HP HP 83491A User manual

User’s Guide
HP 83491/2/3A
Clock Recovery Modules

ii
© Copyright Hewlett-Packard
Company 1999
All Rights Reserved. Repro-
duction, adaptation, or trans-
lation without prior written
permission is prohibited,
except as allowed under copy-
right laws.
HP Part No. 83491-90011
Printed in USA
June 1999
Hewlett-Packard Company
Lightwave Division
1400 Fountaingrove Parkway
Santa Rosa, CA 95403-1799,
USA
[phone]
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one year from date of ship-
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For warranty service or repair,
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instructions when properly
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the instrument, or software,
or firmware will be uninter-
rupted or error-free.
Limitation of Warranty.
The foregoing warranty shall
not apply to defects resulting
from improper or inadequate
maintenance by Buyer, Buyer-
supplied software or interfac-
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CAUTION
The caution sign denotes a
hazard. It calls attention to a
procedure which, if not cor-
rectly performed or adhered
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or destruction of the product.
Do not proceed beyond a cau-
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WARNING
The warning sign denotes a
hazard. It calls attention to a
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required nature of the
line module input
power.
|The ON symbols are
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tions of the instrument
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❍The OFF symbols
are used to mark the
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This text denotes the
instrument is an
Industrial Scientific
and Medical Group 1
Class A product.
ISM1-A

iii
General Safety Considerations
General Safety Considerations
WARNING Light energy can radiate from the front panel Output connectors on
HP 83492A and HP 83493A modules. The light emitted from these
connectors is the slightly attenuated light that is input to the front-
panel Input connector.
WARNING If this instrument is not used as specified, the protection provided by
the equipment could be impaired. This instrument must be used in a
normal condition (in which all means for protection are intact) only.
WARNING NO OPERATOR SERVICEABLE PARTS INSIDE. Refer servicing to
qualified Hewlett-Packard personnel. To prevent electrical shock, do
not remove covers.
CAUTION This product is designed for use in INSTALLATION CATEGORY II and
POLLUTION DEGREE 2, per IEC 1010 and 664 respectively.
CAUTION Electrostatic discharge (ESD) on or near input connectors can damage circuits
inside the instrument. Repair of damage due to misuse is not covered under
warranty. Before connecting any cable to the electrical input, momentarily
short the center and outer conductors of the cable together. Personnel should
be properly grounded, and should touch the frame of the instrument before
touching any connector.
This product has been designed and tested in accordance with IEC Publica-
tion 1010, Safety Requirements for Electronic Measuring Apparatus, and has
been supplied in a safe condition. The instruction documentation contains
information and warnings which must be followed by the user to ensure safe
operation and to maintain the product in a safe condition.

iv
General Safety Considerations

Contents
Contents-1
General Safety Considerations iii
1 Installation
Installation 1-2
2Operation
HP 83491/2/3A Modules—at a glance 2-2
Front-Panel Features 2-4
Block Diagrams 2-7
To display a signal 2-8
To compensate for module insertion loss 2-9
Using Probes with an HP 83491A 2-10
3 Specifications and Regulatory Information
HP 83491A Specifications 3-3
HP 83492A Specifications 3-4
HP 83493A Specifications 3-6
HP 83491/2/3A Operating Specifications 3-7
Declaration of Conformity 3-8
4 Reference
Front-Panel Optical Adapters 4-2
In Case of Difficulty 4-3
Error Messages 4-5
Electrostatic Discharge Information 4-8
Cleaning Connections for Accurate Measurements 4-10
Returning the Module for Service 4-21
Hewlett-Packard Sales and Service Offices 4-24

Contents-2
Contents

1
To install the module 1-3
To connect cables to an HP 83492A 1-7
Installation

1-2
Installation
Installation
Installation
HP 83491/2/3A modules require that firmware revision A.06.25 or later be
installed in the HP 83480A. If you wish to install the module in an HP 54750A
digitizing oscilloscope, you must first install the HP 83480K communications
firmware upgrade kit.
To check the HP 83480A’s firmware revision code
1Press the Utility key and then the System config softkey.
2The firmware revision number is listed under the Frame section of the display.
CAUTION Fiber-optic connectors are easily damaged when connected to dirty or
damaged cables and accessories. The HP 83492A and HP 83493A front-panel
input connectors are no exception. When you use improper cleaning and
handling techniques, you risk expensive instrument repairs, damaged cables,
and compromised measurements. Before you connect any fiber-optic cable to
an HP 83492A or HP 83493A module, refer to “Cleaning Connections for
Accurate Measurements” on page 4-10.
CAUTION The circuits on electrical inputs and outputs can be damaged by electrostatic
discharge (ESD). Therefore, avoid applying static discharges to any front or
rear-panel electrical connector. Before connecting any coaxial cable to a front-
panel connector, momentarily short the center and outer conductors of the
cable together. Avoid touching the front-panel connectors without first
touching the frame of the instrument. Be sure that the instrument is properly
earth-grounded to prevent buildup of static charge. Refer to “Electrostatic
Discharge Information” on page 4-8.

1-3
Installation
Installation
To install the module
1Verify that all system components ordered have arrived by comparing the
shipping forms to the original purchase order. Inspect all shipping containers.
The shipment includes:
❒An HP 83491/2/3A Clock Recovery Module
❒Fiber-optic adapter cable (HP 83492/3A module only)
❒Two RF adapter cables (HP 83491A module only)
❒
HP 83491/2/3A Clock Recovery Modules User’s Guide (this book)
If your shipment is damaged or incomplete, save the packing materials and
notify both the shipping carrier and the nearest Hewlett-Packard Sales and
Service office. HP will arrange for repair or replacement of damaged or incom-
plete shipments without waiting for a settlement from the transportation com-
pany. Notify the HP customer engineer of any problems.
1Make sure that the serial number listed on the module’s rear-panel label
matches the serial number listed on the shipping document.
Figure 1-1. Serial number label
2Install the HP 83491/2/3A module into the HP 83480A mainframe’s left slot.
Finger-tighten the knurled screw on the front panel of the plug-in module to
ensure that the module is securely seated in the mainframe.
NOTE Installing the module into the left slot ensures that the supplied adapter cable
will fit. See Figure 1-2.

1-4
Installation
Installation
Figure 1-2. Position of modules in the mainframe
3Clean all optical interfaces as described in “Cleaning Connections for Accurate
Measurements” on page 4-10,before making measurements.
4Perform the following steps if you’re installing an HP 83492/3A module:
aUnscrew and remove the fiber-optic adapter that is located on the optical
module’s front-panel optical input connector.
bConnect the adapter that was removed in the previous step onto the
HP 83492/3A module’s front-panel Input connector.
On HP 83492A module’s, the input connector used depends on the
wavelength of the input signal. Refer to “To connect cables to an
HP 83492A” on page 1-7.
5Connect the supplied adapter cable as shown in Figure 1-3.
WARNING Light energy can radiate from the front panel Output connectors on
HP 83492A and HP 83493A modules. The light emitted from these
connectors is the slightly attenuated light that is input to the front-
panel Input connector.
6Turn on the HP 83480A, and connect a modulated signal to the HP 83491/2/3A
module’s Input connector.

1-5
Installation
Installation
Figure 1-3. The adapter cable
CAUTION HP 83491A Modules:
HP 83491A Modules:HP 83491A Modules:
HP 83491A Modules: Maximum safe signal input level is ±5V. The input circuits
can also be damaged by electrostatic discharge (ESD). Before connecting any
coaxial cable to the connectors, momentarily short the center and outer
conductors of the cable together. Avoid touching the front-panel input
connectors without first touching the frame of the instrument. Be sure that the
instrument is properly earth-grounded to prevent buildup of static charge.
CAUTION HP 83492/3A Modules: Maximum safe signal input level is +3 dBm.
7On the HP 83480A, press the Trigger key and then the Source softkey. Then,
select trigger 2 (the HP 83491/2/3A module) for the trigger source.
8On the HP 83491/2/3A module, repeatedly press the SELECT key until a front-
panel light indicates the data rate of the signal. See Figure 1-4 on page 1-6.
Green and red data-rate lights
The data-rate indicator lights change color between red and green to show which data
rate is selected. A red light does not indicate a problem. A red light shows that the adja-
cent red data rate label is selected. A green light shows that the adjacent green data
rate label is selected. Repeatedly pressing the SELECT key cycles through the selections
in one color before switching to the opposite color. On HP 83491A modules for example,
the first selection cycle shows 155 Mb/s selected. The second section cycle shows 1062
Mb/s selected.

1-6
Installation
Installation
Figure 1-4. Front-panel lights
9Confirm that the Unlocked light is off.
10 Observe the Clock and Data outputs on an oscilloscope. Waveforms should be
present. The instrument is now ready for you to begin making measurements.

1-7
Installation
Installation
To connect cables to an HP 83492A
On HP 83492A modules, the front-panel fiber-optic connectors reverse input
and output roles depending on the wavelength of the signal. Signals in the
750 nm to 860 nm wavelength range are input to the left connector and output
from the right connector. Signals in the 1000 nm to 1600 nm wavelength range
are input to the right connector and output from the left connector.
Figure 1-5. Input and output connections versus wavelength

1-8
Installation
Installation

2
HP 83491/2/3A Modules—at a glance 2-2
Front-Panel Features 2-4
Block Diagrams 2-7
To display a signal 2-8
To compensate for module insertion loss 2-9
Using Probes with an HP 83491A 2-10
To compensate for a passive probe 2-11
To compensate an HP 54701A active probe 2-11
To compensate for other devices 2-11
Operation

2-2
Operation
HP 83491/2/3A Modules—at a glance
HP 83491/2/3A Modules—at a glance
The HP 83491/2/3A Clock Recovery Modules are designed to operate in an
HP 83480A Digital Communications Analyzer. These modules recover clock
and data information at standard telecom and datacom rates. The resulting
trigger signal is made available to the HP 83480A mainframe via a connector
located on the module’s rear-panel. An external front-panel cable passes the
data signal, with some insertion loss, to the receiver module.
Figure 2-1. An HP 83493A installed in an HP 83480A mainframe
Table 2-1. Module Features
Module Input Connector Selectable Rates (Mb/s)
HP 83491A 50Ωelectrical 155, 622, 1060, 1250, 2120, 2488, 2500
HP 83492A Multimode fiber (62.5/125 µm) 155, 622, 1060, 1250, 2120, 2488, 2500
HP 83493A Single-mode fiber (9/125 µm) 155, 622, 1250, 2488, 2500

2-3
Operation
HP 83491/2/3A Modules—at a glance
WARNING Light energy can radiate from the front panel Output connectors on
HP 83492A and HP 83493A modules. The light emitted from these
connectors is the slightly attenuated light that is input to the front-
panel Input connector.
Use with HP 71603B or HP 71612B Error Performance Analyzers
The front-panel Data and Clock outputs provide electrical recovered clock and
regenerated data signals for simultaneous testing with other instruments,
such as the HP 71603B or HP 71612B error performance analyzers.
Multimode module and single-mode reference receivers
HP does not recommend using the HP 83492A multimode module with single-
mode reference receivers such as the HP 83481A, HP 83482A, or
HP 83485A,B modules. Connecting multimode to single-mode fibers causes
large reflections and insertion loss because of the reduction of the optical
fiber’s core from 62.5 µm to 9 µm.
Single-mode module and multimode reference receivers
It is acceptable to use an HP 83493A single-mode module with a multimode
reference receiver such as the HP 83486A module. This is true provided that
single-mode fiber is connected to the HP 83493A module’s front-panel Input
connector.
What you won’t find on these modules . . .
Unlike other modules designed to be used with the HP 83480A digital communications
analyzer, the HP 83491/2/3A modules do not include Channel keys or menus. Also, there
are no GPIB programming commands for these modules.

2-4
Operation
Front-Panel Features
Front-Panel Features
Figure 2-2. HP 83491/2/3A front panels
SELECT key
keykey
key Pressing this key changes the modulation rate of the input signal. The recov-
ered and retimed clock trigger is sent to the mainframe. The Trigger On Data
selection is a bypass mode where the data stream directly triggers the main-
frame. Refer to “Block Diagrams” on page 2-7 to view a schematic of the nor-
mal and bypass paths.

2-5
Operation
Front-Panel Features
UNLOCKED
indicator
This light shows when clock recovery cannot be established on the signal. If a
clock rate is selected, the trigger output to the mainframe is disabled to pre-
vent free-run triggering. However in bypass mode (Trigger On Data selected),
triggering is not disabled. When the UNLOCKED light is on, you can establish a
trigger on the data input to the reference receiver.
Auxiliary outputs DATA connector:
connector:connector:
connector: This connector provides a fully regenerated version of the
input signal. It is intended for monitoring purposes only and not for rigorous
eye mask compliance testing. The frequency response does not conform to the
requirements for eye mask testing as described in ITU-T G.957 and Bellcore
GR-253-CORE. On HP 83492A and HP 83493A modules, this port is amplitude
stabilized for input signals greater than approximately –23 dBm.
CLOCK connector:
onnector:onnector:
onnector: This connector provides the recovered clock signal. You can
use this signal to measure jitter transfer, because this output can track and fol-
low input data with very fast jitter; it has a wide bandwidth jitter transfer func-
tion when compared to the recovered clock signal which is routed through a
rear-panel connector to the mainframe for triggering. Note that the CLOCK Aux-
iliary Output remains synchronized to input signals several dB below the onset of
errors at the DATA Auxiliary Output.
Input and Output
connectors
The input connectors pass the digitally modulated signal to the receiver mod-
ule. The input signal, slightly attenuated and available at the Output connector,
is connected to the input of any of the HP 83481,2,3,4,5,6, or 7 modules. The
connectors on optical modules include adapters which can easily be changed
to match the type of connectors that are used on your fiber-optic cables. Refer
to “Front-Panel Optical Adapters” on page 4-2 for a description of the avail-
able adapters.
Green and red data-rate lights
The data-rate indicator lights change color between red and green to show which data
rate is selected. A red light does not indicate a problem. A red light shows that the adja-
cent red data rate label is selected. A green light shows that the adjacent green data
rate label is selected. Repeatedly pressing the SELECT key cycles through the selections
in one color before switching to the opposite color. On HP 83491A modules for example,
the first selection cycle shows 155 Mb/s selected. The second section cycle shows 1062
Mb/s selected.

2-6
Operation
Front-Panel Features
Recovered Clock The recovered clock signal is routed directly to the HP 83480A mainframe
through the module’s rear panel. This output has a lower jitter modulation
bandwidth than the front-panel CLOCK Auxiliary Output. Because of the reduced
jitter modulation bandwidth on the mainframe trigger signal, a more complete
view of the jitter on the waveform data is obtained.
Multimode and single-mode connections
HP 83492A modules use multimode fiber. Connecting the output to the Optical Input con-
nector on HP 83481/2/5 single-mode modules results in large reflections and insertion
loss.
HP 83493A modules use 9/125 µm single-mode fiber. Connecting multimode fiber to the
Optical Input connector results in large reflections and insertion loss.