Agilent Technologies N3970A Operating manual

Operating and
Maintenance Guide
N3970A OPTICAL POWER METER

■N3970A OPTICAL POWER METER SOURCE QUICK REFERENCE GUIDE
■To remove interchangeable connector, move interface to
mid position, and pull off adaptor.
■To defeat auto power-off, hold POWER for 3 seconds at
turn on until ON and perm are displayed.
■To access hidden keypad, pull up display cover.
Select POWER,Source, then:
■To set reference, push Abs/Rel and hold Set Ref for
3 seconds (3 buzzer sounds).
■To display reference, hold Abs/Rel, so Ref flashes.
■To stop / start display update, push Hold.
■If a test tone is detected, meter will display Hz.
AUTOTEST OPERATION
■No user action is required for meter to enter Autotest
mode.
■Autotest:
Push Autotest on source and wait a few
seconds.
■Can also push Autotest on meter for faster lock-on.
■To display one wavelength only, on the power meter
push the left side of -/+ and again for the other wavelength.
Push right side of -/+ (twice) to exit.
■Autotest remains for >8 seconds after signal loss, to allow
quick connection change.
■Toexit autotest,removetestleadorturnoff source for>8seconds.
MANUAL OPERATION
■To turn on and select wavelength, push: POWER, Power
Meter, -/+.
■To display linear mode, push dBm/W.
■To display max/min values, push MAX/MIN repeatedly.
Hold MAX/MIN to reset (3 buzzer sounds). .
MEMORY
■Enter Power Meter or Autotest modes first
■While in Autotest mode, it is only possible to STORE.
■To clear all memory, push both RECALL and CANCEL
together for 3 seconds. clr will display.
■To store in next location, push STORE.
■To change next store location, push SELECT -/+, SET.
■To recall, push RECALL -/+ to scroll through data.
■To exit memory display, push CANCEL.
ADDITIONAL AUTOTEST MEMORY OPERATION
■To read or cancel memory, first exit Autotest mode, and
enter Power Meter mode.
■Autotest memory: use -/+ to scroll wavelengths.

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OPTICAL POWER METER
N3970A
Congratulations on your purchase of this instrument,
which has been engineered to provide the best possible
reliability, convenience and performance. To get the best
use from your equipment and ensure its safe operation,
please spend a few minutes to read this manual.
■INTRODUCTION AND APPLICATIONS

2
■CONTENTS
BEFORE READING FURTHER, OPEN THE CONTROL PANEL PICTURE AT THE BACK OF THE MANUAL
Service and Support 3
Introduction & applications 4-5
Safety Summary 6-7
Battery and external power 8
Optical connector 9-10
How to use:
Getting started and turning on 11-12
Autotest operation 13-14
Power meter operation 15
Storing & recalling readings 16-17
RS232 interface 18
Care of your instrument 19
Accuracy considerations 20-21
Calibration, maintenance & instrument returns 22-24
Specifications - Definition of terms 25
Specifications and ordering information 26-28
Performance test 29-38
Cleaning information 39-40
Cleaning procedures 41
Disclaimer & warranty 42
Notes 43-44

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N3970A UM-1
■ SERVICE AND SUPPORT
Any adjustment, maintenance, or repair of this product must be
performed by qualified personnel. Contact your customer
engineer through your local Agilent Technologies Service
Center. You can find a list of local service representatives on the
Web at: http://www.agilent.com/find/assist
If you do not have access to the Internet, one of these centers
can direct you to your nearest representative:
United States 1 800 452 4844
Canada 1 877 894 4414
[phone] (Fax)
Europe (31 20) 547 2323
(31 20) 547 2390 (Fax)
Japan (81) 426 56 7832
(81) 426 56 7840 (Fax)
Latin America [phone]
[phone] (Fax)
Australia 1 800 629 485
(613) 9272 0749 (Fax)
New Zealand 0800 738 378
64 4 495 8950 (Fax)
Asia-Pacific (852) 3197 7777
(852) 2506 9284 (Fax)

4
■ INTRODUCTION AND APPLICATIONS
The N3970A Optical Power Meter is used for field or laboratory
testing of fiber optic systems at typically 850, 1300, 1310 and
1550 nm. It features superb measurement confidence, ease of
use and reduced cost of ownership, and is for use by installers,
technicians and engineers.
Superior measurement confidence is achieved with a unique
Total Uncertainty specification over the full temperature,
measurement and connector range, and a NATA traceable
calibration certificate. The display hold and back light facilities
help acquire readings, and the flexible memory helps record
your results
Autotest mode enables automatic λ(wavelength) detection and
attenuation measurement (in combination with an Autotest
source). A single or dual λsource and meter in Autotest mode
automatically measure single or dual λattenuation in one
direction.
High operational reliability & availability is achieved with 250
hour battery life, 3 year recommended re-calibration cycle,
negligible warm up and no range-changing delays. Dark current
offset is not required. An external power input is also provided.
The combination of features enables reduced equipment
inventory, simpler training, shorter procedures, lower skill
levels and direct labour savings in many situations, combining
to give lower cost of ownership.
The innovative optical connector port provides drop protection
during use, and is dust protected by a snap on cover. The
interchangeable optical connector system is very versatile, and
easily disassembled for cleaning.
The simple user interface guides the operator through functional
sequences, and a hidden keypad is used to access advanced
features such as log/linear display, and memory functions.

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N3970A UM-1
The tone detector is very sensitive, and is useful for fiber
identification, and calibrating the modulation frequency of test
tone sources.
The instrument has shock absorbent corners, and a tough
polycarbonate housing which has passed extensive drop testing.
Typical applications
■Singlemode testing, with versatile interchangeable
connectors.
■Telecom construction, maintenance, CATV, LAN and R&D
applications.
■Measurements where traceability and documentation are
required.
■Quality assurance and acceptance tests.
■Automated testing and reporting using optional Excel software.
■Test tone measurement & fiber identification.
■ INTRODUCTION AND APPLICATIONS

6
■ SAFETY SUMMARY
The following general safety precautions must be observed
during all phases of operation, service, and repair of this
instrument. Failure to comply with these precautions or with
specific warnings elsewhere in this manual violates safety
standards of design, manufacture, and intended use of the
instrument. Agilent Technologies Inc. assumes no liability for
the customer’s failure to comply with these requirements.
Before operation, review the instrument and manual, for safety
markings and instructions. You must follow these to ensure safe
operation and to maintain the instrument in safe condition.
WARNING
The WARNING sign denotes a hazard. It calls attention to a
procedure, practice or the like, which, if not correctly performed
or adhered to, could result in injury or loss of life. Do not
proceed beyond a WARNING sign until the indicated conditions
are fully understood and met.
CAUTION
The CAUTION sign denotes a hazard. It calls attention to an
operating procedure, or the like, which, if not correctly
performed or adhered to, could result in damage to or
destruction of part or all of the product. Do not proceed beyond
a CAUTION sign until the indicated conditions are fully
understood and met.
CAUTION
m
The apparatus will be marked with this symbol when it is
necessary for the user to refer to the instruction manual in order
to protect the apparatus against damage.

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N3970A UM-1
■ SAFETY SUMMARY
Initial Inspection
Inspect the shipping container for damage. If there is damage to
the container or Cushioning, keep them until you have checked
the contents of the shipment for completeness and verified the
instrument both mechanically and electrically.
The Performance Tests give procedures for checking the
operation of the instrument. If the contents are incomplete,
mechanical damage or defect is apparent, or if an instrument
does not pass the operator’s checks, notify the nearest Agilent
Technologies Sales/Service Office (see page 3).
WARNING
To avoid any hazard, do not perform electrical tests when there
are signs of shipping damage to any portion of the outer
enclosure (covers, panels, and so on).
WARNING
You MUST return instruments with malfunctions to an Agilent
Technologies Service Center for repair and calibration (see page 3).
Line Power Requirements
The Agilent N3970A Power Meter operates at line power when
applied to the optional external power supply N3979A 9V DC
Operating Environment
The Agilent N3970A Power Meter can be operated at
temperatures between - 10°C and + 55°C and at relative
humidity of <95%.
Storage and Shipment
The Agilent N3970A Power Meter can be stored or shipped at
temperatures between - 25°C and + 70°C and at relative
humidity of less than 95%. Protect the module from
temperature extremes that may cause condensation within it.
REQUIREMENT COMPLIANCE
N 10149

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■BATTERY AND EXTERNAL POWER
The instrument is powered by two 1.5V dry batteries (Alkaline C) for
an operating period of typically 250 hours or two 1.2V
rechargeable batteries for an operating period of approximately
125 hours.
Do not use lithium batteries or other batteries with a nominal
voltage greater than 1.8 V. The instrument will be damaged.
When the batteries are low, the low-battery indicator is shown
on the display. At this stage, there is approximately enough
energy for another 30 minutes of use.
For saving of energy the instrument automatically turns off after
10 minutes without operation.
For changing the battery, open the cover of the battery
compartment at the base of the instrument, remove the batteries,
insert new batteries (check polarity) and close the cover again.
Rechargeable batteries must be charged by an external charger.
For operation of the instrument by external power use Agilent
AC adaptor N3979A (9V DC, 1.33 A, ).
Use of the external power supply disconnects the batteries.
Ensure that the mains supply has the correct voltage rating and
safety compliance as relevant. Do not use non-compliant or
doubtful mains equipment.

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N3970A UM-1
■OPTICAL CONNECTOR
The optical port is mounted on a swivel, which allows the
connector to be angled outwards for accessibility, and then
pushed back and covered with the snap cover to provide dirt and
drop protection.
The other port can be used to store a spare interchangeable
optical connector.
To install the connector adaptor, align the locating slot on the
side of the adaptor with that on the instrument connector, and
push it on.
To remove the connector adaptor, move the connector port to it’s
mid-way point (see dotted line on diagram at back of manual),
and then pull off the adaptor. It is not possible to remove the
adaptor in the ‘open’ or ‘shut’ positions. With some styles of
connector, it is easier to pull off the adaptor with a test lead in
place, since this gives better grip.
Different styles of connector adaptor ( ST, SC, FC, ) can be
easily fitted by the user.
Optical connectors are precision components, and require care
in use:
■Always clean the mating connector tip and ferrule before
mating, using approved materials.
■This instrument can be used with both PC and APC
connector styles (unlike sources, which are factory
configured for PC only ).
■The soft carry case enables the instrument to be stored
without removing the test leads. This practice saves time,
and is to be recommended.
■When not in use, keep all test ports and connectors covered
and away from dust.
■Do not touch connector tips with your fingers,
since body oils and dirt can impair connector performance.
■Do not use damaged or incompatible connectors.

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■OPTICAL CONNECTOR
Cleaning
The glass power meter interface does not make contact with the
inserted connector: there is a slight air gap. Therefore it should
not wear out, and only needs occasional cleaning.
To clean the glass power meter interface: remove the
interchangeable adaptor to access the glass interface, then use
a sticky material such as ‘ Blu tac ‘ to dab the glass and remove
any dirt. A soft brush, alcohol, or air can are also appropriate.
Do not use anything hard that could scratch the glass.
In this manual, refer to the sections on Cleaning Information
and Procedures for further information.
Bare fiber adaptors
Bare fiber adaptors used with this power meter must achieve
fiber eccentricity of + _ 100 microns and end tolerance of
+
_ 0.3 mm, relative to the ferrule end. Be careful not to scratch
the detector interface when using adaptors, since permanent
meter inaccuracy may result. Preferred bare fiber adaptors
consist of a connector with fiber retention device.
If you work regularly with bare fibers, to avoid potential damage
to the meter, it is generally preferable to use an alternative
arrangement such as a multimode pigtail with a
v-groove or mechanical splice.

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N3970A UM-1
■ GETTING STARTED AND TURNING ON
This and following sections show you how to use your
instrument:
Check that the correct accessories have been supplied, and an
optical connector adaptor has been fitted. If you have any
queries, call your supplier to resolve the situation.
Put in the batteries, or plug external power into the socket at the
top of the instrument (see Battery and External Power section).
Push the green POWER button. The display will come on.
If the battery is low, this will be indicated on the display.
Pushing POWER again will turn the instrument off.
To stop the instrument turning off 10 minutes after the last key
press, hold POWER down for 3 seconds during turn-on. PERM
on the display indicates that the unit will stay on permanently.
To back light the display temporarily, select LIGHT. To back light
continuously, hold down the button for 3 seconds. Use of the
back light will drain the batteries faster.
This instrument uses a menu driven keypad. The function of
each button is shown on the display.
To access the optical connector, grasp a top corner of the
instrument, and pull off the cover. The connector can be
swivelled to improve access.
After instrument turn on, the instrument will perform a self-
calibration sequence, set the dark current adjustment, and then
display absolute power in dBm at the previously set λ. If HI or
LO are displayed, the input is out of range.
The hidden keypad is accessed by pulling up the hinged display
cover. The hidden keypad can operate in two modes. The
second mode is accessed by SHIFT. Access to the second mode
can be denied / permitted by typing the button sequence
: POWER (turn on instrument), SHIFT, CANCEL, SET, SELECT,
RECALL, STORE.

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■ GETTING STARTED AND TURNING ON
To disable or enable the buzzer, hold down SHIFT for 3 seconds.
To add the carry strap: slip the end of the strap through the slit
on the curved section at the back of the instrument, and secure
the buckle.
This instrument requires no warm up, and no user adjustment
of dark current to achieve it’s specified performance.
To learn how to use the instrument features, go to the next
section.
Should the instrument fail to turn on, the microprocessor may
need re-booting. To do this, remove batteries and external
power for at least 40 seconds. This will not lose stored data.

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N3970A UM-1
■ AUTOTEST OPERATION
General Autotest features
For Autotest to function, all instruments involved in the test
must be Agilent Handheld instruments with an Autotest
function.
The Autotest feature performs automated measurement (and
automatic λdetection) by data exchange between instruments,
and requires minimal operator knowledge: turn the instrument
on, connect a test lead, and select AUTOTEST on the source.
Subsequent operation is automated, although some choices can
be made for convenience.
Functionality is determined by the options fitted to the
instrument(s) used. Autotest configures itself according to the
options available, and carries out the most comprehensive test
possible.
Autotest remains synchronised for about 8 seconds, which
enables the user to change optical connections without
re-starting Autotest each time.
A light source transmits Autotest signals at one or two
wavelengths to an appropriate power meter.
Operation
Turn on the source and meter, and connect them with a test lead.
On the light source,push AUTOTEST.
This is all that is required to start Autotest operation on the
power meter.
The meter will automatically set to the correct λand display
absolute power in dBm. The display will alternate between
wavelengths. To display only one λat a time, push +/-.
You may also select AUTOTEST on the meter, which forces the
meter into Autotest mode, with faster synchronisation in this
mode (the source must be in Autotest mode). Push MENU to
exit.
The source power transmitted from the source is displayed on
the left hand side of the display.
Push ABS/REL to make the meter display relative power.
The stored reference value(s) are displayed on the left hand side
of the display.
To take a reference under Autotest, connect the source and

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■AUTOTEST OPERATION
meter with a test lead. Set the source to Autotest mode, and then
push SET REF on the meter for 3 seconds. This will store the
reference at all relevant wavelengths.
Either a ‘local’ or ‘remote’ reference can be stored.
To exit Autotest mode, either disconnect the optical test lead, or
exit Autotest mode on the light source for > 8 seconds.
Refer also to manual sections on:
■Storing and recalling readings.

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N3970A UM-1
■ POWER METER OPERATION
After instrument turn on, the meter will be calibrated at the last
used λ. To change parameters, push POWER METER, then:
To select a calibrated λ, push +/-.λis displayed on the top right
side of the display.
To display relative power, push ABS/REL. The display will
show dB R.
To store a new reference, push SET REFfor 3 seconds.
To display the stored reference value, keep ABS/REL depressed.
To change the dBm display between linear and log, access the
hidden keypad and push dBm/W.
If the meter detects a modulated signal, the display will change
to show the actual measured modulation frequency in Hz,
and if a standard tone is detected ( eg 270 Hz, 1 KHz,
2 KHz ), a buzzer will sound. This is useful for fiber
identification and signalling. The meter can also be used to
check the actual modulation frequency of test sources.

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■STORING & RECALLING READINGS
There are various ways of storing and recording data, giving the
user flexible ways of working. They are summarised here for
your convenience.
Storage of reference values: A separate reference is stored for
each λand can be recalled when the instrument is next turned
on.
Display hold: To hold the display at it’s current value, push
HOLD. This value can then be stored. Push HOLD again to
continue updating the display.
Automatic recording of maximum & minimum limits: To display
the minimum and maximum value over a period, access the
hidden keypad and push MAX/MIN. The display will show the
maximum and minimum values in sequence. Then push
MAX/MIN for 3 seconds to re-start the recording process. This
function re-sets automatically when instrument parameters are
altered.
Storing & recalling readings using non-volatile memory
In Autotest, stored data includes absolute & relative values at all
possible wavelengths.
Note: To recall data, the unit must be in manual ‘power meter’
mode.
In manual mode, stored data includes absolute, relative and
reference values.
You can store, display or download up to 845 readings in non-
volatile memory.
Memory No Identifier Space
1 - 199 mem 199
200 - 1990 (steps of 10) mem 179
1 - 199 ID 199
200 - 1990 (steps of 10) ID 179
1 - 199 mem / ID 89
Total memory 845

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■STORING & RECALLING READINGS
The memory location is shown at the top right of the display.
When storing data, the memory automatically increments to
facilitate the collection of data on a job.
You can also go back and over-write particular records.
After the data has been recorded, the entire memory can be
cleared ready for the next job.
Memory operating sequence
Store data in next location: push STORE
Store data starting at a particular location: push SELECT, +/-,
SET, STORE
The memory can not be read in Autotest mode. Exit Autotest
before reading the memory.
Read from any location: push RECALL, +/-. To display the
relative value, push ABS/REL, and to display the reference, hold
down ABS/REL.
Clear the whole memory: push CANCEL and RECALL together
for 2 seconds. CLR will display.