How to Reference and Measure
BR – SM BR5

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How to Reference Power and Test IL
SM BR5• When making any connections ensure that each connector is cleanand free of contaminants.
• A CS400K scope with monitor as shown below is perfect for this.

NOT SAFE TO CONNECT. CLEAN FIRST!
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CLEAN. SAFE TO CONNECT.

How to Reference and Measure BR
SM BR5• Once all connectors are ensured to be clean a reference jumper canbe connected to the BR5 output. This jumper will be used to set theBR # to allow the unit to measure an accurate BR down to -80dB.

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How to Reference and Measure BR
SM BR5• To set the BR # a mandrel will need to be used. There are different
diameters to be used with different wavelengths and fiber types.
• See Below for a guide to which wavelengths require whichdiameter.
1650
1625
1550
1490

1310
(3.0mm Jacketedbend sensitive)

1310(.9mm Jacketed andbend insensitive)• For bend insensitive fibers an index matching block works best.
• See below.
Effect of index
matching block onreflections back intothe fiber.

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How to Reference and Measure BR
SM BR5• Using the appropriate section of the mandrel, wrap the fiber justbefore the connector as shown below. (keep the wraps tighttogether)• Wrap the fiber until the number no longer decreases regardless ofadded wraps. In the case as shown below for 1550nm the fiber waswrapped 7 times.

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How to Reference and Measure BR
SM BR5• Once the BR is at its lowest value, unwrap until the number starts toincrease again.

Lowest Value (7 wraps)
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Starts to increase again (3 wraps)

How to Reference and Measure BR
SM BR5• Add one more turn and press the BR # button on the unit.

One more wrap brings it back to its
lowest value (4 wraps)
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How to Reference and Measure BR
SM BR5• Once the BR # is set the BR # button will be illuminated and the BR #will be set. Complete the same steps for every wavelength that will
be tested.

**NOTE**
If the same mandrel wrap
is done in the same spot
the unit will read BR<80.0dB since it cannot see
any more reflections asthese were referenced out
when the BR # was set.

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How to Reference and Measure BR
SM BR5• The unit is now ready to test a DUT for BR.
• Clean and connect a DUT to the end of the reference jumper as shown
below.

ReferenceJumper

DUT

Notice how the unit readsa BR of -55.7dB. This is not
the correct measurement
value. Another mandrel
wrap will need to be done.
See next slide.

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How to Reference and Measure BR
SM BR5• In order to complete the most accurate measurement possible,
complete the same number of wraps on the same section of themandrel that was done to set the BR # .
(In this example it will be 4 wraps for 1550nm)

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How to Reference and Measure BR
SM BR5• Now the unit reads -76.7dB. This is the accurate measurement ofthe connection shown below.

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How to Reference and Measure BR
SM BR5• The section of the DUT that is going to be measured will depend on
where the BR # is set. If just the one connection is under testcomplete the BR # an measurement as seen in the previous slides.
• If the entire cable is to be tested (connection and length of cable)
then complete the BR # in the same place as before but complete
the measurement mandrel at the other end of the DUT (see below.
Mandrel here
to measure DUT.

DUT
Reference
JumperBackreflection
Measurement Area

Mandrel here
to set BR # .
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How to Reference and Measure BR
SM BR5• One more example is to measure a DUT excluding any connectors.
• To do this set your BR # after the connection point, and measure theBR before the last connector.
Mandrel here
to measure DUT.
Backreflection
Measurement AreaDUT
Reference
JumperMandrel here
to set BR # .
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