Measurement Errors And Their Characteristics; Drift Errors; Random Errors; Instrument Noise Errors - Agilent Technologies E5071C Manual

Measurement Errors and their Characteristics

Overview
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Drift Errors

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Random Errors

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Systematic Errors
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Other topics about Calibration
Overview
It is important to understand the factors contributing to measurement
errors in order to determine the appropriate measures that should be
taken to improve accuracy. Measurement errors are classified into three
categories:
Drift Errors
Drift errors are caused by deviations in the performance of the measuring
instrument (measurement system) that occur after calibration. Major
causes are the thermal expansion of connecting cables and thermal drift of
the frequency converter within the measuring instrument. These errors
may be reduced by carrying out frequent calibrations as the ambient
temperature changes or by maintaining a stable ambient temperature
during the course of a measurement.
Random Errors
Random errors occur irregularly in the course of using the instrument.
Since random errors are unpredictable, they cannot be eliminated by
calibration. These errors are further classified into the following sub-
categories depending on their causes.

Instrument noise errors

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Switch repeatability errors
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Connector repeatability errors
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Instrument noise errors
Instrument noise errors are caused by electric fluctuations within
components used in the measuring instrument. These errors may be
reduced by increasing the power of the signal supplied to the DUT,
narrowing the IF bandwidth, or enabling sweep averaging.
Switch repeatability errors
Switch repeatability errors occur due to the fact that the electrical
characteristics of the mechanical RF switch used in the measuring
instrument change every time it is switched on. These errors may be
reduced by carrying out measurements under conditions in which no
switching operation takes place.
Measurement
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