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MEASUREMENT THEORY FUNDAMENTALS, 361-1-3151
MEASUREMENT THEORY FUNDAMENTALS
361-1-3151
Eugene Papernohttp://www.ee.bgu.ac.il/~paperno/
Eugene Paperno, 2006 ©
3MEASUREMENT THEORY FUNDAMENTALS. Grading policy
GRADING POLICY
20% participation in lectures
30% home exercises
50% presentation
4MEASUREMENT THEORY FUNDAMENTALS. Grading policy
HOMEWORKBuild in LabView the following virtual instruments (VI):
1. Lock-in amplifier SR830www.thinksrs.com/mult/SR810830m.htm
2. Spectrum analyzer SR785http://www.thinksrs.com/mult/SR785m.htm
MEASUREMENT THEORY FUNDAMENTALS
The mathematical theory of measurement is elaborated in:
Krantz, D. H., Luce, R. D., Suppes, P., and Tversky, A. (1971). Foundations of
measurement. (Vol. I: Additive and polynomial representations.). New York: Academic
Press.
Suppes, P., Krantz, D. H., Luce, R. D., and Tversky, A. (1989). Foundations of
measurement. (Vol. II: Geometrical, threshold, and probabilistic representations). New
York: Academic Press.
Luce, R. D., Krantz, D. H., Suppes, P., and Tversky, A. (1990). Foundations of
measurement. (Vol. III: Representation, axiomatization, and invariance). New York:
Academic Press.
Measurement theory was popularized in psychology by S. S. Stevens, who originated the
idea of levels of measurement. His relevant articles include:
Stevens, S. S. (1946), On the theory of scales of measurement. Science, 103, 677-680.
Stevens, S. S. (1951), Mathematics, measurement, and psychophysics. In S. S. Stevens
(ed.), Handbook of experimental psychology, pp 1-49). New York: Wiley.
Stevens, S. S. (1959), Measurement. In C. W. Churchman, ed., Measurement: Definitions
and Theories, pp. 18-36. New York: Wiley. Reprinted in G. M. Maranell, ed., (1974)
Scaling: A Sourcebook for Behavioral Scientists, pp. 22-41. Chicago: Aldine.
Stevens, S. S. (1968), Measurement, statistics, and the schemapiric view. Science, 161,
849-856.
Reference: http://www.measurementdevices.com/mtheory.html
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CONTENTS
1. Basic principles of measurements
1.1. Definition of measurement
1.2. Definition of instrumentation
1.3. Why measuring?
1.4. Types of measurements
1.5. Scaling of measurement results
2. Measurement of physical quantities
2.1. Acquisition of information
2.2. Units, systems of units, standards2.2.1. Units
2.2.1. Systems of units
2.2.1. Standards
2.3. Primary standards
2.3.1. Primary voltage standards
2.3.2. Primary current standards
2.3.3. Primary resistance standards
2.3.4. Primary capacitance standards
MEASUREMENT THEORY FUNDAMENTALS. Contents
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2.3.5. Primary inductance standards
2.3.6. Primary frequency standards
2.3.7. Primary temperature standards
3. Measurement methods
3.1. Deflection, difference, and null methods
3.2. Interchange method and substitution method
3.3. Compensation method and bridge method
3.4. Analogy method
3.5. Repetition method
3.6. Enumeration method
4. Measurement errors
4.1. Systematic errors
4.2. Random errors
4.2.1. Uncertainty and inaccuracy
4.2.2. Crest factor
4.3. Error propagation (תרגום, העברת שגאיות )
4.2.1. Systematic errors
4.2.1. Random errors
MEASUREMENT THEORY FUNDAMENTALS. Contents
9
5. Sources of errors
5.1. Influencing the measurement object: matching
5.4.1. Anenergetic matching
5.4.2. Energic matching
5.4.3. Non-reflective matching
5.4.4. When to match and when not?
5.2. Noise types
5.2.1. Thermal noise
5.2.2. Shot noise
5.2.3. 1/f noise
5.3. Noise characteristics
5.3.1. Signal-to-noise ratio, SNR
5.3.2. Noise factor, F, and noise figure, NF
5.3.3. Calculating SNR and input noise voltage from NF
5.3.4. Two source noise model
5.4. Low-noise design: noise matching
5.4.1. Maximization of SNR5.4.2. Noise in diodes
5.4.3. Noise in bipolar transistors
5.4.4. Noise in FETs
5.4.5. Noise in differential and feedback amplifiers
5.4.6. Noise measurements
MEASUREMENT THEORY FUNDAMENTALS. Contents
10
5.5. Interference: environment influence5.5.1. Thermoelectricity
5.5.2. Piezoelectricity
5.5.3. Leakage currents
5.5.4. Cabling: capacitive injection of interference
5.5.5. Cabling: inductive injection of interference
5.5.6. Grounding: injection of interference by improper grounding
5.5. Observer influence: matching
6. Measurement system characteristics
6.1. Sensitivity
6.2. Sensitivity threshold
6.3. Signal shape sensitivity
6.4. Resolution
6.5. Non-linearity
6.6. System response
MEASUREMENT THEORY FUNDAMENTALS. Contents
11
7. Measurement devices in electrical engineering
7.1. Input transducers
7.1.1. Mechanoelectric transducers
7.1.2. Thermoelectric transducers
7.1.3. Magnetoelectric transducers
7.2. Signal conditioning
7.2.1. Attenuators
7.2.2. Compensator network
7.2.3. Measurement bridges
7.2.4. Instrumentation amplifiers
7.2.5. Non-linear signal conditioning
7.2.6. Digital-to-analog conversion
8. Electronic measurement systems
8.1. Frequency measurement
8.2. Phase meters
8.3. Digital voltmeters
8.4. Oscilloscopes
8.5. Data acquisition systems
MEASUREMENT THEORY FUNDAMENTALS. Contents
12
1. BASIC PRINCIPLES OF MEASUREMENTS
1.1. Definition of measurement
Measurement is the acquisition of information about
a state or phenomenon (object of measurement)
in the world around us.
This means that a measurement must be descriptive
with regard to that state or object we are measuring:
there must be a relationship between the object of
measurement and the measurement result.
The descriptiveness is necessary but not sufficient aspect
of measurement: when one reads a book, one
gathers information, but does not perform a measurement.
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.1. Definition of measurement
Reference: [1]
13
This aspect too is a necessary but not sufficient aspect of
measurement. Admiring a painting inside an otherwise empty
room will provide information about only the painting, but does
not constitute a measurement.
A third and sufficient aspect of measurement is that it must be
objective. The outcome of measurement must be independent
of an arbitrary observer.
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.1. Definition of measurement
A second aspect of measurement is that it must be selective:
it may only provide information about what we wish to
measure (the measurand) and not about any other of the many
states or phenomena around us.
Reference: [1]
14
Image space
Abstract ,well-definedsymbols
In accordance with the three above aspects: descriptiveness,
selectivity, and objectiveness, a measurement can be described
as the mapping of elements from an empirical source set
with the help of a particular transformation (measurement
model).
Empirical space
Source set S
si
States ,phenomena
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.1. Definition of measurement
Source set and image set are isomorphic if the transformation
does copy the source set structure (relationship between the
elements).
Reference: [1]
onto elements of an abstract image set
אבסטרקטי מרחב
Image set I
ii
Transformation
מרחב אמפירי
15
Image space
Example: Measurement as mapping
Empirical space
State (phenomenon):
Static magnetic field
VR
Instrumentation
Abstract symbol
Transformation
B= f (R, V )
Measurement model
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.1. Definition of measurement
מרחב אמפירי אבסטרקטי מרחב
16
The field of designing measurement instruments and systems
is called instrumentation.
Instrumentation systems must guarantee the required
descriptiveness, the selectivity, and the objectivity of the
measurement.
1.2. Definition of instrumentation
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.2. Definition of instrumentation
In order to guarantee the objectivity of a measurement, we
must use artifacts (tools or instruments). The task of these
instruments is to convert the state or phenomenon into a
different state or phenomenon that cannot be misinterpreted by
an observer.
Reference: [1]
171 .BASIC PRINCIPLES OF MEASUREMENTS. 1.3. Why measuring?
1.3. Why measuring?
Let us define ‘pure’ science as science that has sole purpose
of describing the world around us and therefore is responsible
for our perception of the world.
In ‘pure’ science, we can form a better, more coherent, and
objective picture of the world, based on the information
measurement provides. In other words, the information allows
us to create models of (parts of) the world and formulate laws
and theorems.
We must then determine (again) by measuring whether this
models, hypotheses, theorems, and laws are a valid
representation of the world. This is done by performing tests
(measurements) to compare the theory with reality.
Reference: [1]
18
2) perform measurement;
3) alter the pressure if it
was abnormal.
We consider ‘applied’ science as science intended to change
the world: it uses the methods, laws, and theorems of ‘pure’
science to modify the world around us.
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.3. Why measuring?
In this context, the purpose of measurements is to regulate,
control, or alter the surrounding world, directly or indirectly.
The results of this regulating control can then be
tested and compared to the desired results and any further
corrections can be made.
Even a relatively simple measurement such as checking the
tire pressure can be described in the above terms:
1) a hypothesis: we fear that the tire pressure is
abnormal;
Reference: [1]
19
REAL WORLDempirical statesphenomena, etc.
IMAGEabstract numbers
symbols, labels, etc.
SCIENCE
)processing, interpretation(
measurement results
PureApplied
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.3. Why measuring?
Measurement
Verification (measurement)Control/change
Control/change
Hypotheses laws
theories
Illustration: Measurement in pure and applied science
20
These five characteristics are used to determine the five types
(levels) of measurements.
Distinctiveness: A B, A B.
Ordering in magnitude: A B, A B, A B.
Equal/unequal intervals:
ABCD,ABCDABCD.
Ratio: A kB(absolute zero is required).
Absolute magnitude: A ka REF, B kb REF
(absolute reference or unit is required).
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.4. Types of measurements
1.4. Types of measurements
To represent a state, we would like our measurements to have
some of the following characteristics.
Reference: [1]
21
States are only namedNOMINAL
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.4. Types of measurements
States can be orderedORDINAL
Distance is meaningfulINTERVAL
Abs. zeroRATIO
Abs. unitABSOLUTE
Illustration: Levels of measurements (S. S. Stevens, 1946)
22
1. nominal scale,
2. ordinal scale,
3. interval scale,
4. ratio scale,
5. absolute scale.
The types of scales reflect the types of measurements:
1.5. Scaling of measurement results
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
A scale is an organized set of measurements, all of which
measure one property.
231 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
A scale is not always unique; it can be changed without loss
of isomorphism.
Image space
Abstract ,well-definedsymbols
Empirical space
Source set S
si
States ,phenomena
אבסטרקטי מרחב מרחב אמפירי
ii
Transformation
Image set I
241 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
A scale is not always unique; it can be changed without loss
of isomorphism.
Image space
Abstract ,well-definedsymbols
Empirical space
Source set S
si
States ,phenomena
אבסטרקטי מרחב
Image set I
מרחב אמפירי
iiii
Transformation
25
Image1
1 1
0 0
State orthogonality
1. Nominal scale
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
Examples:
numbering of
football
players,
detection
and alarm
systems,
etc.
26
1 1
0 0
Image2=(Image1+1)State orthogonality
1. Nominal scale
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
Examples:
numbering of
football
players,
detection or
alarm
systems,
etc.
27
Image3=Cos(Image2)
1 1
1 1
State orthogonality
1. Nominal scale
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
Examples:
numbering of
football
players,
detection or
alarm
systems,
etc.
28
1 1
1 1
Image4=Image32
2 2
2 2
State orthogonality
1. Nominal scale
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
Examples:
numbering of
football
players,
detection or
alarm
systems,
etc.
29
2 2
2 2
Image5=Cos(Image4)
1 1
1 1
State orthogonality
1. Nominal scale
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
Examples:
numbering of
football
players,
detection or
alarm
systems,
etc.
The structure is lost!
Any one-to-one transformation can be used to
change the scale.
30
A 11
A 21
A 21
A 12
Image1
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
State order
2. Ordinal scale
Examples:
IQ test,
etc.
31
A 11
A 21
A 21
A 12
A 11
A 41
A 41
A 14
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
State order
2. Ordinal scale
Image2 Image12
Examples:
IQ test,
etc.
32
A 11
A 41
A 41
A 14
A 11
A 41
A 41
A 14
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
State order
2. Ordinal scale
Image3 Image2
Examples:
IQ test,
competition
results,
etc.The structure is lost!
Any monotonically increasing transformation, either linear or
nonlinear, can be used to change the scale.
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Image1
A 44
A0
A 67
A1
A 84
A4
A 54
A1
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
State interval
Interval scale
Examples:
time scales,
temperature
scales, etc.,
where the
origin or zero
is not fixed
(floating).
34
A 44
A0
A 67
A1
A 84
A4
A 54
A1
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
State interval
Interval scale
Examples:
time scales,
temperature
scales, etc.,
where the
origin or zero
is not fixed
(floating).
Image210Image12
A 4242
A0
A 6272
A10
A 8242
A40
A 5242
A10
Any increasing linear transformation can be used to change
the scale.
35
Image1
A 44
A1
A 67
A6/7
A 84
A2
A 54
A5/4
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
State ratio
4. Ratio scale
Examples:
measurement
of any physical
quantities
having fixed
(absolute)
origin.
36
A 44
A1
A 67
A6/7
A 84
A2
A 54
A5/4
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
State ratio
4. Ratio scale
Image210Image1
Examples:
measurement
of any physical
quantities
having fixed
(absolute)
origin.
The only transformation that can be used to change the scale
is the multiplication by any positive real number.
A 4040
A1
A 6070
A6/7
A 8040
A2
A 5040
A5/4
37
Image
A 1
A 3/2
A 2
A 5/4
1 .BASIC PRINCIPLES OF MEASUREMENTS. 1.5. Scaling of measurement results
State absolute value
5. Absolute scale
Examples:
measurement
of any physical
quantities by
comparison
against an
absolute unit
(reference).
Ref . Ref .
Ref . Ref .
No transformation can be used to change the scale
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