Measurement Calibration
Measurement calibration is procedures that transfers the measured accuracy and uncertainty of standard devices to  the measured accuracy and uncertainty of a test devices. Since the characteristics of standards is known with high degree of accuracy, the system can measure one or more standards, then use the results of this measurements to greatly enhance the measurement accuracy. 
Transmission calibration types

 Calibration type
Corresponding Mesurement 
Error Removed
Standard Devices
Normalize (2)
Well mathced low insertion loss devices
Frequency response
Trough
Normalize&Isolation (1&2)
High insertion loss devices or high leakage test fixture
Frequency response and Crosstalk
Trough and Load (50W)