Agilent 83446A
Lightwave Clock/Data Receiver
Product Overview
High gain optical receiver for recovering clock
and data directly from optical fiber
• OC-48/STM-16 data rate (2.48832 Gb/sec)
• Operates over full range of power levels specified in SONET/SDH
standards
• 1310/1550 nm operation
• Auxiliary input recovers clock and data from 2.48832 Gb/sec
electrical signals
Clock/
Data
Recovery
AGC
Amplifier
Photodiode
Optical
Input
Aux Out
Clock Out
Data Out
Front Panel
Rear Panel
Electrical
Input
Input Select
Switch
Agilent’s 83446A Lightwave
Clock/Data Receiver is designed
to extract clock and data information from digitally modulated
lightwave signals. The 83446A is
for use with OC-48/STM-16
(2.48832 Gb/sec) signals. It incorporates a high-gain avalanche
photo-diode (APD), gain-controlled
amplifier, and clock/data recovery
hybrid to deliver clean, errorfree outputs from optical signals
with powers as low as –27 dBm
at either 1310 or 1550 nm wavelengths. The Agilent 83446A is
designed especially for use with
high speed bit-error-ratio testers
(BERTs) such as the Agilent
86130A. By connecting the
83446A clock and data outputs
to the corresponding inputs on
the BERT’s error detector, biterror-ratio analysis can be performed directly on optical signals,
making it easy to do system
acceptance and BER floor analysis.
The high sensitivity of the
Agilent 83446A assures accurate results over the full range of
optical powers specified in
SONET/SDH standards such as
ITU G.957 and Bellcore
TA-NWT-000253. It can also be
useful for optical eye diagram
analysis on sampling oscilloscopes. In situations where no
separate clock signal is available,
the clock output of the 83446A
can be used to trigger the oscilloscope. Unlike schemes that use
the data pattern as the trigger
source, triggering from a recovered clock assures that the eye
diagram is an accurate representation of all possible bit combinations on the incoming data
stream.
For analog monitoring of
unconditioned data, the Agilent
83446A provides an auxiliary
electrical output. This high-gain
AGC controlled output is useful
for general diagnostic analysis of
the incoming waveform.
(Because its frequency response
does not meet the stringent
requirements for eye mask compliance testing defined in
SONET/SDH standards, mask
tests should be done with an
appropriate reference receiver.
Another feature of the 83446A is a
rear-panel input for recovering
clock and data from an electrical
waveform. A rear panel switch
selects between either the front
optical input or the rear electrical input. (The electrical input
bypasses the internal high-gain
amplifier, so external amplification must be used when operating on low power signals to
achieve a level sufficient for
proper operation.) The Agilent
83446A uses a 50 µm fiber core
diameter which is compatible
with either single-mode or multimode fibers. The optical input
incorporates a universal adapter
for use with any of the connector
interfaces in the Agilent 81000
series. The standard instrument
includes an FC/PC connector
interface. Option 010 deletes the
FC/PC connector. Interfaces for
other optical connector types
must be ordered separately.
Example uses of the
Agilent 83446A
Laser Transmitter Optimization
The Agilent 83446A, in conjunction with an Agilent
86130A Error Performance
Analyzer and Agilent 8156A
High-performance Optical
Attenuator, can help determine
the optimum bias setting for
laser transmitters. The optimum
bias is found when the improvement in BER, due to higher
extinction ratio, is balanced by
degradation due to increased
nonlinear waveform distortion
effects. BER floors are easily
identified by monitoring the
error rate as the input power
level to the 83446A is increased.
The Agilent 83446A operates
error-free at input powers above
–27 dBm, so any residual errors
at higher input powers can be
associated with the transmitter
under test.
2
86130A BERT
83446A
Clock
In
Data
In
Data
Out
DUT
Laser
8156A
Variable Optical
Attenuator
Clock
Out
Data
Out
Optical
In
Optical
Out
Data
In
In Out
Setup for Optimizing
Laser Transmitter Extinction Ratio
Loading...