EI Module 4.pdf

7/27/2019 EI Module 4.pdf

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EI MODULE 4



DATA ACQUISITION SYSTEM (DAS)

• Data acquisition generally relates to the

process of collecting the i/p data in digital

form as rapidly, accurately, and economically

as necessary.



GENERALIZED DATA ACQUISITION

SYSTEM



VARIOUS GENERAL CONFIGURATION

1. Single channel possibilities

• Direct conversion

• Pre-amplification and direct conversion

•Sample and hold, and conversion

• Pre-amplification, signal conditioning and any of the above

2. Multi channel possibilities

• Multiplexing the o/p of single channel converters• Multiplexing the o/p of sample-hold circuits

• Multiplexing the i/p of sample-hold circuits

•

Multiplexing low level data



DIGITAL DAS

Transdu

cer

Signal

conditioni

ngequipment

Multipl

exer

Signal

convert

er

A/D

convert

er

Digital

recoder

Auxiliary equipment and systemprogrammer



SINGLE CHANNEL DAS

A/D Converter BufferTo

Computer

Print Out/

Storage

Convert

Command



OBJECTIVE OF DAS

DAS in ‘Electronic Instrumentation’ by H S Kalsi



SIGNAL ANALYZERS

• Wave analyzers – frequency selective

voltmeter, carrier frequency voltmeter, and

selective level voltmeter.

• Distortion analyzer – Harmonic distortion

analyzers.

• Spectrum analyzers.

• All case analysis in frequency domain.



WAVE ANALYZER

• To measure the amplitude of each harmonic

or fundamental individually.

• It has a very narrow pass – band.

• Range – low RF range below 50Mhz and down

through AF range.



BASIC WAVE ANALYZER



FREQUENCY SELECTIVE WAVE

ANALYZER



RELATIVE RESPONSE IN DBS



HETERODYNE WAVE ANALYZER



RF HETERODYNE WAVE ANALYZER



Harmonic distortion analyzer

• Total harmonic content

• Simplest method – high pass filter whose cut

off freq is a little above fundamental freq.

• Other types

Employing A Resonance Bridge

Wien's Bridge MethodBridged T-Network Method



RESONANCE BRIDGE METHOD



WIEN'S BRIDGE METHOD



BRIDGED T-NETWORK METHOD



HARMONIC DISTORTION ANALYZER

USING BRIDGED T-NETWORK



SPECTRUM ANALYZER

• Frequency domain view.

• Graphical display on its CRT, with freq on

horizontal axis and amplitude (voltage) on

vertical axis.

• Spectrum analyzer use either Parallel Filter

Bank or a Swept Frequency Technique



SPECTRUM ANALYZER



SPECTRUM ANALYZER USING SWEPT

RECEIVER DESIGN



TEST WAVE AND DISPLAY OF

SPECTRUM



TEST WAVEFORM ON X AXIS(TIME) & Z

AXIS(FREQ)



RF SPECTRUM ANALYZER



Signal Analyzers in ‘Electronic Instrumentation’ by HS Kalsi



PROGRAMMABLE LOGIC CONTROLLER

(PLC)

• The processor in a PLC system has software that

is easily programmable and flexible, making the

initial program, updates, modifications, and

changes easy to implement.• PLCs are categorized into low-end, midrange, and

high-end, where low-end is from 64 expandable

up to 256 I/Os, midrange is expandable up to2,048 I/Os, and high-end is expandable up to

8,192 I/Os.



BLOCK DIAGRAM OF A CONTROL LOOP



BLOCK DIAGRAM OF PROGRAMMABLE

CONTROLLER



COMPUTER-BASED DIGITALLY

CONTROLLED PROCESS



BLOCK DIAGRAM OF PROCESSING

UNIT



PH MEASUREMENT

• pH is a parameter that quantifies the level of

acidity or alkalinity in a chemical solution

• pH ranges from 0 to 14

• An excess of hydrogen ions causes acidic, and

an excess of hydroxyl ions causes alkaline

• Neutral solution like pure water has a pH

value of 7



PH MEASUREMENT

• The pH value is given by

pH = log10 [1/hydrogen ion concentration]

• Scale range from 0 to 14

• Acidic solution pH value b/w 0 to 7

• Alkaline solution pH value b/w 7 to 14



PH APPLICATION CONSIDERATIONS



THERMAL-CONDUCTIVITY(GAS

ANALYZER)

• Chemical purity of gas

• Based on vast difference in heat conductivity

among gases

• Measured by bridge circuit using sensing

resistors and thermistors



DSO (Digital Storage Oscilloscope)

• DSO – processing and non processing

• Processing type – built in computing power(data

in digital form), processing capability ranges from

simple (avg, area, rms etc.) to complete FFTspectrum analysis capability

• Non processing type – designed as replacement

for analog instrument or both storage and nonstorage types. Their many desirable features seen

set to replace analog scopes entirely (within BW

range where digitization is feasible)



COMPONENTS OF DSO

Amplifier/Atte

nuatorA/D Converter

Acquisition

Memory

Display

Display

Memory Microprocessor

I/p

Voltage

S/g



DSO

• Scope of DSO

• Commercial DSO – features

• Precaution

• ‘Electronic Instrumentation’ by H S Kalsi



Strain measurement

• Ballast circuit

• Deflection type Wheatstone bridge

• Temp compensation technique

• Uses of strain gauge

• “Electrical and Electronic Measurement &

Instrument” by A K Sawhnay



• Pressure, flow, temp, force, torque, mass

measurements any three method.

• Syllabus Reference – 1, 4 & 7

• Doeblin, Morris and Rangan

Documents

EI Module 4.pdf