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Chapter 2
Calculating transmission distance
This chapter will help you determine the maximum transmission distance for your CWDM network configuration.
This chapter includes the following topics:
•“About transmission distance and optical link budget” next
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•“Mesh ring transmission distance” on page 30
•“Hub and spoke transmission distance” on page 33
About transmission distance and optical link budget
By calculating the optical link budget, you can determine a link’s transmission distance, or the amount of usable signal strength between the point where it originates and the point where it terminates. The loss budget, or optical link budget, is the amount of optical power launched into a system that is expected to be lost through various mechanisms acting on the system, such as the absorption of light by molecules in an optical fiber. Factors that affect transmission distance include:
•fiber optic cable attenuation (typically 0.25 dB - 0.3 dB per kilometer)
•network devices the signal passes through
•connectors
•repair margin
Note: Insertion loss budget values for the optical routing system CWDM
OADM and CWDM OMUX include connector loss.