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ELECTRONIC MEASUREMENT & MEASURING INSTRUMENTS
Accuracy, Precision, resolution, reliability, repeatability, validity,
Errors and their analysis, Standards of measurement.
Bridge Measurement: DC bridges- wheatstone bridge, AC bridges – Kelvin, Hay, Maxwell,
Schering and Wien bridges, Wagner ground Connection.
Electronic Instruments for Measuring Basic Parameters: Amplified DC meter, AC Voltmeter,
True- RMS responding Voltmeter, Electronic multi-meter, Digital voltmeter, Vector
Voltmeter.
Module-II (12 Hours)
Oscilloscopes: Cathode Ray Tube, Vertical and Horizontal Deflection Systems, Delay lines,
Probes and Transducers, Specification of an Oscilloscope. Oscilloscope measurement
Techniques, Special Oscilloscopes – Storage Oscilloscope,
Sine wave generator, Frequency – Synthesized Signal Generator, Sweep
frequency Generator. Pulse and square wave generators. Function Generators.
Module-III (10 Hours)
Signal Analysis: Wave Analyzer, Spectrum Analyzer.
Frequency Counters: Simple Frequency Counter; Measurement errors; extending frequency
range of counters
Transducers: Types, Strain Gages, Displacement Transducers.
Module-IV (6 Hours)
Digital Data Acquisition System: Interfacing transducers to Electronics Control and
Measuring System. Instrumentation Amplifier, Isolation Amplifier. An Introduction to
Computer-Controlled Test Systems.IEEE-488 GPIB Bus
Text Books:

term measuring instrument is commonly used to describe a measurement system.
The static characteristics of an instrument are, in general, considered for instruments which
are used to measure an unvarying process condition. All the static performance
characteristics are obtained by one form or another of a process called calibration. There are
a number of related definitions (or characteristics), which are described below, such as
accuracy% precision, repeatability, resolution, errors, sensitivity, etc.
 Instrument: A device or mechanism used to determine the present value of the
quantity under measurement.
 Measurement: The process of determining the amount, degree, or capacity by
comparison (direct or indirect) with the accepted standards of the system units being
used.
 Accuracy: The degree of exactness (closeness) of a measurement compared to the
expected (desired) value.
 Resolution: The smallest change in a measured variable to which an instrument will
respond.
 Precision: A measure of the consistency or repeatability of measurements, i.e.
successive readings does not differ. (Precision is the consistency of the instrument
output for a given value of input).
 Expected value: The design value, i.e. the most probable value that calculations
indicate one should expect to measure.
 Error: The deviation of the true value from the desired value.
 Sensitivity: The ratio of the change in output (response) of the instrument to a
change of input or measured variable.
1.1 Accuracy
The accuracy of an instrument is a measure of how close the output reading of the
instrument is to the correct value. In practice, it is more usual to quote the inaccuracy
figure rather than the accuracy figure for an instrument. Inaccuracy is the extent to
which a reading might be wrong, and is often quoted as a percentage of the full-scale
(f.s.) reading of an instrument. If, for example, a pressure gauge of range 0–10 bar has a
quoted inaccuracy of š1.0% f.s. (š1% of full-scale reading), then the maximum error to be
expected in any reading is 0.1 bar. This means that when the instrument is reading 1.0
bar, the possible error is 10% of this value. For this reason, it is an important system
design rule that instruments are chosen such that their range is appropriate to the
spread of values being measured, in order that the best possible accuracy is maintained
in instrument readings. Thus, if we were measuring pressures with expected values
between 0 and 1 bar, we would not use an instrument with a range of 0–10 bar. The
term measurement uncertainty is frequently used in place of inaccuracy.
1.2 Precision/repeatability/reproducibility
Precision is a term that describes an instrument’s degree of freedom from random
errors. If a large number of readings are taken of the same quantity by a high precision
instrument, then the spread of readings will be very small. Precision is often, though
incorrectly, confused with accuracy. High precision does not imply anything about
measurement accuracy. A high precision instrument may have a low accuracy. Low
accuracy measurements from a high precision instrument are normally caused by a bias
in the measurements, which is removable by recalibration.
The terms repeatability and reproducibility mean approximately the same but are
applied in different contexts as given below. Repeatability describes the closeness of
output readings when the same input is applied repetitively over a short period of time,
with the same measurement conditions, same instrument and observer, same location
and same conditions of use maintained throughout.