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very engineer responsible for a test system is also responsible for the accuracy and repeatability of the measurements it makes. Repeatability, perhaps more than pure accuracy, is often the key to success in design, manufacturing and ongoing operations. In a test system, repeatability is also the foundation of the warranted performance of the included instruments. This is especially true for crucial equipment such as network analyzers, signal analyzers, power meters, oscilloscopes and signal generators. If any specified parameter is out of tolerance, measurement results can be negatively affected.
An accurate, professional and accredited calibration is the bedrock that ensures rehable and repeatable results. Calibration and metrology are a specialized subset of engineering, and relatively few engineers have been trained in these topics. Fortunately, developing familiarity with a few fundamental concepts will improve measurement performance, enhance the interpretation of results and, ultimately, reduce the risks associated with every decision that is based on measured results.
MEETING MEASUREMENT REQUIREMENTS
A test system supports a test plan, and the essential first step is to identify the crucial specifications that characterize the performance of the device under test (DUT). Each specification will have an associated set of tests, tolerances and accuracy requirements. The development of the test plan includes the selection of hardware elements that provide the necessary features and functions. For an engineer, the natural response is to thoroughly understand the choices and tradeoffs in the various hardware alternatives.
Typically, less time is spent considering the calibration and repair services needed to sustain the warranted specifications of each instrument. It's easy to assume that periodic calibration is all that's needed to ensure measurement integrity over the long term. In reality, test equipment ages and drifts, and sometimes it breaks. What's more, calibration is not a generic commodity, and the process of ensuring long-term measurement repeatability is not as simple as "set it and forget it." Taking a proac- tive stance can have a significant impact on the ongoing accuracy and repeatability of the test system, not only reducing the risk or out-of-tolerance measurements, but actually improving the systems effective accuracy. This can help ensure the performance of the DUT and enhance overall productivity in manufacturing.
USING CALIBRATION TO IMPROVE SPURIOUS MEASUREMENTS
An example focused on the pursuit...