Determining Expected System Performance

Use the uncertainty equations, dynamic accuracy calculations in this appendix, and tables of system performance values from the “Specifications and Measurement Uncertainties” chapter in the HP 87533 User’s tiide to calculate the expected system performance. The following pages explain how to determine the residual errors of a particular system and combine them to obtain total error-corrected residual uncertainty values, using worksheets provided. The uncertainty graphs in the user’s guide are examples of the results that can be calculated using this information.

Procedures

Use the measurement uncertainty worksheet to calculate the residual uncertainty in transmission and reflection measurements. Determine the linear values of the residual error terms and the nominal linear S-parameter data of the device under test as described below and enter these values in the worksheets Then use the instructions and equations in the worksheets to combine the residual errors for total system uncertainty performance. The resulting total measurement uncertainty values have a confidence factor of 99.9%.

S-parameter Values. Convert the S-parameters of the test device to their absolute linear terms.

Noise Floor and Crosstalk. If a full 2-port calibration is performed, the residual crosstalk term can be ignored. Connect an impedance-matched load to each of the test ports and measure S21 or S12. Use the statistic function to measure the mean value of the trace. Use this value plus one standard deviation as the noise floor value of your system.

Dynamic Accuracy. Determine the absolute linear magnitude dynamic accuracy from the dynamic accuracy graph on the previous page.

Other Error ‘l&ms. Depending on the connector type in your system, refer to residual error specifications in the “Specifications and Measurement Uncertainties” chapter in the HP 87533 User’s Guide, and the “Characteristic values ‘Iable” in this chapter to find the absolute linear magnitude of the remaining error terms.

Combining Error ‘lbrms. Combine the above terms using the reflection or transmission uncertainty equation in the worksheets.

Determining System Measurement Uncertainties B-7

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HP 8753E manual Determining Expected System Performance, Procedures