Vayudoot Aviation

1. 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 geostationary to provide global coverage.

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

2. The reason why the measured distance between a NAVSTAR/GPS satellite navigation system satellite and a receiver is called a "Pseudo-Range' is because the

Movement of satellite and receiver during the distance calculate is not taken into account.

Calculated range includes receiver clock error.

Measured distance is based on the Pseudo Random Noise code.

Calculated range is based on an idealised Keplerian orbit.

3. Clock bias is a process of correcting pseudo range for?

Receiver clock errors.

Receiver and satellites clock errors.

Satellites clock errors.

UTC errors.

4. GPS satellites transmit on two L-band frequencies with different types of signals. Which of these are generally available for use by civil aviation?

L2-for communications purpose.

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

L20-coarse acquisition (C/A).

L1-precise(P).

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

3.

4.

5.

6

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

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

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.

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

A sphere.

A geoid.

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

An ellipsoid.

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

Pass satellite ephemeris information.

Differentiate between satellites.

Pass satellite time, ephemeris and other information.

Pass satellite time and ephemeris information.

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

Any hand held type.

Sequential.

Multiplex

Multi-channel.

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

L1 = precise (P).

L1 = coarse acquisition.

L2 = precise (P).

L2 = coarse acquisition (C/A).

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

Mechanical.

Laser.

Quartz.

Atomic.

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

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

GPS altitude.

Radar altitude.

Barometric altitude.

13. 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).

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

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

By reference to the SV and receiver positions to WGS84.

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

By synchronising the receiver clock with the SV clock.

15. 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.

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

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

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

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

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

To control continuously the position and motion of GPS satellites.

To regulate the transmitted power of the satellites.

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

17. Which of the following procedures must be adopted if, on a flight under IFR conditions using a NAVSTAR/GPS satellite navigation system receiver, the position fix obtained from the GPS receiver differs from the position of conventional navigation systems by an unacceptable amount?

It must be continued under VFR conditions.

It may be continued using conventional navigation systems.

It may be continued using NAVSTAR/GPS; prior to the next flight all system must be checked.

The pilot must determine the reason for the deviation and correct the error or switch off the faulty system.

18. Which of the following lists all the parameters that can be determined by a GPS receiver tracking signals from 4 different satellites?

Latitude, longitude and time.

Latitude, longitude and altitude.

Latitude, longitude, altitude and time.

Latitude and longitude.

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

Local Area Augmented System (LADGPS).

Local Area Differential GPS (LADGPS).

GLONASS.

Wide Area Differential GPS (WADGPS).

20. What is the minimum number of satellites required for Satellite-Assisted Navigation-System (GNSS/GPS) to carry out two-dimensional operation?

2

3

5.

4.

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

Minimised by computing the average of all signals.

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

Negligible.

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

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

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.

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.

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

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.

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

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

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

6 orbital planes with 4 satellites in each plane.

4 orbital planes with 6 satellites in each plane.

3 orbital planes with 8 satellites in each plane.

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

Geo-stationary.

Pole to Pole.

Elliptical.

Nearly Circular.

26. In GPS on which frequencies are the C/A and P codes transmitted?

Neither frequency.

Both frequencies.

The higher frequency.

The lower frequency.

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

Manufacture and launch the satellites.

Monitor the status of the satellies.

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

Grant and monitor user authorisations.

28. 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 GNSS can be used to update a drifting INS.

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

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

29. 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 a code used for the identification of the satellites and the measurement of the time taken by the signal to reach the receiver.

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)

30. Unauthorised civilian users of NAVSTAR GPS can access?

The P code.

The C/A code.

The C/A and P codes.

The P and Y codes.

31. 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

5

6

4

32. Which of the following NAVSTAR/GPA satellite navigation system codes can be processed by "unauthorised" civil aviation receivers?

P.

P and Y.

C/A and P.

C/A.

33. In a Satellite-Assisted Navigation System (GNSS/GPS) a position line is obtained by?

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

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

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

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

34. Differential GPS (D-GPS)?

Is used to differentiate between signals from different satellites.

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.

35. The receiver aerial for a NAVSTAR/GPS system should be mounted

In the vicinity of the receiver to avoid long transmission lines.

Inside the tail fin to minimise the influence of reflections from the wing and Fuselage.

Under the fuselage in order to receive correction data transmitted by D-GPS Stations.

On the upper side of the fuselage in the vicinity of the centre of gravity.

36. RAIM is achieved

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

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.

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

24 seconds (=1 second per data frame).

12 hours (=satellite orbit time).

12.5 minutes (=30 seconds per data frame).

25 seconds (= 1 second per data frame).

38. 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 1 227 MHz carrier wave and one code.

Only the 1 1575 MHz carrier wave and one code.

The two carrier waves and one public code.

39. 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.

Almanac data; satellite status information.

Data to correct receiver clock error; almanac data.

Time; positions of the satellites.

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

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

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.

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

41. 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.

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

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.

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

65 degrees.

45 degrees.

55 degrees.

35 degrees.

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

Time measurement using the receiver clock.

Time measurement using the satellite clock.

Time measurement using secondary radar principles.

Time measurement using UTC.

44. 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?

7

4

5

6.

45. Almanac data stored in the receiver of the satellite navigation system NAVSTAR/GPS is used for the

Recognition whether Selective Availability (SA) is operative.

Correction of receiver clock error.

Fast identification of received signals coming from visible satellites.

Assignment of received PRN-codes (pseudo Random Noise) to the appropriate satellite.

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

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.

47. In accordance with ICAO Annex 10, the NAVSTAR GPS global average 95% position accuracy in SPS should be?

30 m horizontally.

13 m horizontally.

22m is 3D.

5 m vertically.

48. What is RAIm and what is its function?

Resolution and intensity monitoring for increased accuracy.

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

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

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

49. What are the data elements transmitted by NAVSTAR GPS satellites? 1. Offset of the satellite clock from UTC 2. Ephemeris data. 3.Health data 4. Ionospheric delays. 5. Solar activity

1, 2, and 3 only

1, 2, 3, and 4 only.

2, 3, 4 only.

1, 2, 3, 4, and 5.

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

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

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

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

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

Question Bank

Questions for GNSS