RNAV Flashcards
A radio signal loses strength as range from the transmitter increases, this is called:
Attennuation
“Hertz” (Hz) unit is defined as:
the number of oscillations per second of an electromagnetic wave.
Due to ‘Doppler’ effect an apparent decrease in the transmitted frequency, which is proportional to the transmitter’s velocity, will occur when
the transmitter moves away from the receiver
An electromagnetic wave consists of an oscillating electric field E and an oscillating magnetic field H. Their propagation speed is:
the speed of light
HF (High Frequency) waves appear in the frequency spectrum
3 MHz-30 MHz
UHF (Ultra High Frequency) waves appear in the frequency spectrum
300 MHz-3000 MHz
An electromagnetic wave consists of an oscillating electric field (E) and an oscillating magnetic field (H). Which statement is correct?
the E and H fields are perpendicular to each other.
Wavelength of frequency 117.95 MHz is
2.5m
300/117.95
LF (low frequency) waves appear in the frequency spectrum
30 kHz - 300 kHz
In the propagation of MF waves, the phenomenon of FADING is particularly found
at night, due to the combination of the sky and ground waves
Fading: Waves cancel each other out
With regard to radio waves propagation, a cycle is defined as
a complete series of values of a periodical process
The super position of two EM-waves of the same or nearly the same frequency is called?
interference
The process by which EM-energy is taken up by the atmosphere is called?
absorption
The phenomenon of a change in direction of an EM-wave occuring at an interfacce between two different media, so that the wave returns into the medium from which it originated, is called?
reflection
The phenomenon of a change in direction of an EM-wave occuring due to a change in its speed is called?
refraction
What is the Doppler effect with reference to radio signals?
It is the shift in frequency of a radio wave due to the relative movement between transmitter and receiver
Which statement about VHF/UHF propagation in connection with Ground Direction Finders is correct?
For both VHF/UHF propagation, the space wave is the only propagation path of practical use. There is no sky wave under normal conditions.
Which of the following summaries lists only directional antennae?
Loop antenna, parabolic antenna, slotted planar antenna, helical antenna
What is meant by keying A1A modulation?
interrupting the carrier wave to break it into dots and dashes.
From which physical phenomenon do skywaves originate?
refraction
Single Side Band (SSB) is used:
In HF two-way communication.
A radio beacon has a range of 10 NM. By what fact should the power be increase for a range of 20 NM?
4
An advantage of a slotted antenna (planar array) over a parabolic reflector are:
Less power required
Which wavelength corresponds to a frequency of 5035 Mhz?
5.96 cm
Due to a doppler effect an apparent decrease in the transmitted frequency, which is proportional to the transmitters velocity, will occur when:
The transmitter moves away from the receiver
From which physical phenomenon do skydives originate?
Refraction
Modulation is:
addition of a LOW frequency signal (tone, voice) onto a HIGH frequency carrier wave
The simplest type of antenna construction is a:
A dipole antenna which is a wire of length equal to one half of the wavelength
What is measured in depth between the 90 Hz modulation and the 150 Hz modulation:
The difference in depth between the 90 Hz modulation and the 150 Hz modulation
In accordance with the ITU (international telecommunication Union) a radio signal may be classified with
Nature of signals modulating the main carrier
EHF (extremely high frequency) waves appear in the frequency spectrum:
30 GHz - 300 GHz
The frequency which corresponds to a wavelength of a 8.25 m is:
36.36 MHz
Radio waves in the VHF and higher frequency bands propagate mainly as
space waves
Modulation is:
Addition of a low frequency signal (tone, voice) onto high frequency carrier wave
Radio waves travel at:
the speed of light
Which of the following is true with reference to frequency of a radio wave?
frequency is the number of cycles in one second in a radio wave expressed in Hertz (Hz)
The frequency which corresponds to a wavelength of 8.25 m is:
36.36 MHz
The frequency which corresponds to a wavelength of 3 km is:
100 KHz
Which of the following terms describes the maximum deflection in an oscillation?
amplitude
Single-sideband modulation (SSB) is a modulation technique where only one sideband is transmitted. SSB is used for:
HF Volmet and HF two-way communication
The polarisation of an electromagnetic wave describes:
the orientation of the plane of oscillation of the electrical component of the wave with regard to its direction of propagation.
The simplest type of antenna construction is a:
dipole antenna which is a wire of length equal to one half of the wavelength.
Which statement about VHF/UHF Frequencies is correct?
for both VHF/UHF propagation, the space wave is the only propagation path of practial use. There is no sky wave under normal conditions.
Modulation is:
the addition of information onto a radio wave during transmission.
VHF (Very High Frequency) waves appear in the frequency spectrum:
30 MHz-300 MHz
In accordance with the ITU (International Telecommunication Union) a radio signal may be classified b\ three symbols. Second symbol indicates (e.g. A1A):
Nature of signal(s) modulating the main carrier.
EHF (Extremely High Frequency) waves appear in the frequency spectrum:
30 GHz - 300 GHz
SHF (Super High Frequency) waves appear in the frequency spectrum:
3 MHz - 30 GHz
VLF (Very Low Frequency) waves appear in the frequency spectrum:
3 kHz - 30 KHz
MF (Medium Frequency) waves appear in the frequency spectrum:
300 kHz - 3000 kHz