REM A LVL 1 Flashcards
A system is said to be defined as non-
causal, when
A. the output at the present does not depend
on the factor of time at all
B. the output at the present depends on the
input at the current time
C. the output at the present depends on
the input at a time instant in the future
D. the output at the present depends on the
input at an earlier time
C. the output at the present depends on
the input at a time instant in the future
A non-causal system’s output is said to
depend on the input at a time in the
future.
If a sine wave begins from above or below the zero axis, how many times will it cross the zero axis in one complete cycle?
A. 4 times
B. 360 times
C. 180 times
B. 360 times
Which of the following signals are
monotonic in nature?
A. log(tan(t))
B. cos(t)
C. 1-exp(-t)
D. 1-exp(sin(t))
B. cos(t)
All of the other functions have a
periodic element in them, which means
the function attains the same value
after a period of time, which should not
occur for a monotonic function.
Digital data refers to the information
that is
A. discrete
B. None of these choices
C. Discrete or Continuous
A. discrete
All causal systems must have the
component of
A. linearity
B. stability
C. time invariance
D. memory
D. memory
Causal systems depend on the
functional value at an earlier time,compelling the system to possess memory.
Time scaling operation is also known as
_____
A. None of the mentioned
B. Sampling
C. Up-sampling
D. Down-sampling
D. Down-sampling
If the signal x(n) was originally obtained
by sampling a signal xa(t), then
x(n)=Xa(nT).Now, y(n)=x(2n)
(say)=xa(2nT). Hence the time scaling operation is equivalent to changing the sampling rate from 1/T to 1/2T, that is
to decrease the rate by a factor of 2. So,
time scaling is also called as down-
sampling.
If a continuous time signal x(t) with
spectrum X(F) is sampled at a rate Fs=1/T samples per second, then what is the scaled spectrum?
A. X(F)
B. None of these choices
C. Fs·X(F)
D. X(F)/Fss
C. Fs·X(F)
When a continuous time signal x(t) with spectrum X(F) is sampled at a rate Fs =1/T samples per second, the spectrum of the sampled signal is periodic
repetition of the scaled spectrum Fs.
X(F).
Given a signal x(t), in order to recover
the original signal from the samples, the sampling frequency must be greater or equal to twice the maximum frequency in x(t).
A. Band limited
B. Sampling theorem
C. Aliasing
B. Sampling theorem
Frequency domain of a periodic
triangular function is a
A. continuous sampling square function
B. discrete sin function
C. discrete sampling function
D. continuous sampling function
A. continuous sampling square function
Because F.T. of a Triangular function is
square sampling function
Which type of filter can exhibit phase
distortion for certain applications?
A. Both FIR and IIR Filters.
B. Neither FIR nor lIR Filters.
C. FIR Filter.
D. IIR Filter.
D. IIR Filter.
IIR filters can exhibit phase distortion
for certain applications due to their
feedback component, which can
introduce phase shifts in the frequency
response.
Brief explanation of the other choices.FIR Filter: FIR filters have linear phase characteristics, and they do not
introduce phase distortion within their
passband. Therefore, they do not exhibit
phase distortion as much as IIR filters.
Which type of filter has a finite impulse
response?
A. Neither FIR nor IIR Filters.
B. Both FIR and IIR Filters.
C. FIR Filter.
D. IIR
C. FIR Filter.
FIR filters have a finite impulse
response, meaning their output
response to an impulse input will decay to zero in a finite number of time steps Brief explanation of the other choices:
IIR Filter: IIR filters have an infinite
impulse response, meaning their output
response to an impulse input may
continue indefinitely or decay very
Which type of filter is more
computationally efficient due to its
simplicity?
A. IIR Filter.
B. Both FIR and IIR Filters.
C. Neither FIR nor IIR Filters.
D. FIR
A. IIR Filter.
IIR filters are generally more
computationally efficient than FIR filters of the same order because they require fewer coefficients to achieve the same filtering performance.
Brief explanation of the other choices:FIR Filter: FIR filters are generally less computationally efficient than IIR filters due to their longer impulse response
and the need for more coefficients.
Which type of filter is always stable?
A. IIR Filter.
B. Both FIR and IIR Filters.
C. FIR Filter.
D. Neither FIR nor lIR Filters.
C. FIR Filter.
FIR filters are always stable, as their impulse response decays in a finite number of time steps.
Brief explanation of the other choices:IIR Filter: IIR filters can be unstable if not designed properly, meaning their
output may grow indefinitely or exhibit
oscillatory behavior.
Is where the z transform has a finite
sum for a region on a complex plane
A. Inside the unit circle
B. All of these choices
C. Region of convergence (ROC)
D. Outside the unit circle
C. Region of convergence (ROC)
For an analog LTI system to be stable,
where should the poles of system
function H(s) lie?
A. Right half of s-plane
B. Left half of s-plane
C. At origin
D. On the imaginary axis
B. Left half of s-plane
An analog linear time invariant system with system function H(s) is stable if all its poles lie on the left half of the s-
plane.
What is the duration of the unit sample
response of a digital filter?
A. Finite
B. Infinite
C. Zero
B. Infinite
Digital filters are the filters which can be designed from analog filters which have infinite duration unit sample response.
All of these are FIR Filter design
techniques except
A. Least Squares
B. Windowing
C. Equiripple or Minimax Design
D. Modeling of desired impulse response
D. Modeling of desired impulse response
Convolution relates three signals: the
input signal, the output signal, and the
A. stability of the system
B. frequency response
C. step response
D. impulse response
D. impulse response
In frequency sampling method,
transition band is a multiple of which of
the following?
A. 2πM
B. π/2M
C. π/M
D. 2π/M
D. 2π/M
In the frequency sampling technique,
the transition band is a multiple of 2n/M
If a continuous time signal x(t) with spectrum X(F) is sampled at a rate Fs=1/T samples per second, the spectrum of the sampled signal is
A. None of these choices
B. Non periodic repetition
C. Periodic repetition
C. Periodic repetition
When a continuous time signal x(t) with
spectrum X(F) is sampled at a rate
Fs=1/T samples per second, the
spectrum of the sampled signal is
periodic repetition.
What is the duration of the unit sample
response of a digital filter?
A. Impulse(very small)
B. Zero
C. Finite
D. Infinite
D. Infinite
Digital filters are the filters which can be
designed
Which type of filter is suitable for
applications requiring linear phase and
high precision?
A. FIR Filter.
B. Both FIR and IIR Filters.
C. IIR Filter.
D. Neither FIR nor IIR Filters.
A. FIR Filter.
FIR filters are suitable for applications
requiring linear phase and high
precision, such as audio processing,
equalizers, and certain types of image
processing.
Brief explanation of the other choices.
IIR Filter: IIR filters do not generally
provide linear phase characteristics, and
they may not be as suitable for
applications that require high precision
due to the potential for phase distortion
Which of the following methods are
used to convert analog filter into digital
filter?
A. Impulse invariance
B. All of the mentioned
C. Approximation of Derivatives
D. Bilinear Transformation
B. All of the mentioned
There are many techniques which are
used to convert analog filter into digital
filter of which some of them are
Approximation of derivatives, bilinear
transformation, impulse invariance and
many other methods.
Which of the following methods are
used to convert analog filter into digital
filter?
A. Impulse invariance
B. All of the mentioned
C. Approximation of Derivatives
D. Bilinear Transformation
B. All of the mentioned
There are many techniques which are
used to convert analog filter into digital
filter of which some of them are
Approximation of derivatives, bilinear
transformation, impulse invariance and
many other methods.
The lack of precise control of cutoff
frequencies is a disadvantage of which
of the following designs?
A. None of these choices
B. Frequency sampling
C. Window design
C. Window design
The major disadvantage of the window
design method is the lack of precise
control of the critical frequencies.
He began the development of antennas
practical for long-distance, wireless
telegraphy.
A. James Maxwell
B. none of these choices
C. Guglielmo Marconi
C. Guglielmo Marconi
James Maxwell - predicted
mathematically the existence of
electromagnetic waves through his
equation.
Heinrich Hertz - conclusively proved the existence of the electromagnetic waves predicted by James Clerk Maxwell’s
equation for electromagnetic wave.
Guglielmo Marconi - publicly
demonstrated the existence of radio waves through long distance wireless transmission.
__used to describe the range of
frequencies required to transmit the
desired information.
A. channel bandwidth
B. information capacity
C. information bandwidth
D. channel capacity
A. channel bandwidth
These are frequencies used in two-way
or amateur radio CB communications.
A. LF
B. VLF
C. MF
D. HF
D. HF
The Hartley law states that
A. the maximum rate of information transmission depends on depth of modulation
B. redundancy is essentials
C. the maximum rate of information
transmission depends on the channel
bandwidth
D. it is necessary to use only binary codes
redundancy is essentials
C. the maximum rate of information
transmission depends on the channel
bandwidth
is a type of transmission
impairment in which the signal loses
strength due to the different
propagation speeds of each frequency
that makes up the signal.
A. Noise
B. Attenuation
C. Distortion
D. Decibel
C. Distortion
Which of the following is not used for
communication
A. Microwaves
B. X-rays
C. Millimeter waves
B. X-rays
X-rays is a form of electromagnetic
radiation. X-rays have a wavelength in
the range of 0.01 to 10 nanometers,
corresponding to frequencies in the
range 30 petahertz to 30 exahertz(3×10 Hz to 3 x 10 Hz) Millimeter waves is the term called for signals which falls under EHF (Extremely High
Frequencies) Infrared refers to
electromagnetic radiation generally
associated with heat. Microwaves are
signals which are greater than 1 GHz
The frequency band used by cellular
telephones and mobile communication
services is _____
A. EHF
B. VLF
C. VHF
D. UHF
D. UHF
Ultra high frequency (UHF) designates a
range of eletromagnetic waves with
frequencies between 300 MHz and 3
GHz (3,000 MHz), also known as
the decimetre band or decimetre wave.
A quarter period for an electromagnetic
wave is equivalent to _ phase shift:
A. 360 degrees
B. 90 degrees
C. 180 degrees
D. 45 degrees
B. 90 degrees
A period of an electromagnetic wave is equivalent to 360 degrees phase shift.Half of a period is 180 degrees phase shift, quarter of a period is 90 degrees phase shift and so on. In radians these are, 360 degrees = 2π radians, 180
degrees = πt radians, and 90 degrees = π/2 radians.
Information signals may be transmitted
across the network in two ways. One
system is to put the information signals
directly into the medium. Another
system may use the information signal to modulate a carrier for transmission over the medium. The first method
described is known as
A. Modulation
B. Carrier transmission
C. Baseband transmission
D. Modulation
C. Baseband transmission
Modulation - it is a process of
impressing low-frequency information
signals into a high-frequency carrier
signals.
Baseband Transmission - direct
transmission of information into the
medium without modulation.
These are frequencies generally known
as short waves.
A. MF
B. VLF
C. HF
D. LF
C. HF
VLF - used for submarine
communications
LF - for marine and aerounautical
applications
MF - for AM broadcasting
A German physicist who first
conclusively proved the existence of the
electromagnetic waves.
A. none of these choices
B. James Maxwell
C. Guglielmo Marconi
D. Heinrich Hertz
D. Heinrich Hertz
James Maxwell- predicted
mathematically the existence of
electromagnetic waves through his
equation.
Heinrich Hertz - conclusively proved the existence of the electromagnetic waves predicted by James Clerk Maxwell’s
equation for electromagnetic wave
Guglielmo Marconi - publicly
demonstrated the existence of radio waves through long distance wireless transmission.
Noise uniformly distributed over the voice frequency band is called ___ noise.
A. Intermodulation
B. impulse
C. white
D. impulse
C. white
Impulse noise is characterized by high
amplitude peaks of short duration in the
total noise spectrum Quantizing noise
also known as quantizing error which is
present during pulse amplitude
modulation Intermodulation noise is the
generation of unwanted sum and
difference frequencies in a nonlinear
device
An overmodulated signal will produce undesirable harmonics of modulating frequency known as:
A. spurious emission
B. all of these choices
C. splatter
B. all of these choices
A type of noise that occurs only in
devices where single current separates
into two or more paths.
A. Shot noise
B. Transistor noise
C. Excess noise
B. Transistor noise
Types of Internal Noise
Thermal Agitation (White, Johnson,
Brownian or Gaussian noise)b-
produced by random motion of
electrons in a conductor due to heat.
Shot noise - due to random variations in current flow in active devices such as tubes, transistors, semiconductor diodes, etc.
Partition noise (Transistor noise) - similar to shot noise but occurs only in devices where single current separates into two or more paths.
Excess noise (Modulation, Flicker, Pink
or 1/f noise) - noise power varies
inversely with frequency.
