AN-110
Insertion Loss/ Return Losson Short Cables (OP930)
Over view
Units using the pulsed (OTDR) method have a specific resolution that has trouble distinguishing pulses less than
2.0m apart. For measuring RL on these cables, one needs to employ a mandrel (single mode only), matching gel, or amatching block to the far end connector to diminish the reflection. As a standard and for consistency, reference cables
should be 3-3.2m in length.

NE W

Insertion Loss

Reference
Insertion loss testing does notchange with the use of short cables.
The procedure is the same for both
Multimode and Single mode.
NE WConnect
the APC side of the 3 meter FC/
APC to PC launch cable to the OP930
front panel connector and the PC
endface to the OPM. Navigate to the IL
screen via channel button B . Press theRef button A to establish a reference
power for both wavelengths.

IL- 1.60

Figure 1: Before performing an insertion
loss reference, connect the reference
cable to the detector.

TestingIL- 0.05

CFigure 2: After performing an insertion loss
reference, the front panel display will begin
updating in real-time. Simply connect the test
cable and the test results will be displayed.

1SANTEC CORPORATION
OptoTestCorp.

5823 Calle
Ohkusa-Nenjozaka,
Komaki,
4750
Quetzal
Aichi 485-0802,
Japan
Camarillo,
CA 93012
12 /13 /13+81-568-79-3536

Doc: AN-110 Rev. A

www.santec.com

The unit will now begin taking
measurements automatically. Connect
the PC-PC DUT C between the PC
endface of the launch cable and theOPM to begin testing. To test the otherend of the DUT, flip the cable from theA side (already connected to launchcable) to B side (already connected toOPM) and measurements will now bemade for that connector.

SANTEC USA CORPORATION
8 05.987.170 0sales@ optotest.com
USA Toll Free
+1-800-726-8321
engineering @ optotest.com
SANTEC EUROPE LIMITED
Tel. +44-20-3176-1550

AN-110Insertion Loss / Return Loss on Short Cables (OP930)

Return Loss
Since launch cables should be longer than 3m, referencing is the same when testing short cables.
NE W

ReferenceWith an insertion loss reference established,navigate to the RL screen by pressing the channel
button A once. If return loss has not yet been
NE W
referenced,
the screen will be blank. Disconnect
the launch cable from the OPM and leave the PC
endface unmated. Referencing to an open PC
connector/endface and forcing to 14dB provide forthe most accurate RL measurements. Press andhold Ref B and the unit will begin establishing
the length of the launch cable by for the Fresnel
reflection at the umated PC endface. When the unit
has found a distance and measurement, it will be
automatically displayed on the front panel screen.
Note: To force a 14dB reference, press and hold thedBm D button after referencing.

RL- 14.00

Figure 3: When referencing return loss, make sure the reference
cable is terminated in an open UPC connection.

Testing
Testing return loss is different for single mode and multimode.

SinglemodeConnect the short cable PC-PC DUT to the PC endface of the launch cable. The unit will automatically start taking
measurements. To reduce the open PC reflection, apply tight a mandrel wrap on the DUT.
Note: The mandrel should only be used during return loss testing.

RL- 57.23

Figure 4: A tight mandrel has been applied to the cable
under test to attenuate the back reflection from the secondconnector. This will allow the unit to isolate and measure thereturn loss from the first connector.

2SANTEC CORPORATION
OptoTest
Corp.

5823 Calle
Ohkusa-Nenjozaka,
Komaki,
4750
Quetzal
Aichi 485-0802,
Japan
Camarillo,
CA 93012
Doc: AN-110 Rev. A 12 /13 /13+81-568-79-3536

www.santec.com

SANTEC USA CORPORATION
8 05.987.170 0
sales@ optotest.com
USA Toll Free
+1-800-726-8321
engineering @ optotest.com
SANTEC EUROPE LIMITEDTel. +44-20-3176-1550

AN-110Insertion Loss / Return Loss on Short Cables (OP930)

MultimodeConnect the short cable PC-PC DUT to the PC endface of the launch cable.
The unit will automatically start taking measurements.
NE W

When testing a short cable, mandrel wrapping will only increase loss for high order modes.
To reduce the open PC reflection, an index matching block or gel should be used.
Apply this matching gel/block to the unmated endface of the DUT after connecting to the reference cable.

Note: Immediately clean the endface after using index matching gel or block to prevent any contamination ordamage to either the endface or connector for both cables.

3SANTEC CORPORATION
OptoTestCorp.

5823 Calle
Ohkusa-Nenjozaka,
Komaki,
4750
Quetzal
Aichi 485-0802,
Japan
Camarillo,
CA 93012
Doc: AN-110 Rev. A 12 /13 /13+81-568-79-3536

www.santec.com

SANTEC USA CORPORATION
8 05.987.170 0sales@ optotest.com
USA Toll Free
+1-800-726-8321
engineering @ optotest.com
SANTEC EUROPE LIMITED
Tel. +44-20-3176-1550