04 VHF Omnidirectional Range (VOR) Flashcards Preview

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Flashcards in 04 VHF Omnidirectional Range (VOR) Deck (22)
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1
Q

What frequency range does VOR operate in?

A

108 MHz to 117.95 MHz

2
Q

Describe the basic operation of a VHF Omnidirectional Range (VOR) system

A
  • Comprises of a ring of antenna surrounding another antenna
  • Each antenna in the ring broardcasts a specific direction (or Radial)
  • This is done by the signal from the centre antenna being at different phases with each signal of the antennas surrounding it
  • Therefore the combination of each signal (centre and surrounding ring) produces a different signal for each radial
3
Q

Are the radial directions from a VOR in true or magnetic?

A

Magnetic

4
Q

For a VOR where does variation need to be accounted for?

A

Variation needs to be applied at the station

5
Q

What are the two types of VOR;

  • What type of modulation is used where?
  • What direction does the centre antenna rotate?
A

Conventional VOR (CVOR)

  • Variable Phase: AM, Reference Phase: FM
  • Rotates clockwise

Doppler VOR (DVOR)

  • Variable Phase: FM, Reference Phase: AM
  • Rotates anti-clockwise
6
Q

When is the signal from a Conventional VOR (CVOR) strongest?

A

When the antenna and AC are pointed directly at each other

7
Q

What are the benefits of using a DVOR over a CVOR?

A
  • Requires less space
  • More accurate
  • Less susceptible to sitting errors
8
Q

Why does a DVOR rotate in the opposite direction from a CVOR?

A
  • To ensure the phase differences produced are the same as a CVOR.
  • This means the same equipment on the AC can use either system
9
Q

How does a VOR system self-check?

A
  • Using a ‘pick-up’ antenna positioned at specific radial

- Since the radial the antenna is placed up is constant and known, it is able to detect any drift in the signal

10
Q

What conditions must be met by a VOR self-check for it register as functioning correctly?

A
  • Bearing must not be out by more than +- 1 degree
  • Power output must be no less than a drop of 15%
  • Monitor itself must be working
11
Q

What is the typical and maximum size of a VOR’s cone of silence?

A
  • 35 degrees

- Max 50 degrees

12
Q

What are the three types of VOR?

A
  • En-route VOR
  • Terminal VOR (TVOR)
  • Test VOR (VOT)
13
Q

What equipment for a VOR is found on the AC?

A
  • Antenna
  • VOR receiver and control unit
  • Indicator system
14
Q

To what level of accuracy does VOR work to?

A

+- 5 degrees

15
Q

Describe the scalloping error

A
  • Caused by the signal being reflected and refracted
  • Generates small oscillations of bearing information
  • Auto pilot may be disconnected if it is not capable of following the rapidly changing flight path
16
Q

For a VOR on an OBI instrument, how are the To and From indicators determined?

A
  • If the AC is +- 10 degrees from the selected course then it is a From reading
  • If the AC is +- 10 degrees from the reciprocal of the selected course then it is a To reading
17
Q

For a VOR on an OBI instrument, how are the Left and Right indicators determined?

A

If the AC is positioned to the right of the selected course (relative to the same direction) then its a turn left, otherwise a turn right

18
Q

By what principle does VOR operate?

A

Reference Phase Comparison

19
Q

What is the equation for calculating the maximum distance between two VORs for a given airway width and VOR accuracy?

A

Distance(nm) = (((Airway width / 2) / Tan (VOR accuracy)) x 2

20
Q

When tracking towards a VOR, what is the equation for the distance off track?

A

Distance Off-Track(nm) = (Angular displacement x Distance to VOR) / 60

21
Q

Using a VOR beyond it’s published protection range, errors could be caused by?

A

Interference from other transmitters on a similar frequency

22
Q

What frequency does a TVOR operate in?

A
  • Same as an ILS

- 108 to 112 MHz