ssp two marks

8/9/2019 SSP Two Marks

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KUMARAGURU COLLEGE OF TECHNOLOGY

COIMBATORE 641 006

DEPARTMENT OF MECHATRONICS

Question BankU07MH601-Sensors & Signal Processing

Prepared By

P.Kalaisevan

Lecturer / Department of Mechatronics

KCT.


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U07MH601-Sensors and Signal Processing

UNIT-I

Part-B

1. Define static characteristics.

Static characteristics of a measurement system are, in general, those that must be

considered when the system or instrument is used to measure a condition not varying with time.

2. Mention different types of static characteristics.

(i) Accuracy (ii) sensitivity (iii) Reproducibility (iv) Drift (v) Static error and (vi) Dead

zone.

3. Define static sensitivity.

Sensitivity should be taken depending on the operating point. The sensitivity is expressed

in output unit/ input unit.

4. Define linearity.Linearity is a measure of the maximum deviation of the plotted transducer response from

a specified straight line .

5. Compare accuracy and precision.

Accuracy is the closeness to true value whereas precision is the closeness amongst the

readings. Precision is the degree of closeness with which a given value may be repeatedly

measured.

6. What is Threshold?

When the input to a transducer is increased from zero, there is a minimum value below

which no output can be detected .This minimum value of the input is defined as the threshold ofthe transducer.

7. Define resolution.

When the input to a transducer is increased slowly from some non-zero arbitrary value,

the change in output is not detected at all until a certain input increment is exceeded. This

increment is defined as the resolution.

8. Define hysteresis.

When the input to a transducer which is initially at rest is increased from zero to full-scale

and then decreased back to zero, there may be two output values for the same input. Hysteresis

effects can be minimized by taking readings corresponding to ascending and descending valuesof the input and then taking their arithmetic average.

9. How are transducer are classified?

They can be classified into different types based on the energy conversion, application

and so on. They are two types

Active transducer: A transducer that gives its output without the use of an excitation

voltage or modulation of a carrier signal is called an active transducer

Passive transducer: A transducer that gives its output using an excitation voltage or

modulation of a carrier signal is called a passive transducer. Generally the active transducer

converts a non- electrical energy into electrical energy and converts an electrical into non

electrical energy.

Department of Mechatronics, Kumaraguru college of Technology, Coimbatore-641

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10. What is meant by rosette?

It is a combination of strain gauges to a single element strain gauge.

11. What is the difference between sensor and transducer?

In the general case, a sensor is the complete assembly required to detect and communicate

a particular event, while a transducer is the element within that assembly which accomplishes

only the detection of the event.

12. Define thermocouples.

When two wires with dissimilar electrical properties are joined at both ends and one

junction is made hot and the other cold, a small electric current is produced proportional to the

difference in the temperature. Seebeck discovered this effect. It is true no matter how the ends are

joined so the cold end may be joined at a sensitive millivolt meter. The hot junction forms the

sensor end.

13. What are all the types of force sensors?

The main types of force sensors are

Mechanical types.

Hydraulic types.

Electrical strain gauge types.

14. What are the types of transducers?

They are broadly divided into two categories;

1. Active transducer

2. Passive transducer

15. What are active transducers and passive transducers? Give examples.

Active transducer: Such type of transducers required external source of energy to

operate. Energy is supplied through a separate voltage source. An example is potentiometer,

which senses the resistance by flow of a minute current through itself. Most of the transducers

now a day are active.

Passive transducer: They convert one form of energy to other form without any use of

energy. Passive transducers convert physical quantities like; temperatures, pressure, speed etc.

Transducers are further subdivided as

Resistive transducer


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RTD

Thermistors

Inductive changing transducer

Capacitive changing transducer

Displacement transducers

Velocity transducers

Pressure transducers

16. What are primary and secondary transducers?

Primary transducer: The Mechanical device which converts physical quantity to be

measured into a mechanical signal.

Secondary transducer: The Electrical device which converts this mechanical signal to the

electrical signal.

17. Differentiate between analog and digital transducers.

Analog transducers convert the input quantity into an analog output which is a continuous

function of time. E.g.-L.V.D.T, Thermocouple, Strain gauge.

Digital transducers convert the input quantity into an electrical output which is in the form of

pulses.

18. What is meant by actuators?

It is a power amplifying device that produces the input/output to the plant according to

the control signals.

19. What is range and span?

The range of the transducer is specified as from the lower value of input to higher value

of input.

The span of the transducer is specified as the difference between the higher and lower

limits of recommended input values.

20. What is Microphone?

It is also a transducer which converts sound energy into electrical energy.

Example is condenser microphone.

21. What is piezo electric transducer?

They convert pressure or force into electrical charge. These transducers are based upon

the natural phenomenon of certain non-metal and di-electric components.

22. What are the suitable materials for piezo electric transducer?

Primary quartz, Rochelle salt, ammonium dihydrogen phosphate (ADP), and ceramics

with barium titanate, dipottasium tartrate, potassium dihydrogen phosphate and lithium sulfate.

23. What is piezo electric effect?

A piezo electric material is one in which an electric potential appears across certain

surfaces of a crystal if the dimensions of the crystal are changed by the application of the

mechanical force.

24. What is digitizer?


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Digital encoding transducer or digitizer enables a linear or rotary displacement to be

directly converted into digital form without intermediate form of analog to digital (A/D)

conversion.

25. What are the classifications of encoder?

1. Tachometer transducer 2.Incremental transducer 3.Absolute transducer.

26. Define Humidity.

It is basically moisture content in air or it is the quantity of water vapour retained by gas.

27. Define Absolute Humidity.

Weight of water vapour in unit wait of gas.

H=Wr / Wg

28. Define Specific Humidity.

It is weight of vapors in unit weight of mixture.

29. Define Relative Humidity.This is the ratio of moisture content of gas to maximum moisture content of the gas at that

temperature.

30. Define Hygrometer.

Used to measure the moisture content in air. It also used to measure humidity.

31. What is the basic principle of Hygrometer?

It consists of mechanical device measuring the dimension change of humidity sensitive

materials like animal hair, animal membrane, paper etc.

32. Define Moisture.

Defined as the amount of water absorbed by solids or liquids.

33. What are the various methods of measurement of moisture?

Based on the weight of the particle

Based on the resistance, capacitance.

34. What are the different types of hygrometer?

Hair hygrometers

Wire electrode hygrometers

Electrolysis type hygrometers Resistive type

Capacitive type

Microwave reflector

35. List the types of instruments.

The 3 types of instruments are

Mechanical Instruments

Electrical Instruments and

Electronic Instruments.


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36. Classify instruments based on their functions.

Indicating instruments

Integrating instruments

Recording instruments

37. Why calibration of instrument is important?

The calibration of all instruments is important since it affords the opportunity to check theinstrument against a known standard and subsequently to errors in accuracy.

38. Define Calibration.

It is the process by which comparing the instrument with a standard to correct the

accuracy.

39. Define Signal.

Signal is a physical quantity that varies with respect to time, space or any other

independent variable.

40. What are the major classifications of the signal?

(i) Discrete time signal

(ii) Continuous time signal

41. Define discrete time signals and classify them.

Discrete time signals are defined only at discrete times, and for these signals, the

independent variable takes on only a discrete set of values.

Classification of discrete time signal:

1.Periodic and Aperiodic signal

2.Even and Odd signal

42. Define continuous time signals and classify them.

Continuous time signals are defined for a continuous of values of the independent

variable. In the case of continuous time signals the independent variable is continuous.

For example:

(i) A speech signal as a function of time

(ii) Atmospheric pressure as a function of altitude

Classification of continuous time signal:

(i) Periodic and A-periodic signal

(ii) Even and Odd signal.

43. Define continuous time system.A continuous time system is a system in which continuous time input signals are applied

and result in continuous time output signals.

44. List three sources of possible errors in instruments.

Gross Error,

Systematic

Random errors.

45. Define Environmental error

These are due to conditions in the measuring device, including conditions in the area

surrounding the instrument, such as the effects of changes in temperature, humidity.Department of Mechatronics, Kumaraguru college of Technology, Coimbatore-641

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46. Give the classification of units.

1. Absolute units2. Fundamental and derived units

3. Electromagnetic units

4. Electrostatic units

47. Define static calibration.

It refers to a process in which all the inputs (desired, modifying, interfering) except one

are kept at some constant values.

48. Define Traceability.

The ability to trace the accuracy of the standard back to its ultimate source in fundamental

standards of National Institute of Science and Technology is termed Traceability

49. Give one property of piezo-electric crystal.

When a force is applied to piezo-electric crystals, they produce an output voltage.

50. What are the factors involved for the selection of transducers?

Selection of transducers depends on the following factors.

a) Physical quantity to be measured.

b) Appropriate transducer principle is to be used for the given physical quantity

c) Order of accuracy needed

51. State See back effect.

When two dissimilar metals of different temperatures are joined together, an emf is induced at

the junction this is see back effect.

Part- C

1. Derive the expression of a strain gauge for rosettes.

2. Show with the help of diagram, how the pressure sensor is integrated with signal

processing ensembles and drive it.

3. Briefly explain the working of any two types of microphone. With a neat sketch.

4. Explain the different types of nuclear radiation sensors with a suitable diagram.

5. Show with the help of diagram, how the pressure sensor is integrated with signal

processing ensembles.

6. Describe the working principle of ultrasonic sensor and its merits and demerits.

7. Explain the different types of nuclear radiation sensors with a suitable diagram.


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8. Draw the block diagram of sound level meter explain the function of each block.

9. Explain the static and dynamic characteristics of sensor with a neat sketch.

10. Briefly explain the humidity sensor with a neat sketch.

UNIT 2

Part - B

1. What are the features that a Smart sensor should have?

1. Automatic ranging and storage of calibration through a built-in digital system.

2. Auto-acquisition and storage of calibration constants in local memory of the field

device,

3. Auto configuration and verification of the hardware for correct operation following

internal

checks,4. Auto correction of offsets, time and temperature drifts,

5. Auto linearization of nonlinear transfer characteristics,

6. Self tuning control algorithms, fuzzy logic control is being increasingly used now,

7. Control program may be locally stored or downloaded from a host system and

dynamic reconfiguration performed,

8. Condition monitoring is also used for fault diagnosis which, in turn, may involve

additional

sensors ,digital signal processing ,and data analysis software, and

9. Communication through a serial bus.

2. What do you mean by Primary sensing element and what should be its characteristic?External stimuli such as strain /stress, thermal /optical agitation and electric/magnetic

field change the behavior of materials at atomic/molecular level or in crystalline state. This

concept is utilized in designing a primary sensing element for particular stimulus or a specific

physical variable so that, in response to this , the considered material yields a maximized output

an its response to other stimuli is minimized .

3. State Parasitic effects.

One way to understand response maximization in electrical forms to one or a set of target

variables while ignoring others on the part of sensor element is to state that it should show

negligible reaction to interferences and parasitic effects. For reliable operation of a sensor

environmental conditions have to be maintained where parasitic effects to exists though limited.

4. State Amplifier.

Considering the output of sensor to be generally small, amplification is essential in all

smart sensors. If the gain requirement is very high, noise becomes a problem. However, stage-

wise approach with adequate compensation realizes the requirement, the design and layout being

critical as well.

5. State Data Communication.

Data communication is essential in smart transmitters where the sensor outputs are

communicated with the host through bus-system. Coded data are processed for communication

by a software processor and a suitable interface system communicates between the processor andDepartment of Mechatronics, Kumaraguru college of Technology, Coimbatore-641

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the bus. The bus was, till lately, being standardized. Commercial versions available for quite

some time used their own protocol .Each smart sensor /transmitter has always been provided with

a local operating system in a ROM, that consists of an application programmer and library

modules, for ADC and DAC hardwires, bus driving hardware , and local interface hardware and

LCD/keyboard hardware.

6. State HART Protocol.

Earlier manufacturers preferred to develop their own protocol. One such protocol is

HART (Highway Addressable Remote Transducer) offered by Rosemount which superposes a

digital transmission protocol on the standard 4-20 mA loop. A typical transmitter with HART

protocol appears as the one shown in Fig 7.16. Some other protocols that find use are High Level

Data Control (HDLC), Synchronous Data Link Control (SDLC), Factory Instrumentation

Protocol (FIP), and so on which are sufficiently advanced.

7. Standards for Smart Senior Interface.

The IEEE P 1451.2 provides the transducer to-microprocessor communication protocols

and transducer electronic data sheet (TEDS) formats. It also provides the digital interface andcommunication protocol between the transducer and microprocessor s.

The IEEE P 1451.3 provides digital communication and TEDS formats for distributed

multi loop systems. This is basically intended to develop a standard digital interface for multiple

physically isolated/separated transducers in multi drop configuration.

The IEEE P 1451.4 provides mixed mode communication and also the TEDS format.

This is intended to develop bidirectional communication of digital TEDS in addition to an

interface for mixed mode transducers.

8. Write about Film Sensors.

Basically, such sensors are produced by film deposition of different thicknesses on

appropriate substrates. The deposition techniques used are different for the thick and thin film

sensors. Sensors produced through these techniques have varying electrical and mechanical

properties while a variable is being sensed.

Thick film deposition is a mature technique and there has not been substantial

improvement whilst thin films are being developed almost at the same pace as microelectronics

incorporating latest technology. It is to be noted that thick film process had been in use for

producing capacitor, resistor, and conductor - and has subsequently been adopted in sensor

development. The processing of a sensor can be expressed schematically as

9. What are the steps that have to be taken for manufacturing a Film sensor?

Step 1: Selection and preparation of a substrateStep 2: Preparation of the initial coating material in paste or paint form.

Step 3: Pasting or painting the substrate by the coating material or screen printing it.

Step 4: Firing the sample produced in step 3 in an oxidizing atmosphere at a

programmed temperature format.

10. Write about Thin Film Sensors.

Thin film sensor processing differs from thick film technology mainly in the film

deposition techniques. This technology is similar to that used in silicon micromechanics. A

number of techniques are used for thin film deposition, such as:

(a) Thermal evaporation

(i) Resistive heating


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(ii) Electron beam heating

(b) Sputter deposition

(i) DC with magnetron

(ii) RF with magnetron

(c) Chemical vapour deposition (CVD)

(d) Plasma enhanced chemical vapour deposition (PECVD)

(e) Metallo-organic deposition (MOD)(f) Langmuir-Blodgett technique of monolayer deposition.

11. Explain about Semiconductor IC Technology.

These sensors are semiconductor micro- and Nano-sensors, ceramic and chemical sensors

using new materials, and optical fiber sensors. These sensors are developed through standard IC

technology as used in VLSI design and micromachining techniques. In fact, the IC processes are

to be complemented by precise micromachining technique for developing three-dimensional

structures of the sensors for better performance, reliability, sensitivity, manufacturing uniformity

and stability, and cost reduction.

12. Write about Microelectromechanical Systems (MEMS).MEMS are basically miniature devices on a silicon chip which have found a major use in

sensors. These find an application in modern times in the car air back systems. In UK and

European continent, these are often referred as micro system technology (MEST). This discipline

is termed as Micro-engineering uses materials such as semiconductors, metal, glass, polymer-

based materials, and so on.

13. Name the technique of manufacturing MEMS.

1. Bulk micromachining

2. Surface micromachining

14. What do you mean by Nano-Sensors?

Microelectronics naturally leads to nanoelectrons for realizing Nano-devices which are

expected to create an impact in the enhancement of energy conversion, control of pollution,

production of food, and improvement in the conditions of human health and longevity. At

present, however, the best examples of Nano-devices, as far as applications are concerned, are

associated with information technology industry.

15. Name some areas where Nano sensors developed.

Discovery and controlled production of carbon nanotubes and the use proximal probe

and lithographic schemes,

Success in placing engineered individual ,molecules onto appropriate electrical contactsand in measuring transport through these molecules ,

Implantation/incorporation of biological motors into nanobiological environments ,

Integration of nano particles into gas sensors ,

Fabrication of photonic level band gap structures,

16. Explain about Automobile sensors.

Engine is the heart of automobile which is exposed to vibration , dust , electrical noise

,extreme temperature variations, and hence , the sensor used too get exposed to all these

conditions even though in the performance level has to be kept unabated . One such sensor is

the flow-rate sensor as discussed in the following subsection. The engine compartment of an

automobile has a temperature varying from -40 to 150 degree Celsius and vibrational


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acceleration ranging from 3g-30g. Exposure to water, oil, mud, electromagnetic interference,

and the like are also to be taken into consideration for better performance.

17. Name some sensors used in Automobile.

1. Flow rate Sensors

2. Pressure Sensors

3. Temperature Sensors4. Oxygen Sensors

5. Torque and Position Sensors

18. State Home appliance Sensors

Home comfort depends to a great extend on the availability of automatic home appliance

such as cleaner , refrigerator ,washing machine , microwave owens , and so forth .

Semiconductor technology has grown fast over a last few decades leading to development of

microminiaturized processors, circuits and of course sensors therefore enhancing the capabilities

of the home appliances in terms of automation, safety and efficiency.

19. Name some sensors used in Aerospace.1. Static pressure Sensors

2. Temperature sensing

3. Fluid Velocity Sensors

4. Sensing direction of Air-flow

5. Measuring Air-speed and Aircrafts

20. State about Environmental Monitoring.

Entire living world is at risk on counts of health and normal survivalist due to hazards

arising out of biological, chemical, and radiation effects on the environment which not only work

locally but are also likely to affect around the globe through transportation. These hazards are

thus critical /serious environmental problems and to access the extent to which they can affect

human and other living entities, measurement of certain selective parameters are needed.

Environmental monitoring is not possible to be done in a simple way by measuring temperature

of a hot body-in fact; a few steps are involved of monitoring. As environment is affected by

pollution, the pollutants are identified. The quantity /concentration of pollutants in specific

collected sample need to be determined.

21. Name some sensors used in Environmental Monitoring.

1. Pollution Hazards

2. Sensing Environmental Pollution

3. Ecological Studies of Air.

22. Write about Medical Diagnostic Sensors.

With the advent of sensor technology involving different materials, processing, and size

and shape, clinical studies are gradually replaced by instrumental studies in medical sciences

with the sensors serving as the interface systems between the instrumental hardware and the

biological systems. This requires that the sensors used have very stringent specification.

23. List the configuration of a smart sensor.

Physical transducer

Network interface.


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A processor and a memory.

Part- C

1. Explain the role of Film, MEMS and Nano sensors and its recent technology.

2. Discuss the information coding / processing in smart sensor.

3. Explain the operation of data communication in smart sensors.UNIT 3

Part - B

1. What is signal conditioning?

The performing of non-linear processes like modulation, detection, sampling, filtering,

chopping and clipping etc. on the signal to bring it to desired form is called signal conditioning.

2. What is the necessity of Sample and Hold?

The purpose of this circuit is to hold the analog value steady for a short time while the

converter or other following system performs some operation that takes a little time.

In most circuits, a capacitoris used to store the analog voltage, and an electronic switch or gate is

used to alternately connect and disconnect the capacitor from the analog input. The rate at which

this switch is operated is the sampling rate of the system.

In a sample and hold circuit the switch opens for a very short duration, while in a track and hold

circuit the switch can be opened continuously.

3. How the aliasing process is eliminated.

i) Sampling rate fs _ 2W.

ii) Strictly band limit the signal to W.

This can be obtained by using the Low pass filer before the sampling process. It is also called as

anti aliasing filter.

4. List out some applications instrumentation amplifier.

1) data acquisition from low output transducers; 2) medical instrumentation; 3)current/voltage monitoring; 4) audio applications involving weak audio signals or noisy

environments; 5) high-speed signal conditioning for video data acquisition and imaging; and

6) high frequency signal amplification in cable RF systems.


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5. Define quantizing process.

The conversion of analog sample of the signal in to digital form is called quantizing

process. Graphically the quantizing process means that a straight line representing the relation

between the input and the output of a linear analog system.

6. What is aliasing? What is the effect of aliasing?

The phenomenon of a high-frequency in the spectrum of the original signal g(t)seemingly taking on the identity of a lower frequency in the spectrum of the sampled signal g(t)

is called aliasing or fold over.

The effect of aliasing as the output of the reconstruction filter depends on both the amplitude and

phase component of the original spectrum G (f), making an exact analysis

of the output difficult resulting in distortion.

7. What are the two fold effects of quantizing process?

1. The peak-to-peak range of input sample values subdivided into a finite set of decision

levels or decision thresholds.

2. The output is assigned a discrete value selected from a finite set of representation levels

are reconstruction values that are aligned with the treads of the staircase.

8. Define quantization error?

Quantization is the value of which equals the difference between the output and input

values of quantizer.

9. Define frequency deviation.

Frequency deviation is the change in frequency that occurs in the carrier when it is acted

on by a modulating signal frequency. The frequency deviation is typically given as the peak

frequency shift in Hertz.

10. Differentiate Digitizer and modulator.

Digitizer converts analog data to digital data. This process is called digitization.

Modulator converts analog / digital data to analog signal. This process is called modulation.

11. Define Quantization noise.

The difference between original signal and Quantized signal is called

Quantization noise/error.

e = m(t) mq(t)

12. Compare Quantization and Sampling operations.


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Quantization is a process by which an analog signal is divided into number of levels on

amplitude.

Sampling is a process by which an analog signal is divided into sequence of samples

(pulses) on regular interval of time.

13. What are the types of sampling?

i) Natural samplingii) Flat-top sampling

14. List the requirements of an instrumentation amplifier.

Low drift

High I/P impedance

High linearity

High CMRR

High noise rejection capability

15. Give few applications of instrumentation amplifier.The instrumentation amplifier finds increasing application in the amplification of the

output signals obtained from thermocouples, Strain Gauge Bridge and biological electrode.

16. What is a filter?

A filter is often a frequency selective circuit that passes a specified band of frequencies

and blocks or attenuated signal of frequencies outside this band.

17. List the different types of filters.

Analog or digital filters

Passive or active filters

Audio (AF) or radio (RF) filters.

18. What is acquisition time of S/H circuit?

Acquisition time is the time required for the capacitor to charge up to the value of the

input voltage after the switch is first started.

19. Define sensor.

A device which provides a usable output in response to a specified measurand.

A sensor acquires a physical parameter and converts it into a signal suitable for processing (e.g.

optical, electrical, mechanical).

20. How to choose sensors.


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21. Define Multiplexer or data selector.

The Multiplexer which sometimes are simply called "Mux" or "Muxes", are devices that

act like a very fast acting rotary switch. They connect multiple input lines 2, 4, 8, 16 etc one at a

time to a common output line and are used as one method of reducing the number of logic gates

required in a circuit. They are usually made from MOSFETs devices encased in a single package

and are controlled using standard logic gates.

22. Define De-Multiplexer or data distributers?

A multiplexer takes several inputs and transmits one of them to the output. A De-

Multiplexer performs the reverse operation; it takes a single input and distributes it over several

outputs. Ex: Cable T.V.

23. State Data conversion.Data conversion is the conversion of one form of data to another--the changing ofbits

from being in one format to a different one, usually for the purpose of application interoperability

or of capability of using new features.

24. What is Linearization?

Linearization refers to finding the linear approximation to a function at a given point. In

the study ofdynamical systems, linearization is a method for assessing the local stability of an

equilibrium point of a system ofnonlineardifferential equations.

25. What is an op-amp? What are the types available?

Operational amplifier is an IC amplifier contains transistors, capacitors, resistors and

diodes. It can be used for performing the mathematical operation like addition, subtraction,

multiplication, division, integration and differentiation.

Types: 1.Inverting Op-amp

2. Non- Inverting Op-amp

26. State the characteristics of an ideal op-amp?

1. Input impedance is infinite

2. Output impedance is zero

3. Open loop voltage gain is infinite

4. Band width is infinite

27. What is a voltage follower circuit?

It is defined as an op-amp circuit in which the output of the op-amp exactly tracks the

input voltage in sign and magnitude.

28. Define (i) CMRR (ii) SVRR (iii) Slew rate.Department of Mechatronics, Kumaraguru college of Technology, Coimbatore-641

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(i) CMRR is defined as the ratio of differential voltage gain to the common mode voltage gain.

(ii) SVRR is defined as ratio of change in input offset voltage to change in supply voltage.

(iii)Slew rate is defined as the maximum rate of change of output voltage per unit time and is

expressed in volts per microseconds.

29. What do you mean by a charge amplifier and instrumentation amplifier?Charge amplifier is a special kind of amplifier in which the output charge of piezo-

electric transducer is converted into voltage.

Instrumentation amplifier is a dedicated differential amplifier with extremely high input

impedance and high CMRR and a single internal or external resistor can preciously set gain of

amplifier.

30. What is a filter? Mention their types.

A filter is an electronic circuit that passes the signals of wanted frequencies and rejects

the signals of unwanted frequencies

Types: 1.Low pass filter

2. High pass filter

3. Band pass filter

4. Band reject filter

31. What is low pass filter?

It passes the signals of low frequencies below the cutoff frequency and attenuates the

signals of high frequencies above the cutoff frequency.

32. What is high pass filter?

It passes the signals of high frequencies above the cutoff frequency and attenuates thesignals of low frequencies below the cutoff frequency.

33. What is band pass filter?

It passes the signals between the two cutoff frequencies and attenuates all other the

signals of frequency.

34. What is band reject filter?

It attenuates the signals between the two cutoff frequencies and passes all other

the signals of frequency.

35. Classify the filter circuits.

1. Passive filter

2. Active filter.

36. What is an active filter?

Active filters use active elements like op-amp in addition with passive elements like

resistors, capacitors and inductors.

37. What is quantization?

Quantization is the process of rounding of the sampled value to its nearest integer values.


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38. What is the function of MUX and DEMUX?

The function of a MUX is to select one of several input signal and transmit to that to

single output.

The function of DEMUX is to transmit a single input to several outputs.

39. What are the techniques available for DAC?

1. Binary weighted resistor DAC

2. R-2R ladder network DAC

3. Inverted R-2R ladder network DAC.

40. What are techniques available for ADC?

1. Successive approximation type

2. Flash type

3. Counter type

4. Potentiometric type

5. Single slope and dual slope type.

41. Define Settling time.

It is the time that a DAC takes to settle for a full scale code change, usually to within

LSB.

42. Draw the circuit for Inverting and Non-inverting of an amplifier.

Part- C

1. Explain the operation of Multiplexer/De-multiplexer.

2. Explain the various operations carried out in signal conditioning process.


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3. Write a short note on (i) Amplification

(ii) Filtering

(iii) Linearization

(iv) Quantization

(v) Buffering4. Explain the operation of Sample and hold circuit with suitable graph.

5. Explain any three types of A/D converter.

6. Explain any two types of D/A converter.

UNIT 4

PART - B

1. What is the purpose of DAC?

The purpose of data acquisition is to measure an electrical or physical phenomenon such

as voltage, current, temperature, pressure, or sound. PC-based data acquisition uses a

combination of modular hardware, application software, and a computer to take measurements

2. What is a data acquisition? Give the functional blocks of a data acquisition system.

The process of collecting data from individual sensors installed at various location of a

system in analog form, converting them into digital form and storing or displaying the digital

data. The various blocks are

1. Sensors

2. Signal conditioners

3. Analog multiplexers

4. ADC

5. Printers or digital display


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3. What are the various general configurations of a data acquisition system?

1. Single channel data acquisition system

2. Multi channel data acquisition system

3. Modular data acquisition system

4. What are the methods of signals conditional?

1. Ratiometric conversion2. Logarithmic compression

5. What is a logger?

Data loggers are used to record data and store them in memory. Process of storing the

data is called logging the data. Hence, in addition to elements of data acquisition system, data

logger consists of microprocessor, memory, connectivity for printer and computer.

6. What are the parameters stored by the data loggers?

1. Type of the channel

2. Channel number3. Absolute value of reading

4. Real time of reading

7. What is the need for a programmable gain amplifier?

In multi-channel data acquisition system, the signal inputs to various channels may not be

at same level. If all the signals are at the same level, the gain required of the amplifier can be a

fixed value. But if the level of the signals differ by an order of magnitude, it is essential to have a

programmable gain amplifier whose gain can be varied at will from channel to channel.

8. Define acquisition time and conversion time.

Acquisition time is the time taken by a sample and holds circuit to acquire the input theinput signal with in a stated accuracy.

Conversion time refers to the time required for a complete measurement by an analog to

digital converter.

9. What are the types of digital data transmission?

1. Serial data transmission

2. Parallel data transmission

In Serial data transmission the digital data is serially transmitted form transmitter to

receiver in bit-by-bit manner.

In parallel data transmission the digital data is transmitted form transmitter side to

receiver in parallel manner as 8 bit, 16 bit according to the size of the processor involved in theoperation.

10. What are the elements of digital data transmission?

1. Information source

2. Source encoder

3. Line- driver

4. Line- receiver

5. Sink decoder

6. Information sink

11. What are the types of digital pulse code format?


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1. Full binary transmission

2. Half binary transmission

3. Multiple binary transmissions

12. What is full binary transmission?

In this, the opposite polarity pulses are used to transmit 1 and 0 bits. It is the most

reliable pulse code format that is employed for low speed data transmission typically up to 600bps.

13. What is half binary transmission?

In this, a pulse or a polarity change represents the binary 1 and the 0 is represented by

a space. This code is very popular in pulse code modulation signals at very high speed.

14. What is multilevel transmission?

This is a four level code in which each level represents two binary bits, (i.e.00, 01, 10,

11). The two bit pair, referred to as a digit is transmitted in a one-bit period resulting in a higher

transmission rate.

15. What are the modulation techniques used for digital data transmission?

1. Amplitude modulation

2. Frequency modulation

3. Phase modulation

16. What is meant modulation?

Modulation is the process of changing one of the parameter of carrier signal in

accordance with modulating signal to be transmitted.

17. What is meant amplitude modulation?

Amplitude modulation is the process of changing the amplitude of the carrier signal in

accordance with modulating signal to be transmitted.

18. What are the types of digital modulation techniques?

1. Amplitude shift keying (ASK)

2. Frequency shift keying (FSK)

3. Phase shift keying (PSK)

19. What is a MODEM?A Modem stands for modulator and demodulator circuits. In the transmitter side, it acts as

modulator i.e. it converts digital bits into analog signals and in the receiver side, it acts as

demodulator i.e. it converts analog signals into digital bits.

20. What is a digital filter?

The term digital filter is used to represent a digital processor which receives a sequence of

input data values, carries out some digital operation on them, and outputs a corresponding

sequence of digital values which are filtered in a prescribed manner with respect to the input.

21. What are the transforms used in filter theory?

1. Analog filter theory-Laplace transform


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2. Digital filter theory z transform

22. What are the elements of pc based data acquisition system?

1. Transducers

2. Signal conditioner

3. Pc with data acquisition hardware, data analysis hardware and software.

23. What is multiplexing? What are the types available?

Multiplexing is the process of sharing a single channel with more than one output. Thus a

multiplexer accepts multiple analog inputs and connects them sequentially to one measuring

output. The types are

1. Frequency division multiplexing

2. Time division multiplexing.

24. What do you mean by TDM and FDM?

In TDM, the information from different channels is transmitted serially one after another

on the same communication channel i.e. the time is shared between channels.In FDM, the information from different channels are simultaneously transmitted at a same

time using different carrier frequencies and different modulating methods i.e. the frequency

bands are shared between channel.

25. What are the types of data transmission systems?

1. Analog data transmission

2. Digital data transmission

Part- C

1. Draw the block diagram of multichannel data acquisition system and explain the function

of each block.

2. Briefly explain (i) Digital filtering (ii) Data Logging.

3. Discuss the introduction to data transmission system with suitable diagram.


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UNIT 5

PART B

1. What is the operation of a serial printer?

The serial printer produces a single character at a time, usually moving from left to right

across a page. It prints 200 characters per second.

2. Mention the purpose of line printers.

The line printers are used to print and entire line simultaneously. It points 4000 lines perminute.

3. Give the operation of pare printers.

The page printer prints in a line at a time mode, but can be stopped and restarted only on

the page basis. The top speed is 45,000 lines per minute.

4. List the classification of printers.

Impact and non-impact printers.

Fully formed character and dot matrix character printer.

Character at a time and a line at a time.

5. What is daisy wheel printer?

Daisy wheel printer is a fully formed character printer, designed for computer usage and

has characters mounted on the periphery of a spinning print head similar to a daisy flow. They

are capable of bi-directional printing.

6. Give short notes on dot-matrix printers.

In dot-matrix printers, the characters are formed by printing a group of dots to form a

letter, no. or other symbols. It can print any combination of dots with all available print position

in the matrix.

7. List the important features of CRTs.


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Size

Phosphor

Operating voltages

Deflection voltages

Viewing screen.

8. What is meant by deflection sensitivity in CRT?

The deflection sensitivity of the CRT is usually stated as the DC voltage required for each

cm of deflection of the spot on the screen.

9. What is meant by recurrent sweep in CRT?

When the saw tooth, being an AC voltage alternates rapidly, the display occurs

respectively, so that a lasting image is seen by the eye. This repeated operation is known as

recurrent sweep.

10. Mention the methods that are used for generating the 2 electron beams within the CRT.

The methods that are used for generating the 2 electron beams within the CRT are thedouble gun tube and split beam method.

11. Explain CRO and its function.

Cathode Ray Oscilloscope (CRO) is a very careful and versatile laboratory instrument

used for display measurement and analysis of waveforms and other phenomena in electrical and

electronic circuits. CRO is in fact a very fast X-Y plotter displaying an input signal versus

another signal or time.

12. Name the components of a CRO.

CRO consists of a cathode ray tube (CRT) along with electron gun assembly, deflectionplate assembly, fluorescent screen, glass envelope and base.

13. What is an electron gun?

The source of focused and accelerated electron beam is the electron gun.

The electron gun which emits electrons and forms them into a beam consists of a heater, a

cathode, a grid a pre-accelerating anode, a focusing anode and an accelerating anode.

14. Name the basic circuitry of CRO.

Vertical (Y) deflection system

Horizontal (X) deflection system

Synchronization

Blanking circuit

Intensity (z-axis) modulation

Positioning controls

Focus control

Intensity control

Calibration control

Astigmatism.

15. What is LED?


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The LED is basically a semiconductor PN junction diode capable of emitting

electromagnetic radiation under forward conductions.

16. Compare common anode and common cathode displays.

Common anode type display require an active low (or current linking) configuration for

code converter circuitry, whereas an active high output circuit is necessary for common cathode

LED type display.

17. List the characteristics of LCD.

Light scattering

Can operate in reflective or Transmissive configuration.

Do not actively generate light and depend for their operation on ambient or back light.

18. On what does the operation of LCD depend?

The utilization of a class of organic materials which remain a regular crystal like structure

even when they have melted.

19. Name the 2 commonly available types of LCDs.

Dynamic scattering

Field effect type.

20. What is the purpose of dot matrix displays?

Excellent alphanumeric characters can be displayed by using dot matrix LEDs with an

LED at each dot location.

21. What are the commonly used dot matrices for the display of characters?

The commonly used dot matrices for the display of prominent characters are 5 x 7, 5 x 8and 7 x 9.

22. What are the 2 writing patterns of dot matrix displays?

Common anode or common cathode connection (uneconomical) X-Y array connection

(economical and can be extended vertically or horizontally using a minimum number of wires)

Part- C

1. Briefly explain (i) X-Y Recorders (ii) Magnetic tape recorder.

2. Describe in detail the working principle of CRO with a neat sketch.3. Explain the segmental displays with a neat sketch.


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