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Radio Navigation > RNAV | Long Range Systems > Flashcards

RNAV | Long Range Systems Flashcards

1
Q

Theses are systems which don’t rely on __ range navaids

A

short

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2
Q

INS is a ___ range nav system

A

long

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3
Q

The two current GNSS are ___ and ___

A

NAVSTAR/GPS and GLONASS

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4
Q

Satellites have ___ clocks on board

A

atomic

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5
Q

To attain an altitude reading from GPS, _ sats are required

A

4

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6
Q

GNSS reliability approaches 100% within 100m of the horizontal for __% of the time, and 300m for __% of the time.

A

95 99

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7
Q

GPS accuracy can be affected by ___, ___, and ___

A

Atmospheric interference, sat positioning, turning inaccuracies

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8
Q

Each satellite has 3 sections:

A
  • Timing
  • Signal Generation
  • Transmitting
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9
Q

Galileo uses two types of clock, ___ and ___

A

Rubidium Frequency standard clock, passive hydrogen master

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10
Q

Galileo should use __ sats in total, with _ and _ spare in each of _ planes.

A

30 9 1 3

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11
Q

Galieo’s orbit is at an altitude of ___km

A

23222

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12
Q

Galileo’s orbit is inclined __ degrees to the Equator

A

53

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13
Q

Galileo’s orbit takes __ hours

A

14

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14
Q

Galileo’s signals are transmitted on the bands ___

A
  • 1164-1215 MHz
  • 1260 - 1300 MHz
  • 1559-1592 MHz
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15
Q

NAVSTAR uses __ satellites, + _, in _ groups of _

A

21 3 6 4

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16
Q

NAVSTAR sats are __ degrees apart

A

60

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17
Q

NAVSTAR aims to have __ satellites operational at any one time

A

21

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18
Q

The NAVSTAR receiving frequency is ___ _Hz

A

1575.42 MHz

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19
Q

NAVSTAR sats orbit in _ circular planes, _____ km above the Earth, with _ in each plane

A

6 20200 4

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20
Q

Each NAVSTAR sat should have a __ degree view of the Earth, at least _ should be in line of sight from any point on the Earth

A

28, 5

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21
Q

Satellites are in view when they are _ degrees above the horizon

A

5

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22
Q

A good combination for GPS reception is _ with a low elevation, with a ___ degree spread, with a _ directly overhead.

A

3 120 4

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23
Q

When a satellite is going North to South, it is in the __ node

A

ascending

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24
Q

The mask angle is the ___ angle above the horizon at which the sat can be used

A

lowest

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25
Q

A sat’s inclination is the angle between the ___ and ___ plane

A

orbital, Equatorial

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26
Q

NAVSTAR satellites move once around the Earth from _ to _ once every __ hours and __ minutes

A

W E 11 58

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27
Q

NAVSTAR sat transmitting power is about __ Watts

A

50

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28
Q

The NAVSTAR system consists of 3 segments:

A

Space, Control, User.

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29
Q

The NAVSTAR space segment consists of ___

A

satellites

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30
Q

The NAVSTAR control segment consists of ___

A
  • Master control station
  • 5 monitoring stations
  • Ground antenna
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31
Q

The purpose of the NAVSTAR control segment is to ____

A
  • Manage performance
  • Upload nav data
  • Monitor sats
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32
Q

The NAVSTAR user segment consists of ___

A

receivers

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33
Q

In the NAVSTAR user segment, single channel receivers move ___

A

from one satellite to another in sequence

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34
Q

In the NAVSTAR user segment, multi channel receivers ___

A

continuously monitor position data whilst locking onto other satellites

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35
Q

In the NAVSTAR user segment, continuous receivers have up to __ channels, and can eliminate GDOP problems by watching up to _ sats

A

12 4

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36
Q

For NAVSTAR, the receiver antenna are ___-___, with the active element being a quarter wavelength of . _Hz; 2.5 cm

A

semi-omnidirectional, 1.6 GHz

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37
Q

The satellite transmits a signal composed of a digital code, modulated on a ___ carrier frequency known as 1.1, whose timing is controlled by an ___ clock.

A

microwave, atomic

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38
Q

A GPS receiver can tune into a satellite by generating its own copy of the ___ code and carrier, matching their timings to the incoming signal; the differences are converted into a distance.

A

Gold

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39
Q

Satellites transmit a ___ ___ code, in which a nav data message is encoded.

A

Coarse Acquisition

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40
Q

The CA code is a ___ bit PRN transmitted at _.___ Mbits/second, repeated every millisecond.

A

1023, 1.023

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41
Q

The ___ of each satellite is known by the receiver, which can generate them internally.

A

PRN

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42
Q

Nav data is transmitted every __ seconds as frames, containing _ subframes.

A

30 5

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43
Q

The 5 subframes contained within the nav data are:

A
  • Clock
  • Ephemeris
  • Ephemeris
  • Almanac
  • Almanac
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44
Q

The Ephemeris subframe contains data about the exact orbital path for the next _ hours

A

4

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45
Q

The Almanac subframe contains ___ precise positioning details

A

less

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46
Q

Time runs ___ slowly with ___ gravity

A

more more

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47
Q

The sat signal is modulated with ___

A

pseudo-random numbers.

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48
Q

Almanac information is transmitted every __._ minutes, taking __._ minutes to download

A

12.5 12.5

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49
Q

The Almanac data covers ___

A
  • Sats operating normally
  • PRN codes of available sats
  • Predicted positions of sats in their orbits.
50
Q

Each satellite transmits its own ephemeris data, every __ seconds and taking __ seconds to download. The data is valid for _ to _ hours.

A

30 12 4

51
Q

For NAVSTAR, two _HF frequencies are used:
- L1, ___ _HZ
- L2 ___ _Hz
Both frequencies are multiples of a base frequency, 10.23 _Hz

A

1575.42 MHz
1227.60 MHz
MHz

52
Q

GLONASS uses _ planes, with _ satellites, equally displaced by __ degrees of latitude

A

3 8 45

53
Q

GLONASS sats fly at ___ km, at an inclination of __._ degrees

A

19100 64.8

54
Q

Each GLONASS orbit takes __ hours __ minutes

A

11 15

55
Q

GLONASAS signals are transmitted on the _ band, which is _HF,

A

L UHF

56
Q

GLONASS L1 is . _Hz, and L2 is . _Hz

A

1.6 GHz, 1.2 GHz

57
Q

The majority of PBN operations can be conducted using ____ satellite systems

A

unaugmented

58
Q

GBAS is the practical application of ___ ___ ___ GPS

A

Local Area Differential

59
Q

GBAS uses a ___ signal from a precisely surveyed ground based transmitter, whose position can be compared against that of the receiver.

A

5th

60
Q

GBAS corrections are sent directly to aircraft receivers form ground stations at airports, within __-__nm

A

20 30

61
Q

The GBAS ground station signal is able to provide ___ and ___ data

A

error correction integrity

62
Q

GBAS coverage is within ___ of the final approach, up to 15 nm away from the landing threshold, _ degrees within 15-20 nm.

A

35 10

63
Q

GBAS + GPS is called ____ in the US

A

Local Area Augmentation System

64
Q

In summary, GBAS can provide ___

A
  • Precision approach down to 200ft

- Horizontal positioning for RNAV in terminal areas

65
Q

SBAS is used to extended ___ GPS to a larger area

A

differential

66
Q

SBAS works on the principle of measuring the signal errors from satellites and providing separate corrections for ___, __, __, and ___ errors.

A

ranging, ephemeris, clock, ionospheric

67
Q

With SBAS, correction data is transmitted to ___ satellites, and then re-transmitted to the ___

A

geostationary user

68
Q

SBAS regionally augments ___ and ___ by making them suitable for safety-critical procedures.

A

GPS, GLONASS

69
Q

WAAS, standing for ___, allows GPS to be used through flight, including a Cat _ precision approach.

A

Wide Area Augmentation System, Cat I

70
Q

With WAAS, sat signals are received by ___, which detect errors and send them to a ___, which adds correction information based on ___, and sends the connection message to ___ for rebroadcast.

A

precisely surveyed ground stations, master station, geographical area, geostationary satellites

71
Q

LPV stands for ____

A

Lateral Precision with Vertical Guidance

72
Q

SBAS guidance is (not) subject to altimeter errors

A

not

73
Q

With SBAS being used, the additional satellites which would be used for ____ are not required as the messages are available wherever the sat signal can be received.

A

RAIM

74
Q

WAAS uses two satellites over the ___ and ___

A

Atlantic and Pacific

75
Q

EGNOS is the ___

A

European Geostationary Navigation Overlay Service

76
Q

EGNOS as the European equivalent to ___

A

WAAS

77
Q

EGNOS coverage is limited to between __N and __S, which is ___ North then WAAS

A

80 80 further

78
Q

EGNOS can improve accuracy to _ to _ m horizontally, and _ to _ m vertically

A

1 2 3 5

79
Q

EGNOS allows users to be alerted of malfunctions within _ seconds, rather than _ hours

A

6 3

80
Q

ABAS uses ___ to develop integrity control

A

excess information within the GNSS constellation

81
Q

ABAS does (not) improve positioning accuracy, unlike GBAS/SBAS

A

not

82
Q

ABAS which uses GNSS information only is ___

A

RAIM

83
Q

A system using information from additional on board sensors is called ___

A

AAIM

84
Q

RAIM helps to detect and correct faults more quickly than the standard ____

A

2 hours

85
Q

RAIM is achieved within the ___, which monitors satellites and verifies their signals.

A

receiver

86
Q

An ___ ___ is required for RAIM

A

extra satellite

87
Q

Basic RAIM needs _ satellites to work, and _ to continue working with one having failed

A

5 6

88
Q 
With RAIM available, the integrity limits are:
_ nm for oceanic
_ nm for enroute
_ nm for terminal
_._ nm for GPS approaches.
A

4
2
1
0.3

89
Q

With RAIM unavailable, GPS must be ____

A

integrated with other systems

90
Q

RAIM can be assisted with baroaiding, this ___ the number of satellites required.

A

reduces

91
Q

Clock coasting uses the atomic clocks in the ___ segment to reduce clock bias

A

user

92
Q

GNSS errors are smallest when satellites are ___

A

overhead

93
Q

When a receiver starts, its own clock is inaccurate by an unknown error called ___ ___ .

A

clock bias

94
Q

Clock bias is correct in the receiver by running ____ ____

A

simultaneous equations

95
Q

Satellites heading towards the sun ___, and those away ___, causing satellite clock drift. This is the largest unmeasureale source of error.

A

decelerate

Accelerate

96
Q

Ephemeris error it the result of the satellite ____

A

not being where it thinks it is

97
Q

Ephemeris error can arise as a result of ___ effects

A

gravitational

98
Q

Ground monitoring stations check satellites every __ hours, with the maximum error being . metres

A

12 2.5

99
Q

UHF signals are (not) normally refractable in the ionosphere

A

not

100
Q

The small amount of refraction which UHF signals do suffer in the ionosphere makes signals travel ___ than they should

A

further

101
Q

The sat signal __ as it passes through the ion layers

A

attenuates

102
Q

The error caused by refraction is called ___ ____ ____ and produces an error of around __m

A

ionospheric group delay, 5m

103
Q

Ionospheric group delay is ___ proportional to the square of the frequency

A

inversely

104
Q

Ionospheric propagation is the ___ natural error

A

worst

105
Q

Internal noise within circuits can cause positioning errors of up to _ m

A

0.3

106
Q

Water vapour in the troposphere will affect ___

A

refraction

107
Q

The maximum error from tropospheric propagation is between _m and _m

A

0.3 0.5

108
Q

Multipath reflection occurs as a result of ___

A

the antenna being shadowed by parts of the aircraft, and preventing signals being transmitted/received

109
Q

The maximum multipath reflection error is _m

A

0.6

110
Q

C/A Selective Authority used to be done by ___ satellite clocks

A

dithering

111
Q

Manoeuvring errors are caused by ___

A

aircraft attitudes

112
Q

GDOP/PDOP stands for ___

A

Geometric or Position Dilution of Position

113
Q

GDOP can occur when satellites are ___ ___ to one another, downgrading their accuracy

A

too close

114
Q

A GDOP of less than __ is required for enroute nav, and less than _ for precision approaches.

A

6 3

115
Q

Normal accuracy of 100m for 95% of the time assumes a PDOP of _, and a range error of __m

A

3 33.3

116
Q

Range errors are multiplied by PDOP to obtain ___ ___

A

stated accuracies

117
Q

GDOP is ___ by RAIM

A

minimised

118
Q

Search the Sky is a procedure which starts___

A

after switching on the receiver if there is no stored satellite data available

119
Q

The closer the receiver is to a LAAS ground reference station, the ____ accurate the fix

A

more

120
Q

The data elements transmitted by NAVSTAR GPS satellites include:

A
  • Offset of sat clock from UTC
  • Ephemeris data
  • Satellite health status data
  • Ionospheric delays
121
Q

The Galileo navigation messages contains ___

A

information about the satellite orbit and clock references

122
Q

Satellites transmit on _HF

A

UHF

Radio Navigation (59 decks)

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