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903-0623-00 Rev. A
Example:
1310 nm Uplink Flux Budget (Up_FB)
Rem_Tx_Pwr = -3.0 dBm
Con_Rx_Pwr = -26 dBm
Up_FB = -3.0 dBm - (-26 dBm) = 23 dB
st
nd
The Model 903 1
or 2
data errors on the program's display screen may be used instead of the "Link" LEDs to determine the
receiver thresholds. This provides a more accurate flux budget, since as received power drops, errors
occur in the data frames before synchronization is lost. By default the FMB-X-2.5 cards are calibrated at
the factory when a new 903 system is shipped and no calibration should be required, but if a calibration is
deemed necessary then please consult the 903-0622-00 diagnostic manual.
When the Model 903 is initially turned on or when the optical connection is initially made, the uplink and
downlink transmitters send synchronization frames to ensure reliable transmission before sending actual
data frames. In the event that either the uplink or downlink is lost or exhibits significant frame errors, the
multiplexer will revert both links to synchronization frames until reliable transmission is re-established. If,
for example, the fiber jumper between the two modules is momentarily disconnected, the uplink and
downlink transmitters will send synchronization frames until the connection is remade. When sufficient
optical power is present, synchronization (lock) occurs within 3 milliseconds. Both data and
synchronization frames are transmitted with a nominal 50% duty cycle allowing accurate and consistent
measurements of optical power regardless of which frame type is active.
8.5
Maintenance
The unit requires no routine maintenance or calibration for the specified performance. Maintenance of the
units is limited to cleaning the various components using the methods described below.
The outer surfaces of the modules can be cleaned using a damp cloth. Do not use solvents or damage to
painted surfaces may result.
Dust or dirt on the cards can be blown off using compressed air. If severe contamination of the cards
should occur, they can be removed and cleaned using distilled water. Cards must be thoroughly dried
before reapplying power.
In order to maintain optical performance, it is necessary to ensure the fiber optic connectors are kept
clean. Use a suitable solvent, such as acetone or isopropyl alcohol, and a lint free cloth to carefully wipe
any dirt off the face of the ceramic ferrules prior to making a connection. Always replace dust caps on the
Model 903 fiber optic bushings when removing connectors. If bushings are left open, they should be
cleared of dust with compressed air prior to connection.
Focal Technologies Corp.
generation diagnostics software is also helpful during bench testing. Presence of
Model 903 User's Guide, FMB-X-2.5 Version
1550 nm Downlink Flux Budget (Down_FB)
Con_Tx_Pwr = +1.0 dBm
Rem_Rx_Pwr = -23 dBm
Down_FB = +1.0 - (-23 dBm) = 24 dB
Page 8-5
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