Applications
Issue 8.0 July 2002
2-41
!
CAUTION:
In WDM applications with bidirectional OC-48 signal transmission over a
single fiber, unprotected fiber or coupler failures are possible. If a fiber break
or coupler failure occurs, sufficient light may be reflected from the break to
the local receiver and cause the local receiver to frame on the signal
transmitted by the local transmitter (optical loopback). If an optical loopback
occurs, the failure would not be detected or alarmed and not protected. The
probability of this condition occurring depends on the type of fiber break and
the distance between the break and receiver.
When WDM is planned for a future addition to a span, the insertion loss of the
WDM devices must be properly allocated in each outside plant repeater section
cable loss design. For more information about loss budgets and WDM
specifications, refer to Volume I, Section 10, "Technical Specifications."
For more information about operation with the FT-LBA, refer to the “FT-Lightwave
Booster Amplifier (FT-LBA) for Extended Distances” application in this section.
Dense Wavelength Division Multiplexing (EON
*
Compatible) 2
DWDM is a technology that meets the customer's need for transporting more
capacity per fiber. Specifically, this technology permits two or more OC-48 signals
(each with a different wavelength) to be multiplexed together and simultaneously
transmitted over a single fiber.
The actual multiplexing is accomplished within the Optical Line System (OLS). On
the FT-2000 side, the 739E[1-16] transmitter circuit packs provide a direct
interface to the OLS product. For FT-2000 Release 7.2.0, sixteen different
wavelengths (739E1 through 739E16) are supported. This will permit the design
of fiber routes that operate up to 40 Gb/s per fiber.
* Metropolis Enhanced Optical Networking.
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