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FI.27.MOD.BASE > EQPT-2 > Flashcards

EQPT-2 Flashcards

1
Q

O que entende por surveillance?

A

Detectar e identificar, quer aeronaves, quer veículos, posicionando-os tridimensionalmente no espaço, de modo a manter a separação

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2
Q

Um sistema ADS-B pertence à categoria de “co-operative dependent surveillance”, o Que se entende por “dependent”?

A

A posição é calculada pela aeronave

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3
Q

Em que domínio ou domínios de surveillance se pode enquadrar o sistema MLAT?

A

Air/Ground

Ground/Ground

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4
Q

O PSR é um sistema não cooperativo, como tal identifica os alvos pelo seu modo A. V ou F

A

Falso

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5
Q

O princípio de funcionamento do PSR é simples, mas a sua emissão é complexa. - V ou F

A

Falso

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6
Q

O tempo que é medido entre a interrogação e a chegada cooperativo ao SSR permite determinar o range. - V ou F

A

Verdadeiro

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7
Q

A largura do feixe principal determina a resolução azimutal do radar. V ou F

A

Verdadeiro

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8
Q

Que equipamento a bordo de uma aeronave tem o papel activo num contexto não cooperativo?

A

Não cooperativo não necessita de equipamento a bordo da aeronave

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9
Q

Que factor influência mais significativamente, num sistema PSR, a potência do sinal recebido?

A

O range, com uma grandeza inversamente proporcional a R^4

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10
Q

Qual o método que o MSSR utiliza para calcular a posição das aeronaves?

A

Range: medição do tempo
Azimute: posição da antena

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11
Q

Um SSR utilizado para controlo de rota deverá ter um refrescamento como?

A

Baixo, de aproximadamente 8segundos por revolução da antena

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12
Q

Existem códigos MODO A com atributos especiais. Quais são?

A

7500 Hijack
7600 radio failure
7700 aircraft emergency

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13
Q

O squawk ident quando solicitado pelo controlador é uma funcionalidade activada pelo piloto, usando o painel de controlo do transponder. Como?

A

O piloto carrega no botão e durante aproximadamente 18s o transponder adiciona o impulso SPI às respostas em modo A

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14
Q

O Control beam tem como finalidade evitar respostas aos lóbulos secundários. Como funciona?

A

O transponder mode A/C suprime a resposta se P1 for igual ao P2

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15
Q

Qual a diferença entre a deteção num equipamento SSR(por sliding window) e num equipamento monopulso (usando OBA)?

A

Precisão azimutal

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16
Q

O cálculo do OBA é efectuado Apartir de que sinais ?

A

Do delta e somatório

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17
Q

O radar modo S veio colmatar uma das limitações do MSSR, qual?

A

O número de códigos identificadores disponíveis para as aeronaves

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18
Q

Como é que um transponder modo A/C identifica o modo de interrogação?

A

Pelo tempo decorrido entre os impulsos P1 e P3

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19
Q

Um sistema MLAT poderá ter várias arquitecturas, dependendo das funcionalidades pretendidas. Uma arquitectura LAM é especialmente indicada para que funções dos serviços de controlo?

A

Serviços TWR

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20
Q

Numa interrogação em modo A ou modo C, que devem os transponders fazer?

A

Transponder modo A/C responde e transponder modo S responde

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21
Q

Um sistema MLAT utiliza o cálculo da TDOA (time diference of arrival) para determinar o quê?

A

A posição das aeronaves ou veículos

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22
Q

ADS-B é um sistema em que a aeronave calcula a sua posição usando GNSS. A informação obtida é fornecida aos serviços ATM usando que equipamento ?

A

Transponder modo S habilitado com extended squitter

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23
Q

O equipamento SDDS tem que função na cadeira surveillance ?

A

SDD - Surveillance Data Distribution

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24
Q

No sistema A-SMGCS há contributos de vários sensores de surveillance, qual entre eles identifica automaticamente aeronaves e veículos?

A

LAM

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25
Q

Qual o sistema que permite correlacionar pistas locais de diferentes sistemas surveillance como MSSR, WAM e ADS-B por exemplo e gerar Tracks de sistemas de utilização nas funções ATM?

A

ARTAS (ATM surveillance tracker and server )

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26
Q

What do we use RADAR for in Air Traffic Control?

A

Area Control

Approach Control

Aerodrome Control

  • Air; traffic integration, approach monitoring
  • Ground; Runway protection, monitoring ground hazards
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27
Q

How does RADAR work?

A

By calculating the time taken for a signal of a known speed to be recevied as an echo we can calculate the distance using the following equation.

Distance= (speed x time)/2 tendo em conta o slant range

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28
Q

What does RADAR stand for?

A

Radio Detection And Ranging.

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29
Q

What are the two types of RADAR used in ATC?

A

PSR

SSR

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30
Q

How does Primary RADAR work?

A

By sending out a pulse of electromagnetic energy and waiting for a reflection, as the speed of the wave is known (c) then the distance can be calculated easily.

distance= (speed x time)/2

This tells us how far away the object is and by combining this with the information about which way the RADAR was facing when the signal was received we can determine the position of an aircraft as well.

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31
Q

What are PE’s?

A

Permanent Echoes

These are the position indications given by permanent objects in the area of operation of a RADAR, they can be used to check that the RADAR is still correctly aligned.

32
Q

What is clutter and how is it formed?

A

Unwanted returns on a RADAR screen, these can be caused by ground, buildings, or weather (the rain droplets in clouds is what causes clouds to reflect RADAR)

33
Q

What is a PSR blip?

A

The visual indication, in non symbolic form, on a situation display of an aircraft obtained by PSR.

34
Q

What is RADAR contact?

A

The situation which exists when the RADAR position of a particular aircraft is seen and identified on a situation display.

35
Q

What are the three basic blocks of RADAR operation?

A

Transmission

Reception

Display

36
Q

What is a duplexer?

A

Is a transceiver that can transmit and receive, but only does one or the other at a time.

37
Q

What is the PRT of a RADAR?

A

The Pulse Repetition time

The time between pulses necessary to receive a return from the unambigious range. ie how long would be needed between pulse replies to receive a signal from the RADARs maximum range.

This determines the PRF

38
Q

What is the PRF?

A

The pulse repetition frequency

The number of pulses that can be trasmitted in a second.

Higher PRF the greater the clarity of the position return displayed as you get more ‘hits’ on it.

39
Q

What is SSR?

A

Secondary Surveillance RADAR

RADAR that works by the sending an interrogation signal to the aircraft transponder which sends a reply to the station. The distance is calculated by the time taken for the response to tbe received and the direction is taken from the direction the RADAR is facing. The response can also contain height and identity information as well.

40
Q

What are the frequencies for SSR?

A

The ground stations transmit the interrogation signal on 1030MHz

Aircraft transponder sends the reply on 1090MHz

41
Q

How does the interrogater actually interrogate the Transponder?

A

By sending a pair of pulses which are seperated by a certain time interval between each pulse.

8.5µs for Mode A

21µs for Mode C

The aircraft will then recognise this and send back the appropriate information.

42
Q

How many binary bits are there in Mode A?

A

12 bits

This limits the possible amount of codes to 4096 discrete codes

43
Q

How many Mode A codes are there?

A

4096

44
Q

What are the different types of squawk codes?

A
  1. Discrete codes- Those assigned to individual aircraft
  2. Non Discrete- Single codes issued to numerous aircraft ie conspicuity
  3. Special codes- Applied to aircraft on certain occassions
45
Q

What are ORCAM codes?

A

Originating Region Code Assignment Method

Codes are assigned depending on what participating area they come from.

It is designed to reduce RTF and cockpit work-load by allocating an SSR code which can be retained from take-off to touchdown.

46
Q

What are conspicuity codes?

A

Codes assigned to individual positions to identify aircraft being controlled by a particular unit to another unit. Helps in coordinating between units.

47
Q

How many bits are there for Mode C?

A

11

this is because the numbers 8 and 9 are now required.

48
Q

What is garbling?

A

Position indications and position symbols may overlap making them impossible to read or even causing the mode A codes to be incorrectly displayed.

Is conteracted by a de-garbler

49
Q

What is fruiting?

A

False Replies Unsynchronised in Time

Falses responses being received.

Removed by a de-fruiter.

50
Q

What effect does shortening the wavelength have on the RADARS coverage?

A

For a given aerial height this will improve the low coverage but decrease the higher coverage

51
Q

What effect does lengthening the wavelength have on the RADARS coverage?

A

For a given aerial height it increases the higher coverage but decreases the lower coverage.

52
Q

What effect will shortening the wavelength have with regards to attenuation and atmospheric effect?

A

It will cause it to attentuate faster and increase the atmospheric effect on the coverage. Due to increased interaction with molecules in the air.

53
Q

How much power does a primary RADAR need?

A

Enough, allowing for attentuation, so that the RADAR can detect an echo from an aircraft at maximum range.

54
Q

What is an MTI?

A

Moving Target Indicator

This makes the RADAR screen display only those targets which are moving as the rest are filtered out. This helps to reduce PE’s and clutter.

However this relies on radial movement of the aircraft between pulses otherwise it appear stationary.

55
Q

What is mode S?

A

Selected

It is a form of SSR that selectively interrogates aircraft instead of just generally interrogating them all. Individual interrogations reduces garbling and Fruiting.

Allows each aircraft to have its own unique code.

56
Q

What frequency band is Mode S?

A

1030-1090MHz same as all other SSR.

57
Q

How many bits does Mode S use to assign codes and how many codes does this allow?

A

24 bits

16.75 million.

58
Q

What are the phases for Mode S?

A
  1. Operation Acquisition Phase- interrogator tracks conventional responders looking for new Mode S transponders and retains in its memory the individual addersses for the next phase.
  2. Addressed survelliance phase- Mode S a/c individually interrogated for ATC identification, altitude, and other data.
59
Q

What information does elementary Mode S provide?

A

Identification
Squawk
Level
Position

60
Q

What information is provided by enhanced Mode S?

A 
Position
Identifiction
Flight level
Selected altitude
IAS
Ground speed
Mag heading
RoC RoD
61
Q

What is ADS-B?

A

Automatic Dependent Surveillance Broadcast

Works like a passive radar receiving signals from onboard equipment from the a/c. A/C deduces its own position and passes down to the ground station. Can also be used as a downlink to send and receive messages from the a/c or ground, much like CPDLC except it has less pilot input.

Can allow non-procedural approach procedures in area of little or no RADAR coverage. Can also be used to augument RADAR coverage in areas of RADAR shadowing, eg hills/ mountains near an airport.

  • ADS-B broadcasts; horizontal position, vertical position, and velocity; as well as other information.
  • Can be used by aircraft or vehicles.
  • Also can be received by ground facilities.
  • Enables a passive system to monitor, uniquely identify, and track all targets in range.
  • Suitable for ground, and airborne application. (For sole-source surveillance)
  • Is reliant on ALL users providing accurate information ALL of the time.

Automatic- Always on-No operator intervention

Dependent- The system relies upon very accurate GNSS navigation data.

Surveillance- Provides aircraft position, heading, speed, altitude, identification, and other data.

Broadcast- No interrogation required. Data is broadcast to any ADS-B station.

-It uses a downlink and messages can also be sent from the antenna to the a/c

62
Q

What are the advantages of ADS-B?

A
  • Relatively inexpensive, 0.01% the cost of equivalent RADAR
  • Smaller Power requirements and footprint, allows installation in remote areas.
  • Comms links are satellite and Microwave
63
Q

What is MLAT?

A

Multilateration

Very similar to ADS-B.

MLAT antennae on the ground receive position reports from a/c via Mode S or ADS-B broadcast, the exact position is then worked out using TDOA (time diffrence of arrival) which uses the difference in receipt times of the signal between different antennae to work out the position.

Displays on the Situation display in the same way as ADS-B

Short range ones can be used to augument SMR, much cheaper and easier to maintain than SMR also more accurate and faster. Need several antennae to achieve necessary coverage.

Wide area MLAT can be used to cover larger volumes of airspace. In augmentation with RADAR (which is sometimes impractical).

64
Q

Who can use ADS-B?

A

Aircraft and vehicles, must be equipped with transponders to be visible though.

65
Q

What are the three message types of ADS-B?

A

Position
Airborne Velocity
Aircraft Identity

66
Q

What is ADS-C?

A

Automatic Dependent Survelliance Contract

A ‘contract’ is established between the aircraft and the ground station. This contract establishes what reports the aircraft must make to the ground station and when they must be made. The ATSU will have to establish what type of contract is to be made before the ADS-C reports will be sent from the aircraft.

67
Q

What are the type of ADS-C reports?

A

Periodic contract
Demand contract- ATC will demand a report from the a/c now, such as a level report.
Event contract- Aircraft is told to make a report when doing a certain thing eg vacating a certain flight level
Mayday contract- only the pilot can cancel this one.

68
Q

What are the advantages of SSR?

A

Advantages

  • Less power for similar range
  • No ground or weather clutter
  • Display and identification of aircraft simplified
  • Level Info
  • Emergency Squawk Codes
  • Can be equipped with safety nets (STCA etc)

Disadvantages

  • All a/c need a transponder
  • No weather returns
  • Fruit
  • Garbling of TDB’s
  • Fading
  • No permanent echoes for calibration
69
Q

Who can use MLAT?

A

Aircraft and vehicles, must be equipped with transponders to be visible though.

70
Q

What are the disadvantages of SSR?

A

Disadvantages

  • All a/c need a transponder
  • No weather returns
  • Fruit
  • Garbling of TDB’s
  • Fading
  • No permanent echoes for calibration
71
Q

What are the advantages of PSR?

A

Self contained
Independent operation-solely provides identification and fix of the aircraft
Non-reliant- A/C dont need a transponder
You get PE’s, which can be used to calibrated
Weather Information

72
Q

What are the disadvantages of PSR?

A

No level info
Identification requires a much higher workload
Weather clutter
PE’s can be obscuring
Range depends on transmitter power, target size and properties
No emergency indicator

73
Q

What is ADS emergency mode?

A

A mode selected by the pilot that informs ATC that the aircraft is experiencing an emergency, including changing the squawk automatically.

Only the crew can initiate and turn this off.

74
Q

What does ADS-B broadcast for the aircraft’s position?

A

Horizontal
Vertical
Velocity

75
Q

What factors determine RADAR coverage?

A 
Aerial size, shape and height
Size of the target
Atmospheric conditions
Transmitter power
Receiver Efficiency
PRF
Pulse length
76
Q

Does Mode S provide better resolution over an SSR installation?

A

Sim

77
Q

What does 1090 ES mean

A

ADS B extended Squitter which transmits the aircraft information on 1090MHz

FI.27.MOD.BASE (14 decks)

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