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903-0623-00 Rev. A
Model 903 User's Guide, FMB-X-2.5 Version
2.3
Optical Configuration
Model 903 systems based on FMB-X-2.5 cards are provided in standard optical configurations with
singlemode fiber and dual fiber connection for redundancy. Typical systems use 1310 nm as the uplink
wavelength (remote to console) and 1550 nm as the downlink wavelength (console to remote), which are
combined with a wavelength division multiplexer (WDM) on the FMB-X-2.5. Dual fiber configurations
increase reliability with an integrated splitter at the remote FMB-X-2.5 and an automatic fiber switch at the
console FMB-X-2.5, as shown in the figure below.
Figure 2.3-1: Model 903 Fiber Optic Transmission System
Standard FMB-X-2.5 cards use lasers with loosely controlled wavelengths that can vary significantly from
unit to unit and over temperature. Since 1310 nm and 1550 nm are widely separated on the optical
spectrum, there is no problem with crosstalk or interference even when the exact wavelengths are
variable.
FMB-X-2.5 cards are also available with more carefully controlled wavelengths for use in multi-channel
systems based on CWDM (Coarse Wavelength Division Multiplexing) or DWDM (Dense Wavelength
Division Multiplexing). CWDM systems support 4 to 16 wavelengths; DWDM systems support 16 or more
wavelengths. Both CWDM and DWDM enable the combination of two or more FMBs, plus other media
converter cards, on a single optical fiber, allowing considerable expansion of the Model 903 video and
data channel capacity.
Focal Technologies Corp.
Page 2-5
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