ECE Board
Exam April 1997
Modulation
means
varying of some parameters of a carrier
such as its amplitude to transmit information.
ECE Board
Exam November 1996
Which of the
following is not a baseband signal of modulation?
RF carrier
ECE Board
Exam April 2001
Which of the
following components is used to produce AM at very high frequencies?
PIN diode:
ECE Board
Exam November 1999
A process
which occurs in the transmitter part of the transceiver.
Modulation
ECE Board
Exam April 1999
In radio
rules and regulation, the extremely high frequency band is referred to as the
millimetric waves
ECE Board
Exam November 1998
It frequency
range of 401.000 MHz to 401.050 MHz has to be channelized at 12.5 kHz between
channel, what is the center of its first channel from the lower limit?
ECE Board
Exam April 1998
Type of
modulation used in TV broadcast visual transmitter.
Vestigial sideband
ECE Board
Exam November 1997
In the
designation of bandwidth and emission, what letter in the first symbol
represent a double-sideband type of modulation?
A
ECE board
Exam March 1996
The carrier
swing necessary to provide 80% modulation in the FM broadcasting band is ____
ECE Board
Exam April 2001
One of the
following refers to an output of a balanced modulator.
DSB
ECE Board
Exam March 1996
In AM, the
carrier carries _____ intelligence.
no
ECE Board
Exam March 1996
Three audio
waves with 100, 200, amd 300 volts amplitude respectively, simultaneously
modulate a 450 volts carrier. What is the total percent of modulation of the AM
wave?
ECE Board
Exam March 1996
Cross
modulation on a receiver is eliminated at the
detector stage
ECE Board
Exam March 1996
If the
percentage modulation of an AM amplifier is 88% and the modulating signal is 1
volt, the carrier has an amplitude of
ECE Board
Exam November 1999
One of the
following is also considered major reason in adopting a modulation/demodulation
processes in radio communication transmission instead of transmitting directly
the intelligence signal.
A mile length of transmission antenna is
impractical.
ECE Board
Exam April 1999
Intelligence
signal in radio modulation transmission technique is not called
Harmonics
ECE Board
Exam November 1998
In amplitude
modulation technique the unmodulated carrier is referred to as having
0% modulation
ECE Board
Exam April 1998
If a
transmitter supplies 8 kW to the antenna when it is unmodulated, determine the
total radiated power when modulated at 30%.
ECE Board
Exam March 1996
What is the
difference between phase and frequency modulation
Lies in the different definitions of the
modulation index.
ECE Board
Exam April 1997
What is the
local oscillator frequency range in commercial AM broadcast if it is equal to
455 kHz?
ECE Board
Exam November 1999
Which of the
following signal is suppressed by balanced modulator circuit?
Carrier signal
ECE Board
Exam November 1998
A third
symbol in radio emission which represents telephone transmission including
sound broadcasting.
E
ECE Board
Exam April 1998
How can
receiver desensitizing be reduced?
Decreased the receiver squelch gain
ECE Board
Exam March 1996
In an FM
receiver, which circuit removes amplitude variations?
Limiter
ECE Board
Exam March 1996
After the IF
stages have been aligned, the next stage to align in FM receiver is
local oscillator.
ECE Board
Exam November 1999
Refers to
the emission on frequency(ies) immediately outside its necessary bandwidth,
resulted from the modulation process except spurious emission.
Out of band
ECE Board
Exam April 1999
The first
symbol of an emission designation having an amplitude modulated main carrier
represented by letter C is referred to as
vestigial sideband
ECE Board
Exam November 1998
Which of the
following is referred to as a radio emission without sidebands.
Carrier
ECE Board
Exam March 2996
What is the
primary advantage of DSBSC in AM?
No transmitter power is wasted in the
carrier
ECE Board
Exam November
1998
One of
the following is not among the advantages of series modulation.
Suppressed white noise
ECE Board
Exam April 1999
What type of
emission is produced when a frequency modulated transmitter is modulated by a facsimile
signal?
F3C
ECE Board
Exam November 1998
Type of
emission produced by one of the early radio transmiotter trains of damped RF ac
waves where its oscillator is coupled to a long wire antenna, normally used in
radio telegraph and having sidebands on its carrier.
Spark Emission
ECE Board
Exam April 1999
What is the
modulation of index of an FM transmitter whose frequency deviation is 50 kHz,
while its audio frequency is 10 kHz?
ECE Board
Exam November 1998
What is
meant by the term deviation ratio?
The ratio of the maximum carrier frequency
deviation to the highest
ECE Board
Exam November 1998
One of the
FM signal generator control which varies the phase of the modulating voltage
applied to the oscillator of the sweep generator.
Phase control
ECE Board
Exam November 1998
In the
modulation technique, which of the following is referred to audible pitch?
Harmonic
ECE Board
Exam November 1998
Assuming a
UHF frequency range of 405.0125 MHz to 405.0875 MHz at 25 kHz channeling plan,
how many channels can you produce?
ECE Board
Exam November 1998
A modulation
which does not follow the sine wave pattern, it produces undesirable harmonics
such as spurious emission.
Over-modulated
ECE Board
Exam April 1999
What is the
capture effect?
The loudest signal received is the only
demodulated signal.
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