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WorksheetsM13-4 Comms
Total questions: 31
Worksheet time: 25mins
1. In Amplitude Modulation, the values of ___________ changes in accordance with the freq variations of the modulating signal.
Carrier Frequency
Carrier Amplitude
Carrier Phase
What happens when the amplitude of the modulating signal is greater than the amplitude of the carrier?
Amplification
Distortion
Attenuation
Function of frequency mixer in super heterodyne receiver is
Amplification
Filtering
Multiplication of incoming signal and the locally generated carrier
The diagram shows the response characteristics of what type of filter?
Low Pass Filter
High Pass Filter
Band Pass Filter
Band Stop Filter
In the diagram, which letter represents the component that;
reduces 2nd channel interference, prevents IF break through, prevents local oscillator ration and improves the receiver's SNR
(a)
In the diagram, which letter represents the component that;
generates a signal that is different from the required signal by the intermediate frequency
(a)
Amplitude modulation is
Change in amplitude of the carrier according to modulating signal
Change in frequency of the carrier according to modulating signal
Change in amplitude of the modulating signal according to carrier signal
Change in amplitude of the carrier according to modulating signal frequency
The graph shows the frequency spectrum of an AM radio wave carrying an audio signal of a single frequency. Determine the frequency of the audio signal.
1kHz
3 kHz
5 kHz
7 kHz
A heterodyne frequency changer is called a
Modulator
Mixer
Demodulator
Frequency translator
In a radio receiver, if the intermediate frequency is too high, then
Selectivity will be poor
Tracking difficulties will be least
Adjacent channel rejection will improve
All of the above will occur
The ratio between the modulating signal voltage and the carrier voltage is called?
Modulation index
Modulation frequency
Ratio of modulation
What is the percentage of modulation if the modulating signal is of 7.5V and carrier is of 9V?
100
91
83.33
When does over-modulation occur?
Modulating signal voltage < Carrier voltage
Modulating signal voltage = Carrier voltage
Modulating signal voltage > Carrier voltage
What do you understand by the term “carrier”?
waveform with constant frequency, phase and amplitude
waveform for which frequency, amplitude or phase is varied
waveform with high amplitude, low frequency and constant phase
Detection is same as ________
Modulation
Demodulation
Filtering
Microwaves are used for mobile phone and other satellite communication because they are not reflected by the
(a)
What factor(s) determine the range of a Ground Wave?
The terrain the wave is traversing (Land or Sea)
The time of day
The height of the ionosphere
The line of sight in relationship to the horizon
Which of the following radio wave bands use Ground (surface) Waves as their method of propagation?
VLF
MF
HF
UHF
VHF
Which of the following radio wave bands use Sky Waves as their method of propagation?
VLF
MF
HF
UHF
VHF
in the diagram regarding sky wave propagation what term is being represented by e?
Critical Frequency
Sky Wave
Ground Wave
Dead Space
Skip Distance
What happens when the VOICE ONLY function is selected on the Audio Selector Panel (ASP)?
Only the voice is heard. All signal sources from VHF-NAV or DME will be muted.
Signal sources from VHF-NAV or DME are heard. Voice signals will be muted.
Which statement is correct about the Flight Interphone System?
Allows cockpit crew to communicate with the ground engineer/mechanic.
Allows cabin crew to communicate with the ground engineer/mechanic.
What is recorded by the Cockpit Voice Recorder?
All incoming and outgoing radio communications and cockpit crew voice communications
Engine parameters; such a s EGT rotational speed and fuel flow
All incoming and outgoing radio communications and cabin crew voice communications.
What is the shortest wavelength possible for HF communications?
0.5 meters
What is the accepted range of speech frequencies?
5 Hz to 30 kHz
30 Hz to 25 kHz
300 Hz to 3 kHz
10 Hz to 15 kHz
What does Single Side Band (SSB) transmission mean?
Transmitting only single frequency side bands
What is the minimum channel spacing of an AM-receiver, if the necessary bandwidth is +/- 2kHz?
2kHz
True or false
FM Signals require more band width than AM Signals.
