals. The fibre chromatic dispersion is
derived from the measurement of the relative group delay using an approx-
imation formula.
10
Maximum PMD
(ps)
40
10
2.5
5
User Manual
PMD coefficient (ps/√ km)
400 km cable length
< 2
< 0.5
< 0.125
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