Flashcards in Mixed Q Feedback Deck (60):
Amplitude vs Frequency Modulation
Amplitude - peaks go higher or lower. Spacing / Frequency stays the same.
Frequency - peak stays constant, frequency/spacing differs. Like an accordion.
How does MLS minimise multipath errors?
Transmissions can be INTERRUPTED to AVOID reflection by stationary objects
What frequency & freq. band does an ILS Marker beacon transmit?
75 Mhz - VHF Band
0.25NM + 1.25% Range
100NM -> 0.25 + 1.25 = 1.5 total error.
Relation between HDG, RB, QDM
QDM = HDG + RB
RB = QDM - HDG
Range of an NDB over Land & Sea
LAND = 2 x square root Power (W)
SEA = 3 x square root Power (W)
What is the maximum range of primary radar determined by
Max Range - PRF
81000/PRF = Range
What is minimum range of primary radar determined by?
Definition of Garbling
2 aircraft, same direction, less than 1.7NM slant range.
Mode S Transponder - Short & Long P4 Calls
Short P4 - exclusively Mode S All Call
Long P4 - Mode A, C, S All Call
What do L1 & L2 codes eliminiate?
IONOSPHERIC PROPOGATION DELAY
NAVSTAR Satellite - orbit angle, duration & height
55 degrees to Earth's Equatorial Plane, orbits in 12H. 20000km above Earth.
64.8 degrees to Earth's Equatorial Plane - orbits in 11h 15' at 19000km. Lowest of all
56 degrees to Earth's Equatorial Plane - orbits in 14H. 23000km
How is distance from NAVSTAR/GPS receiver to the ground receiver transmitted?
Time taken for signal to arrive x speed of light.
Types of interference
'REFLECTION' is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.
'DIFFRACTION' is the phenomenon, which may be described as the apparent bending of waves around small obstacles and the spreading out of waves past small openings.
'REFRACTION' is a change in direction of a radio wave as it passes from one medium to another and is most prevalent in lower frequencies.
This is seen in NDB LF/MF signals at night as the weakening layers of the Ionosphere (which completely attentuate the Space Wave by day) 'bend' the signal back towards the denser medium, i.e. The lower levels of the atmosphere, as it passes into the less dense regions. This can result in a signal being sufficiently refracted to return it to earth in the form of Skywave.
It is also seen in coastal refraction as the signal passes from land to sea and the signal 'bends' back towards the land.
'INTERFERENCE' is a phenomenon in which two waves superimpose to form a resultant wave of greater or lower amplitude.
In aviation electronic systems the so-called Doppler principle may be used in:
VOR, GPS and MTS and the turbulence mode of AWR
What does the VDF provide?
The ILS receiver of an aircraft on approach and flying on the Glide Path will receive:
The modulation from both lobes at equal depth.
Rapid indicator changes, side to side of the approach path - cannot be followed by the aircraft.
What selection on the transponder must be made to transmit Mode A, C, S?
"ALT" / "ALT RPTG"
Which combination of characteristics gives best "screen picture" in a primary search radar?
Short pulse length and narrow beam
> example surface movement radar
Kalman filtering is used within:
Electronic filter used for putting together multiple data sources, of different types, to return an estimate better than any one source.
Which of two L-band frequencies are generally available for use by civil aviation?
L1 - Coarse Acquisition (C/A) with selected availability (S/A)
The GPS control segment consists of:
A Master Control Station, Monitor Stations and Ground Antennas.
The Control Segment will analyse the data from the satellites and establish whether there are any errors in the information supplied and if so it will apply correction factors which will then be uploaded to the satellites.
What is the time transmitted by the NAVSTAR GPS?
Navstar satelites transmit GPS TIME with a correction to obtain UTC.
GPS time is not linked with the earth and does not cater for leap years etc. At the time of writing, GPS time is behind TIA by about 19 seconds.
Orbital plane and the equatorial plane
Addition of a low frequency to a high carrier wave
What does skip distance increase with?
Higher frequency, higher ionospheric level
To what accuracy should an NDB flown to?
5 degrees of approach track.
Accuracy of Mode S Altitude (ft)
Flat plane Antenna vs Parabolic
Flat plane antenna generates less side lobes
Frequency band of a Locator
LF/MF - Locator is a NDB on final approach.
ILS Scale Deflection
5 dots - 0.25 per dot - Total 2.5 degrees.
Maximum - half scale deflection off the approach.
VOR Full Scale Deflection
5 dots - 2 per dot, total 10 degrees.
A2A symbology meaning.
On-off keying amplitude modulated transmission for aural telegraphy.
Wave bends around an impenetrable obstacle
2 DME distances are measured & plotted on a chart. What does this show?
2 circle arcs on the chart, intersecting at two points and providing slant range.
MLS Frequency categories
Azimuth and Elevation stored on same frequency
What kind of aerials are used in primary radar?
One directional antenna both for transmitting and for receiving.
On an RMI the front end of a VOR pointer indicates the:
Radial plus 180º
VDF measures the bearing of the aircraft with reference to:
True or Magnetic North at the station.
The type of modulation used for the ILS frequency carrier is:
When switching on the weather radar, after start-up a single very bright line appears on the screen
Scanning of the cathode ray tube is faulty
On switching on the AWR a single line appears on the display
The antenna is not scanning
Frequency of SBAS
Standard GPS L1 Frequency.
Using SBAS corrections, this accuracy can be improved to around the 1m mark in typical operation.
When will the ILS warning flag appear on either the localiser or the glideslope?
Either the 90 Hz or the 150 Hz signal is lost by one of the aircraft receivers.
Receiver Autonomous Integrity Monitoring( RAIM)
It is a technique by which a receiver checks the reliability of the signals it is receiving and can detect if one of the signals is incorrect.
5 Satellites required.
NAVSTAR/GPS "All in View"
Tracking all currently visible satellites above the receiver's mask angle and can instantly replace a faulty satellite
The maximum range obtainable from an ATC En-Route Surveillance Radar is approximately:
Frequency band of the GBAS data link is:
VHF band 108.0 to 111.975 MHz
For Long Range NDB's the most common type is:
How does Microwave Landing System (MLS) indicate distance from the runway threshold?
A precision facility DME
What is the maximum latitude of a GPS-satellite ground track?
How does TCAS II determine the bearing of an intruding aircraft?
Using a specific directional antenna
When a DME arc is used to guide an aircraft to join a holding procedure which entries are permitted
Sector 1 & 3