Vayudoot Aviation

1. In what type of nominal orbit are NAVSTAR GPS satellites placed

Nearly Circular.

Elliptical.

Geo-stationary.

Pole to Pole.

2. Which of the following statements about the 'visibility' of NAVSTAR/GPS satellites is correct?

It is greatest at the equator.

It varies, depending on the time and observer's location.

It is the same throughout the globe.

It is greatest at the poles.

3. The inclination to the equatorial plane of the NAVSTAR GPS orbits is?

65 degrees.

55 degrees.

35 degrees.

45 degrees.

4. The main task of the user segment (receiver) of the satellite navigation system NAVSTAR/GPS is to calculate receiver position by

To monitor the status of the satellites, determine their positions and to measure the time.

Transit signals which, from the time taken, are used used to determine the distance to the satellite.

Monitor the orbital planes of the satellites.

Select appropriate satellites automatically, to track the signals and to measure the time taken by signals fro the satellites to reach the receiver.

5. What is the time taken to receive a complete navigation message (complete data set) from a satellite?

24 seconds (=1 second per data frame).

25 seconds (= 1 second per data frame).

12.5 minutes (=30 seconds per data frame).

12 hours (=satellite orbit time).

6. Which of the following NAVSTAR/GPS satellite navigation system codes can be processed by 'unauthorised' civil aviation receivers?

C/A -and P.

P and Y.

P.

C/A.

7. In the NAVASTAR/GPS satellite navigation system, re-use of Selective Availability would give the option to artificially degrade the accuracy by?

Dithering the satellite clock.

Offsetting satellite clocks by a predetermined constant amount.

Shutting off selected satellites.

Using less accurate atomic clocks in a satellite for signal processing.

8. In the NAVSTAR/GPS satellite navigation system, receiver clock error

Is the biggest part of the total error; it cannot be corrected.

Is negligible small because of the great accuracy the atomic clocks installed in the satellites.

Can be minimised by synchronisation of the receiver clock with the satellite clocks.

Is corrected by using signals from four satellites.

9. Using GPS, the primary position information is the form of?

Spheres with the satellites at the centres of the spheres.

Spheres with the aircraft at the centres of the spheres.

Bearing and distance from the satellites.

Three-dimensional position, with the Earth's centre as the reference point.

10. 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 may satellites?

6.

5

4

7

11. In relation to the NAVSTAR/GPS satellite navigation system, ' Search the Sky' is a

Continuous procedure performed by the receiver that searches the sky for satellites rising above the horizon.

Procedure that starts after switching on a receiver if there is no stored satellite data avaiable.

Procedure performed by the receiver to recognise new satellites becoming Operaional.

Continuous process by the ground segment to monitor the GPS satellites.

12. The NAVSTAR GPS system transmits in the L1 and Is frequency bands. Which bands are used for the P codes and which for the C/A codes?

Higher frequency for the P code only.

Higher frequency for the C/A and P codes.

Lower frequency for the C/A code and higher frequency for the P code.

Lower frequency for the P code and higher frequency for the C/A code.

13. 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 the atmospheric jamming that affects the signals transmitted by the satellites.

PRN descrines the continuous electro-magnetic background noise that exists in space.

PRN occurs i the receiver. It is caused by the signal from one satellite being received from different directions (multipath effect)

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.

14. A pseudo range is GNSS is in error to the actual range because?

Receiver clock error.

All of these errors.

Ionospheric delays.

Satellite clock error.

15. The orbital planes of the satellite navigation system NAVSTAR/GPS are

Parallel to the equatorial plane.

Inclined 90° to the equatorial plane.

Inclined 55° to the equatorial plane.

Inclined 55° to the earth axis.

16. One of the tasks of the GPS control segment is?

To determine and send new ephemeris and new satellite clock errors data to the GPS satellites.

To control continuously the position and motion of GPS satellites.

To calculate and transmit differential corrections to users which are able to receiver Wide Area Differential GPS systems.

To regulate the transmitted power of the satellites.

17. Selective availability may be used to degrade the accuracy of the NAVSTAR GPS position, This is achieved by?

Introducing an offset in the satellite clocks.

Random dithering of the broadcast satellites X,Y and Z co-ordinates.

Random dithering of the broadcast satellite clock time.

Introducing offsets in the broadcast satellites X, Y and Z co-ordinates.

18. Which of the following statements is correct concerning the principle behind the correction of one of the NAVSTAR/GPS satellite navigation system errors by the transmission of the signals on two frequencies (L1 and L2)?

The effect of receiver noise can be reduced due to the interference of both frequencies.

The path delay of the signals in the earth atmosphere is proportional to the inverse of the carrier frequency squared..

The influence of shadowing on the GPS signals is proportional to the inverse of the carrier frequency squared.

The effect of signal reflection (multipath effect) can be reduced due to the interference of both frequencies.

19. Of the types of GPS receivers available for civilian aviation, which are the most advanced type?

The multiple satellite receiver.

The single channel receiver.

The multiplex receiver.

The continuous tracking receiver.

20. 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?

Time; data to impair the accuracy of the position fix.

Time; positions of the satellites.

Almanac data; satellite status information.

Data to correct receiver clock error; almanac data.

21. 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.

Multi-sensor systems are not certificated for flights under IFR conditions.

The prescribed IFR-equipment must be in working correctly and the navigation information continuously displayed.

The RAIM-function of the GPS receiver must be able to monitor all prescribed navigation systems.

22. The required 24 NAVSTAR/GPS operational satellites are located on

4 orbital planes with 6 satellites in each plane.

6 orbital planes with 4 satellites in each plane plus 6 reserve satellites positioned in a geostationary orbital plane.

3 orbital planes with 8 satellites in each plane.

6 orbital planes with 4 satellites in each plane.

23. What is EGNOS (European Global Navigation Overlay System)?

GLONASS.

Local Area Augmented System (LADGPS).

Local Area Differential GPS (LADGPS).

Wide Area Differential GPS (WADGPS).

24. The height derived from the NAVISTAR GPS is?

Above mean sea level.

Above the WGS84 elipsoid.

Pressure altitude.

Above ground level.

25. GPS satellites transmit on two band frequencies with different type of signal. Which of these are generally available for use by civil aviation?

L2 = precise (P).

L1 = precise (P).

L1 = coarse acquisition.

L2 = coarse acquisition (C/A).

26. In NAVSTAR GPS the PRN codes are used to?

Eliminate satellite clock error and ephemeris error.

Reduce ionospheric and tropospheric errors.

Determine satellite range.

Remove receiver clock error.

27. The influence of the ionosphere on the accuracy of the satellite navigation system NAVSTAR/GPS is

Only significant if the satellites are located at a small elevation angle above the horizon.

Negligible.

Minimised by computing the average of all signals.

Minimised by the receiver using a model of the atmosphere and comparing signals transmitted by the satellites.

28. In relation to the satellite navigation system NAVSTAR GPS, "All in View" is a term used when a receiver?

Requires the signals o all visible satellites for navigation purpose.

Is tracking all currently visible satellites above the receiver's mark angle and it using them to compute position.

Is receiving and tracking the signals of all 24 satellite simultaneously.

Is receiving the signals of all visible satellites but tracking only those of the 4 with best geometric coverage.

29. In order for a GPS receiver to perform basic RAIM functions it must use a minimum of?

Five satellites.

Five satellites plus a barometric unit.

Three satellites plus a barometric unit.

Four satellites.

30. Which of the following statements is true in respect of GNSS?

The C/A code is the only code available for civilian use. It is transmitted only on L1.

The C/A code is for authorised (military) use only.It is transmitted only one L1 and L2.

The P code is for authorised (military) use only.It is transmitted only one L1.

The P code is the only code authorised for civilian use. It is transmitted on L.

31. The time taken for a GNSS receiver to download the satellite almanac for NAVSTAR GPS is?

15 minutes.

30 seconds.

12 hours.

12.5 minutes.

32. What type of satellite navigation system NAVSTAR/GPS receiver is most suitable for use of board an aircraft?

Any hand held type.

Multi-channel.

Sequential.

Multiplex

33. Which of the following satellite navigation system has Full Operational Capability (FOC) and is approved for specified flights under IFR conditions in Europe?

NNSS-Transit.

NAVSTAR/GPS.

COSPAS-SARSAT.

GLONASS.

34. 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.

Latitude, longitude and altitude.

Latitude and longitude.

Latitude, longitude and time.

35. In which frequency band do Satellite-Assisted Navigation systems (GNSS/GPS) provide position information that is available to civil aircraft?

UHF.

EHF

SHF

VHF.

36. 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.

The aircraft's receiver measuring the phase angle of signal received from a number of satellites, in known positions, and return to the aircraft's receiver.

Meaning the pulse length of signal received from a minimum number of satellites received in a specific sequential order.

The aircraft's receiver measuring the phase angle of signal received from a number of satellites, in known positions.

37. Which of the following coordinate system is used by the GPS receiver to determine position (Latitude, longitude and altitude)?

ED 87.

ED 50.

WGS 84.

EUREF 92.

38. One of the tasks of the space segment of the satellite navigation system NAVSTAR/GPS is to

Compute the user position from the received user messages and to transmit the computed position back to the user segment.

Transmit signals which can be used, by suitable receivers, to determine time, position and velocity.

Transmit signals to suitable receivers and to monitor the orbital planes Auronomously.

Monitor the satellites' orbits and status.

39. The GPS system used L1 and L2 frequency bands. Which band is used for the P code and which for the C/A code?

L2 is modulated with P and C/A codes.

L2 is modulated with the C/A code only.

L1 is modulated with P code only.

L1 is modulated with P and C/A code only.

40. In the NAVSTAR/GPS satellite navigation system, Selective Availability' (SA) gives the option to artificially degrade the accuracy by

Offsetting satellite atomic clocks by a predetermined constant amount.

Shutting off selected satellites.

Using a less accurate atomic clock in satellite for signal processing.

Dithering the satellite clock.

41. 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 accuracy by reducing the number of available satellites.

It degrades position accuracy by manipulating satellite signals.

It increases because only signals from satellites in the most suitable geometric constellation are selected by the receiver.

It has no influence because, by selecting of the most suitable signals, the computing process in the receiver is quicker.

42. How long does it take a NAVSTAR/GPS satellite to orbit the earth?

365 days because the satellites are located in a geostationary orbit.

12 days.

Approximately 24 hours (one sidereal day).

Approximately 12 hours (1/2 of a sidereal day).

43. In accordance with ICAO Annex 10, the GPS NAVASTAR position accuracy is SPS should be for 95% of the time?

5 metres vertically.

2 metres in 3-D.

30 metres horizontally.

13 metres horizontally.

44. 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 as planned if at least 4 satellites are available and the pilot monitors the GPS-System manually.

A constant heading and speed must be flown until the required number of satellites are again available.

The flight has to be continued under VFR conditions.

The flight may be continued using other certificated navigation systems.

45. 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 ephemiris; atospheric propagation.

Satellite mutual interference; satellite ephemeris; atmospheric propagation.

Satellite mutual interference; frequency drift; satellite to ground time lag;

Satellite to ground time lag; atmospheric propagation; satellite clock.

46. In the NAVSTAR/GAS satellite navigation system, what is the maximum time taken to receive the complete set of almanac data from all satellites?

25 seconds (= 1 second per data frame).

12.5 minutes (=30 seconds per data frame).

12 hours (=period of the satellites orbit).

24 seconds (=1 second per data frame).

47. Differential GPS (D-GPS)?

Is used to differentiate between signals from different satellites.

Means to find the difference between a DR position and the real position and the GPS position.

Means to use the GPS receiver while in a known position, ad register the difference.

It used to improve the accuracy of GPS signals within an area, by using data from a receiver placed at a known position as a correction to data received in the aircraft from the satellites.

48. 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.

GPS altitude if 4 or more satellites are received otherwise barometric altitude

The average of GPS altitude and barometric altitude.

GPS altitude.

49. Which of the following combinations of satellite navigation system provide the most accurate position fixes in air navigation?

NAVSTAR/GPS and GLONASS.

NNSS-Transit and GLONASS.

GLONASS and COSPAS-SARSAT.

NAVSTAR/GPS and NNSS-Transit.

50. Concerning NAVSTAR GPS orbits, which of the following statements is correct?

The inclination is 55 degrees with an orbital period of 12 hours.

The inclination of the orbits is 55 degrees with an orbital period of 24 hours.

The orbits are inclined at 65 degrees with an orbital period of 11 hours 15 minutes.

The orbits are geostationary to provide global coverage.

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