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Appendix B Measurement Calibration 145
Appendix B
Measurement Calibration
This section describes the calibration techniques employed in the manufacturing
and maintenance of the WireScope 350 and DualRemote 350 to assure accurate
and consistent measurement performance.
Multiple Levels of Calibration
Multiple levels of calibration are employed in the design and production of the
WireScope 350 and DualRemote 350 to assure reliable measurement accuracy.
Baseline calibration assures NIST traceability and precise agreement with a
laboratory Spectrum Analyzer. This is performed at the factory.
Remote calibration
establishes a zero reference for accurate attenuation
measurements. This should be performed in the field on a daily basis.
Environmental calibration
ensures maximum accuracy in the presence of
temperature and humidity variations. This is executed automatically by the
WireScope 350 and the DualRemote 350 before every test.
Baseline Calibration
The baseline calibration process consists of comparing the measurement output
of the WireScope 350 or DualRemote 350 with a traceable reference instrument
and then “zeroing out” any differences between the field test equipment and the
reference instrument. The resulting calibration data is automatically downloaded
to the WireScope 350 or DualRemote 350 and stored in non-volatile memory.
Under normal use conditions, the WireScope 350 will require baseline re-
calibration no more frequently than once per year, and in most cases, far less
frequently.
Remote Calibration
The purpose of remote calibration is to establish a common zero reference basis
between the WireScope 350 and its associated DualRemote 350 before any end-
to-end measurements are taken.
You must perform a remote re-calibration if you use your WireScope 350 with a
different DualRemote 350 or if you upgrade the software in either the
WireScope 350 or the DualRemote 350. The WireScope 350 stores the serial
number information of the DualRemote 350 that it has been calibrated to. Before
each measurement, the WireScope 350 checks the serial numbers of the
DualRemote 350 to which it is connected. If the WireScope 350 does not have
remote calibration data stored for the detected DualRemote 350, a warning
appears, asking you to calibrate the DualRemote 350.
Agilent Technologies recommend that the remote calibration be run once a day,
preferably at the beginning of a testing session.