A measurement system is a collection of interconnected elements designed to quantify or determine the values of physical quantities. It plays a crucial role in various fields such as science, engineering, medicine, and industry, as accurate and reliable measurements are essential for making informed decisions and conducting experiments. The fundamental elements of a measurement system include:
Input Quantity or Measurand: This is the physical quantity that needs to be measured. It could be anything from temperature, pressure, length, voltage, current, etc.
Sensor or Transducer: The sensor is responsible for converting the physical quantity being measured (measurand) into an electrical signal that can be easily processed and measured. Different types of sensors are used depending on the nature of the measurand, such as thermocouples for temperature, strain gauges for mechanical strain, photodiodes for light intensity, etc.
Signal Conditioning Circuit: The raw electrical signal generated by the sensor might be weak, noisy, or of the wrong type for processing. The signal conditioning circuit amplifies, filters, and adjusts the signal to make it suitable for further processing. It may involve processes like amplification, filtering, impedance matching, and isolation.
Data Acquisition System (DAQ): The DAQ system digitizes the conditioned analog signal from the signal conditioning circuit into a digital form that can be processed and analyzed by a computer or controller. This involves an analog-to-digital converter (ADC), which samples the signal at discrete intervals and quantizes it into digital values.
Processing and Display Unit: The digitized signal is then processed by a microprocessor, microcontroller, or computer. This processing can involve calculations, statistical analysis, and calibration. The processed data can then be displayed in a user-friendly format, such as numerical values, graphs, charts, or even control signals for automation.
Output Display or Indication: The final measurement result is presented to the user through an output display. This could be a simple numerical readout, a graphical representation, an indicator light, or even a combination of these. The goal is to provide the user with a clear understanding of the measured value.
Recording or Data Logging: In many cases, it's important to record the measurement data over time for analysis, troubleshooting, and quality control. Data logging systems store the measured values over a period of time and can also trigger alarms or alerts if certain conditions are met.
Calibration and Accuracy Verification: Regular calibration is essential to ensure that the measurement system provides accurate and reliable results. Calibration involves comparing the measurement system's readings to a known standard or reference. Any deviations or errors can be compensated for or corrected through calibration procedures.
Environmental Factors: Measurement systems are often affected by environmental conditions such as temperature, humidity, electromagnetic interference, and vibration. Design considerations and protective measures are taken to minimize these effects on the accuracy and reliability of the measurements.
Power Supply: All elements of the measurement system require a stable and appropriate power supply to function correctly. The power supply must be reliable and well-regulated to prevent fluctuations that could affect the accuracy of the measurements.
Overall, a measurement system's elements are carefully designed and integrated to ensure accurate, repeatable, and reliable measurements of physical quantities, catering to the specific needs of the application or experiment.