Vayudoot Aviation

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

PZ90

WGS90

PZ84

WGS84

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

21

30

24

12

3. EGNOS is

the proposed European satellite navigation system

a LAAS

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

a WAAS

4. The availability of two frequencies in GNSS

reduces errors caused by GDOP

reduces propagation errors

removes receiver clock errors

removes SV ephemeris and clock errors

5. The most significant error of GNSS is

Ionospheric propagation

Ephemeris

Receiver clock

GDOP

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

3

5

6

4

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

1575.42 MHz

1602 MHz

1246 MHz

1227.6 MHz

8. 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

satellite time is the same as UTC

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

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

receiver clock, GDOP, satellite ephemeris and clock

propagation, selective availability, satellite ephemeris and clock

elective availability, satellite ephemeris and clock

GDOP, selective availability and propagation

10. 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

11. The PRN codes are used to

determine the range of the satellites from the receiver

synchronise the receiver clocks with the satellites clocks

pass ephemeris and clock data to the receivers

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

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

20180 km, 65°

19099 km, 65°

19099 km, 55°

20180 km, 55°

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

receiver clock errors

receiver and satellite clock errors and ephemeris errors

receiver and satellite clock errors

receiver and satellite clock errors and propagation errors

14. 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 prime meridian, equator and pole

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 sun

15. The most accurate fixing information will be obtained from

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

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

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

16. The NAVSTAR/ GPS control segment comprises

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

a ground segment and the INMARSAT geostationary satellites

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

the space segment, the user segment and the ground segment

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

12.5 minutes

2.5 minutes

15 minutes

25 minutes

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

UHF, secondary radar principles

SHF, secondary radar principles

SHF, range position lines

UHF, range position lines

19. 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

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

Radio altimeter height

GPS altitude

barometric altitude

Either barometric or radio altimeter altitude

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

GDOP, static interference, instrument

selective availability, skywave interference, GDOP

propagation, selective availability, ephemeris

ephemeris, GDOP, siting

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

The P code

The C/A and P PRN codes

The C/A code

50 Hz modulation

23. 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 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

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

24. An all in view receiver

requires 5 satellites to produce a 4D fix

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

uses all the satellites in view for fixing

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

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

TRANSIT & NAVSTAR/GPS

NAVSTAR/GPS & COSPAS/SARSAT

COSPAS/SARSAT & GLONASS

NAVSTAR/GPS & GLONASS

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

3

6

5

4

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