Amplitude Modulation I

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It is the process of superimposing information content, into high frequency carrier.

Modulation

Low Frequency signal cannot be propagated directly due to:

None of these

It is the oldest and simplest modulation.

Amplitude Modulation

In AM, the amplitude of the carrier is changed, in accordance with the amplitude and frequency, or the characteristics of the modulating signal. The carrier frequency ________

remains constant

The effect of modulation is to translate modulating signal in frequency domain so that modulating signal will be ______

reflected about symetrically

An unmodulated wave has ____ modulation and simply a ____ wave.

zero, carrier

The amplitude variation of the carrier peaks has the shape of the modulating signal.

Envelope

It is conventional AM used in TV broadcasting.

Double Sideband

Double Sideband Full Carrier provides narrowband communications with nearly quality achieved with FM while using _____ the bandwidth.

one third

What is emission designation for Double Sideband Full Carrier?

A3E

What is emission designation for Single Sideband Full Carrier?

H3E

What is emission designation for Single Sideband Suppressed Carrier?

J3E

What is emission designation for Single Sideband Reduced Carrier?

R3E

What is emission designation for Vestigial Sideband Full Carrier?

C3E

What is emission designation for Independent Sideband Full Carrier?

B8E

Form of AM in which carrier is transmitted at full power, while one of sidebands is transmitted.

SSBFC

Form of AM in which carrier is suppressed, while one of sidebands is transmitted.

SSBSC

Form of AM in which carrier is transmitted at 10% of its unmodulated amplitude, while one of sidebands is transmitted.

SSBRC

SSBRC is also known as

Reinserted Carrier

It is the reinserted carrier for demodulation purposes.

Pilot Carrier

The circuit where the carrier is reinserted.

Linear Summer

Form of AM in which both carrier and one sideband is transmitted, while other of sideband is transmitted partially.

VSBFC

Circuit that simplify the frequency stability problem in reception.

C3E or R3E

Circuit that produces Vestigial Sideband.

Diplexer

ISBFF is form of AM in which carrier is modulated by at least ___ different modulating signals.

Tuning is not easy in ______

Single Sideband

Time-domain display shows _______

amplitude versus time variation of AM and other signals.

At beginning cycle of envelope, carrier is ___ degree out of phase with both sidebands while sidebands are ____ degree out of phase with each other.

90, 180

It performs a mathematical multiplication of the carrier and information signals.

Modulator

The output of modulator from mixing carrier signal and modulating signal is ______

Analog Product

In order to modulate the carrier signal, the carrier signal is passing through an attenuator that changes the amplitude of carrier in accordance to modulating signal. The attenuator works on principle of _____.

variable resistance

The carrier in an AM signal is a sine wave, that may be modulated by, either _____ or _____ information signals.

analog, digital

An ideal modulation index is ______

Typical modulation index is _____

Less than 1

At 100% Modulation, sideband amplitudes equals to _____ carrier voltage while maximum carrier voltage equals ______ carrier voltage while minimum voltage is ____.

half, twice, zero

A frequency domain display shows

amplitude versus frequency variation of a signal and other signals

The maximum peak carrier amplitude and minimum peak carrier amplitude of AM waveforms are displayed on an _______

oscilloscope

The following statement is false except:

The total transmitted AM power is distributed among the carrier and sidebands.

If three modulating tone is added to input with same amplitude but different frequency, modulation index is increased by factor of ______

square root of 3

The maximum power delivered to the antenna transmission line by RF transmitter during one cycle at crest of modulation envelope.

Peak Envelope Power

Ratio of Peak Envelope Power to Average Power during a modulation peak in a single sideband phone.

2.5 : 1

It isolate modulating circuitry from high power RF stages to preserve modulating amplitude.

Buffer Amplifer

It is the process of frequency change of local oscillator.

Pulling

What causes pulling of local oscillator?

By loading

It protects local oscillator from pulling.

Buffet Amplifier

It is modulation in which modulated wave is always present.

Continuous Modulation

The modulation takes place prior to the output element of the final stage.

Low Level Modulation

The modulation takes place in the final element of the final stage where the carrier signal is at its maximum amplitude.

High Level Modulation

Modulated Power Amplifier is based on _____.

High Level Modulation

Linear Power Amplifier is based on _____

Low Level Modulation

What does it indicate when the average value of current in a Class C Amplifier does not change at all?

It is normal condition.

Class B RF Amplifier is used than Class C in order to ______"

amplify AM

Both Base Modulation and Collector Modulation uses

Common Emitter

It is used for observing the modulation characteristics of AM transmitters.

Trapezoidal Pattern

Trapezoidal Method apply modulated wave to the ______ deflection of oscilloscope and modulating signal to ________ deflection

vertical, horizontal

Form of amplitude distortion introduced when the positive and negative alternations in the AM modulated signal are not equal.

Carrier Shift

It is refers as downward or upward modulation. It is also referred as asymmetrical.

Carrier Shift

Form of AM where signals from two separate signals modulate the same carrier simultaneously without interfering with each other.

Quadrature Amplitude Modulation

In Phase Division Modulation, The two modulating signals are ________ with each other.

90 degree out of phase

AM form in which carrier wave is modulated by a pulse or rectangular wave.

Amplitude Shift Keying

What happens when there is too high gain?

Any of these

It is any frequency outside AM spectrum in which harmonics can overlap into adjacent channels where other signals may present and interfere.

Splatter

Circuit that increase signal amplitude to a usable level while producing minimum nonlinear distortion.

Preamplifier

What is used to prevent overmodulation and splatter?

AGC

It maintains relatively constant output level

Forward AGC

It is process whereby received signal is momitored closer to front end of receiver and the correction voltage is feed forward to IF Amplifier.

Forward AGC

It is used where adjustment in gain is not immediate but occurs after a certain time.

Delayed AGC

It prevents rapid change in gain in response to short term fluctuations.

Delayed AGC

The automatic gain control is zero when tuned to strong signals due to following except:

Open Filter Capacitor

It is simplest amplitude modulator

Peak Detector

Diode Detector is _______ amplitude detector

noncoherent

Diode Modulator acts as _____

switch

In Diode Modulator, negative half of AM is supplied by _____'

Tank Circuit

It generate modulated signals or double sidebands while supresses carrier signal.

Balanced Modulator

Class C amplifier produces Double Sideband by:

Modulating the plate voltage

It is used to produce Single Sideband

Crystal Filter

The following are method of generating single sidebands except:

Wein Bridge

It is phasing method of Single Sideband, in which one sideband is cancelled out.

Phase Shift

It is a mechanically resonant transducer that receives electrical energy, converts it to mechanical vibrations, and vice versa.

Mechanical Filter

It use acoustic energy rather than electromechanical energy to provide excellent performance for precise bandpass filtering.

SAW Filter

The first detector in AM used to demodulate Single Sideband signals.

None of these

Product Detector is used in ______

Any of these

Tuned Frequency Receiver consists ______

Radio Frequency Amplifier, Detector, Audio Frequency Amplifier, and Speaker

Product Detection requires the process of

Heterodyning

Tuned Frequency Receiver requires ______ to the desired radio frequency.

manual tuning

Superheterodyne Receiver has

RF Amplifier, Mixer, IF Amplifier, Detector, AF Amplifier

Most receivers conform to a type of receiver.

Superheterodyne

It is mixing process to generate new frequencies by combining two inputs resulting to their difference and sum.

Any of these

Mixer must be

nonlinear

Mixer down converts ____ to ____

RF, IF

Desired output from mixer is selected with _______

resonant circuit

Amplifiers must be _____ as it following the modulated stage in low level AM.

linear

Ability of the receiver to accept a given band of frequencies and reject all others.

Selectivity

Auto interference to radio reception can be eliminated by:

installing resistive spark plugs.

The minimum RF signal level that can be detected at the input to the receiver and still produce a usable demodulated information signal.

Sensitivity

SBB Signal is the signal in which receiver selectivity of 2.4 kHz in the IF Circuitry is ______.

optimum

Which amplifier class is not used in single sideband transmission?

Class C

Receiver Interference can be reduced by following except:

insulating enclosures around it.

The first stage of the receiver of which primary functions are detecting, band limiting, and amplifying the received.

RF Section

100

It precedes mixer for better rejection ratio.

RF Section

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