Sources Of Random Errors - HP 8719ET Reference Manual

Determining System Measurement Uncertainties
Sources of Measurement Errors

Sources of Random Errors

The random error sources are noise, connector repeatability and interconnecting cable
stability. There are two types of noise in any measurement system: low level noise (noise
floor) and high level noise (trace noise).
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 trace noise is due to the noise floor, the phase noise of the LO source
inside the test set, or by reducing the IF bandwidth.
Connector repeatability is the random variation encountered when connecting a pair of RF
connectors. Variations in both reflection and transmission can be observed.
Cable stability is dependant on the cable used and the amount of cable movement between
calibration and measurement.
The listing below shows the abbreviations used for random errors in the error models and
uncertainty equations.
• N = noise floor
F
• N = trace noise
T
• C = port 1 cable reflection stability
R1
• C = port 1 cable magnitude transmission stability
TM1
• C = port 1 cable phase transmission stability
TP1
• C = port 2 cable reflection stability
R2
• C = port 2 cable magnitude transmission stability
TM2
• C = port 2 cable phase transmission stability
TP2
• R = port 1 connector reflection repeatability
R1
• R = port 1 connector transmission repeatability
T1
• R = port 2 connector reflection repeatability
R2
• R = port 2 connector transmission repeatability
T2
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