578
14 Basic Measurement and Monitoring Techniques
Fig. 14.1 Components of a typical WDM link and some performance-measurement parameters of
user interest
and polarization-mode dispersions are important factors that can limit the transmission distance or data rate. Chromatic dispersion effects are of particular importance
in high-speed DWDM links, because their behavior depends on the link configuration. Measurement and monitoring of polarization-mode dispersion is important for
data rates at and above 10 Gb/s, because its statistical behavior ultimately can limit
the highest achievable data rate.
When a link is being installed and tested, the operational parameters of interest
include bit-error rate, timing jitter, and signal-to-noise ratio as indicated by the eye
pattern. During actual operation, measurements are needed for maintenance and
monitoring functions to determine factors such as fault locations in fibers and the
status of remotely located optical amplifiers and other active devices.
This chapter discusses measurements and performance monitoring tests of interest
to designers, installers, and operators of fiber optic links and networks. Of particular
interest here are measurements for WDM links. Figure 14.1 shows some of the
relevant test parameters and at what points in a WDM link they are of importance.
The operational impact or impairment for many of these factors can be accounted
for and controlled through careful network design. Other parameters may need to be
monitored and possibly compensated for dynamically during network operation. In
either case, all of these parameters must be measured at some point during the time
period ranging from network design concept to service provisioning.
First, Sect. 14.1 addresses internationally recognized measurement standards for
component and system evaluations. Next, Sect. 14.2 lists basic test instruments for
optical fiber communication link characterizations. A fundamental unit in lightwave
communications is optical power and its measurement with optical power meters,
which is the topic of Sect. 14.3. Turning to measurement techniques, Sect. 14.4 gives
an overview of methods and specialized equipment for characterizing optical fiber
parameters. In addition to determining geometric parameters, this equipment also
14 Basic Measurement and Monitoring Techniques
Fig. 14.1 Components of a typical WDM link and some performance-measurement parameters of
user interest
and polarization-mode dispersions are important factors that can limit the transmission distance or data rate. Chromatic dispersion effects are of particular importance
in high-speed DWDM links, because their behavior depends on the link configuration. Measurement and monitoring of polarization-mode dispersion is important for
data rates at and above 10 Gb/s, because its statistical behavior ultimately can limit
the highest achievable data rate.
When a link is being installed and tested, the operational parameters of interest
include bit-error rate, timing jitter, and signal-to-noise ratio as indicated by the eye
pattern. During actual operation, measurements are needed for maintenance and
monitoring functions to determine factors such as fault locations in fibers and the
status of remotely located optical amplifiers and other active devices.
This chapter discusses measurements and performance monitoring tests of interest
to designers, installers, and operators of fiber optic links and networks. Of particular
interest here are measurements for WDM links. Figure 14.1 shows some of the
relevant test parameters and at what points in a WDM link they are of importance.
The operational impact or impairment for many of these factors can be accounted
for and controlled through careful network design. Other parameters may need to be
monitored and possibly compensated for dynamically during network operation. In
either case, all of these parameters must be measured at some point during the time
period ranging from network design concept to service provisioning.
First, Sect. 14.1 addresses internationally recognized measurement standards for
component and system evaluations. Next, Sect. 14.2 lists basic test instruments for
optical fiber communication link characterizations. A fundamental unit in lightwave
communications is optical power and its measurement with optical power meters,
which is the topic of Sect. 14.3. Turning to measurement techniques, Sect. 14.4 gives
an overview of methods and specialized equipment for characterizing optical fiber
parameters. In addition to determining geometric parameters, this equipment also