During my engineering studies, a lecturer in Measurement Systems made a statement that has stayed with me throughout my career: “All electronic measurements are a lie. The trick is making the lie as small as possible.”
During my engineering studies, a lecturer in Measurement Systems made a statement that has stayed with me throughout my career: “All electronic measurements are a lie. The trick is making the lie as small as possible.”
At first, this sounds like a contradiction. After all, engineers and technicians depend on measurements to design, test, troubleshoot, and validate electronic systems. Yet the statement highlights an important reality: every measurement contains some degree of uncertainty. No instrument is perfect, no test setup is ideal, and no measurement can reveal an absolutely exact value. The goal of test and measurement is therefore not to eliminate error completely, but to understand, minimise, and manage it.
This principle lies at the heart of modern electronics.
Whether developing a medical device, maintaining an industrial control system, designing telecommunications infrastructure, or repairing consumer electronics, accurate measurement is essential. Engineers rely on instruments such as multimeters, oscilloscopes, spectrum analysers, logic analysers, power analysers, and network analysers to observe and quantify electrical behaviour. These tools allow them to verify that a design performs as intended and complies with required specifications.
Without effective test and measurement, even the most carefully designed circuit remains little more than an assumption. A simulation may predict a particular voltage, frequency, or timing characteristic, but only measurement can confirm what is actually happening in the physical world. Components have tolerances, environmental conditions change, and unexpected interactions occur. Testing provides the evidence needed to separate theory from reality.
For technicians, measurement is equally important. Fault finding depends on comparing actual values against expected values. A technician troubleshooting a power supply, for example, must determine whether voltages are within acceptable limits, whether ripple levels are excessive, or whether signals are present where they should be. Accurate measurements reduce diagnostic time, prevent unnecessary component replacement, and improve repair success rates.
As electronic systems become more sophisticated, the importance of measurement continues to grow. Modern devices operate at higher frequencies, lower voltages, and greater levels of integration than ever before. A signal integrity issue that may be invisible to a basic instrument could cause intermittent failures in a high-speed digital system. Selecting the correct instrument and understanding its limitations are therefore just as important as performing the measurement itself.
Calibration and adhering to compliance standards is another often overlooked function. Over time, instruments can drift from their specified accuracy. Regular calibration ensures that measurements remain traceable to recognised standards and provides confidence in the results obtained. In industries such as aerospace, defence, telecommunications, and medical electronics, calibration is often a regulatory requirement because inaccurate measurements can have significant safety, financial, or operational consequences.
Equally important is understanding measurement uncertainty. Experienced engineers know that a measurement result is not simply a number displayed on a screen. It is a value accompanied by a degree of confidence. Factors such as instrument accuracy, probe loading, environmental conditions, and operator technique all influence the final result. Recognising these influences enables better engineering decisions and more reliable system performance.
Ultimately, test and measurement provide the foundation upon which engineering confidence is built. Every design decision, quality assurance process, and maintenance procedure depends on trustworthy data. While no measurement can ever represent absolute truth, modern instruments and sound measurement practices allow engineers and technicians to get remarkably close. This month we present a feature on test and measurement with various instruments and insights into techniques detailed.
Perhaps my lecturer back then was right. Every electronic measurement may indeed be a small lie. However, through careful instrument selection, proper calibration, and sound measurement techniques, engineers can ensure that the lie is so small that it becomes negligible.
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