Textron GREENLINE 920XC Series Installation guide

XC fiber TOOLS™
920XC
Handheld OTDR
Training Presentation
920XC Training
VER 1.0

OTDR Basic Operation
The Optical Time Domain Reflectometer (OTDR) is an instrument that uses the inherent backscattering
properties of an optical fiber to detect faults and categorize its condition. The OTDR sends high-power
pulses of laser light down the fiber and captures the light that is reflected back (much like a radar system).
By measuring the timing and power levels of the return pulses, the instrument correlates the reflected
information with physical locations along the fiber and displays a “trace” that shows optical power versus
distance.Attenuation of the fiber is displayed as the slope of the trace. Interruptions such as splices,
connectors, bends, breaks or flaws in the fiber appear as transitions (“events”) that represent their nature
and location.
Display Processor
Detector
Laser
Coupler
Fiber
under test
Probe
pulse
End of
fiber
Rayleigh
backscatter Fresnel
reflection

Dynamic Range
The measure of a system’s
ability to distinguish signals
in the presence of noise.
Several definitions exist for
OTDR dynamic range.
Bellcore defines the
dynamic range as the
displayed attenuation (in
dB) from the backscatter
level at the front panel to an
imaginary line (past the end
of the fiber)that lies just
above 98% of the noise.
Another common definition
(based on Signal-to-noise
ratio = 1) uses an imaginary
line that lies just above
roughly 63% of the noise.

Attenuation Deadzone
The minimum distance after a
reflective event before the
OTDR can accurately measure
the loss of a non-reflective
event. Typically, the
attenuation dead zone is the
distance from the leading edge
of the reflection to the point
past the reflection where the
OTDR signal level returns to
within 0.5 dB of the
backscatter level.

Event Deadzone
The minimum distance after a
reflection before the OTDR
can accurately measure the
distance to a second
reflection, sometimes called
the “two point spatial
resolution.” The event dead
zone is measured from the
leading edge of the reflection
to the point past the reflection
where the level of the OTDR
signal drops at least 1.5 dB
from the top of the reflection.

920XC Product Overview
Features
•Easy to Use/Compact Handheld Design
•Automated Measurement/Analysis/File Save
•38dB Dynamic Range
•1.5 meter event deadzone
•Large color LCD display
•Measure length and defects of coiled fiber
•RS-232 and USB interface
•Store 1000 measurement results
•NiMH battery for 8 hours continuous use
•Internal VFL (650nm)

920XC Measurements
Measurement Application
•The 920XC instruments display power relating to the distance of returning signals. This
information can be used to identify the main properties of an optical fiber chain.
Measurement Contents
•Event location (distance), end, or rupture of optical fiber chain.
•Attenuation coefficient of fiber.
•Loss of a single event (for example, one optic tie-in), or total loss from upper end to end.
•Range of a single event like reflection of connectors (or grade of reflection).
•Auto measurement of cumulative loss of a single event.
Trace Analysis
•The trace analysis of the 920XC OTDR is fully automatic. The trace locates:
•Reflection events of connections and mechanical tie-ins.
•Non-reflection events.
•End of optical fiber.
•Through scanning the first loss event that is larger than the end threshold, identifies the end of
optical fiber.
•Events list: Event type, loss, reflection, and distance.

920XC -Ports and Indicators
1. Charge Indicator: When lit, measurement
power is charging.
2. Power Indicator: When lit, measurement
power is on.
3. AC Power Jack: Power adapter jack
requirements are 13.8 VDC at 1.2 A.
4. Data Transfer Ports: USB and RS-232
interfaces to transfer saved traces in the
instrument to a PC for further analysis
with Trace Viewer software (provided).
5. Fiber Optic Output for OTDR and VLS
(visual fault locator): The VLS Connector
is used for the OTDR interface at 1625nm.
6. Invisible Laser Caution: Do not look
directly at the optical output or stare at the
laser beam.

Keypad Definitions
1. On/Off:
•Press to turn power on or off to the instrument.
2. Run/Stop:
•Under GUI, press to start measurement.
•While testing, press to stop measurement.
3. Enter:
•Under GUI, press to confirm the current operation.
•Use with the Shift key to browse down the events
list.
4.  (up and down) arrows:
•Move menu bar in menu operation.
•Highlight the icon to be selected.
•Adjust parameter in parameter configuration.
•Use with the Shift key to zoom out or zoom in
trace vertically.

Keypad Definitions
5.   (left and right) arrows
•Select parameter to be adjusted in parameter configuration.
•Move marker left or right in trace operation.
•Turn page while in Help submenu.
•Use with the Shift key to zoom out or zoom in trace horizontally.
6. Arrow
•Read Help menu when power .on.
•Cancel the current operation.
•Exit menu configuration.
•Switch between information windows.
•Use with the Shift key to browse up the events list.
7. Shift
•Under GUI, press to return a trace to original size without any
zoom.
•Activate the integration function by pressing this key together with
other keys.

Main Display

Measurement Window
Manual Measurement View
Event Finder View
Instrument Setup View
Fiber Analysis View
Measurement Window

Event List
Events
•No.: Event sequence number.
•Four types of events: . .begin .end; . reflection
event; fiber end; attenuation event.
•Location: Distance from beginning point to
event.
•Refl.: Magnitude of reflection.
•Ins.L.: Loss of inserted event.
•Attn.:Attenuation characteristic from one
event point to the current event.
•Cum.L.: Cumulative loss, calculating from
beginning point to the current event.

A & B Markers
A & B Markers
A marker is used to mark and analyze a single
event, trace section, and distance. Distance,
attenuation, and loss at a marker or between
markers will be displayed in marker information
The following parameters are measured
between marker A and B. Changing either
marker will change the record accordingly.
A-B: Distance between two markers.
2Pt. Loss: Loss between two markers; power
difference between two markers.
2Pt.Atten: 2 points loss of unit length

Measurement Trace Parameters
Measurement Trace Parameters
•Important measurement and analysis
parameters are displayed in the
information window .
•For definitions and configurations of
items (average time, sample distance,
range, IOR, wavelength, and pulse
width) as well as definitions of item
(date, reflection threshold, non-
reflection threshold, end threshold, and
scattering coefficient), refer to “Setup
Configuration” later in the presentation.

Menu Bar and Icons

Setup Parameters

Setup – Range Setting
Range Setting
•Use and to select an adequate range.
Press Enter to confirm.
Notes:
•“Auto” means automatic measurement. When
this function is selected, the instrument
automatically selects an adequate range and
pulse width for the measurement. The process of
measurement does not require any intervention
by the user.
•“Auto” is the default setting.

Setup – Pulsewidth
Pulse Width Configuration
•The selection of pulse width affects the dynamic range
and resolution of the measurement. With a narrow pulse
width there will be higher resolution and smaller
deadzone; however, the dynamic range will be
decreased.A wide pulse width will bring higher dynamic
range and measure comparatively longer distance, but
resolution and deadzone will be increased. Therefore,
users should make the choice between dynamic range
and deadzone. .
•The options for pulse width will change according to the
distance range selected.
•Under the parameter configuration menu use and 
to highlight “PulseWidth.” Press Enter to select a value.
(Press  to .exit.)
•“Auto” is the default setting.
•When the range is set to “Auto,” the pulse width
automatically is set to “Auto.”

Setup – Avg. Time
Averaging Time
•Average time will affect the SNR directly. The
longer the average time is, the higher SNR is,
as well as dynamic range. Therefore, when
measuring long-distance optical fiber, a long
average time should be selected in order to
review events at the long-distance end.
•Under the parameter configuration menu use
.and to highlight “Avg. Time.” Press Enter
.to .confirm (Figure 3-12). Press .to .exit.
•Use .and to highlight the desired time.
Press Enter to confirm.
•There are five levels of predefined average
time: 15 s, 30 s, 1 min, 2 min, and 3 min.
•The default setting is “30 s.”