Radiance T3/E3 Single Interface Line Cards 17
Local T3/E3 Card
with Copper Loopback
Remote T3/E3
Card
Coax
Coax
Fiber
Local
Device
Remote
Device
X
Fiber Loopback
In this mode, the incoming data and clock on the fiber line are looped back.
The loop occurs in the FPGA. The data is still sent out the coaxial transmit-
ter. However, the data received at the BNC interface is ignored.
In the diagram below, the remote T3/E3 line card has fiber loopback
enabled. Data received at the fiber optic port is simultaneously returned to
the local device and sent to the remote device. However, data from the
remote device is ignored by the remote T3/E3 line card at its coaxial
interface.
Local T3/E3
Card
Remote T3/E3 Card
with Fiber Loopback
Coax
Coax
Fiber
Local
Device
Remote
Device
X
Loopback with Port Disabled
If loopback is enabled on a port that has been disabled, the loop will still
occur and the loopback LED will be lit. However, only an unframed all-
ones pattern (AIS for E3) will be sent from the opposite transmitter. No
signal will be sent from the disabled transmit port, as shown in the example
below.
Local T3/E3 Card
with Copper Loopback
and Copper Disable
Remote T3/E3
Card
Coax
Coax
Fiber
Local Device
Detects
No Signal
Remote
Device
X
All Ones
All Ones
X
