5-5
Optimizing Measurement Results
Increasing Measurement Accuracy
Temperature Drift Electrical characteristics will change with temperature due to the thermal expansion
characteristics of devices within the analyzer, calibration devices, test devices, cables, and
adapters. Therefore, the operating temperature is a critical factor in their performance.
During a measurement calibration, the temperature of the calibration devices must be
stable and within 25 ±5 °C.
• Use a temperature-controlled environment.
• Ensure the temperature stability of the calibration devices.
• Avoid handling the calibration devices unnecessarily during calibration.
• Ensure the ambient temperature is ±1 °C of measurement error-correction
temperature.
Frequency Drift Minute changes in frequency accuracy and stability can occur as a result of temperature
and aging (on the order of parts per million). If you require greater frequency accuracy,
override the internal crystal with a high-stability external source, frequency standard, or
(if your analyzer is equipped with Option 1D5) use the internal frequency standard.
Performance Verification You should periodically check the a ccur acy of the analyzer measurements, by performing a
measurement verification at least once per year. The service guide includes the
measurement verification procedure.
Reference Plane and Port Extensions Use the port extension feature to compensate for the phase shift of an extended
measurement reference plane, due to such additions as cables, adapters, and f ixtures , after
completing an error-correction procedure (or when there is no active correction).
Using port extensions is similar to using electrical delay. However, using port extensions is
the preferred method of compensating for test fixture phase shift. T able 5-2 explains the
difference between port extensions and electrical delay.