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
3
Dispersion Power Penalty Testing
Signal degradation due to fiber
dispersion can have a major
impact on the maximum distance over which optical data
can reliably be sent. This is a
particular concern when 1550 nm
lasers are used with fiber optimized for transmission at 1300
nm. To evaluate the dispersion
power penalty of a system, the
83446A can be used in conjunction with the Agilent 86130A
Error Performance Analyzer. By
testing the error performance of
the laser when used with a long
length of the intended fiber, the
power penalty due to dispersion
can easily be evaluated.
Waveform Test: Example of
Measuring Eye Diagram With
Recovered Clock Signal As a Trigger
Eye diagrams are important
tools for characterizing the
waveform performance of a
laser source. An eye diagram is
generated on an oscilloscope by
observing the data output from
the laser while triggering the
oscilloscope from a separate signal at the clock frequency.
In many cases a separate clock
signal is not readily accessible.
To generate a valid eye diagram,
clock must be recovered from the
data waveform and used to trigger the oscilloscope. The
Agilent 83446A is ideal for generating this recovered clock. In
addition, the waveform from the
Agilent 83446A’s AUXILIARY OUT
port is often adequate as the
data input to generate the eye
diagram.
Certain industry standards such
as SONET and Fibre Channel
require that the eye diagram be
measured through a reference
receiver having a carefully-controlled frequency response. In
this case, the Agilent 83446A can
be used to recover the clock and
a separate reference receiver
used to display the eye diagram.
83446A
Clock
In
Data
In
Data
Out
Laser
8163A
Optical
Power Meter
11890A
Lightwave
Coupler
8156A
Variable Optical
Attenuator
Clock
Out
Data
Out
Optical
In
OutputAInput
Output
B
Optical
Out
Data
In
In Out
Fiber
Spool
86130A BERT
Setup to Measure Dispersion Power Penalty
of Single-Mode Fiber
83446A
Laser
Under Test
Optical
Coupler*
Optical
Output
Data
In
86100B Infiniium Digital
Communications Analyzer
*Split ratio of coupler should
be selected to provide optimum
power to the analyzer for
waveform analysis.
Setup for Measuring Eye Diagram by
Triggering From Recovered Clock
4
Specifications/Characteristics
Operating Data Rate 2.48832 GHz ±0.5%, NRZ coding
Sensitivity
1, 2, 4, 5
–27 dBm min
Wavelength Range 1200 to1600 nm
Data Out Amplitude
3
0.5 v pk-pk
Clock Out Amplitude 0.5 v pk-pk
Max Operating Input Power
1, 4
–9 dBm min Input
Optical Return Loss
7
27 dB
Output Electrical Return Loss 12 dB* @ 1 GHz
9 dB* @ 2 GHz
6 dB* @ 2.5 GHz
Max Safe Optical Input Power +10 dBm
RMS Jitter
On Clock/Data Outputs
6
5 degrees
Auxiliary Out Bandwidth 0.1 to 1500 MHz
Electrical Clock Recovery
Input Sensitivity 200 mv pk-pk
Max Safe Electrical Clock
Recovery Input 2 v pk-pk
Auxiliary Output (Optical Input) 0.5 v pk-pk for >–24 dBm input
(AGC Stabilized)
0.25 v pk-pk for >–27 dBm input
Auxiliary Output (Electrical Input)<6 dB* down from input
signal level
General/Environmental
Temperature Range Operational: 0° to +55°C
Storage: –40° to +70°C
EMI Conducted and radiated emis-
sions are in compliance with
the requirements of CISPR
Publication 11 and EN 55011
Group 1, Class A
Power Requirements 100,120,220, or 240 volts
(±10%), 47 to 63 Hz
Power consumption <75VA
Weight 3.36 kg (7.5 lb)
Dimensions 102 mm (4.02 in.) height
213 mm (8.39 in.) width
368 mm (14.49 in.) length
Performance Specifications
and Characteristics
Specifications describe the instrument’s warranted performance over the 0°C to 55°C temperature
range, except where noted. Characteristics (italicized) provide information about non-warranted instrument performance in the form of nominal values. All amplitude specifications are in optical power units
unless noted by an asterisk (*).
1. Better than 1E-10 bit error ratio with 2^23-1 PRBS pattern, 50% mark density.
2. Sensitivity may be degraded if signals are applied simultaneously to both front optical input and rear electrical input.
3. Non-inverting output.
4. Source extinction ratio ≥ 8.2 dB at eye center.
5. Sensitivity specification applies over temperature range of 25±5°C
6. Clock edges nominally aligned with data transitions to ±0.25 unit interval.
7. Measured using single mode fiber from source.
Ordering Information
Agilent 83446A Lightwave Clock/Data Receiver
Optical connectors (choose one)
Option 83446A-011 No optical connector
Option 83446A-012 FC/PC connector interface
Related Accessories
Agilent 86100B Infiniium Digital Communications Analyzer
Agilent 10086A ECL Terminator
Agilent 83440B/C/D Lightwave Converters
Agilent 86130A BitAlyzer® Error Performance Analyzer
Agilent 8156A Optical Attenuator
Agilent 11980A Lightwave Directional Coupler
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Product specifications and descriptions in this document subject to change without notice.
© 1994, 2000, 2002 Agilent Technologies, Inc.
Printed in USA June 12, 2002
5964-1682E
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