National Thermal Power Corporation

Management Trainee

Electronics & Communication 

• Given four unit-circle plots identify the one corresponding to a bandpass filter.
• A 4 kHz signal is sampled at thrice the Nyquist rate and sent through a channel with error 1%. Calculate the bandwidth of the channel.
• Given a two port network in the form of a T find o/p admittance in terms of y-parameters.
• Connect two 1? resistors in series, then connect two 1H inductors across one of the resistors such that the ckt looks like a 1? resistor in series with a ?-section of a resistor and two inductors. With the series resistance on the i/p side, calc the transfer function of this ckt
• Inverse laplace transform of 1/s2[d/ds(e-3s/s)]
• Lower useful input limit of a transducer is determined by?
• Air-cored inductors are used for low frequency/high frequency/equal frequency operations.
• Given 4 pole-zero plots identify which one corresponds to the driving point impedance of a series resonant ckt.
• Expression for ?(n): u(n)-u(n-1)/ u(n-1)-u(n+1)/ u(n)+u(n+1)/?
• The sequence (2,3,4,3) is circularly even/circularly odd/circularly zero/both circularly even and odd.
• Z-transform of 3n u(n).
• Match the following with their characteristics: LED/LCD/nixie tube/optical fibre.
• Numerical on a photodiode: to calculate the responsivity/sensitivity when a specified no of incident photons cause a specified no of electron generation.
• Given an op-amp ckt obtain an expression for o/p voltage.
• No. of encirclements made about the origin of the nyquist plot of the open loop TF:1/[(s-1)(s+2)(s+3)].
• For a radioactive sample which decays to 12.5% of its initial value in x days, the half life is given by____
• For a repeater in a PCM cable identify the correct sequence of actions amongst threshold/equalization/etc.
• O/P of a delta modulator when a ramp input is fed to it.
• Steady state error with ramp i/p for a type-0 system.
• Creeping occurs in energy meters bcoz?
• Ultrasonic method of flow measurement cannot be used in liquids with air bubbles/has less attenuation in air compared to liquid-identify the false statement (if any) among these.
• Major cause of losses in a fibre optic cable: dispersion/total internal refraction/presence of core and cladding/?
• Which layer in the OSI model is concerned with printer buffering,etc: network/session/transport/?
• Given some function F(j?) calc its inverse CTFT.
• Relation between laplace and z-transform: s=z/ s=ln z/ s=( ln z/T) /?
• Maxm and minm probability error among ASK,PSK,FSK,DPSK etc
• Which of the following is a non linear modulation scheme: PAM/QAM/PCM/?
• Match the following functions: e-t , e-t + et, sin(?t) with causal and stable system, causal and unstable system, etc.
• Given a ckt with a 50 ? resistor in series between two voltage sources of 10 V and 5 V magnitude calc power delivered by 5 V source.
• Laplace transform of e-3tu(t)+e2tu(-t).
• Which photodetector has output affected by own intrinsic noise: PN/APD/PIN/all.
• AC signal conditioning is used for inductive and capacitive/resistive/piezoelectric transducers/all of the above.
• When I mode is added to proportional control system stability increases/ decreases/ steady state performance deteriorates/damping increases.
• Reset control is another name for integral/derivative/proportional/? Control.
• Time response of system having transfer function 625/(s2+25) will be of the form?
• Given some transfer function calc the peak response time.
• The nyquist sampling rate of the function [sin(at)/t]2 will be?
• The feedback topology that results in increased i/p and o/p impedance is current series/voltage series/current shunt voltage shunt.
• Numerical on cardiac output calculation given heart rate and volume per beat.
• In an ECG instrumentation amplifier the differential gain is provided by 1st stage/2nd stage/mismatched resistors/output stage.
• Repeat ques 40 above for the classic 3-op amp instrument amplifier.
• EMG signals are of the order of mV/V/?V/?
• Computer assisted tomography is used for?
• Numerical on electrostatic instrument, to calculate deflection given spring constant, torque etc.
• To prevent loading of a ckt i/p impedance of a CRO should bee high/low/inductive/capacitive.
• Addition of a zero to a 2nd order under-damped system results in increase/decrease of rise time and increase/decrease of peak overshoot.
• For PI ctrl we obtain improved bandwidth/improved steady state performance/ worsened steady state performance/?
• SNR of normal AM system is comparable/3 dB lower/3 dB higher/6 dB lower over DSB-SC and SSB system.
• Which is an effective measure of the noise related performance of an amplifier: SNR/noise ratio/thermal noise/shot noise.
• Given  signal freq and carrier freq calculation which of the freq given will not be present for conventional AM.
• Distinction between FM and PM at high frequencies.
• Which of these has the least propagation delay RTL/ECL/I2L/CMOS.
• Switching speed of CMOS is affected/unaffected by changes in supply voltage.
• Which of these provides a measure of heart rate P/QRS complex/T/none of these.
• Given a ckt of a logarithmic amplifier you had to identify what ckt was it.
• JFET can operate in depletion/enhancement/both/none of the above modes.
• When a BJT operates in saturation the junctions are fwd biased/reverse biased/?
• BIBO stability criterion implies that poles are within/outside/on the unit circle.
• For faithful amplification of low amplitude signals the cut-off/active/saturation regions of a transistor is used.
• Lissajous pattern of a signal rotates 36 times per minute. if the oscillator frequency is 560 kHz then the unknown freq is?

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