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
Antennas An AC will be induced:
In a wire, parallel to the wire fed with a AC, but remote from it.
The frequency which corresponds to a wavelength of 12 cm is:
2500 MHz
The wavelength of a radio signal transmitted at the frequency of 75 MHz is:
4 m
What is the wavelength corresponding to a frequency of 375 kHz?
800 m
A radio beacon has a range of 10 nm. By what factor should the power be increased to achieve a range of 20 nm?
4
The ASMR operates in the …… band, the antenna rotates at …… rpm can …… distinguish between aircraft types.
SHF, 60, sometimes
Which wavelength corresponds to a frequency of 5035 MHz?
5.96 cm
The maximum range an ATC facility at 1369 ft amsl can provide a service to an aircraft at FL350 is:
280 nm
The time interval between the transmission of a pulse and receipt of the echo from a target is 925.5 microseconds. The range of the target is:
75 nm
An advantage of a slotted antenna (planar array) over a parabolic reflector are:
less power required
In accordance with the ITU (International Telecommunication Union) a radio signal may be classified b\ three symbols. THIRD symbol indicates (e.g. A1A):
Type of information to be transmitted.
What is the effective range over land for
REYKJAVIK NDB, RK 355
Power is 6400 Watts
160 NM
2x (power output squared)
What is the maximum range for a VHF ground station at 475 ft and an aircraft at 7066 ft?
130 NM
SKAGI NDB, SA 379 KHz has a power output of 625W.
What is the effective range over land?
What about over sea?
Land: 50 NM
Sea: 75 NM
Attenuation of radio waves is usually caused by:
- Absorption
- Scattering
- Geometrical dispersion
What describes polarization?
orientation of the plane of oscillation of the electrical component.
During the daytime as opposed to the night time, which of the following scenarios is correct with regard to HF communications that are used?
Both dead space and skip distance decrease
The distance travelled by a radio wave in the direction of propagation during one cycle is:
Wavelength
The range at which ground waves can be received depends upon:
- The frequency and power of transmission
- Height of aerials and interference
- Nature of terrain
Answer: All of the above
A frequency band in which there are strong sky waves by night but weak, or no, sky waves by day is:
MF
300 - 3000 kHz / 1000 - 100m
During the daytime as opposed to the night time, which of the following scenarios is correct with regard to HF communications that are used?
Both dead space and skip distance decrease
he principal source of attenuation in the ionosphere and of the refraction of VLF waves during daylight is:
The D layer
FED mnemonic
An aircraft approaches on a 3° glide path and passes the OM at 4.1nm. At what height should the aircraft be?
1230 ft
4.1 x 6080) x cos(87
Skip distance is longest by (i) … and with a (ii) … frequency:
Night higher
The skip distance of an HF transmission will increase with:
An increase in frequency and an increase in height of the reflective layer
If the strength of a radio signal decreases away from the transmitter, this effect is called:
Attenuation
Which of the following is an advantage of single sideband (SSB) emissions?
- Better signal/noise ration
- More frequencies available
- Reduced power requirement
Answer: All of the above
Concerning …………. Modulation, the
of the Radio Frequency is modified by the ………….. of the AF
Amplitude
Amplitude
What is the phase difference between the reference wave/Variable wave phases:
40°/10°
20°
What is the phase difference between the reference wave/Variable wave phases:
320°/60°
260°
What is the phase difference between the reference wave/Variable wave phases:
10°/350°
20°
What is the phase difference between the reference wave/Variable wave phases:
30°/270°
120°
The bandwidth produced when a radio frequency (RF) of 4716 kHz is amplitude modulated with an audio frequency (AF) of 6 kHz is:
12 kHz
page 50 RNAV
The advantage of the use of slotted antennas in modern radar technology is to
virtually eliminate lateral lobes and as a consequence concentrate more energy in the main beam
The ideal length for a Marconi aerial for a frequency of 406 MHz is…
17.5 cm
Wave length / 4 x 0.95
The ideal length for a di-pole aerial for a frequency of 406 MHz is…
35 cm
Wave length / 4 x 0.95
A disadvantage of directivity is
sidelobes
The ideal length of a half wave dipole for a frequency of 75 MHz
1.9
Wave length / 2 x 0.95
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
The change in frequency measured in an aircraft from a radio transmission reflected from the ground is used to determine:
the drift and groundspeed of the aircraft
Doppler operates on the principle that ___ between a transmitter and receiver will cause the
received frequency to ___ if the transmitter and receiver are moving ___.
relative motion, decrease, apart
VORs are alined after _____ north
Magnetic
TVOR is a _______
Terminal VOR
VOTs are:
Test VORS which always should be alined with 360M
For testing
VOR freq range
108.0 - 117.95 MHz with horizontal polarisation
A9W
sometimes allocated with ATIS
ILS VOR freqs are
108-117.1,3,5,7,9
VOR signals are displayed on the
RMI, HSI & CDI
VOR-Beacon accuracy must be
+/- 1 degree
VOR-equipment accuracy must be within
+/- 5 degrees
1/60-rule
Cone of confusion ICAO limits
max 40 degress horizontal
An aircraft, at FL220, is 220 nm from a VOR, at sea level, but the receiver fails to detect a signal. The reason for this is:
(185 NM range)
the aircraft is beyond line of sight range
The maximum range an aircraft at FL370 can receive signals from a VOR at 1024 ft is:
280 nm
An aircraft at FL240 is 220 nm from a VOR, at 50 ft above mean sea level, but the aircraft receiver fails to lock on to the VOR transmissions, this is because:
(202 NM range)
the aircraft is beyond line of sight coverage
In a conventional VOR if the measured phase difference is 300°, the radial is:
300
The phase difference between the FM and AM signals is measured at the VOR receiver as 120°. The radial is:
120
Which of the following is a valid VOR frequency?
a. 118.25 MHz
b. 111.95 MHz
c. 107.20 MHz
d. 109.25 MHz
109.25 MHz
Only ILS have un-even
The phase difference measured at the aircraft between the FM and AM signals of a VOR is 240°. The track that should be flown to overhead the VOR is:
060°
Terminal VOR/DME max spacing?
30 m
Enroute VOR/DME max spacing?
600 m
DME accuracy requirements?
+/- 1.25% of range and +/- .25 NM
Precision DME:
.20 NM +/-
DME range
962 - 1213 MKZ (UHF)
DME channels available
252 channels
DME transponder delay?
50 mikro seconds
When a VOR and DME are associated each will have the same identification; to distinguish between two identifications:
the DME audio frequency is higher than the VOR’s
An aircraft’s DME transmitter is operating on a frequency of 1180 MHz. The receiver will be tuned to receive replies on a frequency of ________ MHz.
1117
The return signal is 63 MHz lower than the interrogation signal
An aircraft at FL250 is 220 nm from a DME, at sea level. The equipment fails to lock onto the DME. The reason for this is:
the aircraft is below line of sight range
When a DME fails to achieve lock it will reduce the search PRF to 60 pulse pairs per second after:
15,000 pulse pairs
If an en-route VOR and DME are associated, the maximum distance between the transmitters will be:
600 m
An aircraft’s DME interrogator is operating on a frequency of 1190 MHz. The frequency the aircraft DME receiver will be selected to is:
1127 MHz
The counters of a DME distance readout are rotating continuously. This indicates:
the DME is in the search mode
A DME transponder becomes saturated when more than about 100 aircraft try to interrogate it. To overcome this problem the transponder:
reduces the gain to eliminate weaker signals
The DME receiver does not lock on to ground reflections from its transmitter because:
they are at a different frequency
When DME is used to provide range for an ILS approach, it gives the range to the runway threshold, although the DME is located elsewhere on the aerodrome. This is achieved by:
the time delay in the transponder being reduced by the time interval for double the distance between the transponder and the runway threshold
A pilot selects a VOR/DME and hears three identifications the same then the fourth identification, at a higher pitch, has the last letter changed to a `Z’. The significance of this is:
the beacons are greater than 600 m apart, but less than 6 nm
DME interrogation
150 pp/sec 100 sec
60 pp/sec, until lock
27 pp/sec, after lock
DME-p: 0,2 NM
slant range formula
(total time - 50 ps) x C / 2
