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Dec 31, 2016

EBOOK - Wiley Survey of Instrumentation and Measurement (Stephen A. Dyer)


Instrumentation and Measurement—Introductory Kelvin’s first rule of instrumentation states, in essence, that the measuring instrument should not alter the event being measured. That rule impacts the design of any instrument.
In broad terms, we can view a measuring instrument or instrument subsystem as comprising an input transducer followed by a signal-conditioning section, which in turn drives a data-processing and display section.
The instrument or piece of test equipment may be completely manual, requiring (sometimes significant) tending by its operator, or it may be automated to one extent or another.
The increasing availability of inexpensive computing power, beginning in the early 1970s, has encouraged the design of instrumentation capable of being controlled by computer, with all but the simplest of instruments today having interfaces built in.
Sensors and Transducers Transducers are energy-conversion devices and are the “molecule” of a measurement system (i.e., the smallest unit from which measurement systems are constructed). Some transducers, such as thermocouples, are active (or selfgenerating); i.e., they are such that the input energy in one form directly produces another form of energy at its output.
Other transducers, such as resistance thermometers, require two forms of input energy to produce some form of output energy; they are termed passive, or non-self-generating.
Traditionally, sensors have been taken to be the passive portions of non-self-generating transducers.
They are usually elements which have one or more physical properties affected by some physical quantity.
In today’s literature there is often a lack of distinction between “sensor” and “transducer.” The terms are often used interchangeably. Furthermore, integrated-circuit technology has led to the inclusion of signal conditioning circuitry and dataacquisition-and-communication interfaces on the same chip as the sensor or transducer. While the entire package is typically referred to as a sensor, in reality it is an instrumentation subsystem, or perhaps a complete instrument, on a chip.
While the need for traditional, discrete sensors and transducers will certainly ontinue, present research and development of integrated sensors, intelligent sensors, and integrated systems on a chip will result in an expanding offering of compact, rugged, relatively inexpensive, and easy-to-apply measurement front ends and systems based on one or more sensors or transducers.
Signal Conditioning
It is the task of the signal conditioner to accept the signal output from the transducer and produce from it a signal acceptable for introduction to the remainder of the instrument.
Signal conditioning is typically analog in nature, and it can involve strictly linear operations, strictly nonlinear operations, or some combination of the two. Examples of linear operations include amplitude scaling (amplification or attenuation), impedance transformation, linear filtering, and modulation.
Some nonlinear operations include obtaining the root-meansquare (rms) value, absolute value, square root or logarithm of the input signal.
The signal conditioning may also provide auxiliary services, such as producing an excitation signal for the transducer, providing a reference signal for the transducer, or introducing electrical isolation.
Building blocks for providing analog signal processing are available in many forms—as modules, as integrated circuits (ICs), and as complete subsystems having universal backplanes and plug-in input and output modules. Operational amplifiers, instrumentation amplifiers, isolation amplifiers, nonlinear processing circuits such as comparators, multiplier/dividers, log/antilog amplifiers, trigonometric-function generators, and rms-to-dc converters are but a few of the building blocks available.
General-Purpose Instrumentation
The electrical quantities most commonly measured include voltage, current, charge, resistance, and impedance. This section surveys general-purpose instrumentation typically used for measurement of such quantities. Many of these instruments can be found on even the most modest of laboratory or test benches.

Instruments 1
Measurement Errors 14
Automatic Test Equipment 25
SENSORS AND TRANSDUCERS 37
Electric Sensing Devices 37
Magnetic Sensors 46
Hall Effect Transducers 60
Pressure Sensors 71
Piezoresistive Devices 84
Strain Sensors 87
Temperature Sensors 101
Thermistors 122
Thermocouples 129
Thermopiles 135
Accelerometers 147
Tachometers 163
Fiber-Optic Sensors 178
Ultraviolet Detectors 199
Chemical Sensors 207
Intelligent Biosensors 222
SIGNAL CONDITIONING 241
Instrumentation Amplifiers 241
Current Shunts 252
Current Transformers 259
Instrument Transformers 266
GENERAL-PURPOSE INSTRUMENTATION
AND MEASUREMENT 277
Multimeters 277
Digital Multimeters 286
Ohmmeters 291
Electrometers 293
Balances 301
Bridge Instruments 309
Oscilloscopes 326
ELECTRICAL VARIABLES 339
Charge Measurement 339
Electric Current Measurement 343
Inductance Measurement 347
Capacitance Measurement 358
Q-Factor Measurement 372
Q-Meters 387
ELECTROMAGNETIC VARIABLES 397
Electric Strength 397
Electromagnetic Field Measurement 401
Magnetic Field Measurement 410
Attenuation Measurement 422
Loss-Angle Measurement 439
Wavelength Meter 452
Reflectometers, Time-Domain 467
Standing Wave Meters and Network Analyzers 476
Millimeter-Wave Measurement 496
MECHANICAL VARIABLES 509
Displacement Measurement 509
Velocimeters 521
Acceleration Measurement 535
Density Measurement 546
Level Meters 557
Flowmeters 568
Dynamometers 580
Torquemeters 587
Weighing 596
Gravimeters 607
Viscometers 611
Compasses 624
Goniometers 635
Gyroscopes 644
Hygrometers 666
Pyrometers 680
Acoustic Variables Measurement 688
TIME, FREQUENCY, AND PHASE 697
Frequency and Time Interval Meters 697
Frequency Standards, Characterization 707
Frequency Stability 715
Phase Meters 721.

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