Tektronix TekRanger 2 TFS3031, Service Manual

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Performance Check – TekRanger 2 (serial nos. B052000 and above)
4–2
TFS3031 TekRanger/TekRanger 2 Service Manual
H
ST/PC to ST/PC multimode jumper cable, 1-meter length
The fiber test fixtures are not supplied by Tektronix. See instructions starting
on page 4–6 for information about how to build your own fixtures. A
characterization and tolerance data sheet for all events on the event-detection
test fixtures is required prior to use.
Adjustments
There are no user or service adjustments required in the TFS3031.
CAUTION.
Do not attempt to adjust any potentiometers on the optical module
assemblies. All adjustments are optimized for peak performance. Any increase in
laser drive current or detector bias may result in damage to the device.
Test Descriptions
Dynamic range is a measure of signal-to-noise ratio for an OTDR. There are
several methods in popular use to measure dynamic range. Nearly all methods
compare the backscatter signal at the front panel with the noise past the end of
the fiber. The dynamic range of the TFS3031 is defined (in dB) as the difference
between the backscatter level at the TFS3031 front-panel connector (0 meters)
and the OTDR’s SNR=1 noise level. The SNR=1 noise level is the 98% noise
level less 1.5 dB. The 98% noise level is the level above which there are ten
noise spikes out of 500l. The noise level is measured beyond the end of the fiber
and any effects of the end reflection.
Dynamic Range