Vayudoot Aviation

1. 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?

The data is determined by the satellite and transmitted together with the navigation message.

The data is stored in the receiver together with the Pseudo Random Noise (PRN) code.

If calculates it by using Almanac data transmitted by the satellites.

The data is based on the direction to the satellite determined at the location of the antenna.

2. The height of the NAVSTAR/GPS system above the Earth in km is?

10 250 km.

20 200 km.

19 000 km.

10 900 km.

3. 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.

4 satellites with azimuth of 90° from each other and a low elevation above the horizen.

3 satellites with an azimuth of 120° from each other together and an elevation 45° above the horizon.

4 satellites with an azimuth of 90° from each other and an elevation of 45° above the horizon.

4. What is the minimum number of NAVSTAR/GPS staellites required to produce an accurate independent 3-D position fix?

24.

3.

5.

4.

5. 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 C/A and P codes.

The higher frequency is only used to transmit the P code.

The lower frequency is used to transmit both the C/A and P codes.

C/A and P codes are transmitted at different times on both frequencies.

6. Which one of the following is an advantage of a multi-sensor system using inputs from a global navigation satellite (GNSS) and an inertial navigational system (INS)?

The GNSS can be used to update a drifting INS.

The average position calculated from data provided by both systems increases overall accuracy.

The only advantage of coupling both systems is double redundancy.

The activation of 'Selective Availability' can be recognised by the INS.

7. How does a NAVSTAR/GPS satellite navigation system receiver recognise which of the received signals belongs to which satellite?

Each satellite transmits its signal on a separate frequency.

The Doppler shift is unique to each satellite.

Each satellite transmits its signal, on common frequencies, with an individual Pseudo Random Noise code.

The receiver detects the direction from which the signals are received an compares this information with the calculated positions of the satellites.

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

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

9. In relation to the satellite navigation system NAVSTAR/GPS, which of the following statements correctly describes the term 'Pseudo Random Noise (PRN)' signal?

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

PRN is the atmospheric jamming that affects the signals transmitted by the satellites.

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.

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

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

5 metres vertically.

13 metres horizontally.

30 metres horizontally.

2 metres in 3-D.

11. In which frequency bands are the L1 and Ls frequencies used by the satellite navigation system NAVSTAR/GPS for transmission of the navigation message?

EHF.

SHF.

UHF.

VHF.

12. 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.

4

5

7

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

Differentiate between satellites.

Pass satellite ephemeris information.

Pass satellite time, ephemeris and other information.

Pass satellite time and ephemeris information.

14. 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?

GPS altitude.

The average of GPS altitude and barometric altitude.

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

Barometric altitude.

15. Which of the following statement concerning DGPS is true?

Local area DGPS gives the same improvement in accuracy regardless of the distance from the ground station.

DGPS can improve the accuracy of position information.

Wide area DGPS accuracy improves the closer the aircraft is to the ground station.

DGPS removes SV ephemeris and clock and propagation errors.

16. The geometric shape o the reference system for the satellite navigation system NAVSTAR/GPS, defined as WGS 84, is

A mathematical model that describes the exact shape of the earth.

A geoid.

A sphere.

An ellipsoid.

17. The GPS control segment consists of?

A Master Control Station, Monitor Stations and geostationarysatellites.

A Master Control Station, Monitor Stations, Ground Antennas, and geostationary satellites.

A Master Control Station, and Monitor Stations.

A Master Control Stations and Ground Antennas.

18. How many clocks are installed in each NAVSTAR GPS satellites?

4.

1.

2.

3.

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

Dithering the satellite clock.

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

Offsetting satellite atomic clocks by a predetermined constant amount.

Shutting off selected satellites.

20. 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 (GNSS/GPS) to carry out independent three-dimensional operation, Receiver Autonomous Integrity Monitoring (RAIM) and to isolate any faulty satellite and remove it from contributing to the navigation solution. The number of satellites is

7

4

5

6

21. 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

3

6

5

22. A pseudo range in GNSS is a range based on?

Time measurement using secondary radar principles.

Time measurement using UTC.

Time measurement using the satellite clock.

Time measurement using the receiver clock.

23. 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 causes multi-path propagation.

It has no influence because high frequency signals are unaffected.

It may prevent the reception of signals.

The signals will be distorted, however the error can be corrected for using an algorithm and information fro unaffected signals.

24. EGNOS (European Geostationary Navigation Overlay System) is a form of?

Local Area DIfferential GPS (LADGPS)

Stand alone Global Navigation Satellite System (BNSS).

Local Area Augmentation System (LAAS).

Wide Area Differential GPS (WADGPS).

25. What is the maximum latitude of a GPS satellite ground track?

55 N/S.

35 N/S.

67.5 N/S.

90 N/S.

26. In relation to the satellite navigation system NAVSTAR/GPS, the term 'inclination' denotes the angle between the?

Horizontal plane at the location of the receiver and the orbital plane of a satellite.

Orbital plane and the earth's axis.

Orbital plane and the equatorial plane.

Horizontal plane at the locatior of the receiver and the direct line to a satellite.

27. The number of satellites required for a fully operational NACSTAR/GPS system is?

21.

12.

30.

24.

28. 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-precise(P).

L2-for communications purpose.

L1-coarse acquisition (C/A) with selected availability(S/A).

L20-coarse acquisition (C/A).

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

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

Monitor the orbital planes of the satellites.

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.

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

To control continuously the position and motion of GPS satellites.

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

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

It is greatest at the equator.

It is greatest at the poles.

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

It is the same throughout the globe.

32. The height derived from the NAVISTAR GPS is?

Above the WGS84 elipsoid.

Above mean sea level.

Above ground level.

Pressure altitude.

33. In relation to the satellite navigation system NAVSTAR/GPS. 'All in View' is a term used when a receiver

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

Is receiving and tracking the signals of all 24 operational satellites Simultaneously.

Requires the signals of all visible satellites for navigation purpose.

Is tracking more than the required 4 satellites and can instantly replace any lost signal with another already being monitored.

34. How may satellites form the nominal NAVSTAR GPS constellation?

12.

36.

6.

24.

35. GPS systems 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 1 1575 MHz carrier wave and two codes.

Only the 1 1575 MHz carrier wave and one code.

The two carrier waves and one public code.

Only the 1 227 MHz carrier wave and one code.

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

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.

Requires the signals o all visible satellites for navigation purpose.

37. Concerning the NAVSTAR/GPS satellite navigation system, what is the meaning of the term 'Receiver Autonomous Integrity Monitoring' (RAIM)?

It is technique whereby the receivers of the world-wide distributed monitor stations (ground segment) automatically determines the integrity of the navigation message.

It is a method whereby a receiver ensures the integrity of the Pseudo Random Noise (PRN) code transmitted by the satellites.

It is the ability of the GPS satellites to check the integrity of the data transmitted by the monitoring stations of the ground segment.

It is a technique by which a receiver checks the reliability of the signal it is receiving and can detect if one of the signals is incorrect.

38. RAIM is achieved

By ground stations determining the X, Y, and Z errors and passing the corrections to receivers using psudolites.

Within the receiver.

All of the above.

By ground monitoring stations determining the satellites range errors which are relayed to receives via geostationary satellites.

39. 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 continuous tracking receiver.

The multiplex receiver.

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

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

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

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.

41. In relation to the NAVSTAR\GRS 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.

The difference between signals transmitted on the L1 and L2 frequencies are processed by the receiver to determine an error correction.

Receivers from various manufacturers are operated in parallel to reduce the characteristical receiver noise error.

Signals from satellites are received by 2 different antennas which are located a fixed distance apart. This enables a suitable receive on the aircraft to recognise and correct multi-path errors.

42. 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.

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

Spheres with the aircraft at the centres of the spheres.

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

Bearing and distance from the satellites.

Spheres with the satellites at the centres of the spheres.

44. What type of clock is used in NAVSTAR GPS satellites?

Mechanical.

Atomic.

Quartz.

Laser.

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

55 degrees.

45 degrees.

65 degrees.

35 degrees.

46. What is RAIm and what is its function?

Integrity monitoring of satellites by the receiver to ensure accurate navigation.

Integrity monitoring of satellites by the master station to increase accuracy.

GPS integrity monitoring of master and slave stations to ensure correct alignment.

Resolution and intensity monitoring for increased accuracy.

47. What is the minimum number of satellites required by a GPS in order to obtain a three dimensional fix?

4.

3.

6

5.

48. The basic elements of the satellite navigation system NAVSTAR/GPS are the

Antenna, the receiver and the central control unit (CDU).

Control, space and user segments.

Main control station, the monitoring station and the ground antennas.

Atomic clock, power supply and transponder.

49. How many operational satellites are required for Full Operational Capability (FOC) of the satellite navigation system NAVSTAR/GPS?

18

30

12

24

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

It degrades accuracy by reducing the number of available satellites.

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

It degrades position accuracy by manipulating satellite signals.

Question Bank

Questions for GNSS