Measurements and measurement systems:
• Definition, significance of measurement, generalized measurement system
• Definitions and concept of accuracy, precision, calibration, threshold, sensitivity,
hysteresis, repeatability, linearity, loading effect, system response-time delay. \
• Errors in measurement, classification of errors.
• Transducers, transfer efficiency, primary and secondary transducers, electrical,
mechanical, electronic transducers, advantages of each type transducers.
Intermediate modifying and terminating devices: Mechanical systems, inherent problems,
electrical intermediate modifying devices, input circuitry, ballast circuit, electronic amplifiers
Terminating devices, mechanical, cathode ray oscilloscope, oscillographs, X-Y plotters.
At the end of unit 5 one will be able to understand;
• The importance of measurement/ Definitions
• The various types of measurement
• Difference between primary, secondary and tertiary measurements
• Error analysis
• Measurement has become a natural part of our everyday life .
• We require measurement for measuring lengths,temperature, force,etc.
• Measurements means determination of anything that exists in some amount.
• Measurement of any quantity is essential in order to control it. For ex, one must be able
to measure a variable such as ‘temperature’ or ‘flow’ in order to control it.
• The accuracy of control is dependent on the accuracy of measurement
• Hence, good knowledge of measurement is essential for design of systems.
Definition of measurement:
Measurement is defined as the process of obtaining a quantitative comparison between a
predefined standard & an unknown magnitude.
Example-consider the measurement of length of bar.
We make use of a scale/steel ruler(i.e a standard)
Definition of Standard
Standard is a value of some quantity which is setup and established by authority as a rule for
measurement of a quantity.
The system of measurement must be related to a known standard or else the standard has no
• Any system may be represented by a simple block diagram.