Agilent Technologies N3970A User Manual

N3970A OPTICAL POWER METER

Operating and

Maintenance Guide

■ 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:

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.

■ To e x i tautotest, remove test lead or turn off source for >8 seconds.

Push Autotest on source and wait a few

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.

■ INTRODUCTION AND A P P L I C AT I O N S

N3970A

OPTICAL POWER METER

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.

1

■ CO N T E N T S

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 re t u rn s 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

BEFORE READING FURTHER, OPEN THE CONTROL PANEL PICTURE AT THE BACK OF THE MANUAL

2

■ S E RVICE AND SUPPORT

Any adjustment, maintenance, or repair of this product must be
p e rf o rmed by qualified personnel. Contact your customer
engineer through your local Agilent Technologies Serv i c e
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)

N3970A UM-1

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)

3

■ IN T R O D U C T I O N A N D AP P L I C AT I O N S

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 λ attenuation in one
direction.

4

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.

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 interc h a n g e a b l e
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 re p o rting using optional Excel software .

■

Test tone measurement & fiber identification.

N3970A UM-1

■ IN T R O D U C T I O N A N D AP P L I C AT I O N S

5

■ 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.

6

CAUTION

The CAUTION sign denotes a hazard. It calls attention to an
operating pro c e d u re, or the like, which, if not corre c t l y
p e rf o rmed 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.

■ 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 Perf o rmance Tests give pro c e d u res 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).

N3970A UM-1

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 fro m
temperature extremes that may cause condensation within it.

REQUIREMENT COMPLIANCE

N 10149

7

■ 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.

8

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.

■ 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.

N3970A UM-1

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.

9

■ 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

10

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
a rrangement such as a multimode pigtail with a
v-groove or mechanical splice.

■ GETTING STA RTED 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.

N3970A UM-1

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 self­calibration 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.

11

■ GETTING STA RTED 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.

12