Vayudoot Aviation

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

55 N/S.

35 N/S.

67.5 N/S.

90 N/S.

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

Nearly Circular.

Elliptical.

Geo-stationary.

Pole to Pole.

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

To calculate and transmit differential corrections to users.

To control continuously the motion of GPS satellites.

To detect the malfunctioning of satellites.

To calculate the accuracy of GPS.

4. Which of the following geometric satellite constellations provides the most accurate NAVSTAR/GPS position fix?

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

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

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

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

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

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

Requires the signals o all visible satellites for navigation purpose.

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

6. 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

5

6

3

4

7. In relation to the NAVSTAR\GRS satellite navigation system, what is involved in the differential technique (D-GPS)?

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

Fixed ground stations compute position errors and transmit correction data to a suitable receiver on the aircraft.

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.

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

8. The distance between a NAVSTAR/GPS satellites and receiver is

Calculated, using the WGS-84 reference system, from the known positions of the receiver.

Calculated from the Doppler shift of the known frequencies.

Determined by the time taken for the signal to arrive form the satellite multiplied by the speed of light.

Determined by the phase shift of the Pseudo Random Noise code multiplied by the speed of light.

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

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.

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

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

Spheres with the aircraft at the centres of the spheres.

Bearing and distance from the satellites.

Spheres with the satellites at the centres of the spheres.

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

11. The sky search carried out by GNSS receiver?

Involves the receiver downloading the almanac from each satellite before determining which satellites are in view.

Is done prior to each fix.

Is done when the receiver position is in error.

Is the procedure carried out by the monitoring stations to check the accuracy of the satellite data.

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

Local Area Differential GPS (LADGPS).

Local Area Augmented System (LADGPS).

GLONASS.

Wide Area Differential GPS (WADGPS).

13. 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 the C/A code only.

L1 is modulated with P code only.

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

L2 is modulated with P and C/A codes.

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

36.

12.

24.

6.

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

3.

6

4.

5.

16. 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.

Data to correct receiver clock error; almanac data.

Almanac data; satellite status information.

17. In a Satellite Assisted Navigation system (GNSS/GPS) a position line is obtained by

Timing the period that is taken for a satellite's transmission to reach the aircraft's receiver.

The aircraft's receiver measuring the phase angle of the signal received from a satellite in a know position.

Timing the period that is taken for a transmission from the aircraft's transmitter/receiver to reach and return from a satellite in a known position.

The aircraft's receiver measuring the time difference between signals received from a minimum number of satellites.

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

Approximately 24 hours (one sidereal day).

12 days.

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

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

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

UHF.

SHF.

EHF.

VHF.

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

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

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.

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

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.

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

22. Differential GPS (D-GPS)?

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.

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

Is used to differentiate between signals from different satellites.

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

13 metres horizontally.

30 metres horizontally.

2 metres in 3-D.

5 metres vertically.

24. 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 only advantage of coupling both systems is double redundancy.

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

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

The GNSS can be used to update a drifting INS.

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

30 seconds.

12.5 minutes.

15 minutes.

12 hours.

26. One of the tasks of the control segment of the satellite navigation system NAVSTAR/GPS is to

Grant and monitor user authorisations.

Monitor the status of the satellies.

Manufacture and launch the satellites.

Manipulate the signals of selected satellites to reduce the precision of the position fix.

27. 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).

28. What is the function of the control segment in GPS NAVSTAR?

To ensure that the transmitted data of the satellites is controlled and updated from time to time by ground stations.

It calculates the aircraft position.

To monitor and ensure that transmitted signals are saved and processed to utilise WAAS.

To transmit a signal used by a suitable receiver to calculate position.

29. What datum is used for the Minimum Descent Altitude (MDA) on a non- precision approach when using the NAVSTAR/GPS satellite navigation system?

GPS altitude.

Radar altitude.

Barometric altitude.

If using Differential-GPS (D-GPS) the altitude obtained from the D-GPS, otherwise barometric altitude.

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

Requires the signals of all visible satellites for navigation purpose.

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.

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

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

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

Monitor the orbital planes of the satellites.

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

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

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

All of these errors.

Ionospheric delays.

Satellite clock error.

Receiver clock error.

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

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

Negligible.

Minimised by computing the average of all signals.

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

34. 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.

35. Which of the following statements concerning the L1 and L2 NAVSTAR/GPS transmission frequencies and codes is correct?

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

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

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

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

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

35 degrees.

65 degrees.

55 degrees.

45 degrees.

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

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

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

Shutting off selected satellites.

Offsetting satellite clocks by a predetermined constant amount.

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

Dithering the satellite clock.

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

WGS 84.

EUREF 92.

ED 87.

ED 50.

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

GLONASS.

COSPAS-SARSAT.

NAVSTAR/GPS.

NNSS-Transit.

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

The continuous tracking receiver.

The single channel receiver.

The multiplex receiver.

The multiple satellite receiver.

42. In a Satellite-Assisted Navigation System (GNSS/GPS), a fix is obtained by

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

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.

43. How is the distance between the NAVSTAR GPS SV (Space Vehicle) and the receiver determined?

By reference to the SV and receiver positions to WGS84.

By synchronising the receiver clock with the SV clock.

By measuring the tine from transmission to reception and multiplying this by the speed of light.

By measuring the time from transmission to reception and dividing by the speed of light.

44. 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.

45. 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.

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

The average of GPS altitude and barometric altitude.

Barometric altitude.

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

EHF

SHF

VHF.

UHF.

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

Orbital plane and the earth's axis.

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

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

Orbital plane and the equatorial plane.

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

C/A.

P and Y.

P.

C/A -and P.

49. 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?

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

The prescribed IFR -equipment must be installed and operational.

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

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

50. 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 has to be continued under VFR conditions.

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 may be continued using other certificated navigation systems.

Question Bank

Questions for GNSS