AM-FM-PHASE-MODULATION-NOISE PROBLEMS

He is recognized as the Father of Electromagnetism
a. Joseph Henry
b. Andre Marie Ampere
c. Hans Christian Oersted
d. Michael Faraday

d. Michael Faraday

An American scientist who discovered electromagnetic self-induction. He was a pioneer of modern forecasting techniques.
a. Joseph Henry
b. Andre Marie Ampere
c. Hans Christian Oersted
d. Michael Faraday

a. Joseph Henry

He discovered Photoelectricity through a photosensitive element, Selenium, that could carry current in direct proportion to the amount of light that struck it.
a. Jonas Jacob Berzelius
b. Charles Babbage
c. James Maxwell
d. Michael Faraday

d. Michael Faraday

The Father of Electrodynamics who exposed the phenomenon of electromagnetism following the discovery of magnet needle by Oersted.
a. Joseph Henry
b. Andre Marie Ampere
c. James Maxwell
d. Michael Faraday

b. Andre Marie Ampere

The range of frequencies represented in a signal.
a. Beam width
b. Crisp
c. Guard band
d. Bandwidth

d. Bandwidth

It refers to the sending, receiving, and processing of information by electronic means.
a. Communications
b. Telemetry
c. Telephony
d. Broadcasting

a. Communications

The big breakthrough in electronics communications came with the invention of the ____________ in 1844.
a. Transistor
b. Phonograph
c. Telegraph
d. Telephone

c. Telegraph

Term for transmission of printed picture by radio (ECE Board April 1998).
a. Facsimile
b. ACSSB
c. Xerography
d. Television

a. Facsimile

A Scottish physicist who established the Theory of Radio or Electromagnetism which held that rapidly oscillating electromagnetic waves exist and travel at the speed of light.
a. James Maxwell
b. Andre Marie Ampere
c. Hans Christian Oersted
d. Michael Faraday

a. James Maxwell

The first words transmitted over the telephone.
a. Mr. Watson, come here, I want you
b. What God has wrought
c. This is the day
d. None of these

a. Mr. Watson, come here, I want you

Most of the communications receiver is in form of ____________ type.
a. Superheterodyne
b. TRF
c. Single-ended
d. High level

a. Superheterodyne

He was the one who developed the wireless telegraph.
a. Edison
b. Armstrong
c. Marconi
d. Bell

c. Marconi

He invented the first practical Multiplex Telegraph and another type of telegraphy codes which consisted of pre-arranged 5-unit dot pulse patterns. This multiplexer allowed signals of up to 6 different telegraph machines to be transmitted over a single wire pair.
a. JM Emile Baudot
b. AC Cowper
c. Thomas Edison
d. Thomas Doolittle

a. JM Emile Baudot

Introduced the first Facsimile Machine or writing telegraph using stylus.
a. JM Emile Baudot
b. AC Cowper
c. Thomas Edison
d. Alexander Graham Bell

Answer: b. AC Cowper

Invented the Microphone transmitter using platinum point bearing against a hard carbon surface.
a. Francis Blake
b. Thomas Watson
c. Thomas Doolittle
d. Henry Hunnings

a. Francis Blake

What type of field does Faraday shield stop?
a. Common
b. Array
c. Electrostatic
d. Magnetostatic

c. Electrostatic

Which of the following is not normally tested in a transmitter?
a. Power
b. Modulation
c. Frequency
d. Amplitude

d. Amplitude

What other term is essentially synonymous with beating?
a. Heterodyning
b. Scrambling
c. Filtering
d. Suppressing

a. Heterodyning

Term in Communication that is referred to “to send in all directions”.
a. Announce
b. Broadcast
c. Transmit
d. Media

b. Broadcast

Invented the telephone transmitter using granular carbon and thin platinum diaphragm and a gold-plated electrode.
a. Nikola Tesla
b. Henry Hunnings
c. Thomas Watson
d. AC Cowper

c. Thomas Watson

He introduced the Dial Switching System, transmitting the desired telephone number electrically without the assistance of a human telephone operator.
a. Thomas Edison
b. Almon Strowger
c. JJ Thomson
d. Lee De Forest

b. Almon Strowger

An Italian physicist who invented the first wireless telegraph, initially transmitting messages over a distance of 1 mile but later improved it to 8000 miles in 1902. He also made the first successful transatlantic radio transmission.
a. Francis Blake
b. Ernst Alexanderson
c. KF Braun
d. Guglielmo Marconi

Answer: d. Guglielmo Marconi

The Father of Quantum Theory. He introduced the revolutionary idea that the energy emitted by an oscillator could take only on discrete values or quanta.
a. Guglielmo Marconi
b. John Fleming
c. Max Karl Ernst Ludwig Planck
d. Christian Hulsmeyer

c. Max Karl Ernst Ludwig Planck

Who developed the CRT capable of tracing curves on phosphor screen?
a. John Fleming
b. Max Karl Ernst Ludwig Planck
c. KF Braun
d. Christian Hulsmeyer

c. KF Braun

He invented the superheterodyne receiver.
a. Edwin Armstrong
b. Alec Reeves
c. Veldemar Poulsen
d. Boris Rosing

a. Edwin Armstrong

He developed a simple radio echo device to prevent ship collisions. He was considered as the forerunner of RADAR.
a. Veldemar Poulsen
b. Christian Hulsmeyer
c. Boris Rosing
d. Reginald Fessenden

b. Christian Hulsmeyer

Who invented the Pulse Code Modulator for digital encoding of PCM signals?
a. Alec Reeves
b. Edwin Armstrong
c. Boris Rosing
d. Reginald Fessenden

a. Alec Reeves

He was the one who developed the mathematical solution to a complex repetitive waveform.
a. Carson
b. P. H. Smith
c. J. Fourier
d. Y. Uda

c. J. Fourier

The volume of transaction proceed in a specific unit of time.
a. Response time
b. Throughout
c. Availability
d. Reliability

b. Throughout

____________ is a device that measures the internal open circuit voltage of an equivalent noise generator having an impedance of 600 ohms and delivering noise power to a 600-ohms load.
a. Phosphometer
b. Barometer
c. Reflectometer
d. Voltmeter

d. Voltmeter

Modulation is used to:
a. Increase the carrier power
b. Reduce the bandwidth used
c. Allow the use of practical antennas
d. Shorten the transmission channel

c. Allow the use of practical antennas

Modulation is done at the:
a. Transmitter
b. Receiver
c. Channel
d. Antenna

a. Transmitter

In an AM wave, useful power is carried by:
a. The sidebands
b. The carrier
c. Both
d. Either

a. The sidebands

Which could not be used to remove unwanted sideband in SSB?
a. Filter Method
b. Phase–Shift Method
c. Third Method
d. Balanced Modulator

d. Balanced Modulator

In amplitude modulation, the ____________ of the carrier is varied.
a. Amplitude
b. Phase
c. Frequency
d. Period

a. Amplitude

The output of a balanced modulator is:
a. USB and LSB
b. LSB
c. USB
d. Carrier

a. USB and LSB

A 900 kHz carrier is AM modulated with a 4000 Hz audio tone. What are the lower and upper sideband frequencies?
a. 450 and 1800 kHz
b. 800 and 1000 kHz
c. 896 and 904 kHz
d. 4000 and 8000 kHz

c. 896 and 904 kHz

The HF band covers the frequency range:
a. 3–30 MHz
b. 30–300 MHz
c. 30–300 kHz
d. 300 kHz–3 MHz

a. 3–30 MHz

In AM, if peak signal is 0.5V and carrier peak is 1V, what is the depth of modulation?
a. 25%
b. 50%
c. 75%
d. 78.5%

b. 50%

In a communications system, noise most affects the signal at the:
a. Transmitter
b. Channel
c. Information source
d. Destination

b. Channel

Another term for Amplitude Modulation is:
a. DSBSC
b. SSBSC
c. DSBFC
d. SSBFC

c. DSBFC (Double Sideband Full Carrier)

Bandwidth of an AM transmitter if carrier = 1000 kHz and modulation frequency varies from 1 kHz to 10 kHz?
a. 2000 kHz
b. 2 kHz
c. 20 kHz
d. 20.1 kHz

c. 20 kHz

If the modulation index of an AM wave increases from 0 to 1, the transmitter power will be:
a. Unchanged
b. Increased by 50%
c. Increased by 100%
d. Decreased by 50%

b. Increased by 50%

When modulation index = 1, the amplitude of carrier is ____________ the modulating signal.
a. Greater than
b. Equal to
c. Less than
d. Double

b. Equal to

Overmodulation results in:
a. Weakening of the signal
b. Excessive carrier power
c. Distortion
d. Either a or b

c. Distortion

If AM modulation index is 0.80, the % modulation is:
a. 20%
b. 80%
c. 0.80
d. 0.20

b. 80%

Both frequency and phase modulation are types of ____________ modulation.
a. Phase
b. Amplitude
c. Digital
d. Angle

d. Angle

The maximum percentage modulation without distortion in AM is:
a. 20%
b. 50%
c. 110%
d. 100%

d. 100%

Form of AM where carrier is transmitted at full power but only one sideband is transmitted?
a. SSBFC
b. SSBSC
c. DSBFC
d. DSBSC

a. SSBFC

Emission with only one sideband transmission?
a. A3E
b. J3E
c. 11BE
d. H3E

b. J3E

Which of the following is NOT an advantage of FM over AM?
a. Better noise immunity
b. Lower bandwidth required
c. Transmitted power is useful
d. Less modulating power

• FM actually requires higher bandwidth

• Answer: b. Lower bandwidth required

In an FM Stereo Multiplex transmission, the:
a. Sum signal modulates the 19 kHz subcarrier
b. Difference signal modulates the 67 kHz subcarrier
c. Difference signal modulates the 38 kHz subcarrier
d. Difference signal modulates the 19 kHz subcarrier

• 38 kHz is for difference signal

• Answer: c. Difference signal modulates the 38 kHz subcarrier

When modulating frequency is doubled, the modulation index is halved. What is the modulation system?
a. AM
b. PAM
c. FM
d. PM

Pre-emphasis and de-emphasis are used in FM stereo multiplex to improve:
a. SWR
b. Power ratio
c. S/N
d. CMMR

• Increases signal-to-noise ratio

• Answer: c. S/N

The commercial FM radio broadcast band is:
a. 535 – 1605 kHz
b. 27 – 29 kHz
c. 88 – 108 MHz
d. 300 – 3000 MHz

• Standard FM broadcast is 88 to 108 MHz

• Answer: c. 88 – 108 MHz

For an FM broadcast station, the maximum deviation by audio modulation is 45 kHz. What is the percent modulation?
a. 10
b. 45
c. 60
d. 100

• 45 kHz out of 75 kHz max deviation = 60%

• Answer: c. 60

The modulation index of an FM signal is half if the modulating frequency is:
a. Doubled
b. Halved
c. Increased
d. Decreased

• If fmfmfm doubles, mfmfmf halves

• Answer: a. Doubled

An FM signal passed through a frequency tripler will have modulation index of:
a. mf/3
b. mf
c. 3mf
d. 9mf

• Multiplied by 3

• Answer: c. 3mf

Which of the following is an indirect method of generating FM?
a. Reactance FET Modulator
b. Varactor Diode Modulator
c. Armstrong Modulator
d. Reactance BJT Modulator

• Armstrong method uses phase modulation to create FM

• Answer: c. Armstrong Modulator

What is the deviation ratio for the station in the commercial FM broadcast band?
a. 5.5
b. 5
c. 4
d. 6

• Standard deviation ratio is 5

• Answer: b. 5

What frequency deviation is needed for 80% modulation in FM broadcast?
a. 75 kHz
b. 75 MHz
c. 60 kHz
d. 60 MHz

• 80% of 75 kHz = 60 kHz

• Answer: c. 60 kHz

In FM, noise affecting amplitude can be eliminated using:
a. Oscillator
b. Integrator
c. FM limiter circuit
d. Differentiator

• Limiter removes amplitude variations

• Answer: c. FM limiter circuit

In FM, if a carrier is modulated by a single frequency, the number of sidebands produced is:
a. 1
b. 2
c. 3
d. Greater than 3

• FM generates infinite sidebands theoretically

• Answer: d. Greater than 3

Maximum frequency deviation of standard FM broadcast station?
a. 25 kHz
b. 40 kHz
c. 75 kHz
d. 200 kHz

• Maximum allowed deviation = 75 kHz

• Answer: c. 75 kHz

The modulation index of an FM signal with 100 kHz swing and 2 kHz modulating frequency?
a. 75
b. 25
c. 50
d. 0.5

• Swing/2 = deviation 50 kHz / 2kHz = 50

• Answer: c. 50

In FM stereophonic transmission, suppressed subcarrier frequency is:
a. 19 kHz
b. 67 kHz
c. 38 kHz
d. 69 kHz

• 38 kHz is the suppressed carrier

• Answer: c. 38 kHz

Maximum FM deviation is 75 kHz; max modulating frequency is 15 kHz. What is max bandwidth?
a. 180 kHz
b. 160 kHz
c. 140 kHz
d. 90 kHz

An FM signal passed through a mixer reducing frequency fivefold. Output deviation is:
a. 5δ
b. Indeterminate
c. δ/5
d. δ

• Deviation is divided by 5

• Answer: c. δ/5

Permissible maximum modulating index range for commercial FM (30 Hz–15 kHz)?
a. 5 and 2500
b. 50 and 250
c. 50 and 2500
d. 5 and 50

• FCC allows 50–2500 modulation index

• Answer: c. 50 and 2500

Carrier swing necessary for 80% modulation in FM broadcast band?
a. 150 kHz
b. 120 kHz
c. 75 kHz
d. 60 kHz

• 80% of 75 kHz swing = 60 kHz

• Answer: d. 60 kHz

Modulation means ____________.
a. Varying carrier parameters like amplitude to transmit info
b. Transmit pulses in DC form over copper wire
c. Varying information
d. Utilization of a single transmission channel

• Modulation varies carrier parameters to carry information

• Answer: a. Varying carrier parameters like amplitude to transmit info

The modulation system used for telegraphy is ____________.
a. Single tone modulation
b. Two-tone modulation
c. Frequency-shift keying (FSK)
d. Pulse code modulation (PCM)

• Telegraphy uses frequency-shift keying

• Answer: c. Frequency-shift keying (FSK)

A process that occurs in the transmitter.

a. Demodulation

b. Modulation

c. Mixing

d. Beating

• Modulation happens at the transmitter

• Answer: b. Modulation

A process that occurs in the receiver.
a. Beating
b. Modulation
c. Mixing
d. Demodulation

• Demodulation happens at the receiver

• Answer: d. Demodulation

What amount of carrier swing necessary to produce 80% modulation for TV audio?
a. 40 kHz
b. 50 kHz
c. 20 kHz
d. 25 kHz

• 80% modulation corresponds to 40 kHz swing

• Answer: a. 40 kHz

The letter number designation B8E refers to:
a. Pilot-carrier system
b. Independent sideband emission
c. LINCOMPEX
d. Vestigial sideband transmission

• B8E = Independent sideband emission

• Answer: b. Independent sideband emission

Which symbol indicates that only one sideband is transmitted?
a. A3E
b. B8E
c. C3F
d. H3E

• H3E = single sideband reduced carrier

• Answer: d. H3E

Emission designation for facsimile transmission?
a. J3E and F4E
b. A3J and A4E
c. A3C and F3C
d. R3E and A3E

• Facsimile is F3C (FM facsimile) or A3C (AM facsimile)

• Answer: c. A3E and F3C

Double sideband full carrier emission?
a. A3E
b. A3J
c. F3
d. R3A

• A3E = double sideband full carrier

• Answer: a. A3E

What is the emission of F3F?
a. Facsimile
b. Modulated CW
c. RTTY
d. Television

• F3F = Television (FM type)

• Answer: d. Television

In a J3E filter system, how many circuits must be balanced?
a. 0
b. 1
c. 2
d. 3

• 2 circuits must be balanced in J3E filter systems

• Answer: c. 2

Independent sideband emission?
a. H3E
b. R3E
c. J3E
d. B8E

• B8E = Independent sideband

• Answer: d. B8E

Emission when an AM transmitter is modulated by a TV signal?
a. F3F
b. A3C
c. F3C
d. A3F

• A3F = AM modulated by TV signal

• Answer: d. A3F

Output of a balanced modulator?
a. AM
b. FM
c. SSB
d. DSB

• Balanced modulator output = DSB (Double Sideband)

• Answer: d. DSB

Emission designation for FM telephony?
a. F3E
b. G3E
c. J3E
d. H3E

• FM telephony = F3E

• Answer: a. F3E

Maximum output power of an A3E emission?
a. 4 W
b. 10 W
c. 3 kW
d. 10 kW

• Standard A3E maximum power is 10 kW

• Answer: d. 10 kW

If the modulation index of AM wave is doubled, antenna current is doubled. AM system type?
a. A5C
b. A3J
c. A3H
d. A3

• A3 = Double Sideband Full Carrier (standard AM)

• Answer: d. A3

Power saving in J3E system at 100% modulation?
a. 33%
b. 100%
c. 83.3%
d. 66.67%

• 83.3% of carrier power is saved

• Answer: c. 83.3%

Letter number designation for FM facsimile?
a. F3E
b. F3C
c. A3E
d. C3C

• FM facsimile = F3C

• Answer: b. F3C

Which symbol indicates that only one sideband is transmitted?
a. A3E
b. B8E
c. C3F
d. H3E

• H3E = Single Sideband Reduced Carrier

• Answer: d. H3E

Vestigial sideband emission is:
a. C3F
b. R3E
c. J3E
d. B8E

• Vestigial Sideband = C3F

• Answer: a. C3F

Third symbol in radio emission for telephone transmission (including sound broadcasting)?
a. W
b. F
c. C
d. E

• Telephone transmission is represented by E

• Answer: d. E

Shape of trapezoidal pattern at 100% modulation?
a. Circle
b. Square
c. Triangle
d. Rectangle

• Perfect rectangle at 100% modulation

• Answer: d. Rectangle

Maximum sideband suppression using filter system?
a. 50 dB
b. 60 dB
c. 40 dB
d. 30 dB

• Maximum suppression = 60 dB

• Answer: b. 60 dB

Test instrument that displays carrier and sidebands amplitude versus frequency?
a. Oscilloscope
b. Spectrum Analyzer
c. Frequency Analyzer
d. Amplitude Analyzer

• Spectrum analyzer shows amplitude vs frequency

• Answer: b. Spectrum Analyzer

In what transmitters are balanced modulators used?
a. SSB
b. A3E
c. F3E
d. FM

• SSB uses balanced modulators

• Answer: a. SSB

Emission C3F corresponds to:
a. Facsimile
b. Modulated CW
c. RTTY
d. Television

• C3F = Vestigial sideband Television

• Answer: d. Television

Emission that transmits lower sideband and half of upper sideband?
a. A5C
b. J3E
c. A3J
d. A3H

• A3H = lower sideband + half upper

• Answer: d. A3H

Single sideband reduced carrier emission type?
a. H3E
b. R3E
c. J3E
d. B8E

• H3E = Single Sideband Reduced Carrier

• Answer: a. H3E

Phase modulation type?
a. F3E
b. F3C
c. F3F
d. G3E

• Phase modulation = G3E

• Answer: d. G3E