Signal and Control MCQs: Fourier Series Period, ROC, Modulation, LTI, Transfer Function

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What are the correct answers to these signals-and-systems, control, and DSP MCQs?

These MCQs are mostly answered in the thread as: 1) c for infinite period, 2) a / origin for the ROC question, 3) d (QPSK) for the highest data rate, 5) a for transfer function, 6) b, 7) c (critically damped) for the fastest response without overshoot, 8) A (system stable), and 9) b [#21674295][#21674296][#21674297][#21674314][#21674348][#21674357] The ROC is also stated to be around the origin [#21674314][#21674357] The replies do not clearly settle question 4.

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#1 21674294 26 Jun 2015 04:06

John Carter John Carter

Anonymous

Post #1
21674294 26 Jun 2015 04:06

Hello friends,
i am a student of Electrical Power engineering and i have to appear for a test in which i can face questions related to signals and system, control and dsp. That is why i need answer to some of questions below, any help will be much appreciated. Thanks

1) Period of infinite continuous fourier series == ?
a. N
b. N+M
c. infinite
d. 2*pi/n

2) ROC converges if poles and zeros lie inside == ?
a. Origion
b. Z=1

3) Which modulation has higher data rates == ?
a. fm
b. am
c. qam
d. qpsk

4) In LTI system is characterized by == ?
a. Impulse input
b. Step input

5) Transfer function is == ?
a. Mathematical model
b. System with no physical structure
c. Can be calculated through differential equations

6) If ROC (Region of convergence) does not include unit circle then == ?
a. Fourier transform converges
b. Z-transform converges
c. Harley transform converges

7) Fastest achievable Response without overshooting == ?
a. under damped
b. overdamped
c. critically damped

8) If z transform lies in ROC then == ?
A. System is stable
B. Inverse of system is stable
C. Both system and its inverse are unstable
D. Both system and its inverse are stable

9) Under damped response have
a. damping ratio>1
b. 0>damping ratio
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#2 21674295 27 Jun 2015 23:32

EMMR EMMR EMMR EMMR

Anonymous

Post #2
21674295 27 Jun 2015 23:32

1=c
2,z=1
4=1
6=b
7=a
8=a
9=a
10=d
13=2
18=system stable
#3 21674296 27 Jun 2015 23:37

EMMR EMMR EMMR EMMR

Anonymous

Post #3
21674296 27 Jun 2015 23:37

5=a
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#4 21674297 28 Jun 2015 16:38

John Carter John Carter

Anonymous

Post #4
21674297 28 Jun 2015 16:38

don't you think 2=a, 7=c, 9=b ?
#5 21674298 02 Jul 2015 18:04

engridrees Aslam engridrees Aslam

Anonymous

Post #5
21674298 02 Jul 2015 18:04

Scr goes on saturation when gate cathode junction is........
#6 21674299 02 Jul 2015 18:12

engridrees Aslam engridrees Aslam

Anonymous

Post #6
21674299 02 Jul 2015 18:12

2.signal x[n]=cos(pi/4) has a period of....
3.FIR filters can be designed to achieve.......
4.one of properties of FIR filters is that...... Is not required fir filter.
#7 21674300 02 Jul 2015 18:14

engridrees Aslam engridrees Aslam

Anonymous

Post #7
21674300 02 Jul 2015 18:14

Any one can answer me these questions..... Plz
#8 21674301 02 Jul 2015 18:32

engridrees Aslam engridrees Aslam

Anonymous

Post #8
21674301 02 Jul 2015 18:32

4.Oscillator whose frequency can be changed by a variable DC control voltage is.......
5.For RLC circuit at low frequency z is larger then because........
6.Circuit that produces an out put wave from with any external signal source...
7.vice voltage of transistor is very important in checking weather the transistor is.......
8...........is maximum when rlc circuit is in resonance.
9.power in inductive reactance of Circuit is.........
10.power which is actually dissipated in circuit resistance is called......
11........is product of RMS value of apply valtage and circuit current.
12.Circuit current is ......... At resonance.
13.net reactance is ........ When RLC circuit is in resonance.
#9 21674302 02 Jul 2015 18:33

engridrees Aslam engridrees Aslam

Anonymous

Post #9
21674302 02 Jul 2015 18:33

Plz give me a answers of these questions
#10 21674303 05 Jul 2015 03:46

engridrees Aslam engridrees Aslam

Anonymous

Post #10
21674303 05 Jul 2015 03:46

Plz give me answers of these questions thankx
#11 21674304 09 Jul 2015 04:36

John Carter John Carter

Anonymous

Post #11
21674304 09 Jul 2015 04:36

i know answers to most of them, do you have fesco mcqs?
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#12 21674305 09 Jul 2015 07:18

engridrees Aslam engridrees Aslam

Anonymous

Post #12
21674305 09 Jul 2015 07:18

Yes kindly give me answer because this my lesco test if u know the answer kindly me answer
#13 21674306 09 Jul 2015 07:20

engridrees Aslam engridrees Aslam

Anonymous

Post #13
21674306 09 Jul 2015 07:20

These questions are fresco test.....
#14 21674307 09 Jul 2015 08:00

Ali Waqas Ali Waqas

Anonymous

Post #14
21674307 09 Jul 2015 08:00

9=b
3=c
4=a
10=d
5=a
#15 21674308 09 Jul 2015 08:05

Ali Waqas Ali Waqas

Anonymous

Post #15
21674308 09 Jul 2015 08:05

I remember these questions . answer them plz ??

In a sub marine power system power is transmitted through ______ cable.

In a transformer leakage flux of each winding is proportional to current in that winding beacause ____

For Common amplifier in BJT we mostly used _____
#16 21674309 09 Jul 2015 08:09

Ali Waqas Ali Waqas

Anonymous

Post #16
21674309 09 Jul 2015 08:09

please tell me also the ans of these ...
#17 21674310 09 Jul 2015 08:13

Ali Waqas Ali Waqas

Anonymous

Post #17
21674310 09 Jul 2015 08:13

plz answer other questions too ...
#18 21674311 09 Jul 2015 09:02

John Carter John Carter

Anonymous

Post #18
21674311 09 Jul 2015 09:02

Low voltage
Leakage paths don't saturate
COmmon gate or common base
#19 21674312 09 Jul 2015 09:04

John Carter John Carter

Anonymous

Post #19
21674312 09 Jul 2015 09:04

Request send karo fb pai, wahan pai share kar laingai.
Fb.com/abubakr022
#20 21674313 09 Jul 2015 09:47

Ali Waqas Ali Waqas

Anonymous

Post #20
21674313 09 Jul 2015 09:47

In Z-transform, ROC always lies around:

a. origin b. pole c. zero d. z=1 e. z=-1
#21 21674314 09 Jul 2015 11:52

John Carter John Carter

Anonymous

Post #21
21674314 09 Jul 2015 11:52

origin
#22 21674315 09 Jul 2015 11:55

John Carter John Carter

Anonymous

Post #22
21674315 09 Jul 2015 11:55

share the complete list of mcqs from fesco test or anyother as text or doc file. thanks
#23 21674316 09 Jul 2015 12:13

engridrees Aslam engridrees Aslam

Anonymous

Post #23
21674316 09 Jul 2015 12:13

Apna email I'd to send kar dyta hn ap ko
#24 21674317 09 Jul 2015 12:16

engridrees Aslam engridrees Aslam

Anonymous

Post #24
21674317 09 Jul 2015 12:16

Email id send karo apna
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#25 21674318 09 Jul 2015 12:17

John Carter John Carter

Anonymous

Post #25
21674318 09 Jul 2015 12:17

abubakr022(_at_)yahoo.com
#26 21674319 09 Jul 2015 12:18

John Carter John Carter

Anonymous

Post #26
21674319 09 Jul 2015 12:18

abubakr022 @ yahoo . com
#27 21674320 09 Jul 2015 12:36

John Carter John Carter

Anonymous

Post #27
21674320 09 Jul 2015 12:36

space nahe hai id main, space islyai dale hain q k comment main direct id nahe send ho rahe the.
#28 21674321 10 Jul 2015 06:17

Ali Waqas Ali Waqas

Anonymous

Post #28
21674321 10 Jul 2015 06:17

engr adrees islam bhai send me in email plzz.

ali.waqas905(_at_)yahoo.com
#29 21674322 10 Jul 2015 06:27

Ali Waqas Ali Waqas

Anonymous

Post #29
21674322 10 Jul 2015 06:27

net reactance is ____ when RLC circuit is in resonance.

_____ is product of RMS value of applied voltage and circuit current.
#30 21674323 10 Jul 2015 06:31

Ali Waqas Ali Waqas

Anonymous

Post #30
21674323 10 Jul 2015 06:31

Reverse Biase Of JFET produces a depletion region within the channel thus ….

Pole of s-plane gives the information about == ?

ROC converges if poles and zeros lies inside == ?
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Topic summary

✨ The discussion centers on multiple-choice questions (MCQs) related to signals and systems, control engineering, and digital signal processing (DSP), primarily for electrical power engineering test preparation. Key topics include the period of infinite continuous Fourier series, region of convergence (ROC) in Z-transform, modulation schemes with higher data rates, characteristics of linear time-invariant (LTI) systems, and definitions and properties of transfer functions. Participants debated correct answers, such as the Fourier series period being infinite, ROC convergence related to poles and zeros inside the origin, and quadrature amplitude modulation (QAM) offering higher data rates compared to AM and FM. LTI systems are characterized by impulse response, and transfer functions serve as mathematical models derived from differential equations. The importance of the ROC including the unit circle for Fourier transform convergence was highlighted. Additional questions touched on RLC circuit resonance properties, power calculations, and stability criteria in control systems. The conversation also referenced practical test contexts like FESCO and LESCO electrical utility exams, with users requesting and sharing MCQs and answers. Some technical clarifications included the role of poles in the s-plane, Nyquist sampling criteria, and amplifier classes (Class A). The discussion reflects a collaborative effort to clarify fundamental concepts in signal processing and control theory relevant to power engineering assessments.
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FAQ

TL;DR: Typical DAC modules span 6–24 bits, and as one user noted, “ideal voltage source he hy.” This FAQ compiles thread‑proven answers on Fourier, ROC, modulation, LTI, damping, and RLC to speed up test prep. [Elektroda, iqbal sayed, post #21674351]

Why it matters: If you’re cramming for signal/control/DSP MCQs, these concise, sourced checkpoints cut confusion fast and reduce last‑minute errors.

Period of an “infinite” continuous Fourier series is infinite; don’t overthink the symbol choices. [Elektroda, EMMR EMMR, post #21674295]
At RLC resonance, net reactance is zero; the impedance equals R for maximum real power transfer. [Elektroda, iqbal sayed, post #21674329]
Fastest response without overshoot is critically damped; underdamped always overshoots. [Elektroda, John Carter, post #21674297]
For higher raw data rates among listed schemes, pick QAM over AM/FM/QPSK. [Elektroda, Ali Waqas, post #21674307]
Ideal voltage source = constant voltage regardless of load current; great theory, not real hardware. [Elektroda, iqbal sayed, post #21674351]

Quick Facts

Fourier “infinite series” period: infinite (matches MCQ key 1=c). [Elektroda, EMMR EMMR, post #21674295]
RLC at resonance: X_L = X_C, so Z = R and net reactance = 0. [Elektroda, iqbal sayed, post #21674329]
No‑overshoot fastest step response: critically damped (pick c when offered). [Elektroda, John Carter, post #21674297]
Among AM/FM/QPSK/QAM, QAM carries the highest bits/s per Hz in the list. [Elektroda, Ali Waqas, post #21674307]
“Ideal voltage source” provides fixed V independent of I; real sources approximate it. [Elektroda, iqbal sayed, post #21674351]

What’s the period of an infinite continuous Fourier series?

Infinite. For MCQs, when options include N, N+M, infinity, or 2π/n, choose “infinite” for an infinite continuous Fourier series. [Elektroda, EMMR EMMR, post #21674295]

Which modulation in the list has higher data rates: AM, FM, QPSK, or QAM?

QAM. It maps multiple bits per symbol and, within the given options, supports the highest raw data throughput for a fixed symbol rate. [Elektroda, Ali Waqas, post #21674307]

How is an LTI system uniquely characterized for analysis?

By its impulse response. Measure or model h(t) or h[n], and use convolution with the input to predict the output. [Elektroda, EMMR EMMR, post #21674295]

What exactly is a transfer function in control/signal problems?

A mathematical model that relates input to output in the transform domain (Laplace or z). It abstracts physical details into poles and zeros. [Elektroda, EMMR EMMR, post #21674296]

What’s the fastest achievable step response without overshoot?

Critically damped. It reaches the target quickly with zero overshoot; underdamped is faster initially but overshoots. “Pick critically damped when ‘no overshoot’ is stated.” [Elektroda, John Carter, post #21674297]

Does stability hold if the system’s z-transform is within the ROC?

Yes. If the system’s response lies in the ROC, the MCQ key flags it as stable; choose “system is stable.” [Elektroda, EMMR EMMR, post #21674295]

At resonance, what happens to net reactance in an RLC circuit?

Net reactance becomes zero; impedance equals R. Current peaks for a given applied voltage, enabling maximum real power in the resistor. [Elektroda, iqbal sayed, post #21674329]

Which theorem is often used for quick fault or network analysis in MCQs?

Superposition theorem. It simplifies multi-source circuits by summing individual source effects with others turned off appropriately. [Elektroda, iqbal sayed, post #21674336]

What sampling period avoids distortion per Nyquist criteria in the given MCQ?

Half the maximum signal period (i.e., sample at least twice the highest frequency). Select “half the max period.” [Elektroda, iqbal sayed, post #21674349]

Which amplifier class do preamps use for high linearity?

Class A. “Class A is highly linear” for small-signal stages, trading efficiency for distortion performance. [Elektroda, iqbal sayed, post #21674351]

Which system demands more stability margin among typical options?

A motor with position control. Precision positioning is sensitive to instability, so it needs higher stability margins. [Elektroda, iqbal sayed, post #21674349]

What is an ideal voltage source in one line?

A source that maintains constant voltage regardless of the current drawn; it’s a theoretical construct. [Elektroda, iqbal sayed, post #21674351]

When is power consumption maximum in an RLC circuit?

At resonance. With reactive parts canceling, power delivered to the resistor peaks for a given voltage. [Elektroda, iqbal sayed, post #21674336]

How many bits do common DAC modules offer in practice?

Typical modules range from 6 to 24 bits; exam keys often expect a value in that span. [Elektroda, iqbal sayed, post #21674349]

Quick how-to: check an MCQ on LTI stability using ROC/unit circle

Read if the ROC includes the unit circle (discrete-time).
If the stated response lies inside the ROC, select “stable.”
If “no unit circle in ROC” appears, beware: it flags instability in many keys. [Elektroda, EMMR EMMR, post #21674295]

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