Vayudoot Aviation

1. The NAVSTAR/GPS reference system is

A geo-centred 3D system based on latitude, longitude and altitude

A geo-centred 3D Cartesian co-ordinate system fixed with reference to the sun

A geo-centred 3D Cartesian co-ordinate system fixed with reference to space

A geo-centred 3D Cartesian co-ordinate system fixed with reference to the prime meridian, equator and pole

2. The navigation and system data message is transmitted through the

The C/A code

The P code

50 Hz modulation

The C/A and P PRN codes

3. The use of LAAS and WAAS remove the errors caused by

elective availability, satellite ephemeris and clock

receiver clock, GDOP, satellite ephemeris and clock

propagation, selective availability, satellite ephemeris and clock

GDOP, selective availability and propagation

4. The most significant error of GNSS is

GDOP

Receiver clock

Ionospheric propagation

Ephemeris

5. The PRN codes are used to

determine the time interval between the satellite transmission and receipt of the signal at the receiver

synchronise the receiver clocks with the satellites clocks

pass ephemeris and clock data to the receivers

determine the range of the satellites from the receiver

6. The purpose of the pseudo-random noise codes in NAVSTAR/GPS is to

pass the almanac data

pass the navigation and system data

pass the ephemeris and time information

identify the satellites

7. An all in view receiver

checks all the satellites in view and selects the 4 with the best geometry for fixing

informs the operator that all the satellites required for fixing and RAIM are in available

requires 5 satellites to produce a 4D fix

uses all the satellites in view for fixing

8. The orbital height and inclination of the NAVSTAR/GPS constellation are

20180 km, 65°

19099 km, 65°

19099 km, 55°

20180 km, 55°

9. The NAVSTAR/ GPS control segment comprises

the space segment, the user segment and the ground segment

a master control station, a back-up control station and five monitoring stations

a ground segment and the INMARSAT geostationary satellites

a master control station, a back-up control station, five monitoring stations and the INMARSAT geostationary satellites

10. The NAVSTAR/GPS operational constellation comprises how many satellites

21

12

30

24

11. The minimum number of satellites required for a 3D fix is

6

4

5

3

12. The initial range calculation at the receiver is known as a pseudo-range, because it is not yet corrected for

receiver and satellite clock errors

receiver and satellite clock errors and propagation errors

receiver and satellite clock errors and ephemeris errors

receiver clock errors

13. The most accurate satellite fixing information will be obtained from

TRANSIT & NAVSTAR/GPS

NAVSTAR/GPS & COSPAS/SARSAT

COSPAS/SARSAT & GLONASS

NAVSTAR/GPS & GLONASS

14. When using GNSS to carry out a non-precision approach the MDA will be determined using

Radio altimeter height

barometric altitude

GPS altitude

Either barometric or radio altimeter altitude

15. The minimum number of satellites required for receiver autonomous integrity monitoring is

4

5

3

6

16. Which of the following statements concerning NAVSTAR/GPS time is correct?

the satellite runs its own time based on seconds and weeks which is correlated with UTC

satellite time is based on sidereal time

the satellite runs its own time based on seconds and weeks which is independent of UTC the satellite runs its own time based on seconds and weeks which is independent of UTC

satellite time is the same as UTC

17. The availability of two frequencies in GNSS

removes SV ephemeris and clock errors

reduces propagation errors

reduces errors caused by GDOP

removes receiver clock errors

18. If a receiver has to download the almanac, the time to do this will be

25 minutes

12.5 minutes

2.5 minutes

15 minutes

19. A LAAS requires

an accurately surveyed site on the aerodrome and a link through the INMARSAT geostationary satellites to pass satellite range corrections to aircraft

an accurately surveyed site on the aerodrome and system known as a pseudolite to pass corrections to X, Y & Z co-ordinates to aircraft

an accurately surveyed site on the aerodrome and a system known as a pseudolite to pass satellite range corrections to aircraft

an accurately surveyed site on the aerodrome and a link through the INMARSAT geostationary satellites to pass corrections to X, Y & Z co-ordinates to aircraft

20. The frequency available to non-authorised users of NAVSTAR/GPS is

1575.42 MHz

1602 MHz

1246 MHz

1227.6 MHz

21. The position derived from NAVSTAR/GPS satellites may be subject to the following errors

selective availability, skywave interference, GDOP

GDOP, static interference, instrument

ephemeris, GDOP, siting

propagation, selective availability, ephemeris

22. The model of the earth used for NAVSTAR/GPS is

WGS90

WGS84

PZ84

PZ90

23. NAVSTAR/GPS operates in the band the receiver determines position by

SHF, secondary radar principles

UHF, range position lines

SHF, range position lines

UHF, secondary radar principles

24. EGNOS is

the proposed European satellite navigation system

a system to remove errors caused by the difference between the model of the earth and the actual shape of the earth

a WAAS

a LAAS

25. If an aircraft manoeuvre puts a satellite being used for fixing into the wing shadow then

the accuracy will be unaffected

the receiver will maintain lock using signals reflected from other parts of the aircraft with a small degrading of positional accuracy

the receiver will automatically select another satellite with no degradation in positional accuracy

the accuracy will be temporarily downgraded

26. The most accurate fixing information will be obtained from

one satellite directly overhead and 3 spaced 120° apart close to the horizon

one satellite directly overhead and 3 equally spaced at 60° above the horizon

one satellite close to the horizon and 3 equally at 60° above the horizon

four satellites spaced 90° apart at 30° above the visual horizon

Question Bank

Questions for GNSS