In electrical and electronic metrology, electrical signals of unknown magnitude are compared with a unit magnitude, quantitatively evaluated and represented as a measured value with its unit. In addition to the numerical representation of the measured values, the measurement technology can represent the signals in their temporal, frequency or logical course. It tries to capture reality and to reproduce it in the form of models in order to be able to make statements about the behavior of electrical and electronic circuits.
The electronic measuring technique corresponds to a model in which a physical quantity is converted into an electrical quantity and measured in a measuring device. In this process, the physical quantity is converted by a measuring transducer, transducer and/or measuring amplifier into a standardized electrical signal which can be measured by measuring instruments. The displayed measured value always corresponds to the physical quantity, regardless of the linearity of the upstream components. The reference quantity is a measuring standard with which the measuring instruments are calibrated and adjusted. The measured variable itself is displayed as an absolute number with the corresponding unit.
Electrical measurement technology is used to measure electrical quantities such as current, voltage, charge, power, frequency. The signals often have to be damped, amplified, galvanically isolated, linearized, decoupled, normalized and transmitted. Before they are displayed, the measurement signals are transformed, compensated, linearized, etc. For the measurement of non-electrical quantities such as pressure, temperature, displacement, physical quantities must be converted into electrical quantities. This is done with transducers that convert physical quantities into electrical quantities such as voltage and frequency.
From the single measuring device to the automated measuring system
The increasing use of computer technology requires the formation of direct digital measurement signals wherever possible. This is realized by successive measuring elements, a so-called measuring chain. The signals are processed by computers accordingly. They acquire measurement data, store and link them. Linearization of measured values is also frequently performed. The output is in numerical values or convenient graphics. The measurement results formed are made available to a higher- level system for querying via bus systems, e.g. IEEE 488bus or interfaces such as the LAN Extensions for Instrumentation( LXI).
Computer-aided measurement systems are those that use the computing power of personalcomputers(PCs), microcontrollers or hosts to perform measurement tasks. Computers take over the acquisition, preparation and processing of measured values. For this purpose, for example, personal computers can be equipped with special multifunction cards. Other examples are digital storage oscilloscopes, data loggers or software packages such as Laboratory Virtual Instrument Engineering Workbench( LabVIEW).
Traditional measurement technology reaches its limits when measuring on extremely densely populated printed circuit boards and especially when measuring on chips, as not all circuit points can be reached with the test probes. This is where the trend towards embedded measurement technology, which is embedded on the chip or PCB, becomes apparent. One example of this on-chip measurement technology is the boundary scan.