Vayudoot Aviation

1. The NAVSTAR/GPS operational constellation comprises ___________ satellites

24

12

21

2. The GPS can

provide two-dimension and three-dimension positions

indicate two-dimension positions or position lines in the horizontal plane.

only provide position in latitude and longitude

3. NAVSTAR/GPS operates in the _______ band and the receiver determines position by ________

UHF, range position line

UHF, secondary radar principles

SHF, secondary radar principles

4. The DGPS is

the correction applied to the 'raw' GPS position to obtain a more precise position.

the time difference between the satellite and the aircraft GPS unit transmitting the same code point on the signal

the time difference between the transmission of the satellite's coded signal and the time that it is received at the aircraft

5. The GPS transmission frequency which can be used by civil aircraft is

2227.5 MHz in the S-band.

1575.42 MHz in the L-band.

1227.6.5MHz in the L-band.

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

WGS90

WGS84

PZ90

7. The US DoD degrades GPS accuracy

to protect the DoD copyright

to prevent 100% reliance on a system which may have to be interrupted for military purposes at a moment's notice.

to protect US national security

8. It may be claimed that GNSS has the advantage over other air navigation systems in that it

is entirely space-based.

has no possible input by the pilot

is basically a military-based system made available to civil users with solar-powered satellites which have an infinite life.

9. Satellites used in GNSS< orbit the earth

once in twelve hours

once in 24 hours.

once in eight hours

10. The reason that the satellites of GPS and GLONASS do not collide is

the GPS satellite orbits are 1200 km higher than the GLONASS orbits

the GPS orbit is at 55° to the equator while the GLONASS is at 60°

GLONASS has only three orbital planes while GPS has six orbital planes.

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

19099 km, 65°

20180 km, 55°

20180 km, 65°

12. Position fixing by satellite is by means of

range and bearing from each known satellite's position

simultaneous ranges from a number of satellites.

simultaneous bearings from a number of satellites

13. Satellite geometry error is greatest when

satellites are nearest the horizon.

satellites are spaced well apart

satellites are closest together

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

3

4

5

15. The accuracy of range measurement of satellite to GPS receiver is

seriously reduced during periods of sunspot activity

seriously eroded during periods of anomalous propagation in an inversion

derived from accurate timepieces in the satellite and the aircraft's GPS receiver.

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