Local Loopback
The local (LLOOP) loopback DIP switch is provided to allow for local loop back of the fiber T1 line for
troubleshooting purposes.
The loop back function begins with the T1 fiber transmit data coming from the remote side module, through the
fiber cable to the local receiver, then back out from the local fiber transmitter to the remote side. Normal
operating position is OFF for All switch positions.
LLOOP (Local Loopback) Switch Diagram
Note:
The LEDs will indicate the matching conditions upon detection of errors or alarms. The LEDs will
remain ON until the error condition has been removed.
Line Build Out (LBO)
The Line Build Out switch simulates cable loss of the signal for compatibility with different installation scenarios.
There are switches corresponding to -7.5dB and -15dB attenuation level. Select a level appropriate for your
particular application by setting one of the switches to the ON position.
The default position is OFF.
LED Indicators
Remote Channel Alarm
The REM CH ALARM (yellow) LED indicates that the far end unit has detected a loss of fiber signal, BPV, or AIS
fault condition from the T1 LIU.
Fiber Optic Receive Frame Valid / Frame Alarm
The FIBR FRM (green) LED will remain ON as long as the fiber optic receiver stays in frame with the far end
Single Channel T1 card. Only if there is a problem with the receive frame does the green LED turn yellow. When
this LED does turn yellow then both of the Single Channel T1 end units will begin a system resynchronization.
This resynchronization requires about ten milliseconds to accomplish.
The LED is continuously ON if the local receiver cannot detect receive frame from the fiber. The loss of the far
end receive frame will cause this LED to blink on and off.
Signal Loop
• Turn on
LLOOP
switch to have fiber
loop back or to check for fiber connection.
LLOOP
RLOOP
ON
LBO-15
LBO-7.5
NOT USED
ON - AMI
OFF - B8ZS
1 2 3 4 5 6
RLH Industries, Inc. • Tel. 866-DO-FIBER • Fax 714 532-1885 • www.fiberopticlink.com
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