REM A LVL 1

Question 1

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

Answer 1

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.

Question 2

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

Answer 2

B. 360 times

Question 3

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))

Answer 3

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.

Question 4

Digital data refers to the information
that is

A. discrete
B. None of these choices
C. Discrete or Continuous

Answer 4

A. discrete

Question 5

All causal systems must have the
component of

A. linearity
B. stability
C. time invariance
D. memory

Answer 5

D. memory

Causal systems depend on the
functional value at an earlier time,compelling the system to possess memory.

Question 6

Time scaling operation is also known as
_____

A. None of the mentioned
B. Sampling
C. Up-sampling
D. Down-sampling

Answer 6

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.

Question 7

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

Answer 7

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).

Question 8

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

Answer 8

B. Sampling theorem

Question 9

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

Answer 9

A. continuous sampling square function

Because F.T. of a Triangular function is
square sampling function

Question 10

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.

Answer 10

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.

Question 11

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

Answer 11

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

Question 12

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

Answer 12

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.

Question 13

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.

Answer 13

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.

Question 14

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

Answer 14

C. Region of convergence (ROC)

Question 15

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

Answer 15

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.

Question 16

What is the duration of the unit sample
response of a digital filter?

A. Finite
B. Infinite
C. Zero

Answer 16

B. Infinite

Digital filters are the filters which can be designed from analog filters which have infinite duration unit sample response.

Question 17

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

Answer 17

D. Modeling of desired impulse response

Question 18

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

Answer 18

D. impulse response

Question 19

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

Answer 19

D. 2π/M

In the frequency sampling technique,
the transition band is a multiple of 2n/M

Question 20

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

Answer 20

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.

Question 21

What is the duration of the unit sample
response of a digital filter?

A. Impulse(very small)
B. Zero
C. Finite
D. Infinite

Answer 21

D. Infinite

Digital filters are the filters which can be
designed

Question 22

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.

Answer 22

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

Question 23

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

Answer 23

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.

Question 24

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

Answer 24

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.

Question 25

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

Answer 25

C. Window design The major disadvantage of the window design method is the lack of precise control of the critical frequencies.

Question 26

He began the development of antennas practical for long-distance, wireless telegraphy. A. James Maxwell B. none of these choices C. Guglielmo Marconi

Answer 26

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.

Question 27

__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

Answer 27

A. channel bandwidth

Question 28

These are frequencies used in two-way or amateur radio CB communications. A. LF B. VLF C. MF D. HF

Answer 28

D. HF

Question 29

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

Answer 29

C. the maximum rate of information transmission depends on the channel bandwidth

Question 30

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

Answer 30

C. Distortion

Question 31

Which of the following is not used for communication A. Microwaves B. X-rays C. Millimeter waves

Answer 31

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

Question 32

The frequency band used by cellular telephones and mobile communication services is _____ A. EHF B. VLF C. VHF D. UHF

Answer 32

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.

Question 33

A quarter period for an electromagnetic wave is equivalent to _ phase shift: A. 360 degrees B. 90 degrees C. 180 degrees D. 45 degrees

Answer 33

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.

Question 34

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

Answer 34

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.

Question 35

These are frequencies generally known as short waves. A. MF B. VLF C. HF D. LF

Answer 35

C. HF VLF - used for submarine communications LF - for marine and aerounautical applications MF - for AM broadcasting

Question 36

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

Answer 36

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.

Question 37

Noise uniformly distributed over the voice frequency band is called ___ noise. A. Intermodulation B. impulse C. white D. impulse

Answer 37

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

Question 38

An overmodulated signal will produce undesirable harmonics of modulating frequency known as: A. spurious emission B. all of these choices C. splatter

Answer 38

B. all of these choices

Question 39

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

Answer 39

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.

Question 40

Which of the following could be a source of industrial noise? A. switching equipment B. high voltage lines leakage C. fluorescent lamps D. all of these choices

Answer 40

D. all of these choices Industrial noise - These are man-made noise usually most intense in industrial and densely populated areas. This noise are commonly generated by automobile& aircraft ignition, electric motors & switching equipment, leakage from high voltage lines, fluorescent lamps etc.

Question 41

Which of the following is an internal type of uncorrelated noise? A. all of these choices B. Thermal Noise C. Shot Noise D. Partition Noise

Answer 41

A. all of these choices Internal Uncorrelated Noise: Thermal Agitation Noise - This type of noise is produced by random motion of electrons in a conductor due to heat. Other names for this noise are, Brownian noise, Johnson noise, Random noise, White noise, or Gaussian noise. The noise intensity of thermal noise is uniformly distributed to the entire electromagnetic spectrum thus named White noise. Shot Noise - This type of noise is due to random variations in the current flow in an active device. e.g. tubes, transistors,semiconductor diodes, etc. Partition Noise - Similar to shot noise but occurs only in devices where a single current separates into two or more paths.

Question 42

Which of the following does not affect noise power? A. temperature B. bandwidth C. all of these choices D. frequency

Answer 42

D. frequency Thermal Noise Power Equation: N=kTB Where: N = noise power in Watts T= temperature in Kelvin B= bandwidth in Hertz k=Boltzmann's constant= 1.38064852 ×10^-23 JK^-1 (constant 25 in your calculator) Based on the Noise Power formula above, only the temperature and the bandwidth affect the noise power, not the frequency.

Question 43

Solar noise is an electrical disturbance due to the solar cycle activities of our sun. This solar cycle repeats its pattern every ______ A. 11 years B. 21 months C. 11 months D. 11 months

Answer 43

A. 11 years Solar noise is cause by the constant noise radiation from the sun. It is an electrical disturbance due to the solar cycle activities. This solar cycle repeats its pattern every 11 years. Extraterrestrial noise - These are noise coming from the outer space such as our sun and distant stars. There are two types of this noise, the solar noise and the cosmic noise. Cosmic noise - are RF noise radiated by distant stars several lightyears away from earth. The noise intensity of cosmic noise are relatively small compared to solar noise because of the considerable distance from the source.Cosmic noise is also called Black Body noise.

Question 44

"Man-made" noise can come from: A. Static B. Temperature C. all of the other choices D. equipment that sparks

Answer 44

D. equipment that sparks

Question 45

One of the following types of noise becomes of great importance at high frequencies. A. shot noise B. transit-time noise C. random noise

Answer 45

B. transit-time noise Transit-time noise (High-frequency noise) - any modification to a stream of carriers as they pass from input to output of a device produces an irregular, random variation. Its greatest effect is in Microwave region.

Question 46

This type of noise is due to random variations in the current flow in an active device. A. Partition Noise B. Shot Noise C. Thermal Agitation Noise

Answer 46

B. Shot Noise Shot Noise - This type of noise is due to random variations in the current flow in an active device. e.g. tubes, transistors,semiconductor diodes, etc. Thermal Agitation Noise - This type of noise is produced by random motion of electrons in a conductor due to heat. Other names for this noise are, Brownian noise, Johnson noise, Random noise, White noise, or Gaussian noise. The noise intensity of thermal noise is uniformly distributed to the entire electromagnetic spectrum thus named White noise. Partition Noise - Similar to shot noise but occurs only in devices where a single current separates into two or more paths.

Question 47

Noise in a communication system originates in: A. the receiver B. the sender C. the channel D. all of these choices

Answer 47

D. all of these choices

Question 48

White noise differs from pink noise, why? A. because in white noise, there is a constant energy at any frequency end of the spectrum B. because in pink noise, there is proportionately more energy at the high frequency end of the spectrum

Answer 48

A. because in white noise, there is a constant energy at any frequency end of the spectrum White noise - the noise intensity of thermal noise is uniformly distributed to the entire electromagnetic spectrum. Pink Noise - there is proportionately more energy at the low frequency end of the spectrum.

Question 49

These are noise coming from the outer space such as our sun and distant stars. A. atmospheric noise B. extraterrestrial noise C. cosmic noise D. solar noise

Answer 49

B. extraterrestrial noise These are some types of External Uncorrelated Noise: Extraterrestrial noise - These are noise coming from the outer space such as our sun and distant stars. There are two types of this noise, the solar noise and the cosmic noise. Atmospheric noise - It is caused by lightning discharges in thunderstorms and is often called static noise. Solar noise - is cause by the constant noise radiation from the sun. It is an electrical disturbance due to the solar cycle activities. This solar cycle repeats its pattern every 11 years.

Question 50

Which term is used to refer to the condition where the signals from a very strong station are superimposed on other signals being received? A. Inter-modulation distortion B. Receiver quieting C. Cross-modulation interference D. Capture Effect

Answer 50

C. Cross-modulation interference

Question 51

Any modification to a stream of carriers as they pass from input to output of a device produces an irregular, random variation called: A. Partition Noise B. Transit Time Noise C. Thermal Agitation Noise D. Excess Noise

Answer 51

B. Transit Time Noise Transit Time Noise -This noise is a result of the production of an irregular,random vibration that is caused by the modification to a stream of carriers as they pass from input to output of a device. Excess Noise - This type of noise is also called Flicker Noise or 1/f Noise because the noise power varies inversely with frequency. This noise is called Pink Noise because there is proportionately more energy at the low frequency end of the spectrum. Partition Noise - Similar to shot noise but occurs only in devices where a single current separates into two or more paths. Thermal Agitation Noise - This type of noise is produced by random motion of electrons in a conductor due to heat. Other names for this noise are, Brownian noise, Johnson noise, Random noise, White noise, or Gaussian noise.

Question 52

It is a form of amplitude modulation in which the carrier and one complete sideband is transmitted, but only part of the second sideband is transmitted. A. ISB B. VSB C. lincompex D. SSBSC

Answer 52

B. VSB

Question 53

Occurs when different frequencies undergo different phase shifts and ay have a detrimental effect on a complex waveform A. Absolute Phase Shift B. Differential Phase Shift C. Insertion Loss D. None of these choices

Answer 53

B. Differential Phase Shift Absolute Phase Shift - The total phase shift encountered by a signal and can generally be tolerated as long as all frequencies undergo the same amount of phase delay Differential Phase Shift - Occurs when different frequencies undergo different phase shifts and ay have a detrimental effect on a complex waveform Insertion Loss - the ratio of the power transferred to a load with a filter in the circuit to the power transferred to a load without the filter

Question 54

The circuit where the carrier is reinserted is called A. Bandwidth circuit B. Carrier circuit C. Linear summer

Answer 54

C. Linear summer Linear summer is the circuit where the carrier is reinserted.

Question 55

What configuration is used in AM amplifiers? A. Common Collector B. Common Base C. Emitter-Follower D. Common Emitter

Answer 55

B. Common Base Common-base configuration (cascode) is used in AM amplifiers since it can operate in high frequencies, common- emitter is not used due to its high miller effect at high frequency of operation.

Question 56

A balanced modulator that is constructed with diodes and transformers. Sometimes called balanced lattice modulator. A. Balanced Ring Modulator B. Balanced Modulator C. DSBSC Modulator

Answer 56

A. Balanced Ring Modulator AM Modulator - A product modulator where the output signal is the product of the modulating signal and the carrier. DSBSC Modulator - Modulator circuits that inherently remove the carrier during the modulation process. Balanced Modulator - A circuit that produces a double-sideband suppressed-carrier signal. Balanced Ring Modulator - A balanced modulator that is constructed with diodes and transformers. Sometimes called balanced lattice modulator.

Question 57

In FM, it is the ratio of the maximum deviation over the maximum modulating frequency. A. Percentage Modulation B. Deviation Ratio C. Modulation Index D. Frequency Deviation

Answer 57

B. Deviation Ratio Frequency Deviation - the amount of change in carrier frequency produced by the modulating signal. Modulation Index - it is the ratio of deviation and the modulating signal. Deviation Ratio - it is the ratio of the maximum deviation over the maximum modulating frequency. Percentage Modulation - the percentage value of the actual and maximum frequency deviation.

Question 58

A modulation where the information is impressed onto the carrier in the form of frequency or phase variations A. None of these choices B. Frequency Modulation C. Angle Modulation D. Amplitude Modulation

Answer 58

C. Angle Modulation In angle modulation, the information is impressed onto the carrier in the form of frequency or phase variations.

Question 59

The L-R stereo channel in FM broadcasting is between A. 23 kHz to 53 kHz B. 50 Hz to 15 kHz C. 60 kHz to 74 kHz

Answer 59

A. 23 kHz to 53 kHz

Question 60

A ring modulator is used in A. Detection of SSB-SC B. Generation of SSB-SC C. Detection of SSB -SD D. Detection of DSB -SC

Answer 60

A. Detection of SSB-SC A Balanced modulator is used to generate a DSB -SC wave. It consists of two AM modulators in a balanced configuration to suppress the carrier signal.

Question 61

A form of amplitude modulation in which a single carrier frequency is independently modulated by two different modulating signals. A. None of these choices B. AM Single-sideband Reduced Carrier （SSBRC) C. AM Independent Sideband (ISB) D. None of these choices

Answer 61

C. AM Independent Sideband (ISB) AM Independent Sideband (ISB) - A form of amplitude modulation in which a single carrier frequency is independently modulated by two different modulating signals. AM Vestigial Sideband (VSB) - A form of amplitude modulation in which the carrier and one complete sideband are transmitted, but only part of the second sideband is transmitted. AM Single-sideband Reduced Carrier (SSBRC) - A form of amplitude modulation in which one sideband is totally removed and the carrier voltage is reduced to approximately 10% of its unmodulated amplitude. Sometimes called single-sideband reinserted carrier.

Question 62

A circuit that produces a double- sideband suppressed-carrier signal. A. DSBSC Modulator B. AM Modulator C. Balanced Ring Modulator D. Balanced Modulator

Answer 62

D. Balanced Modulator AM Modulator - A product modulator where the output signal is the product of the modulating signal and the carrier. DSBSC Modulator - Modulator circuits that inherently remove the carrier during the modulation process. Balanced Modulator - A circuit that produces a double-sideband suppressed-carrier signal. Balanced Ring Modulator - A balanced modulator that is constructed with diodes and transformers. Sometimes called balanced lattice modulator.

Question 63

In an FM stereo multiplex transmission, the A. difference signal modulates the 38-kHz subcarrier B. a sum signal modulates the 19-kHz subcarrier C. difference signal modulates the 19-kHz subcarrier D. difference signal modulates the 67-kHz subcarrier

Answer 63

A. difference signal modulates the 38-kHz subcarrier

Question 64

What kind of filter would you use to attenuate an interfering carrier signal while receiving an SSB transmission? A. A notch filter B. An all pass filter C. A non pass filter

Answer 64

A. A notch filter The problem presented here is an offending signal within the receiver passband (the range of frequencies allowed though the Intermediate Frequency chain). A 'Notch Filter' which attenuates a very narrow range of frequencies can be used to remove the interfering carrier.

Question 65

A condition in double-sideband transmission where one sideband is significantly attenuated. A. Sideband B. Phase shift C. Sideband fading D. Headband fading

Answer 65

C. Sideband fading Sideband fading is a condition in double-sideband transmission where one sideband is significantly attenuated.

Question 66

Modulator circuits that inherently remove the carrier during the modulation process. A. Balanced Modulator B. AM Modulator C. Balanced Ring Modulator D. DSBSC Modulator E. Balanced Court Modulation

Answer 66

D. DSBSC Modulator AM Modulator - A product modulator where the output signal is the product of the modulating signal and the carrier. DSBSC Modulator - Modulator circuits that inherently remove the carrier during the modulation process. Balanced Modulator - A circuit that produces a double-sideband suppressed-carrier signal. Balanced Ring Modulator - A balanced modulator that is constructed with diodes and transformers. Sometimes called balanced lattice modulator.

Question 67

A form of amplitude modulation in which the carrier is totally suppressed and one of the sidebands removed. A. AM Single-sideband Reduced Carrier (SSBRC) B. AM Single-sideband Suppressed Carrier (SSBSC) C. Pilot Carrier D. AM Single-sideband Full Carrier (SSBFC) E. AM Single-sideband Reduced Carrier (SSBRC)

Answer 67

B. AM Single-sideband Suppressed Carrier (SSBSC) AM Single-sideband Full Carrier (SSBFC) - A form of amplitude modulation in which the carrier is transmitted at full power but only one of the sidebands is transmitted. AM Single-sideband Suppressed Carrier (SSBSC) - A form of amplitude modulation in which the carrier is totally suppressed and one of the sidebands removed. AM Single-sideband Reduced Carrier (SSBRC) - A form of amplitude modulation

Question 68

A "frequency synthesizer" is: A. a VFO with selectable crystals to change frequency B. a VCO phase-locked to a reference frequency C. a fixed-frequency RF generator

Answer 68

B. a VCO phase-locked to a reference frequency

Question 69

Modulation is required A. All of these choices B. To make the low frequency signals travel long distance C. To transmit electrical signals over an antenna through free space

Answer 69

A. All of these choices Modulation is the process of combining signal and radio frequency. It is needed to match the characteristics of the input signal to that of channel characteristics.Low frequency signals can be multiplexed with high-frequency signals to travel long distances. Some modulation technique reduces the effect of noise on the signal.

Question 70

The total phase shift encountered by a signal and can generally be tolerated as long as all frequencies undergo the same amount of phase delay A. None of these choices B. Differential Phase Shift C. Absolute Phase Shift D. Insertion Loss

Answer 70

C. Absolute Phase Shift Absolute Phase Shift - The total phase shift encountered by a signal and can generally be tolerated as long as all frequencies undergo the same amount of phase delay Differential Phase Shift - Occurs when different frequencies undergo different phase shifts and ay have a detrimental effect on a complex waveform Insertion Loss - the ratio of the power transferred to a load with a filter in the circuit to the power transferred to a load without the filter

Question 71

What can be done to keep a CW transmitter from chirping? A. Keep the power supply current very steady B. Keep the power supply voltages very steady C. Add a low pass filter D. Add a key-click filter

Answer 71

B. Keep the power supply voltages very steady "Chirp": Inadequate voltage regulation causes the Master Oscillator frequency to shift when the Telegraph Key is pressed. Perceived at the receive location as a change of pitch during each Morse element. Current varies as demand varies in a transmitter. Low- Pass filter reduces 'harmonics'.

Question 72

The typical voltage-versus-frequency response curve for a Foster-Seeley discriminator A. L-curve B. V-curve C. None of these choices D. S-curve

Answer 72

D. S-curve The typical voltage-versus-frequency response curve for a Foster-Seeley discriminator is the S-curve.

Question 73

Sometimes called a phase shift discriminator that is a tuned-circuit frequency discriminator whose operation is very similar to that of a balanced slope detector A. Slope Detector B. Balanced Slope Detector C. Foster-Seeley Discriminator

Answer 73

C. Foster-Seeley Discriminator Tuned-Circuit Frequency Discriminators - Circuits that convert FM to AM and then demodulate the AM envelope with conventional peak detectors Slope Detector - tuned-circuit frequency discriminator that has the most nonlinear voltage-versus- frequency characteristics Balanced Slope Detector - simply two single-ended slope detectors connected in parallel and fed 180° out of phase Foster-Seeley Discriminator - a phase shift discriminator that is a tuned-circuit frequency discriminator whose operation is very similar to that of a balanced slope detector

Question 74

In these receivers, the voltage at the output of the audio detector is directly proportional to the frequency deviation at its input. A. FM Receivers B. PM Receivers C. AM Receivers D. Noon E. All of these choices F. None of these choices

Answer 74

A. FM Receivers FM Receivers - the voltage at the output of the audio detector is directly proportional to the frequency deviation at its input PM Receivers - the voltage at the output of the audio detector is directly proportional to the phase deviation at its input

Question 75

Is simply two single-ended slope detectors connected in parallel and fed 180° out of phase A. Slope Detector B. Foster-Seeley Discriminator C. Balanced Slope Detector D. Tuned-Circuit Frequency Discriminators

Answer 75

C. Balanced Slope Detector Tuned-Circuit Frequency Discriminators - Circuits that convert FM to AM and then demodulate the AM envelope with conventional peak detectors Slope Detector - tuned-circuit frequency discriminator that has the most nonlinear voltage-versus- frequency characteristics Balanced Slope Detector - simply two single-ended slope detectors connected in parallel and fed 180° out of phase Foster-Seeley Discriminator - a phase shift discriminator that is a tuned-circuit frequency discriminator whose operation is very similar to that of a balanced slope detector

Question 76

A tuned-circuit frequency discriminator that has the most nonlinear voltage- versus-frequency characteristics A. Tuned-Circuit Frequency Discriminators B. Slope Detector C. Foster-Seeley Discriminator D. Balanced Slope Detector

Answer 76

B. Slope Detector Tuned-Circuit Frequency Discriminators - Circuits that convert FM to AM and then demodulate the AM envelope with conventional peak detectors Slope Detector - tuned-circuit frequency discriminator that has the most nonlinear voltage-versus- frequency characteristics Balanced Slope Detector - simply two single-ended slope detectors connected in parallel and fed 180° out of phase Foster-Seeley Discriminator - a phase shift discriminator that is a tuned-circuit frequency discriminator whose operation is very similar to that of a balanced slope detector

Question 77

Coherent receivers are also known as A. asynchronous B. sensitive C. insensitive D. synchronous

Answer 77

D. synchronous Coherent receiver or also known as synchronous receiver. Non-coherent receiver or asynchronous receiver or envelope detector.

Question 78

Which of the following is the simplest form of tuned-circuit frequency discriminator? A. PLL detector B. Slope detector C. Ratio detector D. Foster-Seeley discriminator

Answer 78

B. Slope detector

Question 79

___ limit the bandwidth of the local loop to 4 KHz. A. Repeaters B. All Pass Filters C. Hubs D. Filters

Answer 79

D. Filters

Question 80

A frequency-independent device comprising three or more ports used to combine two or more signals. It is identical to a splitter, except for the direction of use. A. Directional coupler B. Combiner C. Combination D. Bridger

Answer 80

B. Combiner

Question 81

___ is suitable for businesses that require comparable upstream and downstream data rates. A. ADSL B. VDSL C. SDSL D. VDSL and ADSL

Answer 81

C. SDSL

Question 82

Defined as the ratio of the power transferred to a load with a filter in the circuit to the power transferred to a load without the filter A. Insertion Loss B. Absolute Phase Shift C. Insertion Phase Shift D. Differential Phase Loss E. Differential Phase Shift

Answer 82

A. Insertion Loss Absolute Phase Shift - The total phase shift encountered by a signal and can generally be tolerated as long as all frequencies undergo the same amount of phase delay Differential Phase Shift - Occurs when different frequencies undergo different phase shifts and ay have a detrimental effect on a complex waveform Insertion Loss - the ratio of the power transferred to a load with a filter in the circuit to the power transferred to a load without the filter

Question 83

___ has a higher transmission rate in the downstream direction than in the upstream direction. A. SDSL B. ADSL C. VDSL and ADSL D. ADSL

Answer 83

C. VDSL and ADSL

Question 84

A(n)_ signal is a composite analog signal with an infinite bandwidth. A. Digital B. Analog C. Neither digital nor analog D. Either digital or analog

Answer 84

A. Digital

Question 85

The portion of the distribution plant between the tap and the individual subscribers home. A. Backbone B. Drop C. Distribution

Answer 85

B. Drop

Question 86

A three-port device for unequally dividing signal between two paths. Can also be used to combine signals with more loss in one input than in the other,with the signal from the high-loss port being routed to only one of the other two ports. A. Directional coupler B. Diplex filter C. Bridger D. Combiner

Answer 86

A. Directional coupler

Question 87

The portion of the coaxial subnetworks that starts at an amplifier fed by an express feeder or trunk and supplies signals directly to subscriber taps. A. Backbone B. Feeder C. Distribution D. Briger

Answer 87

B. Feeder

Question 88

When propagation speed is multiplied by propagation time, we get the ___ A. distance a signal or bit has traveled B. distortion factor C. wavelength of the signal D. distance a signal or bit has stayed E. wavelength of the frequency

Answer 88

A. distance a signal or bit has traveled

Question 89

It is defined as the difference in decibels between the minimum input level necessary to discern a signal and the input level that will overdrive the receiver and produce distortion. A. fidelity B. threshold C. dynamic range D. blocking

Answer 89

C. dynamic range Blocking is a reduction in sensitivity to the desired signal Threshold is the another name for sensitivity Fidelity is a measure of the ability of a communications system to produce the output of the receiver an exact replica of the original source of information

Question 90

The frequency of an SCA channel subcarrier A. 38 kHz B. 67 kHz C. 53kHz

Answer 90

B. 67 kHz

Question 91

Baseband transmission of a digital signal is possible only if we have a ___ channel. A. low-pass B. low rate C. bandpass D. high rate

Answer 91

A. low-pass

Question 92

Morse code is usually transmitted by radio as: A. a series of key-clicks B. an interrupted carrier C. a continuous carrier

Answer 92

B. an interrupted carrier Telegraphy is equivalent to 'on-off keying' (an 'interrupted carrier). The Telegraph Key allows the operator to send bursts of RF energy to the antenna per the rhythm of his hand movement on the key. Key-Clicks is a type of interference where a CW signal generates unwanted sidebands.

Question 93

Also known as lock range A. tracking range B. natural frequency C. free-running frequency

Answer 93

A. tracking range Capture range is also known as acquisition range Free-running frequency is the default frequency of the VCO of a phase-locked loop

Question 94

The difference between DC input power and RF output power of a transmitter RF amplifier: A. radiates from the antenna B. appears as heat dissipation C. is lost in the feed line D. is due to oscillating

Answer 94

B. appears as heat dissipation Power Amplifiers have a certain lefficiency', the ratio of DC power required to obtain an RF output. The difference goes up in heat. This is the reason for the 'heat sinks' on the back of transmitters.

Question 95

A system satisfying both linearity and time invariant conditions are called A. Boxcar B. LTI C. Cascade

Answer 95

B. LTI

Question 96

It is the ratio of the power transferred to the load with the filter in the circuit to the power transferred to the load without the filter. A. coupling loss B. attenuation C. fading D. insertion loss

Answer 96

D. insertion loss Coupling loss also known as connector loss Fading is a reduction in signal strength Attenuation is a reduction of signal strength due to spreading of waves

Question 97

The largest portion of the bandwidth for ADSL carries ___ A. Voice Communication B. Control data C. Upstream data D. Downstream data

Answer 97

D. Downstream data

Question 98

___ was designed as an alternative to the T-1 line. A. ADSL B. HDSL C. SDSL D. VSL

Answer 98

B. HDSL