Transcript Definitions of the SI base and derived units

University of Pitesti
Dolnośląska Wyższa Szkoła Przedsiębiorczości i Techniki
w Polkowicach
Measurament systems in electronics
Damian Constantin
Dr inż. ZDZISŁAW PÓLKOWSKI
Polkowice, 2015
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Definition of measurament systems in electronics
Definitions of the SI base and derived units
Definitions of the SI base units
SI derived units
Other not SI units
Voltmeter
Analog Voltmeter
Digital Voltmeter
Oscilloscope
Analog ammeter
Digital ammeter
Digital-to-Analog Convertors (DAC)
Analog-to-Digital Convertos(ADC)
Frequency meter
Types of frequency
Ohmmetermeters
Definition of measurament systems in electronics
Electronic Measurements
Measurement of some electric, magnetic, or electromagnetic quantity or of
the relationships between such quantities characterizing the operation of electronic
equipment over the range of frequencies from the infrasonic to the superhigh.
http://cie-wc.edu/Electronics-Technology-Troubleshooting.aspx
Definitions of the SI base and derived units
The International System of Units, universally abbreviated SI (from the
French Le Système International d'Unités), is the modern metric system of
measurement. The SI was established in 1960 by the 11th General Conference on
Weights and Measures (CGPM, Conférence Générale des Poids et Mesures). The
CGPM is the international authority that ensures wide dissemination of the SI and
modifies the SI as necessary to reflect the latest advances in science and
technology.
http://www.eformulae.com/physics/derived_units.php
Definitions of the SI base units
The SI is founded on seven SI base units for seven base
quantities assumed to be mutually independent
https://www.boundless.com/chemistry/textbooks/boundless-chemistrytextbook/gases-5/properties-of-gases-50/si-units-of-pressure-2531861/
SI derived units
Other quantities, called derived quantities, are defined in terms of the
seven base quantities via a system of quantity equations. The SI derived units for
these derived quantities are obtained from these equations and the seven SI base
units.
For ease of understanding and convenience, 21 SI derived units have
been given special names and symbols, as shown in Table. The special names and
symbols of the 21 SI derived units with special names and symbols given in Table
may themselves be included in the names and symbols of other SI derived units.
http://www.technick.net/public/code/cp_dpage.php?aiocp_dp=guide_si_units/
Other not SI units
Bit:
A bit is the smallest unit of data in a computer. A bit has a single binary value, either
0 or 1. Although computers usually provide instructions that can test and manipulate
bits, they generally are designed to store data and execute instructions in bit
multiples called bytes. In most computer systems, there are eight bits in a byte. The
value of a bit is usually stored as either above or below a designated level of
electrical charge in a single capacitor within a memory device. Half a byte (four bits)
is called a nibble. In some systems, the term octet is used for an eight-bit unit
instead of byte. In many systems, four eight-bit bytes or octets form a 32-bit word. In
such systems, instruction lengths are sometimes expressed as full-word (32 bits in
length) or half-word (16 bits in length).
Decibel (dB):
One tenth of the common logarithm of the ratio of relative powers, equal to 0.1 B
(bel).
Note 1: The decibel is the conventional relative power ratio, rather than the bel, for
expressing relative powers because the decibel is smaller and therefore more
convenient than the bel. The ratio in dB is given by
dB = 10 log10(P1/P2)
http://physics.nist.gov/cuu/Units/outside.html/
Other not SI units
Neper (Np):
A unit used to express ratios, such as gain, loss, and relative values.
Note 1: The neper is analogous to the decibel, except that the Naperian base
2.718281828. . . is used in computing the ratio in nepers.
Note 2: The value in nepers, Np , is given by Np = ln(x 1/x 2), where x 1 and x 2 are
the values of interest, and ln is the natural logarithm, i.e., logarithm to the base e.
Note 3: One neper (Np) = 8.686 dB, where 8.686 = 20/(ln 10).
Note 4: The neper is often used to express voltage and current ratios, whereas the
decibel is usually used to express power ratios.
Note 5: Like the dB, the Np is a dimensionless unit.
Note 6: The ITU recognizes both units.
http://www.bipm.org/en/publications/si-brochure/section4-2.html/
Voltmeter
A voltmeter, also known as a voltage meter, is an instrument used for
measuring the potential difference, or voltage, between two points in an electrical or
electronic circuit. Some voltmeters are intended for use in direct current (DC)
circuits; others are designed for alternating current (AC) circuits. Specialized
voltmeters can measure radio frequency (RF) voltage.
http://www.ibiblio.org/kuphaldt/electricCircuits/Exper/EXP_2.html/
Analog Voltmeter
A basic analog voltmeter consists of a sensitive galvanometer (current
meter) in series with a high resistance. The internal resistance of a voltmeter must
be high. Otherwise it will draw significant current, and thereby disturb the operation
of the circuit under test. The sensitivity of the galvanometer and the value of the
series resistance determine the range of voltages that the meter can display.
http://www.directindustry.com/prod/circutor/product-11644-436892.html
Digital Voltmeter
A digital voltmeter shows voltage directly as numerals. Some of
these meters can determine voltage values to several significant figures.
Practical laboratory voltmeters have maximum ranges of 1000 to
3000 volts (V). Most commercially manufactured voltmeters have several
scales, increasing in powers of 10; for example, 0-1 V, 0-10 V, 0-100 V, and
0-1000 V.
http://notebook.pege.org/2004-car-adapter/digital-voltmeter.htm/
Oscilloscope
An oscilloscope can be used to measure low voltages; the vertical
displacement corresponds to the instantaneous voltage. Oscilloscopes are
also excellent for the measurement of peak and peak-to-peak voltages in
AC and RF applications. Voltmeters for measuring high potential
differences require heavy-duty probes, wiring, and insulators.
http://www.printcapture.com/
Analog ammeter
Analog ammeters are metered instruments that measure current
flow in amperes. They display current levels on a dial, usually with a
moving pointer or needle. Analog ammeters provide information about
current draw and current continuity in order to help users troubleshoot
erratic loads and trends. They have both positive and negative leads and
feature extremely low internal resistance. Ammeters are connected in
series with a circuit (and never parallel) so that current flow passes through
the meter. High current flow may indicate a short circuit, unintentional
ground, or defective component. Low current flow may indicate high
resistance or poor current flow within the circuit.
http://www.directindustry.com/prod/ime/product-14561-56640.html
Digital ammeter
In much the same way as the analogue ammeter formed the basis
for a wide variety of derived meters, including voltmeters, the basic
mechanism for a digital meter is a digital voltmeter mechanism, and other
types of meter are built around this.
Digital ammeter designs use a shunt resistor to produce a calibrated
voltage proportional to the current flowing. This voltage is then measured
by a digital voltmeter, through use of an analog to digital converter (ADC);
the digital display is calibrated to display the current through the shunt.
Such instruments are generally calibrated to indicate the RMS value for a
sine wave only but some designs will indicate true RMS (sometimes with
limitations as to wave shape).
http://www.enertechdevices.com/products/digital_ammeter_48_X_96.php
Digital-to-Analog Convertors (DAC)
As the world’s leading provider of data converters, Analog Devices
has the industry’s largest portfolio of D/A converters (DACs) ranging from 8
bits to 24 bits. ADI DACs are unmatched in their ability to deliver
performance and value by providing accurate and reliable conversion for a
range of applications including industrial automation, programmable logic
controllers, optical transceivers, data acquisition, and more. Our portfolio
includes integrated output amplifier options for ease of use, dynamic range
DACs for multicarrier generation over a very wide bandwidth, and a variety
of other DACs to suit your design needs.
http://www.analog.com/en/products/digital-to-analog-converters.html
Analog-to-digital Convertor(ADC)
Linear Technology offers a complete family of high performance analog
to digital converter products (ADCs), including 16-bit to 24-bit delta sigma
converters for precision measurements, up to 16-bit high-speed pipeline ADCs for
communications and 8-bit to 20-bit low power successive approximation register
(SAR) analog to digital converter for everything in between. Our analog to digital
converter portfolio offers unmatched noise performance (SINAD, SNR and SFDR),
low power consumption and small package size.
http://www.analog.com/en/products/digital-to-analog-converters.html
Frequency meter
A frequency meter is an electronic instrument that displays
the frequency of a periodic electrical signal.
Frequency meter, device for measuring the repetitions per unit of time
(customarily, a second) of a complete electromagnetic waveform. Various types of
frequency meters are used. Many are instruments of the deflection type,
ordinarily used for measuring low frequencies but capable of being used for
frequencies as high as 900 Hz. These operate by balancing two opposing forces.
Changes in the frequency to be measured cause a change in this balance that can
be measured by the deflection of a pointer on a scale.
http://www.allaboutcircuits.com/textbook/alternating-current/chpt12/frequency-and-phase-measurement/
Types of frequency meters
Deflection-type meters are of two types, electrically resonant circuits
and ratiometers. An example of a simple electrically resonant circuit is a movingcoil meter. In one version, this device possesses two coils tuned to different
frequencies and connected at right angles to one another in such a way that the
whole element, with attached pointer, can move. Frequencies in the middle of the
meter’s range cause the currents in the two coils to be approximately equal and
the pointer to indicate the midpoint of a scale. Changes in frequency cause an
imbalance in the currents in the two coils, causing them and, in turn, the pointer
to move. Another type of frequency meter, not of the deflection type, is the
resonant-reed type, ordinarily used in ranges from 10 to 1,000 Hz, although
special designs can operate at lower or higher frequencies. These work by means
of specially tuned steel reeds that vibrate under the effect of electric current; only
those reeds that are in resonance vibrate visibly, however.
http://www.electronicecircuits.com/electronic-circuits/analog-frequency-meter-circuit
Ohmmeter
Though mechanical ohmmeter (resistance meter) designs are rarely used
today, having largely been superseded by digital instruments, their operation is
nonetheless intriguing and worthy of study.
The purpose of an ohmmeter, of course, is to measure the resistance
placed between its leads. This resistance reading is indicated through a
mechanical meter movement which operates on electric current. The ohmmeter
must then have an internal source of voltage to create the necessary current to
operate the movement, and also have appropriate ranging resistors to allow just
the right amount of current through the movement at any given resistance.
Starting with a simple movement and battery circuit, let’s see how it
would function as an ohmmeter:
http://www.tigerstop.com/tigertamer/Using_an_Ohm_Meter.htm