Agilent Technologies E8285A manual Confidence, Sets a confidence coefficient of 95%

Chapter 4, Description of Fields

Fields

Confidence

This field sets the confidence coefficient for FER testing.

GPIB Example

“DISP CRXT;MEASure:CDManalyzer:FERasure:CONFidence:INTerval 95”

sets a confidence coefficient of 95%.

Operating Considerations

When Confidence is on (a value is displayed in the Confidence field) and an FER measurement is made, the Test Set performs an interval estimate of the true FER. This means that as the test is running, point estimates of FER calculate an interval (range) of FER values that the true error rate of a mobile station is likely to fall within. Testing will stop when the number of frames tested (which determines the sample size of the estimate) is sufficient to narrow down the interval to the value specified in the FER Spec field. At this point it can be presumed that the true FER performance of the mobile station being tested will fall within the specified FER range with the degree of confidence entered in this field.

The Test Set, in addition to performing the one-sided confidence limit testing described above, also applies confidence limit testing for a failed FER test condition. If the criteria for meeting the passed or failed confidence limit testing is not met, the test will end when the number of frames entered in the Max Frames field is reached.

Graphically, the criteria for Passed, Failed, and Max Frames test results is shown below.

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