Equip Summery Flashcards
1
Q
Describe Ampere’s law.
A
An electric current produces a magnetic field perpendicular to the flow direction.
2
Q
What speeds do radiowaves travel at?
A
300 million metres per second
3
Q
Can radio waves travel through a vacuum?
A
Yes
4
Q
What is a cycle?
A
Each time a wave travels from 0 up, down and back to 0. Know as a cycle.
5
Q
Define amplitude
A
Max displacement or value attained by the wave from its mean value during a cycle.
6
Q
What is a wavelength?
A
Distance in metres or part of a metre between corresponding points in a consecutive wave.
7
Q
Define Frequency
A
The rate of repetition of the cycle in one second
8
Q
What is a Hurt (Hz)?
A
One cycle per second is known as a hert
9
Q
How many hertz in a Kilohertz
Megahertz
Gigahertz
A
1,000
1,000,000
1,000,000,000
10
Q
The longer the wavelength the ________ the frequency
A
Lower
11
Q
What device produces modulate wave?
A
The local oscillator
12
Q
What are the two types of Modulation?
A
AM and FM
13
Q
3 advantages of FM?
A
1) Resilient to Noise
2) Easy to apply Modulation at a low power
3) Use of efficient RF amplifiers
14
Q
Advantages of AM?
A
1) Stronger stations can override weaker stations
2) creates a Heterodyne if multiple stations transmit at once
15
Q
What part of the wave is used for a half-wave Aerial ?
A
Top positive part of the cycle?
16
Q
What part of the wave is used for a quarter wave aerial?
A
90 degree cycle
17
Q
If you half the wave length you must _________ the power to get the same range?
A
Double
18
Q
What is attenuation?
A
When a radio-wave reduces in strength with range or time from the point of transmission
19
Q
What 2 things cause attenuation?
A
1) Expanding Wave Front
2) medium through which the wave passes resists the passage of energy passing through it.
20
Q
As a signal is attenuated its _________ decreases but _______ and _________ remain unchanged
A
Amplitude
Wavelength
Frequency
21
Q
Which frequency is more attenuated, High or Low?
A
High
22
Q
Radio waves are divided according to frequency of transmission into internationally recognised bands called?
A
Wave bands
23
Q
What is the frequency spectrum and wavelength size for VLF?
A
3-30KHz
100km-10km
24
Q
What is the frequency spectrum and wavelength size for EHF?
A
30-300GHz
1cm-1mm
25
Which frequencies are Line of Site and which follow the curvature of the earth?
High frequencies LoS
| Low frequencies Curve
26
Which frequencies are best for long range communications?
Low
27
What waveband does NDB use?
Low/medium frequency
28
What waveband does RTF/VOR/VDF/ILS And Surveillance Radar use?
Very/Ultra High Frequency
29
Which waveband is prone to severe attenuation?
S/EHF
30
Which waveband is prone to static?
VLF
31
Which waveband is prone to Diurnal Variation?
HF
32
What meteorological conditions cause Ducting?
A marked temperature inversion plus a rapid decrease in humidity may form a duct.
33
What 3 frequencies suffer from ducting in particular?
VHF
UHF
SHF
34
Explain antenna shadowing
When the radio wave is above the aircraft and does above the curvature of the earth
35
Explain low frequency propagation characteristics
Low frequencies will bend around objects and be heard at a great distance.
36
Low frequency means less attenuation. True or False?
True.
37
What does RADAR stand for?
RAdio
Detection
And
Ranging
38
How is the position of the object that reflects radio energy determined?
1) Direction the Aerial was pointing
| 2) Time between Transmitting
39
What part of the the waveband spectrum is Radar part of?
1mm-100cm
40
How many pulses does a radar transmit? And what is the equivalent range?
1200 pulses
| 67nm
41
What is ground Clutter?
Reflections from an object
42
What does PE stand for?
Permanent Echoes
43
What causes Weather clutter?
Reflection of the pulse from the rain drops
44
Define PSR Blip
A visual indication in non-symbolic form on a situational display of the position of the aircraft obtained by Primary Radar
45
What wavelength does the SMR/Weather Radar use?
2-3cm
46
What wavelength does Primary Approach Radar use?
3-10cm
47
What wavelength does Primary Area Radar use?
23-50cm
48
Define Position Indicator
Visual indication in non-symbolic and/or symbolic on a situation display of the position of an aircraft, AD, vehicle or other object.
49
Define Position Symbol
Visual indication in symbolic form on a situation display, of the position of the aircraft
50
Define Radar Contact
The situation which exists when the Radar position of a particular aircraft is seen and identified on a situation display
51
Define Radar Control
Indicates that radar delivered information is employed directly in the provision of ATC services
52
Define Situation Display
An electronic display depicting the position and movement of aircraft and other information as required.
53
What are the 3 basic blocks of radar?
Transmission
Reception
Display
54
What is a duplexer?
A transceiver but can only do one at a time.
55
Describe the Trigger unit
Output
| Initiated action pulses at regular intervals
56
Describe the Modulator
When triggered fires high power high voltage pulses to transmitter
(On/off switch transmitter)
57
Describe the High gain low noise receiver
Amplifies weak return signal
58
Describe the Time based unit
Used to calculate range
59
What does SSR stand for?
Secondary surveillance Radar
60
How does SSR work?
A system of radar using ground interrogators and airborne transponders to determine the position of the aircraft in range and azimuth.
Wen agreed Modes and codes are used
61
What frequency are the ground interrogators and Transposers on?
1030MHz
| 1090MHz (Trans)
62
Wavelength used for SSR?
30cm
63
How does the aircraft know the difference between the Mode A and Mode C pulses?
The timing of the pulses
64
What information does Mode A and Mode C provide
SQK (Position)
| Vertical position
65
How many “Bits” are in Mode A?
12 bits
66
What numbers are used in a SQK?
0-7
67
What are maximum SQK codes?
4096
68
Name the 3 categories of codes(squawks)
1) Discrete- individual a/c
2) Non-Discrete-single codes issued to numerous aircraft (7000)
3) Special Codes-Applied by a/c on certain occasions (7700)
69
What does ORCAM stand for
```
Originating
Region
Code
Assignment
Method
```
70
What does PA stand for and how many PAs in Europe Region?
Participating Areas
| 5 PAs
71
How many SQK blocks are ACCs issues?
| How are they divided?
2 blocks
1 for domestic flights
1 for international (ORCAM) Flights
72
Do discrete codes include special purpose ones eg 0020
Yes
73
How many bits does Mode C use? And are 8 and 9 read?
11 bits
| Yes
74
Define Garbling
False codes displayed if aircraft are so close to each other their response to Mode A interrogator overlap
75
What does FRUIT stand for?
```
False
Replies
In-synchronised
In
Time
```
76
What is FRUIT?
Asynchronous interferences , which arise from replies not triggered by the Interrogator
77
How is FRUIT and Garbling stopped?
DeFruiter
| DeGarbler
78
The benefits of Monopulse SSR
Improves clarity and accuracy
Reduces FUIT and Garbling
79
What is a Monopulse SSR?
A single pulse used averaging measurements made on several or all pulses received in reply from aircraft
80
List the factors that effect radar coverage
| 7 of them.
1) Aerial size/shape/height above ground
2)Size of Target (PSR)
3) Atmospheric conditions
4)Transmitter Power
5) Receiver Efficiency
6)Pulse Recurrence Frequency (PRF)
[PSR]
7) Pulse length
81
What is the usual beam requirement in ATC?
Narrow in Azimuth
| Wide in elevation
82
What is usual beam width?
2-3 degrees
83
If a narrow beam is required aerial dimensions must be_______
Large
84
Radars use “Cosecant Squared” to avoid wasting energy. True or False?
True
85
What will a vertical coverage diagram display?
Theoretical coverage of the display
86
What 3 factors does a vertical coverage diagram take into account?
1) General design factors
2) Environment Conditions
3) Atmospheric Conditions
87
What does a unit coverage diagram display?
Actual coverage of a radar system after being installed at a specific location.
Considers local terrain
88
What does Anoprop do?
Can produce radar echoes from below normal
| Cover and from ranges in excess of those allowed for in the design of the Radar
89
Why must PRF be lowered
It must be low enough to accommodate the required maximum range
90
Explain PRF
The higher the rate the more hits on a target and the stronger and more recognisable the return
91
What does circular polarisation do?
Removes weather clutter
92
How does circular polarisation work?
The EMF is reflected and is reversed by reflection from aspherical objects
93
What is the problem with circular polarisation
Receiver can be gated to ignore returns that allow aircraft to be seen
94
Is MTI fitted to PSR or SSR?
PSR
95
What does MTI do?
Displays moving targets and rejects echoes from fixed targets (removes ground clutter)
96
How does tangential fading occur
When moving tangentially to the radar beam. Won’t happen if you move radially to the beam
97
What happens aircraft flies directly towards/away from the radar?
Blind Velocity will occur (cancellation of the blip)
98
List the 4 ways data is transmitted?
1) Microwave
2) Satellite
3) Line of Site
4) Telephone/Fibre Optics
99
Coaxial cables cover log or short distances?
Small
| And signal deteriorates rapidly
100
Radio link operates in which frequency band and are used for what distance?
UHF n SHF
| Long distances
101
Telephone link may be used for considerably long distances if they are of sufficient higher grade and is being sent in a processed form (e.g. digital from a plot extractor) True or False?
True
102
Fibre optics are used over relatively ________ distances. Used to connect radar site to the tower, True or False?
Short
| True
103
What are Radar Sort Boxes?
Columns of air from the ground which are covered by multiple radars
104
What are the dimensions of Radar Sort Boxes?
16nm x 16nm
105
How many radar systems per Radar Sort Boxes
4
106
In a radar box set the radars are grouped into
Preferred
Supplementary
Reserved
107
What does Mode S mean
Selected
108
How many bits does Mode S use and how many codes?
24 bits
| 16.75 million codes
109
What are the two phases of Mode S
Acquisition Phase:
interrogator looks for new Mode S transponders and retains in memory
Addressed Surveillance Phase:
Mode S interrogated individually for identification, Altitude, Information. Using longer communications.
110
Mode S TCAS
| Explain
Air to Air transponder communication exchange of data for collision avoidance
111
What does TCAS calculate?
Closest point of approach and produces two level warnings
112
What are the two stages of Mode S
```
Elementary Surveillance (ELS)
Enhanced Surveillance (EHS)
```
113
What does Mode S multilateration do?
Provides accurate surveillance and identification of all transponder equipped a/c on the airport surface
114
What does ADS-B stand for?
Automatic
Dependent
Surveillance
Broadcast
115
What does ADS-B do?
Obtains horizont/Vertical Position, Velocity as well as other information
116
Who can sue ADS-B?
Vehicles and aircraft
117
Frequency of ADS-B extended squitter?
1090MHz
118
What information is displayed on a ELS display? (5 things)
```
Callsign
SQK
Level
POS
Track history
```
119
What information is displayed on an EHS display?
```
Callsign
Speed (Ground+IAS)
Level
Magnetic Heading
Vertical Rate
Selected Altitude
```
120
What are the two types of ADS-B messages?
Primary:
- Position
- Airborne Velocity
- Aircraft Identity
On Event
- Trajectory
- Status
- Test
121
Maximum updates permit on ADS-B?
| How are they divided?
```
6.2 mps
2 Position Messages
2 Velocity Messages
2 on event messages per second
0.2 flight identity
```
122
Maximum and minimum accuracy of ADS-B?
7.5m
| >20nm
123
What are the 3 types of ADS-C contracts?
1) Periodic
2) Demand
3) Event Contract
124
How does MLAT work?
MLAT antennae on the ground receive broadcast from aircraft and vehicles with Mode S transponders
125
How does MLAT determine the position of the aircraft?
Time
Difference
Of
Arrival
(TDOA)
126
Short range MLAT can be used to enhance or replace more old fashioned SMR.
True or False?
True
127
What is WAM used for?
Surveillance of large volumes of airspace
128
Pros and Cons of MLAT
Pros:
Cheap
Rapid updates/greater coverage/ Fill gaps
Cons:
Only detects aircraft win with Mode S transponders
129
What are the 5 advantages of PSR?
1) Self contained
2) Independent Operation (ident n fix)
3) Non reliant
4) PEs for calibration
5) Weather Information
130
Cons of PSR
| List all 6
1) No level info
2) Identification is hard
3) Weather Clutter
4) PEs
5) Range dependent
6) No emergency indication
131
Pros SSR
1) less Transmitter power
2) No clutter
3) Identification of aircraft
4) Vertical Position Information
5) Emergency SQK
6) Independent If equivalent Echoing Area
132
Cons SSR
1) All A/C require transponder
2) No weather
3) Fruiting
4) Garbling
5) Fading
6) No PEs
133
What does CPDLC stand for
```
Controller
Pilot
Data
Link
Communications
```
134
What is a FMS?
A computerised avionics components to assist in navigation flight planning and aircraft control functions
135
What is a FMS made out of?
FMC
AFS
Navigation
136
What was CPDLC created for?
Reducing RTF on oceanic routes
137
Benefits of CPDLC
- Flight crew can print messages
- allows auto load of uplink messages
- Allows crew to downlink complex route clearances
138
CPDLC and ADS similarities
1) accept messages from the ground receivers
2) both Controlled by FMS
3) Both data link Applications
139
What is SELCAL?
It is selective calling
| Replaces RTF by coded tones
140
What does ACARS stand for?
```
Aircraft
Communications
Addressing and
Reporting
Systems
```
141
What is ACARS used for?
A data link system for the manual or automatic transmission of messages between aircraft and ground stations
142
ACARS messages may be of three types based up their content:
- Air Traffic Control
- Aeronautical Operation Control
- Airline Administrative Control
143
List the priorities
| For AFTN messages
1) SS
2) DD or FF
3) GG or KK
