06 GNSS Flashcards
ATPL RADIO
Which statement about a Satellite Based Augmentation System (SBAS) is correct?
SBAS is able to provide approach and landing operations with vertical guidance.
How long does it take a Galileo satellite to orbit the earth?
14 hours
What is EGNOS (European Global Navigation Overlay System)?
Wide Area Differential GPS (WADGPS)
…………………………………
The European geostationary navigation overlay system (EGNOS) is a satellite based augmentation system (SBAS), i.e. it is using geostationary satellites to transmit correction signals to global navigation satellite system (GNSS) receivers. As these satellites transmit their signals cover a large area, EGNOS is a wide area differential GPS system.
SBAS messages are broadcast via:
geostationary satellites.
…………………………………..
The satellite based augmentation system (SBAS) use geostationary satellites to transmit error corrections to satellite navigation receivers within their coverage. By using geostationary satellites, their coverage area will be constant and significantly larger than the coverage area of a ground based augmentation system (GBAS).
With reference to GNSS, the ground based augmentation system (GBAS) sends corrections for:
errors due to ionospheric and tropospheric disturbances.
……………………………………
Which of the following statements about the ‘visibility’ of NAVSTAR/GPS satellites is correct?
It varies, depending on the time and observer’s location
…………………………………………………
The visibility of NAVSTAR/GPS satellites is depending on the location of the observer and the time. As the satellites are in constant movement there will be a varying number of satellites in view at any time. Generally, the coverage will be the lowest in the polar regions.
Which statement is correct about the SBAS (Satellite-Based Augmentation Systems)?
In an SBAS the pseudo range corrections are sent to the users by geostationary satellites.
When considering a GPS navigation system the following is true:
For precise position fixing the satellite clock error is very important.
GPS time can be converted to UTC by application of the:
UTC parameters sent in the navigation message.
How many clocks are installed in each NAVSTAR GPS satellite?
4
……………
Present generation NAVSTAR/GPS satellites have 4 rubidium atomic clocks.
Consider SBAS and GBAS:
SBAS can cover more area than GBAS.
The reason why the measured distance between a NAVSTAR/GPS satellite navigation system satellite and a receiver is called a ‘Pseudo-Range’ is because the:
calculated range includes receiver clock error
The term ‘SBAS’ signifies:
Satellite Based Augmentation Systems.
………………………….
There are two types of augmentation systems for satellite navigation:
- Ground based augmentation system (GBAS)
- Satellite based augmentation system (SBAS)
What advantage is there, if any, of using a combination of EGNOS and GPS?
To improve the integrity by alerting users within 6 seconds instead of 3 hours.
Which information about the NAVSTAR GPS is correct?
Note: the orbital heights are approximate values
Satellites: 24, Orbital planes: 6, Orbital height: 20 200 km
………………………….
The NAVSTAR GPS constellation has the following properties: Satellites: 24, Orbital planes: 6, Orbital height: 20 200 km
Which of the following data, in addition to the Pseudo Random Noise (PRN) code, forms part of the so called ‘Navigation Message’ transmitted by NAVSTAR/GPS satellites?
almanac data; satellite status information
……………………………………………
The navigation message from a NAVSTAR/GPS satellite contain almanac data and satellite status information. The receiver clock error is calculated by the receiver based on the signals from several satellites.
GPS system satellites transmit their signals on two carrier waves 1575 MHz and 1227 MHz and supply two possible codes accessible according to user (civil or military). Commercial aviation uses:
only the 1575 MHz carrier wave and one code
…………………………………..
The NAVSTAR/GPS satellites transmit two signals:
L1 – 1575.42 MHz
L2 – 1227.60 MHz
The L1 signal contain the C/A code (coarse acquisition code) for civilian use in addition to the P code (precision code), reserved for military use. The L2 signal has been P code only but there is now a new, civilian L2C code available from newer satellites and the P code is changing to M code.
Which information about the Galileo system is correct?
Note: the orbital heights are approximate values
Satellites: 30, Orbital planes: 3, Orbital height: 23 200 km
Which of the following statements concerning the L1 and L2 NAVSTAR/GPS transmission frequencies and codes is correct?
The higher frequency is used to transmit both the C/A and P codes
Which of the following, if any, is a prerequisite if a receiver of a NAVSTAR/GPS satellite navigation system is to be used in combination with a multi sensor system?
The prescribed IFR-equipment must be installed and operational
In accordance with ICAO Annex 10 the NAVSTAR/GPS global average 95% position accuracy in SPS should be :
13m horizontally
Which of the following is the datum for altitude information when conducting flights under IFR conditions on airways using the NAVSTAR/GPS satellite navigation system?
Barometric altitude
………………………………
Regardless of type of navigation system, barometric altitude (either based on QNH or 1013 hPa) is the reference for altitude in aircraft. The only time GPS altitude can be of limited use is in the event of a total altimeter failure in the aircraft.
Concerning the NAVSTAR/GPS satellite navigation system, what is the meaning of the term ‘Receiver Autonomous Integrity Monitoring’ (RAIM)?
It is a technique by which a receiver ensures the integrity of the navigation information.
What is the time taken to receive the complete Navigation Message (complete set of data) from all satellites?
12.5 minutes (= 30 seconds per data frame)
When talking about the Galileo GNSS we can say that every satellite has two types of atomic clock:
1 - which are identical.
2 - which are not identical.
3 - where one is the master and one is the slave.
4 - which are not synchronised with each other.
Which of the above is/are correct?
2 & 4
What is true concerning UTC parameters within the navigation message of a NAVSTAR GPS satellite?
They are used for the satellite’s clock correction to convert from satellite-time to GPS time.
How long does it take a GLONASS satellite to orbit the earth?
11 hours 15 minutes
For what reason is a mask angle set-up in a GPS-receiver?
To deny the receiver the use of GPS-satellites with an elevation less than the mask angle.
What difference, if any, is there between NAVSTAR GPS and GLONASS?
GLONASS satellites orbit faster around the Earth than GPS satellites.
Which of the following satellite navigation systems has Full Operational Capability (FOC) and is approved for specified flights under IFR conditions in Europe?
NAVSTAR/GPS
What is the function of the control segment in GPS NAVSTAR?
To ensure the transmitted data of the satellites is controlled and updated from time to time by ground stations.
GBAS ground subsystems provide two services, the precision approach service and the GBAS positioning service. The precision approach service provides:
deviation guidance for Final Approach Segments.
The required 30 Galileo operational satellites are located on:
3 orbital planes with 9 satellites and 1 spare replacement in each plane.
At what approximate height above the WGS 84 ellipsoid are Galileo satellites circling the Earth?
23 200 km
The influence of the ionosphere on the accuracy of the satellite navigation system NAVSTAR/GPS is:
minimised by the receiver using a model of the atmosphere and comparing signals transmitted by the satellites
In relation to the satellite navigation system NAVSTAR/GPS, the term ‘inclination’ denotes the angle between the:
orbital plane and the equatorial plane
Which of the following NAVSTAR/GPS satellite navigation system codes can be processed by ‘unauthorised’ civil aviation receivers?
C/A
Which of the following geometric satellite constellations provides the most accurate NAVSTAR/GPS position fix?
3 satellites with a low elevation above the horizon and an azimuth of 120° from each other together with a fourth directly overhead
One of the tasks of the GPS control segment is
to determine and send new ephemeris and new satellite clock error data to the GPS-satellites.
Which of the following statements about the accuracy that can be obtained with the LAAS (local area augmentation system) of the satellite navigation system NAVSTAR/GPS is correct?
The closer the receiver is to a LAAS ground reference station, the more accurate is the aircraft position fix.
The frequency band of the Galileo GNSS is:
1164 - 1215 MHz, 1260 - 1300 MHz, 1559 - 1591 MHz
In a Satellite-Assisted Navigation System (GNSS/GPS), a fix is obtained by:
measuring the time taken for a minimum number of satellites’ transmissions, in known positions, to reach the aircraft’s receiver
Which of the following coordinate systems is used by the NAVSTAR/GPS receiver to calculate position (latitude, longitude and altitude)?
WGS 84
In relation to the NAVSTAR/GPS satellite navigation system, ‘Search the Sky’ is a:
procedure that starts after switching on a receiver if there is no stored satellite data available
Which of the following procedures must be adopted if, on a flight under IFR conditions using a NAVSTAR/GPS satellite navigation system receiver, the position fix obtained from the GPS receiver differs from the position of conventional navigation systems by an unacceptable amount?
It may be continued using conventional navigation systems
In the ‘timing section’ of the Galileo satellite system, how many clocks have been developed?
2 clocks have been developed, a Rubidium Frequency Standard clock and a Passive Hydrogen Maser clock.
Which statement concerning Galileo GNSS is correct?
GPS, EGNOS and GALILEO are compatible, with not interfere with each other, and the performance of the receiver will be enhanced by the interoperability of the systems.
Which of the following statements is correct regarding Galileo satellites?
1 - In each satellite there are two identical atomic clocks.
2 - In each satellite there are two types of non-identical atomic clock.
3 - In each satellite there is one master atomic clock and one reference clock.
4 - The clocks of the satellites are synchronised with each other.
5 - The clocks of the satellites are synchronised with a network of clocks which are located on the ground.
2
The required 24 NAVSTAR/GPS operational satellites are located on:
6 orbital planes with 4 satellites in each plane
An SBAS (Satellite Based Augmentation System) consists of:
3 elements.
The term “GBAS” signifies:
Ground Based Augmentation Systems.
In civil aviation, the height value computed by the receiver of the satellite navigation system NAVSTAR/GPS is the:
height above the WGS-84 ellipsoid
The main task of the user segment (receiver) of the satellite navigation system NAVSTAR/GPS is to calculate receiver position by:
selecting appropriate satellites automatically, to track the signals and to measure the time taken by signals from the satellites to reach the receiver
Which statement about a Satellite Based Augmentation System (SBAS) is correct?
SBAS is able to provide guidance for precision approaches.
Using the attached image:
What is the value of the selected course shown on the EFIS display?
110°
The GPS control segment consists of
a Master Control Station, Monitor Stations and Ground Antenna’s.
Which information about GLONASS is correct?
Note: the orbital heights are approximate values
Satellites: 24, Orbital planes: 3, Orbital height: 19 100 km
Which one of the following errors can be compensated for by a NAVSTAR/GPS receiver comparing L1 and L2 frequencies?
Ionospheric delay
The orbital planes of the satellite navigation system NAVSTAR/GPS are:
inclined 55° to the equatorial plane
With reference to the navigation message of a GPS, what is contained in the almanac data?
Orbital data about all satellites in the GPS constellation.
The frequency band of the SBAS data link is:
a signal with the same frequency as GPS.
In relation to the NAVSTAR/GPS satellite navigation system, what is involved in the differential technique (D-GPS)?
Fixed ground stations compute position errors and transmit correction data to a suitable receiver on the aircraft
A RAIM system has excluded a satellite. How many satellites are required to maintain a 3D Position fix with RAIM capability?
5
Assuming that one of the GPS/NAVSTAR satellites used by the receiver is faulty and that the PDOP has relatively low value when signals from the GPS satellites are received (including the one that is faulty), the RAIM software in the receiver:
is able to detect that one satellite is faulty and identify which one.
At what approximate height above the WGS-84 ellipsoid are NAVSTAR/GPS satellites circling the earth?
20200 km
What is true about a navigation message when referring to the Galileo GNSS?
The navigation message basically contains information concerning the satellite orbit and the clock references.
Errors occur in GPS satellite orbits because of:
solar winds and gravitation of the sun, moon and planets.
How many satellites does the space segment of NAVSTAR/GPS system consist of in the notional constellation?
24
The system capable of measuring on the ground, the signal errors transmitted by GNSS satellites and transmitting differential corrections and integrity messages for navigation satellites is:
SBAS
One of the tasks of the GPS control segment is
to detect the malfunctioning of satellites.
In the event of the re-use of Selective Availability, how does this affect, if at all, the navigation accuracy of the NAVSTAR/GPS satellite navigation system ?
It degrades position accuracy by manipulating satellite signals
Which of the following statements about the accuracy that can be obtained with the differential technique (D-GPS) of the satellite navigation system NAVSTAR/GPS is correct?
The nearer a receiver is situated to a D-GPS ground station, the more accurate the position fix
What is the minimum number of NAVSTAR/GPS satellites required to produce an accurate independent 3-D position fix?
4
………………………
The NAVSTAR/GPS receiver require the following number of satellites to establish a position fix:
2D – 3 satellites.
3D – 4 satellites.
RAIM – 5 satellites.
RAIM with fault detection and exclusion – 6 satellites.
Which statement about the monitoring system of the Galileo GNSS is correct?
The system is monitored in a similar way for both GPS NAVSTAR and GLONASS but also by a new method based on spread-spectrum signals.
The influence of the ionosphere on the accuracy of the satellite navigation system NAVSTAR GPS is:
reduced by using a model of the ionosphere by the satellites in Standard Positioning Service (SPS) receivers.
Minimum Ground-Based Augmentation System (GBAS) plan coverage is:
15NM from the landing threshold within 35° apart the final approach path and 10° apart between 15 and 20NM.
The navigation message contains clock correction parameters which are used for:
correction of satellite time.
Which one of the following is an advantages of a multi-sensor system using inputs from a global navigation satellite system (GNSS) and an inertial reference system (IRS)?
The GNSS can be used to update the FMS position from a drifting IRS.
In the NAVSTAR/GPS satellite navigation system, receiver clock error:
is corrected by using signals from four satellites
How long does it take a NAVSTAR/GPS satellite to orbit the earth?
Approximately 12 hours (1/2 of a sidereal day)
Which of the following combinations of satellite navigation systems provide the most accurate position fixes in air navigation?
NAVSTAR/GPS and GLONASS
………………………………………………….
NAVSTAR/GPS is the American satellite navigation system and GLONASS is the Russian counterpart. The European GALILEO satellite navigation system is not fully operational yet.
GPS satellites transmit on two L-band frequencies with different types of signals. Which of these are generally available for use by civil aviation?
L1-coarse acquisition (C/A) with selected availability (S/A)
……………………………..
As the NAVSTAR/GPS is primarily a military satellite navigation system, the signals available to civilian users are restricted to the course acquisition (C/A) code with selected availability, which is part of the L1 signal.
What is the minimum number of satellites required for the NAVSTAR/GPS to carry out two dimensional operation?
3
In accordance with ICAO Annex 10 the GPS NAVSTAR position accuracy in SPS should be for 95% of the time:
13 metres horizontally.
……………………………………….
ICAO Annex 10 specify that the NAVSTAR/GPS standard positioning service (SPS) shall perform to a worldwide accuracy of at least 13 metres horizontally and 22 metres vertically for 95% of the time.
In a GPS satellite system the navigation message contains ionosphere model data. These parameters are used by:
receivers to calculate the delay of GPS signals.
Which of the following lists all the parameters that can be determined by a GPS receiver tracking signals from 4 different satellites?
Latitude, longitude, altitude and time
GPS satellites transmit on two L-band frequencies with different types of signals. Which of these are generally available for use by civil aviation?
L1-coarse acquisition
What is the minimum number of satellites required by a GPS in order to obtain a three dimensional fix?
4
Frequency band of the GBAS data link is:
VHF band of ILS and VOR systems.
…………………………………………….
The ground based augmentation system (GBAS) transmit its correction signals in the VHF band, namely using the ILS and VOR frequency range (108.00 MHz – 117.95 MHz).
What is the maximum latitude of a GPS-satellite ground track?
55° N/S
The different segments of the satellite navigation system NAVSTAR/GPS are the:
control, space and user
What is the inclination to the equatorial plane of the satellite’s orbit in the NAVSTAR GPS constellation?
55°
…………………………….
Inclination is the term used for the angle between the Equatorial plane and the orbital plane of the satellite. For NAVSTAR/GPS the inclination is 55º
A GBAS signal is sent to:
a receiver which is located in the aircraft and modifies horizontal and vertical guidance corrections.
Which of the following lists are all errors that affect the accuracy and reliability of the Satellite-Assisted Navigation system (GNSS/GPS)?
Satellite clock; satellite ephemeris; atmospheric propagation
The basic elements of the satellite navigation system NAVSTAR/GPS are the:
control, space and user segments.
SBAS systems improve the performance of GPS by:
providing an additional signal coming from the geostationary satellites.
What datum is used for the Minimum Descent Altitude (MDA) on a non-precision approach when using the NAVSTAR/GPS satellite navigation system?
Barometric altitude
……………………………………
Regardless of type of navigation system, barometric altitude based on QNH is the reference for altitude in aircraft performing a non-precision approach. The only time GPS altitude can be of limited use is in the event of a total altimeter failure in the aircraft.
In a Satellite-Assisted Navigation system (GNSS/GPS) a position line is obtained by:
timing the period that is taken for a satellite’s transmission to reach the aircraft’s receiver
What are the effects, if any, of shadowing by parts of the aircraft (e.g. wing) on the reception of signals from NAVSTAR/GPS satellites?
It may prevent the reception of signals
One type of Airborne Based Augmentation Systems (ABAS) is called Aircraft Autonomous Integrity Monitoring (AAIM). This system:
depends on additional onboard systems and on information from GNSS.
The “GBAS” positioning service provides:
horizontal position information to support RNAV operations in terminal areas.
What type of satellite navigation system NAVSTAR/GPS receiver is most suitable for use on board an aircraft?
Multichannel
How many satellites form the nominal NAVSTAR GPS constellation?
24
Which one of the following is an advantages of a multi-sensor system using inputs from a global navigation satellite system (GNSS) and an inertial reference system (INS)?
The GNSS can be used to update a drifting INS
How many sections does each Galileo GNSS satellite have?
3 sections. Timing, Signal generation and Transmit.
The distance between a NAVSTAR/GPS satellite and receiver is:
determined by the time taken for the signal to arrive from the satellite multiplied by the speed of light
In relation to the satellite navigation system NAVSTAR/GPS, which of the following statements correctly describes the term ‘Pseudo Random Noise (PRN)’ signal?
PRN is a code used for the identification of the satellites and the measurement of the time taken by the signal to reach the receiver
…………………………………………
The pseudo random noise (PRN) code is the means by which the NAVSTAR/GPS is identifying the various satellites.
In relation to the satellite navigation system NAVSTAR/GPS, ‘‘All in View’’ is a term used when a receiver:
is tracking more than the required 4 satellites and can instantly replace any lost signal with another already being monitored.
Signal reception is required from a minimum number of satellites that have adequate elevation and suitable geometry in order for a Satellite-Assisted Navigation System (GPS) to carry out independent three dimensional operation without the Receiver Autonomous Integrity Monitoring (RAIM) function. The number of satellites is:
4
………………………..
The NAVSTAR/GPS receiver require the following number of satellites to establish a position fix:
2D – 3 satellites.
3D – 4 satellites.
RAIM – 5 satellites.
RAIM with fault detection and exclusion – 6 satellites.
The term “ABAS” signifies:
Airborne Based Augmentation Systems.
In the Galileo satellite system the inclination of the satellite orbits to the plane of the equator is:
56°
One of the tasks of the space segment of the satellite navigation system NAVSTAR/GPS is to:
transmit signals which can be used, by suitable receivers, to determine time, position and velocity
In the NAVSTAR/GPS satellite navigation system, ‘Selective Availability’ (SA) is the artificial degradation of the navigation accuracy by:
dithering the satellite clock
The VDB (VHF data broadcast) broadcasts the GBAS signal within its coverage area to avionics in GBAs-equipped aircraft. The VDB signal provided are:
error correction data, integrity data and approach data for more than one runway.
The receiver aerial for a NAVSTAR/GPS system should be mounted:
on the upper side of the fuselage in the vicinity of the centre of gravity
One of the tasks of the control segment of the satellite navigation system NAVSTAR/GPS is to:
monitor the status of the satellites
The geometric shape of the reference system for the satellite navigation system NAVSTAR/GPS, defined as WGS 84, is:
an ellipsoid
…………………………..
The WGS-84 geometric model of the Earth is based on the Earth being an ellipsoid.
The inclination to the equatorial plane of the NAVSTAR/GPS orbits is:
55°
…………………….
The NAVSTAR/GPS satellites follow an orbit that cross the Equator at an angle of 55º. This means that the highest point of their orbit will be N55 or S55 which limits the coverage in the polar regions.
How does a NAVSTAR/GPS satellite navigation system receiver recognise which of the received signals belongs to which satellite?
How does a NAVSTAR/GPS satellite navigation system receiver recognise which of the received signals belongs to which satellite?
How does a receiver of the NAVSTAR/GPS satellite navigation system determine the elevation and azimuth data of a satellite relative to the location of the antenna?
It calculates it by using Almanac data transmitted by the satellites
EGNOS (European Geostationary Navigation Overlay System) is a form of:
Wide Area Differential GPS (WADGPS)
A Ground-Based Augmentation System (GBAS) supports all phases of approach, landing, departure and surface operations within an area of coverage having a radius of approximately:
40 km
In what type of nominal orbit are NAVSTAR GPS satellites placed?
Circular
……………………..
The NAVSTAR/GPS satellites follow a near circular orbit.
Which statement is correct about GLONASS/NAVSTAR GPS/Galileo?
All three systems use time measurement to determine position.
In which frequency band do Satellite-Assisted Navigation systems (GNSS/GPS) provide position information that is available to civil aircraft?
UHF .................................... The NAVSTAR/GPS satellites transmit in the UHF band (300 MHz – 3 GHz). L1 – 1575.42 MHz L2 – 1227.60 MHz
In the event of the use of Selective Availability, how does this affect, if at all, the navigation accuracy of the NAVSTAR/GPS satellite navigation system ?
It degrades position accuracy by manipulating satellite signals
In order to carry out an Independent three-dimensional fix, Receiver Autonomous Integrity Monitoring (RAIM) and failure detection and exclusion of any faulty satellite, signal reception is required from a minimum number of how many satellites?
6
An ABAS system is installed:
in the aircraft.
In which frequency bands are the L1 and L2 frequencies used by the satellite navigation system NAVSTAR/GPS for transmission of the navigation message?
UHF
How many operational satellites are required for Full Operational Capability (FOC) of the satellite navigation system NAVSTAR/GPS?
24
…………………………….
The NAVSTAR/GPS system require minimum 24 operational satellites in order to maintain full operational coverage.
Almanac data stored in the receiver of the satellite navigation system NAVSTAR/GPS is used for the:
fast identification of received signals coming from visible satellites
What type of clock is used in NAVSTAR GPS satellites?
Atomic
Satellite-Based Augmentation Systems (SBAS) include:
- EGNOS in Europe
- IGAN in India
- MSAS in Japan
- SNAS in China
- SDCM in Russia
- WAAS in USA
- GAGAN in India
- SKGPS in South Korea
1, 3, 4, 5, 6, 7
………………………………..
EGNOS (European Geostationary Navigation Overlay Service) - Europe
WAAS (Wide Area Augmentation System) - USA
MSAS (Multi-functional Satellite Augmentation System) - Japan
GAGAN (GPS and GEO Augmented Navigation) - India
SNAS (Satellite Navigation Augmentation System) - China
SDCM (System for Differential Corrections and Monitoring) - Russia
WADGPS (Wide Area Differential Global Positioning System) - South Korea
What is the procedure to be followed if, on a flight under IFR conditions using the NAVSTAR/GPS satellite navigation system, the number of satellites required to maintain the RAIM (Receiver Autonomous Integrity Monitoring) function are not available?
The flight may be continued using other certificated navigation systems
…………………………………….
Receiver autonomous integrity monitoring (RAIM) is a requirement in order to use NAVSTAR/GPS as reference for IFR navigation. If RAIM is lost at any stage during the flight, it can only continue by reverting to conventional navigation systems.
The system capable to measure on ground the signal errors transmitted by GNSS satellites and relay the measured errors to the user for correction is?
GBAS
………………………..
The task of GBAS is to provide horizontal position information to support RNAV operations in terminal areas. It supports all phases of approach, landing, departure, and surface operations within its area of coverage.
EGNOS (European Geostationary Navigation Overlay Service) is a:
Satellite Based Augmentation System (SBAS).
