GUJARAT TECHNOLOGICAL UNIVERSITY BE SEM-VII Examination ... · load current. Determine mean load voltage at firing angle 0 0 ,45 0 90 0 Neglect all devices drops .If commutating diode

1

Seat No.: _________ Enrolment No._______________

GUJARAT TECHNOLOGICAL UNIVERSITY BE SEM-VII Examination-Nov/Dec.-2011

Subject code: 171002 Date: 22/11/2011

Subject Name: Power Electronics

Time: 10.30 am-01.00 pm Total marks: 70

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.

Q.1 (a) Give classification of thyristor family. Draw and explain SCR in

detail. Also draw and explain SCR V-I characteristics with required

terms.

07

(b) What is GTO ? Draw and Explain GTO structures . Also explain

GTO Turn off mechanism with desired equation and figures.

07

Q.2 (a) List all SCR triggering circuits and explain any two of them in detail

using circuit diagram, Waveforms and equations.

07

(b) Draw and explain construction of power BJT. Also explain I-V

characteristics of power BJT. How power BJT are differed then

normal BJT.

07

OR

(b) Draw and explain the structure of power MOSFET. Also explain

principle of operation and I-V characteristics of power MOSFET

07

Q.3 (a) Draw and Explain Full wave controlled rectifier with the inductive

load using required waveforms and equations. Also explain use and

function of free wheeling diode with the inductive load.

07

(b) An SCR with latching current of 100 mA is connected with series

resistance of 10 ῼ and inductance of 1H. DC source voltage is 207 V.

calculate minimum gate pulse width to turn ON SCR.

07

OR

Q.3 (a) Draw and explain Three Phase Half wave controlled rectifier with

required waveforms and equations

07

(b) A 3 Phase bridge circuit is supplied by 200 V .Assume continuous

load current. Determine mean load voltage at firing angle 00 ,450 ,900

Neglect all devices drops .If commutating diode is placed across the

load then what will be the mean load voltage at ∞ = 1200 .

07

Q.4 (a) Classify the chopper. List all types of Chopper and explain any two

of them.

07

(b) In a step UP chopper applied voltage is 200V and O/P voltage is

600V . If conducting time of thyristor is 200µSec Compute

(a) Chopper frequency

(b) Find O/P voltage for when pulse width is half for constant

frequency of operation.

07

OR

2

Q.4 (a) Draw and explain Full bridge invertors. Also give comparison of

Half bridge and Full bridge Inverter

07

(b) A 3 Phase bridge inverter operating in a 1800 mode with a wye

connected resistive load . If supply voltage is 230 V Find the rms

phase voltage.

07

Q.5 (a) What is UPS / Why we need that ? Draw and explain Online UPS

system with their operation and features

07

(b) List types of Heating mechanism available and explain any one of

them in detail.

07

OR

Q.5 (a) What is SMPS ? Give classification of SMPS. Also explain any one

of the SMPS.

07

(b) Draw the circuit diagram of a Battery charging Regulator and Explain

them in detail.

07

*************

1

Seat No.: ________ Enrolment No.______________

GUJARAT TECHNOLOGICAL UNIVERSITY BE- VII

th SEMESTER–EXAMINATION – MAY/JUNE- 2012



Time: 02:30 pm – 05:00 pm Total Marks: 70

Instructions:




Q.1 (a) Explain the principle of operation of SCR with

(i) Device structure (ii) Characteristics and (iii) two transistor analogy.

07

(b) Describe the construction and working of IGBT. Also enumerate the advantages of

IGBT over BJT and MOSFET.

07

Q.2 (a) What are the various thyristor ratings? 07

(b) Describe any two forced commutation methods. 07

OR

(b) What are the needs of series and parallel operations of thyristors? Explain the

problems with series and parallel operations of thyristors and possible solutions.

07

Q.3 (a) Explain Single phase Full (Bridge) controlled rectifier with resistive load in detail. 07

(b) Explain the principle of operation of pulse width modulated inverters with

performance parameters.

07

OR

Q.3 (a) Explain three-phase half-wave controlled rectifier with resistive load. 07

(b) Describe the operation of three-phase inverter with 180-Degree conduction. 07

Q.4 (a) What is the principle of operation of step-down converter? Show complete analysis

of step-down converter with RL load with all necessary diagrams.

07

(b) Describe Uninterruptible power supply with necessary diagrams in detail. 07 OR

Q.4 (a) Show chopper classification and explain any four types of chopper with necessary

diagrams in detail.

07

(b) Describe Switched mode power supply with necessary diagrams in detail. 07

Q.5 (a) If the half-wave controlled rectifier has a purely resistive load of R and the delay

angle is π/3, determine (i) rectification efficiency (ii) Form factor (iii) Ripple factor

(iv) Transformer utilization factor and (v) Peak inverse voltage of SCR.

07

(b) The single-phase half-bridge inverter has a resistive load of 2.4 Ω and the dc input

voltage is 48V. Determine (i) the rms output voltage at the fundamental frequency,

(ii) the output power, (iii) the average and peak currents of each transistor, (iv) the

peak reverse blocking voltage of each transistor, (v) the THD, (vi) the DF, (vii) the

HF and DF of the LOH.

07

OR

Q.5 (a) A boost regulator has an input voltage of 5 V. The average output voltage is 15V

and the average load current is 0.5 A. The switching frequency is 25 kHz. If L = 150

µH and C = 220 µF, determine (i) the duty cycle, (ii) the ripple current of inductor,

(iii) the peak current of inductor, (iv) the ripple voltage of filter capacitor, and (v)

the critical values of L and C.

07

(b) Explain Battery charger with necessary diagrams. 07 *************

1


GUJARAT TECHNOLOGICAL UNIVERSITY B. E. - SEMESTER – VII • EXAMINATION – WINTER 2012

Subject code: 171002 Date: 31/12/2012 Subject Name: Power Electronics Time: 10.30 am - 01.00 pm Total Marks: 70 Instructions:

1. Attempt any five questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks.

Q.1 (a) Define the following terms with respect to SCR

1 Latching current 2. The holding current 3.On state Voltage 4.Forward dv/dt rating 5.Minimum gate current Igmin

05

(b) List the ideal characteristics of a power switching device. 03 (c) Explain the function of the following:

(i) free wheeling diode (ii) UPS and (iii) heat sink 06

Q.2 (a) Explain the operation of the SCR using the Two transistor analogy. Obtain the

condition for the breakdown of the device. 05

(b) Discuss the various turn on methods of a thyristor. 05 (OR) (b) Explain the Triggering modes of TRIAC with the aid of the structure

diagram and characteristics. 05

(c) Explain the control characteristics of GTO and IGBT 04

Q.3 (a) Explain the series operation of ‘n’ thyristors in the string with appropriate derivation for string voltage. Define String efficiency and derating factor.

06

(b) Draw the structure and explain the principles of operation of the following power devices: (i)SCR (ii) Power MOSFET

08

OR Q.3 (a) What do you understand by phase control of SCR?. 03

(b) Derive the expressions for the average load voltage, average load current, RMS load voltage of a single phase half-wave controlled rectifier with resistive load .Show the necessary waveforms.

05

(c) Explain the classification of DC converters with the help of circuit diagram and the quadrant of operation.

06

Q.4 (a) Explain the working of the following converters with the help of circuit

diagrams and waveforms : (i) Single Phase Full converter (ii) Three Phase Half Wave converter.

08

(b) A chopper circuit is operating on Time Ratio Control(TRC) principle at a frequency of 1KHz.on a 220V dc supply. If the load voltage is 180 V, calculate the conducting and the blocking period of the power device in each cycle .

03

( c) State the advantages & disadvantages of buck-boost converter 03 OR

2

Q.4 (a) Explain the principle of operation of step down Chopper with resistive load. Differentiate between constant frequency and variable frequency operation of this chopper.

04

(b) Explain the principle of operation of step up Chopper , Discuss the modes of operation with equivalent circuits and mathematical relations..Sketch the current and voltage waveforms. Obtain the condition for controllable power transfer.

07

( c) List the applications of dc to dc converter. 03 Q.5 (a) Explain the principle of operation of the buck converter discussing the modes

.Sketch the equivalent circuits and the waveforms for the voltage and the current for a continuous flow. Obtain Expressions for (i) peak to peak ripple current ii) peak to peak ripple voltage. Show that peak to peak ripple voltage is inversely proportional to square of the switching frequency.

08

(b) Explain dv/dt and di/dt protection for thyristor. 06 OR

Q.5 (a) How do you classify the inverters? 03 (b) Explain the principle of working of a single phase half bridge inverter

with the help of the circuit and waveforms for both resistive and inductive loads. Calculate rms output voltage at the fundamental frequency and the output power for a dc input voltage of 48 V and resistive load of 2.4 Ω.

07

( c) Distinguish between natural and forced commutation of SCR. Explain any one commutation method for DC circuits .

04

*************

1

Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–VII • EXAMINATION – SUMMER 2013

Subject Code: 171002 Date: 24-05-2013


Time: 02.30 pm - 05.00 pm Total Marks: 70 Instructions:




Q.1 (a) Define following terms.

(i) Holding current (ii) Latching current (iii) Reverse recovery charge (iv)

Turn off time.

08

(b) Draw the symbols, V-I characteristics and give one application of

following devices:

i) IGBT ii) GTO iii) TRIAC

06

Q.2 (a) Explain operation of series-connected thyristors in detail 07

(b) Nine thyristors are used in a string to withstand a DC voltage of Vs= 15

KV. The maximum leakage current and recovery charge differences of

thyristors are 10 milli-ampere and 150 micro-C respectively. Each

thyristor has a voltage sharing resistor of R= 56 kilo-ohm and

capacitance of C1=0.5 micro-F. Determine (i) The maximum steady

state voltage sharing (ii) The steady state voltage-derating factor (iii)

maximum transient voltage sharing and (iv) The transient voltage -

derating factor.

07

OR

(b) Discuss following in detail:

(1) Parrallel operation of thyristor

(2) di/dt protection circuits of thyristor.

04

03

Q.3 (a) Draw the circuit arrangements for the Single Phase full converter with

Resistive load. Derive expression for the average output voltage and

RMS output voltage. Sketch the voltage and current waveforms.

07

(b) For a single phase half converter with purely resistive load and delay

angle π/3, determine (i) the rectification efficiency, (ii) the form factor

(FF), (iii) the ripple factor (RF), (iv) the TUF, and (v) the PIV of

thyristor.

07

OR

Q.3 (a) Draw the circuit arrangements for the Three Phase half-wave converter.

Derive expression for the average output voltage and RMS output

voltage. Sketch the voltage and current waveforms.

07

(b) Describe various ways to turn on thyristor. 07

Q.4 (a) List and explain performance parameters of an inverter. 07

(b) Explain Buck regulator with circuit diagram and waveforms. 07 OR

Q.4 (a) Describe the working of a single phase full bridge inverter with

diagram and waveforms.

07

2

Q.4 (b) Explain principal of step-up chopper with circuit diagram, current and

output voltage wave-forms.

07

Q.5 (a) Discuss second quadrant (Type –B) chopper with circuit diagram and

waveform.

07

(b) List all categories of Switched mode Power Supply and discuss any one

in detail.

07

OR

Q.5 (a) Explain three-phase bridge Inverter for 1200

conduction with waveform. 07

(b) Draw and explain Uninterruptable Power supply and explain battery

charging mechanism in it.

07

*************

1

Seat No.: _____ Enrolment No.______

GUJARAT TECHNOLOGICAL UNIVERSITY

BE-Semester VII Examination Nov/Dec-2011


Subject Name: Microwave Engineering


Instructions: 1. Attempt all questions.



Q.1 (a) (i) “Vessels in microwave oven should be of dielectric

material.” Justify with proof.

(ii) Explain impossibility of TEM wave propagation

through the waveguide.

07

(b) (i) What is magic associate with magic tee junction?

(ii) What do you mean by apple gate diagram? Explain

bunching in two cavity klystron.

07

Q.2 (a) Explain in brief standing wave and reflection coefficient of

transmission line and derive the expression for the

impedance and reflection coefficient at any point on the

line.

07

(b) A rectangular waveguide has dimension of 2.29 cm and

1.02 cm. It is desired that this waveguide is to be operated

only in dominant mode and operating frequency is at least

25% above cut off frequency of dominant mode and not

higher than 95% of the next cut off frequency. What is

allowable operating frequency?

07

OR

(b) What do you mean by reciprocal network? Draw and

explain series tee junction and find its simplified

S-matrix using S-parameter.

07

Q.3 (a) What is micro strip line? Derive expression of

characteristics impedance of micro strip line using

comparative or alternative method.

07

(b) Draw schematic of four port circulator and explain its

working, also show and explain how one can construct a

four port circulator using two magic tees and a phase

shifter.

07

OR

Q.3 (a) A 5.2 cm length of lossless 200 Ω line is terminated in a

load impedance of 60 + j100 Ω. Using smith chart

(i) Determine ׀τL ׀ , φL and SWR along the line.

(ii) Determine the Z and Y at the input and at a point 2.0

cm from the load end. The signal frequency is 750 MHz

and λ = λ0.

07

2

(b)

Give difference between two cavity klystron and reflex

klystron. Also draw the schematic of reflex klystron and

explain its working.

07

Q.4

(a)

Draw different slow wave structures and write why slow

wave structures are used in traveling wave tubes? Also

explain working of TWT with neat sketch.

07

(b) Give at least three differences between microwave

transistor and TEDs (i.e. transfer electron devices). Write

the statement of Gunn effect and explain GaAs diode.

07

OR

Q.4 (a) What do you mean by favorable electrons? Draw cross-

sectional view of cavity magnetron and discus field inside

the interaction gap.

07

(b) (i) Explain figure of merit of various surface geometries of

microwave bipolar transistor.

(ii) Describe the applications of the parametric amplifier.

07

Q.5 (a) Derive expression for range of the radar. Practically how

one can increase the range of radar?

07

(b) (i) Explain microwave characteristic of Tunnel diode.

(ii) Discuss quality factor for a varactor diode.

07

OR

Q.5 (a) What is Doppler effect? With block diagram explain

Doppler radar.

07

(b) An X-band pulsed cylindrical magnetron has the following

operating parameters:

Anode voltage V0 = 26KV, beam current I0 = 27A,

magnetic flux density = 0.336 tesla, radius of cathode

cylinder a = 5 cm, radius of vane edge to center b = 10 cm.

Find (i) The cyclotron angular frequency, (ii) The cut off

voltage for fixed B0, (iii) The cut off magnetic flux density

for fixed V0.

07

*************

1





Subject Name: Microwave Engineering


Instructions:




Q.1 (a) What are microwaves? Explain advantages of microwave and its applications. 07

(b) Derive necessary equations for attenuation constant and phase constant with

reference to EM wave propagating along transmission line. 07

Q.2 (a) Sketch circular and rectangular waveguide and compare their dominant mode

,advantages and disadvantages. 07

(b) The dimension of a waveguide is 2.5X1cms.The frequency is 8.6GHz Find the

possible modes that can propagate through the waveguide also find the cutoff

frequencies for the same.

07

OR

(b) A rectangular waveguide is filled by dielectric material of εr =9, with inside

dimension of 7X3.5cm. It operates in the dominant TE10 mode. Determine (i) cut

off frequency (ii) phase velocity at a frequency of 2 GHz (iii) guided wavelength

at the same frequency.

07

Q.3 (a) Draw and explain waveguide band, corners and twist in detail with their

applications. 07

(b) What is the purpose of directional Coupler. Define coupling factor, directivity,

isolation of Directional coupler and write expression for each. 07

OR

Q.3 (a) A typical transmission line has a resistance of 6Ω /km, inductance of 2.2mH/km,

a capacitance of 0.005 µF/km and a conductance of 0.05µmho/km. Calculate the

characteristic impedance, attenuation constant and phase constant of the

transmission line at a frequency of 1kHz.Alo calculate the phase velocity of the

signal

07

(b) Explain the operation of Magic TEE with its s-parameter. Also list some

applications of magic TEE 07

Q.4 (a) Explain the mechanism of oscillations of Magnetron Oscillator with the aid of

suitable diagram and discuss its performance characteristics. 07

(b) Explain the amplification process for a helix type travelling wave tube. What are

its different applications? 07

OR

Q.4 (a) Describe the construction and working of a reflex klystron. Explain how velocity

and current modulation takes place using the Applegate diagram. 07

(b) Explain the Tunnel diode characteristics with the aid of Energy band diagram. 07

Q.5 (a) Derive the radar range equation. Calculate the maximum range of a radar system

which operates with a wavelength at 3 cm with a peak pulse power of 600KW if

effective aperture of antenna Ae is 5 m2, minimum detectable signal is 10

-13 W

and the radar cross sectional area of the target is 20 m2.

07

(b) Explain Gunn effect using two valley theory. 07

OR

Q.5 (a) What is a pulsed radar? Explain the pulsed radar with its block diagram. 07

(b) Explain IMPATT Diode with its construction, working and application. 07 *************

1

Seat No.: ________ Enrolment No.______________ GUJARAT TECHNOLOGICAL UNIVERSITY

B. E. - SEMESTER – VII • EXAMINATION – WINTER 2012 Subject code: 171001 Date: 26/12/2012 Subject Name: Microwave Engineering Time: 10.30 am - 01.00 pm Total Marks: 70 Instructions:


Q.1 (a) A1). Define following terms: 1. Standing wave ratio and 2. Return loss.

A2). A lossless transmission line with characteristic impedance of 300 ohm is fed by a generator with impedance 100 ohm. The line is 100 m long and is terminated by a resistive load of 200 ohm. Calculate the load reflection coefficient, VSWR, the transmission loss and the return loss.

02 05

(b) Draw equivalent circuit of transmission line and derive basic equations for voltage and current on transmission line. Define characteristic impedance of transmission line.

07

Q.2 (a) What is the importance impedance matching? Give your answer w.r.t. transmission line. Derive expression of the length of short-circuit stub for impedance matching on transmission line.

07

(b) A 100 ohm line with air as dielectric is terminated by a load impedance of 75 + j40 ohm and is excited at 1 GHz by a matched generator. Find the position of a single stub of 100 ohm impedance on the line, and determine the length of the stub. Solve using Smith chart. OR

07

(b) A lossless 50 ohm air line has Vmax = 2.5 V and Vmin = 1 V when terminated with an unknown load. The distance between the successive voltage minima is 5 cm and the first voltage minimum from the load end is 1.25 cm. Design a short circuited single stub for impedance matching. Solve using Smith chart.

07

Q.3 (a) Why does the TEM mode can not propagate through hollow rectangular waveguide? Derive wave equation/s for rectangular waveguide.

07

(b) Explain with diagram the pattern of field lines observed in strip lines and microstrip lies. 07 OR

Q.3 (a) Define following terms with respect to waveguide: 1. Phase velocity and 2. Group velocity. Derive expression for both of them.

07

(b) Enumerate merits and demerits of microstrip line compared to other types transmission media at microwave frequencies. Explain briefly parallel strip lines.

07

Q.4 (a) Draw diagram of E-plane Tee junction and derive s-parameter matrix for the same. 07 (b) Draw cavity magnetron and explain its working with clear diagrams for π-mode and phase

focusing effect. 07

OR Q.4 (a) Derive s-parameter matrix for the E-H-plane Tee under the condition that all four ports are

matched. Draw necessary diagrams. 07

(b) Using applegate diagram explain working of reflex klystron. Differentiate between klystron and travelling wave tube.

07

Q.5 (a) Explain Doppler effect and continuous wave Doppler radar along with necessary diagrams. 07 (b) What do you understand by avalanche transit time effect? Explain working, construction,

and applications of TRAPATT device. 07

OR Q.5 (a) What are the factors which limits the sensitivity of a radar receiver? Derive the range

equation considering the noise figure of the radar receiver. 07

(b) Explain working of tunnel diode and give its applications. 07 *************

1


GUJARAT TECHNOLOGICAL UNIVERSITY BE SEM-VII Examination-Nov/Dec.-2011


Subject Name: Digital Signal Processing

Time: 10.30 am-01.00 pm Total marks: 70 Instructions:




Q.1 (a) Check the following systems for time invariance and

linearity

i) y(n) = n[x(n)]2 ii) y(n) = x(n)cos(nπ/4)

06

(b) Find convolution of two sequences

i) x(n) = (-1)n u(n) and h(n) = u(n)

ii) x(n) = [1,2,4] and h(n) = [1,1,1,1]

08

Q.2 (a) Explain impulse response and step response of a system.

Find the step response of a system whose impulse response

is h[n] = a—n

u( --n) for 0 < a < 1

07

(b) Define Stability of Discrete Time System. Derive the

necessary and sufficient condition to test the stability.

Test the stability of a system whose Impulse response is

h[n] = an u[n].

07

OR

(b) Define DTFT. Using DTFT, find impulse response of a LTI

system described by difference equation

y(n) – ½ y(n – 1) = x(n) – ¼ x(n – 1)

07

Q.3 (a) State and prove the differentiation property of Z transform.

Using this property , determine Z transform and ROC of

signal x(n) = nanu(n)

06

(b) Calculate DTFT of following signals

i) x(n) = [ ¼ ¼ ¼ ¼ ]

ii) x(n) = 2( ¾ )n u(n)

08

OR

Q.3 (a) State and prove time shifting property of Z transform.

Using this property ,determine Z transform and ROC of

signal x(n) = (4)n+2

u(n-1)

07

(b) Find inverse Z transform of

z(z2 – 4z + 5)

X(z) = -------------------

(z-1)(z-2)(z-3)

07

For ROC i) 2 < |z| < 3 ii) |z| <1

2

Q.4 (a) Discuss the relationship of DFT with Z transform and DFS

Calculate 4 point DFT of sequence

x(n) = sin(nπ/2) for n=0,1,2,3

07

(b) i) Find inverse DFT of X(k) = [1 2 3 4 ] 07 OR

Q.4 (a) Obtain Direct Form I & II realization of a system described

by

y(n) – 1/6 y(n – 1) + 1/3 y(n-2) = x(n) + 2x(n-2)

07

Q.4 (b) What is circular convolution? How is it different from

linear convolution? Determine the circular convolution of

two sequences

x(n) = cos(πn/2) for n=0,1,2,3

h(n) = 2n for n= 0,1,2

07

Q.5 (a) Develop radix 2 FFT algorithm using decimation in time

approach. Compute 4 point DFT of sequence

x(n) = [1 1 1 1] using DIT FFT algorithm .

07

(b) List the various methods of designing IIR filter. Explain the

bilinear transformation method of designing of IIR filter.

How does this method overcome the limitation of other

methods?

07

OR

Q.5 (a) Write short note on

i) Windowing

ii) Concept of Sampling and aliasing in sampled

system

08

(b) With help of block diagram explain architecture of

TMS320C6XXX processor

06

*************

1







Instructions:




Q.1 (a) For each of the following systems, determine whether the

system is (1) Stable (2) Causal (3) Linear (4) Time

invariant

(i) y[n] = x[n]+ 3u[n+1]

(ii) y[n] = x[Mn] M is an integer, greater than 1.

07

(b) List the properties of the region of convergence for the Z

transform.

07

Q.2 (a) Compute the linear convolution of the following sequences

graphically:

[ ] 1, 2,1, 1h n↑

= − , [ ] 1, 2,3,1x n↑

=

07

(b) Determine the inverse Z-transform.

1

1 2

11

2( ) , 1/ 23 1

14 8

z

X z z

z z

−

− −

−= >

+ +

07

OR

(b) The system function of a causal linear time invariant

system is

1

1

1( )

31

4

zH z

z

−

−

−=

+

The input to this system is

1[ ] [ ] [ 1]

3

n

x n u n u n

= + − − .

(a) Find the impulse response of the system, h[n].

(b) Find the output y[n].

(c) Is the system stable?

07

Q.3 (a) Draw a signal flow graph implementing the system

function 1 2

1 2

1 2( )

1 0.75 0.125

z zH z

z z

− −

− −

+ +=

− + as a

(i) parallel form structure using a second order system

(ii) cascade form structures.

07

2

(b) Determine the z transform, including the ROC of the

sequence

1 1[ ] [ ] [ 1]

3 2

n n

x n u n u n

= − − − −

07

OR

Q.3 (a) Draw a cascade form structure for the system function

1 2 35( ) 1 2 2

2H z z z z

− − −= + + +

07

(b) Discuss frequency domain representation of sampling. 07

Q.4 (a) Compare FIR and IIR filters. 07

(b) For the given two 4 point sequence x[n] and h[n] where

[ ] cos2

nx n

π =

n=0,1,2,3

h[n]= 2n n=0,1,2,3

(i) Calculate 4-point DFT of x[n].

(ii) Calculate 4-point DFT of h[n].

07

OR

Q.4 (a) The desired response of a low pass filter is

( ) 3jw jw

d cH e e for w w−= <

=0 otherwise

Determine H(ejw

) for M= 7 using Hamming window.

Wc = 1 rad/sec.

07

(b) Sketch the six point circular convolution of following

sequences.

1[ ] 1, 2,3,4,5,6x n↑

= 1[ ] 0,0,1x n↑

=

07

Q.5 (a) Discuss decimation in time FFT algorithm for radix-2. 07

(b) Explain IIR filter design by Bilinear Transformation

method.

07

OR

Q.5 (a) Discuss decimation in frequency FFT algorithm for radix-

2.

07

(b) List the properties of DFT. Prove any two properties. 07

*************

1



Subject code: 171003 Date: 01/01/2013 Subject Name: Digital Signal Processing Time: 10.30 am - 01.00 pm Total Marks: 70 Instructions:


Q.1 (a) Define the following with respect to discrete time systems:

(i) Linear Shift Variant System (ii) Recursive system (iii)Stable System(iv) Causal system

04

(b) Find the Z Transform of :

(i) )1(21)(

41)( −⎟

⎠⎞

⎜⎝⎛−⎟

⎠⎞

⎜⎝⎛= nununx

nn

(ii) )1(31)(

1

−⎟⎠⎞

⎜⎝⎛=

−

nunxn

(iii) ( ) )(cos)( 0 nunrnx n ω=

06

© Check for the shift invariance and stability of an accumulator 04

Q.2 (a) Justify the following statements with respect to discrete time systems. (any TWO) (i)An impulse input to an accumulator yields a unit step output (ii) For a causal LTI system impulse response h(n)=0 for n<0 (iii) The convolution operation satisfies the commutative property.

04

(b) Define Z transform . Explain the following properties of Z transform: (i) Multiplication of an exponential Sequence (ii) Differentiation of X(Z)

05

OR (b) Prove [ ] )()()()( 2121 ZXZXnxnxZ +=∗

Prove [ ] ( )( )ω

ω

dedXjnnxF

j

=)(

05

( c) Define region of Convergence of Z transform. Explain right sided and left sided discrete time sequences and discuss the region of convergence with suitable illustrations and sketches.

05

Q.3 (a) Explain the Concept of Sampling and alising in Sampled data System 03

(b) Explain the symmetry property of the Fourier Transform for real, real-odd and real-even discrete time signals.

04

(b) Find y(n) using linear Convolution property of Z transform for x(n)=2,1,0,0,5 , h(n)=2,2,1,1) Also verify by the graphical method

07

OR Q.3 (a) List the applications of DSP 02

(b) Explain the design of IIR filter using Bilinear transformation method and discuss its advantages over other design methods Discuss the stability aspects and frequency warping

06

( c) Determine the inverse Z transform of the following: 06

2

(i))231(

)31()( 21

1

−−

−

+++

=ZZ

zzX (Long Division Method) for x(n) causal and x(n)

anticausal

(ii) )23)(21(

)5()( 11

1

−−

−

−−=

ZZzzX (Partial Fraction Method)

Q.4 (a) Explain the window functions used in FIR filter design. 04

(b) Obtain the system function H(Z) for the system described by the difference equation,

)1()()2(2)1(3)( −−=−+−− nxnxnynyny Realize the filter using (i) Direct Form I (ii) Direct Form II (iii)Cascade form (iv) Parallel Form for all cases, draw the structures neatly with system equations at different points.

08

( c) Determine the frequency spectrum of the signal

x(n) = )5(31

−⎟⎠⎞

⎜⎝⎛ nu

n

02

OR Q.4 (a) Compute the circular convolution of the sequences

x1=1,2,2,1 and x2=1,2,3,1) showing the steps in detail 06

(b) Discuss two properties of DFT. 04 (c) Find the IDFT of Y(K)=1,0,1,0 04

Q.5 (a) Define (i)DTFT(ii)DFT and (iii)IDFT of a discrete time sequence with mathematical representation

03

(b) Find 4 point DFT of x(n) and h(n) for the given sequences x(n)=2,0,0,1) and h(n)=4,3,2,1). Compute Y(K)=X(K).H(K)

07

( c) Find the DFT of the sequence x(n)=1,0,0,1 using DIF algorithm 04 OR

Q.5 (a) Compute the 8 point DFT of the sequence x(n)=1,1,1,1,1,1,1,1 using DIT FFT and draw the flow diagram. Compute the values at the output of all stages and indicate them in the table.

08

(b) Explain any one of the following: (i)Decimation in frequency FFT algorithms (ii) Architecture of DSP Processor (iii) Impulse Invariance method for IIR filter design.

06

*************

1

Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–VII • EXAMINATION – SUMMER 2013

Subject Code: 171003 Date: 28-05-2013


Time: 02.30 pm - 05.00 pm Total Marks: 70 Instructions:




Q.1 (a) Find if following systems are linear, causal, stable, time-invariant and

memoryless

(i) ∑∞

−∞=

=k

kxnxT )()]([ 1

(ii) )()]([ 02 nnxnxT −=

(iii) )1()()]([ 3 ++= nnnxnxT

07

(03)

(02)

(02)

(b) A discrete-time signal is defined as

≤≤

−≤≤−+

=

otherwise ,0

30 ,1

13 ,3/1

)( n

nn

nx

(i) Find the values of x(n) and sketch the sequence

(ii) Find x(-n+4)and sketch

(iii) Find x(n-4) and sketch

07

(03)

(02)

(02)

Q.2 (a) Find the convolution of following pairs of discrete sequences

(i) 5,4,3,2,1,0)( 5,4,3,2,1,0)( 11↑↑

== nhnx

(ii) 1,2,3,4,3,2,1)( 1,1,1,1,1,1,1)( 22↑↑

== nhnx

07

(04)

(03)

(b) An LTI system has the system function given below

(i) Write the difference equation for this system

(ii) Draw the block diagram

07

(04)

(03)

OR

31

21

5.075.01

321)(

−−

−−

+−

−+=

zz

zzzH

2

(b) For the discrete-time system shown below

(i) Write the difference equation

(ii) Find the poles and zeros

07

(04)

(03)

Q.3 (a) The pole zero plot of a sequence is shown in the z-plane.

(i) Write the z-transform X(z)

(ii) Find the sequence x(n), and

(iii) Sketch the sequence

07

(03)

(02)

(02)

(b) Find the z-transform of following sequence

≤≤

=otherwise 0

50 2)(

nnx

n

07

OR

Q.3 (a) Find the sequence for which the z-transform is given below

21 651

1)(

−− +−=

zzzX , for ROC |z|>2 and |z|>3

07

(b) Draw the block diagram of a digital signal processor with Harvard

architecture and describe the important differences with Von-Neumann

architecture.

07

Q.4 (a) Describe the difference between Fourier transform, Fourier series,

Discrete time Fourier transform and Discrete Fourier transform and

their corresponding time-domain signals.

07

(b) A continuous time signal is sampled at regular intervals of 0.1ms and

DFT coefficients are obtained for segments of 100 samples. What is the

frequency separation (resolution) between the DFT coefficients?

07

OR

Q.4 (a) Describe the properties of discrete Fourier transform 07

Q.4 (b) A discrete sequence is given by

x(n)= 1, 1, 0, 0

Find the DFT coefficients of this sequence.

07

0.25

0.5

x(n)

y(n)

0.5

Z-1

Z-1

Im z

Unit circle

x 0 Re z

3

Q.5 (a) State if following statements are True or False

1. Convolution of two sequences is equivalent to the convolution of

their Z transforms

2. Multiplying the z transform of a sequence by z-5

advances the

sequence by 5 samples

3. A two sided sequence can be causal or anticausal

4. If the ROC of a z-transform is outside of the unit circle, all the

poles lie inside the circle

5. For group delay to be constant phase response should be linear with

frequency

6. When two LTI systems with impulse responses h1(n) and h2(n) are

cascaded the resulting impulse response is obtained by multiplying

h1(n) and h2(n)

7. The frequency response of a discrete-time linear filter is periodic

07

(b) Describe the advantages and disadvantages of FIR filter over IIR filter 07

OR

Q.5 (a) Find the number of complex multiplications and complex additions

required in the direct computation of 1024 point DFT. How many

complex multiplications and complex additions will be required using

FFT algorithm?

07

(b) Describe the following terms in the context of FFT

1. Twiddle factor

2. Butterfly operation

3. Decimation in time and decimation in frequency

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY B. E. VII

th Semester–Examination – Nov- 2011

Subject code: 171004

Subject Name: Wireless Communication Date:26/11/2011 Time: 10:30 am – 01:00 pm Total Marks: 70




Q.1 (a) Define following terms:

(A.) - Control Channel (B.)- Forward Channel (C.)- Handoff

(D.)- Reverse Channel (E.)- Half Duplex System (F.)- Paging System

(G.)- Mobile switching center

07

(b) Explain in details the third generation(3G) wireless networks standards:- 1) 3G

W-CDMA (UMTS) 2) 3G cdma2000 3) 3G TD - SCDMA 07

Q.2 (a) Explain in detail the types of small scale fading (including time delay and

Doppler spread). 07

(b) If a total of 33 MHZ of bandwidth is allocated to a particular FDD cellular

telephone system which uses two 25 KHZ simplex channels to provide full

duplex voice and control channels , compute the number of channel available per

cell if a system uses (a) four-cell reuse ,(b) seven-cell reuse , and (c) 12 –cell

reuse. If 1MHZ of the allocated spectrum is dedicated to control channels,

determine an equitable distribution of control channels and voice channels in

each for each of the three systems.

07

OR

(b) Explain the difference between cell splitting and sectoring. Prove that the co-

channel reuse ratio is given by

,

where N = i2 + ij + j

2 (Use cosine law & hexagonal geometry)

07

Q.3 (a) Explain the difference between co-channel interference and adjacent channel

interference. Derive the equation for the signal to interference ratio. 07

(b) Explain in detail the impulse response model of a multipath channel. 07

OR

Q.3 (a) Explain in detail the spread spectrum slinding correlator channel sounding and

frequency domain channel sounding 07

(b) What is large scale propagation? Explain in detail the free space propagation

model. 07

Q.4 (a) Explain in detail the time division multiple access with its key features and

comments on the efficiency of TDMA. 07

(b) Explain in detail the operation of CDMA2000 cellular technology with it key

features. 07

OR

Q.4 (a) What is a non linear effect in FDMA? Explain in detail the operation of OFDM

with neat diagram.

07

(b) Explain in detail about the various types of channel used in GSM. 07

2

Q.5 (a) Explain in detail the signal processing in GSM including speech coding ,channel

coding(data & control channels). 07

(b) What is soft handoff? Explain in detail RAKE receiver with neat diagram. 07

OR

Q.5 (a) Explain in detail the CDMA forward channel operation. 07

(b) Explain in detail the wireless Ad-Hoc network with neat diagram. 07

*************

1





Subject Name: Wireless Communication


Instructions:




Q.1 (a) Differentiate between 2G-GSM and 3G-W-CDMA cellular wireless

communication systems in terms of channel bandwidth, modulation

technique and frame duration.

06

(b) Give complete classification of types of small-scale fading. 06

(c) Select the most appropriate option:

GSM cellular services uses

A) FDMA for multiple channel access and FDMA for multiple users

B) FDMA for multiple channel access and TDMA for multiple users

C) TDMA for multiple channel access and FDMA for multiple users

D) TDMA for multiple channel access and TDMA for multiple users

02

Q.2 (a) For a regular cellular structure with equal size hexagonal cells, show that

D/R= (21)½, Where D is the minimum distance between the centers of

adjacent cells and R is the radius of each cell. Assume 7-cell reuse

pattern.

07

(b) Determine the Signal-to-Interference (Co-channel) ratio for the system in

Q.2 (a) in dB, assuming path loss exponent n=4.

For the same system, if, each cell is sectored in 120° sectors, what will be

the improvement in Signal-to-interference ratio compared to non-sectored

system, in dB?

Also, determine adjacent channel interference for the same system.

07

OR

(b) Define: Coherence Bandwidth (BW) and Coherence time.

Determine Coherence BW(90%) and Coherence BW (50%) for an rms

delay spread of 8.47 ns

07

Q.3 (a) Derive an expression for the received power for a two-ray reflection point

to point mobile communication propagation model. Assume path loss

exponent n=4.

08

(b) Answer following questions with respect to Wi-MAX technology:

1. What is its full-form?

2. Which multiple access method does it use?

3. What is its approximate coverage range in km?

4. What is the upper limit on data rate ?

5. What is the range of radio channel bandwidth?

6. Write two applications.

06

OR

2

Q.3 (a) Consider two different cellular systems that share the following

characteristics. The frequency bands are 825-845 MHz for uplink and

870-890 MHz for the downlink. A duplex circuit consists of one 30 kHz

channel in each direction. The systems are distinguished by the reuse

factor, which are 4 and 19 respectively. For these systems, (i) Find the

number of simultaneous communications that can be supported by a

single cell in each system. (ii) Suppose that in each systems the cluster of

cells (4,19) is duplicated 16 times, find the number of simultaneous

communications that can be supported by each system. (iii)Suppose the

average user makes 6 calls per 24 hours and mean call duration is 6

minutes, estimate the total number of users that can be supported by each

system. (iv) If the billing for each customer is at the rate of 50

paisa/minute, determine average revenue per user (ARPU).

08

(b) Calculate mean excess delay, rms delay spread and maximum excess

delay (10 dB) for the multipath profile given in FIG.1.

06

Q.4 (a) Explain the advantages of CDMA over GSM system in terms of

Multipath characteristics, Privacy features, Security and Quality

degradation.

08

(b) Compare CDMA, FDMA and TDMA in terms of concept, key

resources, sharing of resources, Bandwidth efficiency, system flexibility

and system complexity

06

OR

Q.4 (a) Draw frame format for a normal burst in GSM. Calculate gross bit

rate/user/second, data rate/user/second and gross bit rate/physical channel

for GSM system.

08

(b) A cellular system has 32 cells; each cell has 1.6 km radius and the system

reuse factor of 7. The system is to support 336 traffic channels in total.

Determine the total geographical area covered, the number of traffic

channels per cell and total number of simultaneous calls supported by this

system.

06

Q.5 (a) Find median path loss using Okumura’s model for d=50 km hte=100 m,

hre=10 m. If EIRP from base station is 1kW at 900 MHz, find received

power. Take Amu(900 Mhz(50 km))=43 dB and GAREA=9 dB.

08

(b) Explain the terms: 1. Hidden- terminal 2. Exposed –terminal 04

3

(c) Select the most appropriate option:

The basic propagation mechanisms for radio waves are

a) Radiation, Diffraction, Scattering b) Radiation, Attenuation,

Scattering

c) Reflection, Diffraction, Scattering d) Reflection, Diffraction,

Radiation

02

OR

Q.5 (a) If a baseband binary message with a bit rate of 100 kbps is modulated by

an RF carrier using BPSK , answer the following:

a. Find the range of values required for the rms delay spread of the

channel such that the received signal is a flat-fading signal b.

If the carrier frequency is 5.8 GHz, what is the coherence time of the

channel, assuming a vehicle speed of 30 miles/hr? c.

For your answer in part b, is the channel “fast” or “slow” fading? d.

Given your answer in part b, how many bits are sent while the channel

appears “static”?

08

(b) For knife-edge diffraction of FIG.2 show that the excess path length ∆ is,

∆=h2(d1+d2)/2d1d2, Where excess path length is the difference of direct

line of sight path and indirect (diffracted) path between the transmitter

and the receiver.

06

*** *** ****

Seat No.: ________ Enrolment No.______________ GUJARAT TECHNOLOGICAL UNIVERSITY

B. E. - SEMESTER – VII • EXAMINATION – WINTER 2012 Subject code: 171004 Date: 27/12/2012 Subject Name: Wireless Communication Time: 10.30 am - 01.00 pm Total Marks: 70 Instructions:


Q.1 Answer The following. 14

(a) Explain channel assignment strategies for GSM Systems. 05 (b) Define following terms:

i) Cluster ii) RSSI iii) MAHO iv) Channel Capacity v) Dwell Time. 05

(c ) Explain the concept of frequency reuse for cellular communication systems. 04 Q.2 (a) Discuss the Okumura’s prediction method with necessary equations. 07

(b) A cellular service provider decides to use a digital TDMA scheme which can tolerate a signal-to-interference ratio of 15 dB in the worst case. Find the optimal value of N for (a) omni directional antennas, (b) 120o sectoring, and (c) 60 o sectoring. Should sectoring be used? If so, which sectoring (120 o or 60 o) will be better? Assume a path loss exponent n=4.

07

OR (b) Compute the absolute mean path loss at d0=3m and at d=22 m for a mobile radio

system operated in the 2.4-to 2.48 GHz authorized band. Assume the path loss exponent is n=3.5. Assume the first two meters are LOS, afterwards NLOS propagation should be assumed.

07

Q.3 (a) What is the delay spread bound maxτ of a 220-MHz public land-mobile radio (PLMR) system if =1 watt (+30 dBm) and = -90 dBm? How much is TP minRP maxτ if the sensitivity of the receiver is improved to = -100 dBm? minRP

05

(b) Derive the expression for S/I ratio for adjacent channel interference for cellular systems.

05

( c) Compare cell splitting and sectoring techniques. 04 OR

Q.3 (a) Assuming six co-channel interfering cells, find the S/I ratio for path loss co-efficients of n=3 and n=4. Consider cluster size N=7. In which case 15 dB requirement is met?what needs to be changed to meet the same condition in second case?

05

(b) Explain the concept of Umbrella cell. 05 ( c) Compare Wi-Fi and WiMAX in brief. 04

Q.4 (a) Briefly Describe the functions of the following for GSM Systems. i. MSC ii. VLR iii. HLR iv. AUC v. EIR.

05

(b) Briefly Describe Hand-off strategies in cellular system. Compare soft and hard Hand-off.

05

( c) Explain GSM Speech Processing in Brief. 04 OR

Q.4 (a) Derive the expression for Feher’s upper bound. 05 (b) Compare HSCSD and GPRS. Explain briefly GPRS. 05 ( c) What is Doppler frequency for 1850 MHz transmitter frequency and mobile is

moving at 60 km/h? 04

Q.5 (a) Explain IS-95 CDMA System. 07 (b) Compare TDMA,FDMA and CDMA Technology for cellular systems. 07 OR

Q.5 (a) Explain IMT-2000 System. 07 (b) Write short note on CDPD.(Cellular Digital Packet Data). 07

1

2

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY

BE-Semester VII Examination Nov/Dec-2011


Subject Name: Embedded Systems





Q.1 (a) Define and classify the embedded systems, give few

examples of such systems. 07

(b) ARM (Acorn RISC Machines) architecture supports the

design of embedded systems. Justify this statement with

special features that are incorporated into ARM controller.

07

Q.2 (a) Describe the flow of ARM development tools for

embedded system design. 07

(b) What is pipeline concept of ARM architecture, explains it

with proper block diagram. How its affects in system

performance.

07

OR

(b) Draw and discuss the basic block diagram of architectural

model of ARM controller. 07

Q.3 (a) Explain the following ARM instruction by giving

examples.

i) ASR ii) LDMIA

07

(b) Which are the wireless and mobile system protocols

available for the embedded systems; explain in short any

two of the wireless protocols that you have mention?

07

OR

Q.3 (a) Explain the following Thumb ARM instruction by giving

examples.

i) CMN ii) MVN

07

(b) Explain the difference between Real Time Clock and

Watch Dog Timer related to embedded systems. 07

Q.4 (a) What do you mean by “Task” and “Task state” related to

embedded operating systems; also discuss about task

control block (TCB) and its data.

07

(b) Explain the use of “semaphore” with respect to embedded

operating systems. List out few semaphore related function

which are found on Real Time OS.

07

OR

Q.4 (a) What do you mean by Inter Process Communication (IPC)

functions? Explain in short. Which are the IPC functions

generally found on Real Time OS.

07

(b) With respect to RTOS (Real Time Operating Systems)

explain the use of Timer and Event functions, and list out

few examples of Timer and Event functions.

07

2

Q.5 (a) Which are the basic services offered by RTOS (Real Time

Operating Systems) for the embedded system design?

Describe any one service in short.

07

(b) Explain the file system organization related to RTOS and

which are basic functions you will find with such file

systems.

07

OR

Q.5 (a) What is task scheduling models of RTOS, explain any two

scheduling models of RTOS in short. 07

(b) What are the RTOS security issues, which are the

important security function generally found on RTOS? 07

*************

1





Subject Name: Embedded Systems


Instructions:




Q.1 (a) Describe the principal features of the ARM architecture in detail. 07

(b) Compare the microprocessor, microcontroller, and single purpose

processors and gives their application example in day to day life.

07

Q.2 (a) List the IO types and explain any two types in detail. 07

(b) Give the difference between RISC and CICS processors. 07

OR

(b) Write a short note on 3-stage pipeline ARM organization. 07

Q.3 (a) Give the detail of kernel functions in an OS. What can be the function outside

the kernel? 07

(b) Write a short note on Real-Time Operating System and its services. 07

OR

Q.3 (a) Write a short note on hyper text transfer protocol. 07

(b) Discuss the OS security issues and give important security functions OS

should carried out. 07

Q.4 (a) Write a short note on CAN Bus. 07

(b) Give detail characteristics of the Functions, ISR, and Task. 07 OR

Q.4 (a) Give the various methods of saving and optimizing the power needs. 07

(b) Explain data processing instruction execution in ARM processor. 07

Q.5 (a) Write a short note on use of Socket function. 07

(b) Explain the concept of condition execution in ARM processor. With compare

to any other processor in what way it is differ. 07

OR

Q.5 (a) Give the properties of thumb instructions in ARM processor. 07

(b) Write about a design process steps in embedded system. 07

*************

1



Subject code: 171005 Date: 28/12/2012 Subject Name: Embedded Systems (Department Elective - I) Time: 10.30 am - 01.00 pm Total Marks: 70 Instructions:


Q.1 (a) Do as directed.

(i) Compare microprocessor, microcontroller, DSP and ASSP. (ii) What do you mean by charge pump? How does a charge pump

supply power in an embedded system without using power-supply lines?

08

(b) Discuss the following terms. (i) ASIP (ii) FPGA (iii) CPLD

06

Q.2 (a) Discuss the ARM programmer’s model in detail. 06

(b) Explain the following ARM instructions with an example. (i) ADDEQ (ii) BNE (iii) LDRB (iv) SMULL

08

OR (b) Explain the following ARM instructions with an example.

(i) SUBS (ii) SWI (iii) CMN (iv) SMLAL 08

Q.3 (a) Explain in detail ARM 3-stage pipelining. 07

(b) Discuss the thumb programmer’s model in brief. 07 OR

Q.3 (a) How branch instructions are executed in ARM? 07 (b) Discuss Thumb data processing instructions. 07

Q.4 (a) Discuss socket functions in detail. 07 (b) Explain three modes of serial communication, ‘synchronous’, ‘iso-

synchronous’ and ‘asynchronous’ using serial devices with one example of each.

07

OR Q.4 (a) List wireless and mobile system protocols and discuss any two in

detail. 07

Q.4 (b) Compare cooperative scheduling and preemptive scheduling. 07

Q.5 (a) Discuss Methods of saving and optimizing the Memory space. 07 (b) Discuss Earlier Deadline First (EDF) precedence and Rate

Monotonic Scheduling (RMS) Models 07

OR Q.5 (a) What are the situations, which lead to priority inversion problems?

How does it is resolved? 07

(b) Discuss use of a semaphore as an Event-signalling or Notifying variable.

07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY B.E SEM-VII Examination-Nov/Dec.-2011


Subject Name: Biomedical Instrumentation


Instructions:




Q.1 (a) Explain an introduction to the man- instrument system in

details.

07

(b) Define terms: i) Electrocardiography ii) Echocardiography. 07

Q.2 (a) Explain a propagation of action potential. 07

(b) Describe different transducers used for biomedical

application in details.

07

OR

(b) Explain difference of action potential, resting potential and

bioelectric potential

07

Q.3 (a) Explain a heart and cardiovascular system in details. 07

(b) Explain a biopotential electrode. 07

OR

Q.3 (a) Explain a biochemical transducer. 07

(b) Explain a plethysmography and colour doppller

measurement.

07

Q.4 (a) Explain terms: i) ECG and ii) EMG 07

(b) Explain the components of a Biotelemetry System in

details.

07

OR

Q.4 (a) Explain terms: i) EEG and ii) Pace Maker 07

(b) Explain the difference between CT scan and PET scan 07

Q.5 (a) Describe the blood pressure measurement in details. 07

(b) Explain a diathermy unit for surgery and therapy. 07

OR

Q.5 (a) Explain a heart rate measurement. 07

(b) Describe the hazards and methods of accident prevention. 07

*************

1/1



Subject code: 171006 Date: 28/12/2012 Subject Name: Biomedical Instrumentation Time: 10.30 am – 01.00 pm Total Marks: 70 Instructions:


Q.1 (a) Explain different lead configuration available for recording an ECG signal. Explain,

in brief, different types of ECG recorders. 07

(b) With neat sketches, describe the depolarization and repolarization process occurring in human cells.

07

Q.2 (a) What is an electrode? Draw an equivalent circuit for measuring the biopotentials using two electrodes. Explain microelectrodes in brief.

07

(b) Draw one ECG beat indicating typical amplitude and time values. Explain the physiology behind the development of ECG beat aided with cardiovascular circulation.

07

OR (b) Draw the diagram that relates blood pressure variations with heart sounds and ECG

waveform. Explain, in brief, indirect method of measuring the blood pressure. 07

Q.3 (a) Draw the block diagram of an electrocardiograph (ECG) machine and explain it in detail.

07

(b) Explain magnetic and ultrasonic blood flowmeters with neat sketches. 07

OR Q.3 (a) Explain electroencephalograph (EEG) and electromyograph (EMG) machines with

their block diagrams and discuss their applications. 07

(b) What is plethysmography? Explain operating principles of different types of plethysmographs.

07

Q.4 (a) What is a pacemaker? Explain competitive and non-competitive types of pacemakers. 07

(b) Explain the principle of electronomy, coagulation, fulguration and desiccation. Also explain the surgical diathermy machine.

07

OR Q.4 (a) What is fibrillation? Explain ac and dc defibrillators with neat sketches and

waveforms. 07

(b) Explain the operating principle of heart lung machine and discuss its applications. 07

Q.5 (a) Explain the principle of radiation. Draw and explain the block diagram of an x-ray machine.

07

(b) Explain the operating principle of Ultrasound imaging. 07

OR Q.5 (a) Discuss the limitations of x-ray imaging. Explain the principle of CT imaging. 07

(b) Explain the operating principle of positron emission tomography (PET). 07

*************

1


GUJARAT TECHNOLOGICAL UNIVERSITY B. E. VII

th Semester–Examination – Nov- 2011

Subject code: 171007

Subject Name: Satellite Communication

Date:29/11/2011 Time: 10:30 am – 01:00 pm Total Marks: 70

Instructions:




Q.1 (a) Which are the different types of orbits used for satellite Communication?

Explain in detail.

07

(b) What do you mean by multiple access technique? Explain Time Division

Multiple Access in detail.

07

Q.2 (a) Explain three laws of Kepler’s for planetary motion in detail.

07

(b) An earth station situated in the Bangalore ,needs to calculate the Look

angles to a geostationary satellite in the Indian ocean operated at

INSAT.The details of the earth station site and the satellite are as follows:

Earth station latitude and Longitude are 52.0 0 N and 0

0

Satellite longitude (subsatellite point) is 66. 0 0 E

07

OR

(b) What is the value of XPD at 0.01% of the time for a 12 GHz link that

experiences 7dB attenuation for this period of time? The elevation angle is

30 0.Calculate the XPD for tilt angles of 20

0 and 0

0.

07

Q.3 (a) What is the purpose of Telemetry, Tracking, Command, and Monitoring in

satellite communication? Explain in detail.

07

(b) Explain calculation of link margins for a VSAT Star network with suitable

equations.

07

OR

Q.3 (a) Write short notes on Satellite Antennas. Support your answer by explaining

main types of antennas are used in satellites

07

(b) Write short notes on Access Control Protocols used in VSAT network.

07

2

Q.4 (a) How the prediction of rain attenuation is possible? Also state the

calculation steps of Long Term Statistics for NGSO System.

07

(b) Write Short notes on Operational Non-Geostationary Satellite Orbit

(NGSO) Constellation design.

07

OR

Q.4 (a) Explain Orbit Consideration with respect to Non-Geostationary Satellite

Orbit (NGSO). 07

(b) Write short notes on Demand Access Multiple Access system. 07

Q.5 (a) Explain following terms in detail regarding GPS.

(1) Signal levels

(2) Timing Accuracy

07

(b) Write short notes on Master Control Station required for Direct Broadcast

Satellite Television (DBS-TV) system. 07

OR

Q.5 (a) Write short notes on GPS Receivers with using simplified block diagram.

07

(b) How the error control done in Digital DBS-TV? Explain it.

07

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1





Subject Name: Satellite Communication


Instructions:




Q.1 (a) Give Comparison of LEO, MEO and GEO satellite orbits and gives application

also.

07

(b) List the orbital elements and explain each of them in detail. Also give their

significance in orbital maintenance.

07

Q.2 (a) List various types of control required to maintain the satellite in space and explain

attitude and orbital control system in detail.

07

(b) What is uplink? Draw and Explain Uplink block-diagram. Also explain all the

steps to followed for Uplink power budget preparation.

07

OR

(b) Give the list of all Multiple Access System used for satellite communication.

Explain any one of them in detail and give comparison of any three

07

Q.3 (a) What is XPD ? properly explain. How XPD are predicted ? Also Draw and Explain

properly The Canting Angle and Tilt Angle with required equations.

07

(b) Determine the visibility of a earth station situated at mean sea level at latitude of

48.420

north and longitude 89.260

west. Assume a minimum angle of elevation of 50.

07

OR

Q.3 (a) What is VSAT ? List the application of VSAT. Also Draw and explain the

architecture of VSAT system.

07

(b) A earth station have equivalent noise temperature of 2000

K, noise bandwidth of 18

MHz, antenna gain of 50dB and carrier frequency of 12 GHz Determine,

Gain to Equivalent Noise temperature ratio, Noise density, and Total Noise Power.

07

Q.4 (a) List Five major types of orbits and explain any two of them in detail. 07

(b) The uplink C/N0 ratio is 88dBHz and downlink value is 78dBHz. Calculate overall

C/N0.

07

OR

Q.4 (a) List all seven operational NGSO constellation design and explain any two of them

in detail.

07

(b) In a TDMA system transmission rate is 60 Mbps, Voice channel bit rate is 64

Mbps Number of burst/ frame are 10, number of bits in a preamble are 150. frame

time 750 µsec. Find Noise channel capacity.

07

Q.5 (a) What is GPS ? Explain principle of GPS position location. Also explain signal

generation in GPS.

07

(b) Draw and Explain the block diagram of satellite transponder in detail 07

OR

Q.5 (a) List all propagation effects which are not associated with hydrometer and explain

them

07

(b) Give all the steps to launch the satellite vehicles for geostationary orbits and

explain it with required figure and equations.

07

*************

1



Subject code: 171007 Date: 28/12/2012 Subject Name: Satellite communication Time: 10.30 am - 01.00 pm Total Marks: 70 Instructions:


Q.1 (a) What are kepler’s three laws of planetary motion? Give the

mathematical formulation of kepler’s third law of planetary motion. 07

(b) What is the earth’s oblateness, sun and moon’s effects on artificial satellite’s orbit.

07

Q.2 (a) A satellite is in an elliptical orbit with a perigee of 1000km and an apogee of 4000km. using mean earth radius of 6378.14 km, find the period of the orbit in hours, minutes, and seconds, and the eccentricity of the orbit.

07

(b) Write a short note on attitude control system. 07

OR

(b) A satellite at a distance of 40,000 km from a point on the earth’s surface radiates a power of 10 W from an antenna with a gain of 17dB in the direction of the observer. Find the flux density at the receiver point, and the power received by an antenna at this point with an effective area of 10 m2

07

Q.3 (a) Write a short note on satellite antennas. 07

(b) Discuss in detail: The parameter that effect the selection of satellite launch vehicle.

07

OR

Q.3 (a) List the advantage and disadvantage of FDMA,TDMA and CDMA multiple access techniques.

07

(b) List the propagation effects that are not associated with hydrometeors. Explain any two of them in details.

07

Q.4 (a) Write a short note on demand access multiple access techniques. 07 (b) Write a short note on access control protocols in VSAT systems. 07 OR

Q.4 (a) Explain Elliptical orbits and Molniya orbit with their uses. 07

Q.4 (b) Write a short note on error control in digital DBS-TV 07 Q.5 (a) Write a short note on GPS position location principles. 07

(b) List the step for design procedure for satellite communication link. 07 OR

Q.5 (a) Explain in detail: GPS receiver operation. 07 (b) Describe the fooling satellite NGSO Systems

(i) Iridium (ii) Orbcomm. 07

*************

Documents

GUJARAT TECHNOLOGICAL UNIVERSITY BE SEM-VII Examination ... · load current. Determine mean load voltage at firing angle 0 0 ,45 0 90 0 Neglect all devices drops .If commutating diode