10
Installation Guide
Theory of Operation
Data Transparency
The Radiance T3/E3 single interface line card offers full data transparency. Any
codes or commands contained within the data stream are passed through to the
remote device. The only commands executed by the T3/E3 card are those set
through the hardware (i.e., DIP switches) or software, which communicates with
the card via the management bus on the chassis backplane.
Functional Block Diagram
Line
Transformers
Line
Interface
Unit
FPGA
VCXO
Fiber
Optic
Circuit
RX
Coaxial
TX
TX
Fiber
RX
Coaxial to Fiber Data Path
The receive (RX) port on the coaxial interface accepts an electrical signal. This
signal is coupled to the line interface unit (LIU) through a line transformer. The
LIU performs clock and data recovery and converts the signal into non-return to
zero (NRZ) data and clock. The NRZ data and clock then pass through the field-
programmable gate array (FPGA), which encodes the data for fiber optic
transmission. The encoding ensures adequate transition density for reliable clock
recovery at the remote T3/E3 fiber optic interface.
Fiber to Coaxial Data Path
The RX port on the fiber interface accepts an optical signal from the remote T3/
E3 line card and converts it back to an electrical signal. The optical signal first
enters the voltage-controlled crystal oscillator (VCXO), which extracts the line
rate clock and data. The recovered clock and data are then sent to the FPGA for
decoding. The decoded data stream goes to the LIU for encoding into T3 or E3
signals. The transmitted signal is coupled to the BNC coaxial connector through
a line transformer.
On both the RX and TX ports of the coaxial interface, surge protection is
provided.
