HP 8753E manual Sources of Random Errors, Abl, Ab2 = dynamic accuracy = frequency

nEtc, Erc = effective crosstalk

nEfl, Erl = effective load match

nEft, Ert = effective transmission tracking w Cnn, Ctm = cable stability (deg./GHz)

nAbl, Ab2 = dynamic accuracy

nF = frequency

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 illter 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.

Connector repeatability is the random variation encountered when connecting a pair of RF connectors. Variations in both reflection and transmission can be observed.

The listing below shows the abbreviations used for random errors in the error models and uncertainty equations.

w Rnt = raw noise on trace (rms)

nRnf = raw noise on floor (rms)

nCrrl = port 1 connector reflection repeatability error

nCrtl = port 1 connector transmission repeatability error

nCrr2 = port 2 connector reflection repeatability error

nCrt2 = port 2 connector transmission repeatability error

Sources of Drift Errors

Drift has two categories: frequency drift of the signal source and instrumentation drift. Instrwnentation drift affects the magnitude and phase of both reflection and transmission measurements.

The primary causes for instrumentation drift are the thermal expansion characteristics of the interconnecting cables within the test set and the conversion stability of the microwave frequency converter.

The list below shows the drift errors in the error models and uncertainty equations. w Dmxbx, Dmsax = drift magnitude

nDpxbx, Dpsax = drift phase

w Dpfxbx, Dpfsax = drift phase/f

B-2 Determining System Measurement Uncertainties