2–26
DECbridge 500/600 Problem Solving
Table 2–2 shows a sample table that you can use to record the receive and
transmit power for the bridge (station A) and for the upstream device (sta-
tion B). You can also use the table to record the cable loss between the
two stations (the transmit power at one station minus the receive power at
its downstream station).
6. Check the recorded values against the specifications given below. If either
measurement falls outside the given range, that optical signal is not within
specifications. Refer to the flow chart in Figure 2–4 for recommended correc-
tive actions.
Multimode:
–
Power level of the transmit signal must be between –14.5 and –19.5 dBm.
–
Power level of the receive signal must be between –14.5 and –30.5 dBm.
Single-mode:
–
Power level of the transmit signal must be between –2.5 and –7.5 dBm.
–
Power level of the receive signal must be between –14.5 and –29.5 dBm.
Table 2–2:
FDDI Transmit and Receive Power Calculation
Tx Power
STA
__________ dBm
STB
__________ dBm
Rx Power
STB
__________ dBm
STA
__________ dBm
Loss
__________ dBm
__________ dBm
