RNAV | Long Range Systems Flashcards
1
Q
Theses are systems which don’t rely on __ range navaids
A
short
2
Q
INS is a ___ range nav system
A
long
3
Q
The two current GNSS are ___ and ___
A
NAVSTAR/GPS and GLONASS
4
Q
Satellites have ___ clocks on board
A
atomic
5
Q
To attain an altitude reading from GPS, _ sats are required
A
4
6
Q
GNSS reliability approaches 100% within 100m of the horizontal for __% of the time, and 300m for __% of the time.
A
95 99
7
Q
GPS accuracy can be affected by ___, ___, and ___
A
Atmospheric interference, sat positioning, turning inaccuracies
8
Q
Each satellite has 3 sections:
A
- Timing
- Signal Generation
- Transmitting
9
Q
Galileo uses two types of clock, ___ and ___
A
Rubidium Frequency standard clock, passive hydrogen master
10
Q
Galileo should use __ sats in total, with _ and _ spare in each of _ planes.
A
30 9 1 3
11
Q
Galieo’s orbit is at an altitude of ___km
A
23222
12
Q
Galileo’s orbit is inclined __ degrees to the Equator
A
53
13
Q
Galileo’s orbit takes __ hours
A
14
14
Q
Galileo’s signals are transmitted on the bands ___
A
- 1164-1215 MHz
- 1260 - 1300 MHz
- 1559-1592 MHz
15
Q
NAVSTAR uses __ satellites, + _, in _ groups of _
A
21 3 6 4
16
Q
NAVSTAR sats are __ degrees apart
A
60
17
Q
NAVSTAR aims to have __ satellites operational at any one time
A
21
18
Q
The NAVSTAR receiving frequency is ___ _Hz
A
1575.42 MHz
19
Q
NAVSTAR sats orbit in _ circular planes, _____ km above the Earth, with _ in each plane
A
6 20200 4
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
21
Q
Satellites are in view when they are _ degrees above the horizon
A
5
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
23
Q
When a satellite is going North to South, it is in the __ node
A
ascending
24
Q
The mask angle is the ___ angle above the horizon at which the sat can be used
A
lowest
25
A sat's inclination is the angle between the ___ and ___ plane
orbital, Equatorial
26
NAVSTAR satellites move once around the Earth from _ to _ once every __ hours and __ minutes
W E 11 58
27
NAVSTAR sat transmitting power is about __ Watts
50
28
The NAVSTAR system consists of 3 segments:
Space, Control, User.
29
The NAVSTAR space segment consists of ___
satellites
30
The NAVSTAR control segment consists of ___
- Master control station
- 5 monitoring stations
- Ground antenna
31
The purpose of the NAVSTAR control segment is to ____
- Manage performance
- Upload nav data
- Monitor sats
32
The NAVSTAR user segment consists of ___
receivers
33
In the NAVSTAR user segment, single channel receivers move ___
from one satellite to another in sequence
34
In the NAVSTAR user segment, multi channel receivers ___
continuously monitor position data whilst locking onto other satellites
35
In the NAVSTAR user segment, continuous receivers have up to __ channels, and can eliminate GDOP problems by watching up to _ sats
12 4
36
For NAVSTAR, the receiver antenna are ___-___, with the active element being a quarter wavelength of _._ _Hz; 2.5 cm
semi-omnidirectional, 1.6 GHz
37
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.
microwave, atomic
38
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.
Gold
39
Satellites transmit a ___ ___ code, in which a nav data message is encoded.
Coarse Acquisition
40
The CA code is a ___ bit PRN transmitted at _.___ Mbits/second, repeated every millisecond.
1023, 1.023
41
The ___ of each satellite is known by the receiver, which can generate them internally.
PRN
42
Nav data is transmitted every __ seconds as frames, containing _ subframes.
30 5
43
The 5 subframes contained within the nav data are:
- Clock
- Ephemeris
- Ephemeris
- Almanac
- Almanac
44
The Ephemeris subframe contains data about the exact orbital path for the next _ hours
4
45
The Almanac subframe contains ___ precise positioning details
less
46
Time runs ___ slowly with ___ gravity
more more
47
The sat signal is modulated with ___
pseudo-random numbers.
48
Almanac information is transmitted every __._ minutes, taking __._ minutes to download
12.5 12.5
49
The Almanac data covers ___
- Sats operating normally
- PRN codes of available sats
- Predicted positions of sats in their orbits.
50
Each satellite transmits its own ephemeris data, every __ seconds and taking __ seconds to download. The data is valid for _ to _ hours.
30 12 4
51
For NAVSTAR, two _HF frequencies are used:
- L1, ___ _HZ
- L2 ___ _Hz
Both frequencies are multiples of a base frequency, 10.23 _Hz
1575.42 MHz
1227.60 MHz
MHz
52
GLONASS uses _ planes, with _ satellites, equally displaced by __ degrees of latitude
3 8 45
53
GLONASS sats fly at ___ km, at an inclination of __._ degrees
19100 64.8
54
Each GLONASS orbit takes __ hours __ minutes
11 15
55
GLONASAS signals are transmitted on the _ band, which is _HF,
L UHF
56
GLONASS L1 is _._ _Hz, and L2 is _._ _Hz
1.6 GHz, 1.2 GHz
57
The majority of PBN operations can be conducted using ____ satellite systems
unaugmented
58
GBAS is the practical application of ___ ___ ___ GPS
Local Area Differential
59
GBAS uses a ___ signal from a precisely surveyed ground based transmitter, whose position can be compared against that of the receiver.
5th
60
GBAS corrections are sent directly to aircraft receivers form ground stations at airports, within __-__nm
20 30
61
The GBAS ground station signal is able to provide ___ and ___ data
error correction integrity
62
GBAS coverage is within ___ of the final approach, up to 15 nm away from the landing threshold, _ degrees within 15-20 nm.
35 10
63
GBAS + GPS is called ____ in the US
Local Area Augmentation System
64
In summary, GBAS can provide ___
- Precision approach down to 200ft
| - Horizontal positioning for RNAV in terminal areas
65
SBAS is used to extended ___ GPS to a larger area
differential
66
SBAS works on the principle of measuring the signal errors from satellites and providing separate corrections for ___, __, __, and ___ errors.
ranging, ephemeris, clock, ionospheric
67
With SBAS, correction data is transmitted to ___ satellites, and then re-transmitted to the ___
geostationary user
68
SBAS regionally augments ___ and ___ by making them suitable for safety-critical procedures.
GPS, GLONASS
69
WAAS, standing for ___, allows GPS to be used through flight, including a Cat _ precision approach.
Wide Area Augmentation System, Cat I
70
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.
precisely surveyed ground stations, master station, geographical area, geostationary satellites
71
LPV stands for ____
Lateral Precision with Vertical Guidance
72
SBAS guidance is (not) subject to altimeter errors
not
73
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.
RAIM
74
WAAS uses two satellites over the ___ and ___
Atlantic and Pacific
75
EGNOS is the ___
European Geostationary Navigation Overlay Service
76
EGNOS as the European equivalent to ___
WAAS
77
EGNOS coverage is limited to between __N and __S, which is ___ North then WAAS
80 80 further
78
EGNOS can improve accuracy to _ to _ m horizontally, and _ to _ m vertically
1 2 3 5
79
EGNOS allows users to be alerted of malfunctions within _ seconds, rather than _ hours
6 3
80
ABAS uses ___ to develop integrity control
excess information within the GNSS constellation
81
ABAS does (not) improve positioning accuracy, unlike GBAS/SBAS
not
82
ABAS which uses GNSS information only is ___
RAIM
83
A system using information from additional on board sensors is called ___
AAIM
84
RAIM helps to detect and correct faults more quickly than the standard ____
2 hours
85
RAIM is achieved within the ___, which monitors satellites and verifies their signals.
receiver
86
An ___ ___ is required for RAIM
extra satellite
87
Basic RAIM needs _ satellites to work, and _ to continue working with one having failed
5 6
88
```
With RAIM available, the integrity limits are:
_ nm for oceanic
_ nm for enroute
_ nm for terminal
_._ nm for GPS approaches.
```
4
2
1
0.3
89
With RAIM unavailable, GPS must be ____
integrated with other systems
90
RAIM can be assisted with baroaiding, this ___ the number of satellites required.
reduces
91
Clock coasting uses the atomic clocks in the ___ segment to reduce clock bias
user
92
GNSS errors are smallest when satellites are ___
overhead
93
When a receiver starts, its own clock is inaccurate by an unknown error called ___ ___ .
clock bias
94
Clock bias is correct in the receiver by running ____ ____
simultaneous equations
95
Satellites heading towards the sun ___, and those away ___, causing satellite clock drift. This is the largest unmeasureale source of error.
decelerate
| Accelerate
96
Ephemeris error it the result of the satellite ____
not being where it thinks it is
97
Ephemeris error can arise as a result of ___ effects
gravitational
98
Ground monitoring stations check satellites every __ hours, with the maximum error being _._ metres
12 2.5
99
UHF signals are (not) normally refractable in the ionosphere
not
100
The small amount of refraction which UHF signals do suffer in the ionosphere makes signals travel ___ than they should
further
101
The sat signal __ as it passes through the ion layers
attenuates
102
The error caused by refraction is called ___ ____ ____ and produces an error of around __m
ionospheric group delay, 5m
103
Ionospheric group delay is ___ proportional to the square of the frequency
inversely
104
Ionospheric propagation is the ___ natural error
worst
105
Internal noise within circuits can cause positioning errors of up to _ m
0.3
106
Water vapour in the troposphere will affect ___
refraction
107
The maximum error from tropospheric propagation is between _m and _m
0.3 0.5
108
Multipath reflection occurs as a result of ___
the antenna being shadowed by parts of the aircraft, and preventing signals being transmitted/received
109
The maximum multipath reflection error is _m
0.6
110
C/A Selective Authority used to be done by ___ satellite clocks
dithering
111
Manoeuvring errors are caused by ___
aircraft attitudes
112
GDOP/PDOP stands for ___
Geometric or Position Dilution of Position
113
GDOP can occur when satellites are ___ ___ to one another, downgrading their accuracy
too close
114
A GDOP of less than __ is required for enroute nav, and less than _ for precision approaches.
6 3
115
Normal accuracy of 100m for 95% of the time assumes a PDOP of _, and a range error of __m
3 33.3
116
Range errors are multiplied by PDOP to obtain ___ ___
stated accuracies
117
GDOP is ___ by RAIM
minimised
118
Search the Sky is a procedure which starts___
after switching on the receiver if there is no stored satellite data available
119
The closer the receiver is to a LAAS ground reference station, the ____ accurate the fix
more
120
The data elements transmitted by NAVSTAR GPS satellites include:
- Offset of sat clock from UTC
- Ephemeris data
- Satellite health status data
- Ionospheric delays
121
The Galileo navigation messages contains ___
information about the satellite orbit and clock references
122
Satellites transmit on _HF
UHF
