Agilent Technologies HP 8719D Service Manual page 448

Sources of Measurement Errors
Sources of Systematic Errors
The residual (after measurement calibration) systematic errors result from
imperfections in the calibration standards, the connector interface, the
interconnecting cables, and the instrumentation. All measurements are affected
by dynamic accuracy and frequency error effects. For reflection measurements,
the associated residual errors are effective directivity, effective source match,
and effective reflection tracking. For transmission measurements, the additional
residual errors are effective crosstalk, effective load match, and effective
transmission tracking.
The listing below shows the abbreviations used for residual systematic errors
that are in the error models and uncertainty equations.
Efd, Erd = effective directivity
n
Efs, Ers = effective source match
n
Efr, Err = effective reflection tracking
n
Etc, Erc = effective crosstalk
n
Efl, Erl = effective load match
n
Crm, Ctm = cable stability (deg./GHz)
n
The sources for dynamic accuracy error effects are from errors during internal
self-calibration routines, gain compression in the microwave frequency
converter (sampler) at high signal levels, errors generated in the synchronous
detectors, localized non-linearities in the IF filter system, and from Lo leakage
into the IF signal paths.
Sources of Random Errors
The random error sources are noise, connector repeatability and dynamic
accuracy. There are two types of noise in any measurement system: low level
noise (noise floor) and high level noise (phase noise of the source).
Low level noise is the broadband noise floor of the receiver which can be
reduced through averaging or by changing the IF bandwidth.
High level noise or jitter of the trace data is due to the noise floor and the phase
noise of the LO source inside the test set.
Determining System Measurement Uncertainties