RADNAV-RH-MODULE4-DME

RADNAV-RH-MODULE4-DME

1. The aircraft DME receiver is able to accept replies to its own transmission and reject replies to other aircraft interrogations because:

a) transmission frequencies are 63 MHz different for each aircraft
b) pulse pairs are amplitude modulated with the aircraft registration
c) aircraft interrogation signals and transponder responses are 63 MHz removed from each other
d) pulse pairs are discreet to a particular aircraft

2. If a VOR station and a DME station, having different locations, are selected to provide a fix:

a) two difference IDs will have to be checked
b) two positions, being ambiguous, will be presented
c) two sets, with separate frequency control, are required in the aircraft
d) all 3 answers above are correct

3. What is the maximum distance between VOR and DME/TACAN ground installations if they are to have the same Morse code identifier?

a) 60 m
b) 2000 m
c) 600 m
d) 300 m

4. When identifying a co-located VOR/DME the following signals are heard in the Morse code every 30 seconds?

a) 4 identifications in the same tone
b) 4 identifications with the DME at a higher tone
c) 4 identifications with the DME at a lower tone
d) no DME identification, but if the VOR identification is present and a range is indicated then this shows that both are serviceable

5. In which situation will speed indications on an airborne Distance Measuring Equipment (DME) most closely represent the groundspeed of an aircraft flying at FL 400?

a) When passing abeam the station and within 5 NM of it
b) When tracking directly towards the station at a range of 100 NM or more
c) When overhead the station, with no change of heading at transit
d) When tracking directly away from the station at a range of 10 NM

6. A VOR and DME are co-located. You want to identify the DME by listening to the call sign. Having heard the same call sign 4 times in 30 seconds the:

a) VOR and DME call signs were the same and broadcast with the same pitch
b) DME call sign was not transmitted, the distance information is sufficient proof of correct operation
c) DME call sign is the one with the lower pitch that was broadcast several times
d) DME call sign is the one with the higher pitch that was broadcast only once

7. The accuracy of a DME:

a) is approximately ±0.5nm
b) decreases with increase of range
c) increases with increase of altitude
d) is approximately ±2 nm

8. Distance Measuring Equipment (DME) operates in the:

a) UHF band and is a primary radar system
b) VHF band and uses the principle of phase comparison
c) UHF band and is a secondary radar system
d) SHF band and uses frequency modulation techniques

9. An aircraft DME receiver does not lock on to its own transmissions reflected from the ground because:

a) the pulse recurrence rates are varied
b) DME transmits twin pulses
c) they are not on the receiver frequency
d) DME uses the UHF band

10. The DME in an aircraft, cruising at FL 210, fails to achieve lock on a DME at MSL at a range of 210NM. The reason for this is:

a) the beacon is saturated
b) the aircraft is beyond the maximum usable range for DME
c) the aircraft is beyond line of sight range
d) the aircraft signal is too weak at that range to trigger a response

11. A DME that has difficulty obtaining a lock-on: (NOTE: PRF = pulse recurrence frequency, PPS = pulses per second)

a) alternates search mode with periods of memory mode lasting 10 seconds
b) stays in search mode without a reduction in PRF
c) stays in search mode but reduces PRF to max. 60 PPS after 100 seconds
d) stays in search mode but reduces PRF to max. 60 PPS after 15000 pulse pairs have been transmitted

12. The DME (Distance Measuring Equipment) operates within the following frequencies:

a) 329 to 335 MHz
b) 962 to 1213 KHz
c) 962 to 1213 MHz
d) 108 to 118 MHz

13. For a conventional DME facility Beacon Saturation will occur whenever the number of simultaneous interrogations exceeds:

a) 80
b) 100
c) 200
d) 60

14. The design requirements for DME stipulate that, at a range of 100 NM, the maximum systematic error should not exceed:

a) + or – 1.5
b) + or – 3 NM
c) + or – 0.25 NM
d) + or – 1.25 NM

15. DME channels utilise frequencies of approximately:

a) 600 MHz
b) 1000 MHz
c) 300 MHz
d) 110 MHz

16. In which of the following frequency bands does DME operate:

a) UHF
b) SHF
c) VHF
d) EHF

17. If an NDB has a published range of 30 nm, its accuracy is:

a) guaranteed to that range
b) only guaranteed at night to that range
c) only guaranteed by day to that range
d) is not protected in any way

18. Which of the following statements is TRUE in respect to microwave landing system?

a) Azimuth and elevation signals use the same aerial on a time share basic
b) Azimuth and elevation signals are transmitted at the same UHF frequency
c) A special precision DME, operating in the SHF band, provides range information
d) Range information is provided by precision DME operating in the UHF

19. DME channels operate in the frequency band which includes:

a) 600 MHz
b) 110 MHz
c) 300 MHz
d) 1000 MHz

20. The design requirements for DME stipulate that at a range of 100 NM the maximum systematic error should not exceed:

a) + or – 1.5
b) + or – 3 NM
c) + or – 0.25 NM
d) + or – 1.25 NM

21. The operating principle of a DME is the measurement of the:

a) time between the transmission and reception of radio pulses
b) frequency change between the emitted wave and reflected wave
c) frequency of the reflected wave
d) phase difference between emitted wave and reflected wave

22. An aircraft at FL 210 cannot receive a signal from a DME 220 nm away. Why:

a) The aircraft is too high
b) The aircraft is not in line of sight of the DME
c) DME is never more than 200 nm
d) The DME is saturated

23. The DME ground transponder has a PRF of:

a) 2700 pulses per second
b) 27 pulses per second
c) 150 pulses per second
d) 1500 pulses per second

24. DME is a radar type of facility and its maximum range is limited by:

a) The pulse repetition interval
b) The height of the aeroplane
c) The transmitter power
d) The receiver sensitivity

25. A DME in tracking mode subsequently experiences a reduction in signal strength will switch the equipment in the first instance to:

a) standby mode
b) search mode
c) memory mode
d) signal controlled search

26. Of what use, if any, is a military TACAN station to civil aviation?

a) It can provide a DME distance and magnetic bearing
b) It is of no use to civil aviation
c) It can provide DME distance
d) It can provide a magnetic bearing

27. Groundspeed measurement using DME equipment is most accurate flying:

a) from the station at long range
b) over the station
c) towards the station at short range
d) past the station at short range

28. During a flight at FL 210, a pilot does not receive any DME distance indication from a DME station located approximately 220 NM away. The reason for this is that the:

a) aeroplane is below the line of sight altitude
b) aeroplane is circling around the station
c) altitude is too high
d) range of a DME system is always less than 200 NM

29. On a DME, display counters rotating throughout their range indicates:

a) ground equipment failure
b) airborne equipment failure
c) the airborne receiver is conducting a range search
d) the airborne equipment is conducting a frequency search

30. Which of the following will give the most accurate calculation of aircraft ground speed?

a) A VOR station sited on the flight route
b) A DME station sited across the flight route
c) A DME station sited on the flight route
d) An ADF sited on the flight route

31. A typical frequency employed in Distance Measuring Equipment (DME) is:

a) 100 MHz
b) 100 GHz
c) 1000 MHz
d) 10 MHz

32. The aircraft DME receiver cannot lock on to interrogation signals reflected from the ground because:

a) DME pulse recurrence rates are varied
b) aircraft transmitter and DME ground station are transmitting on different frequencies
c) reflections are subject to Doppler frequency shift
d) DME transmits twin pulses

33. ICAO specifications are that range errors indicated by Distance Measuring Equipment (DME) should not exceed:

a) + or – 0.5 NM or 3% of the distance measured whichever is the greater
b) + or – 1.25 NM plus 0.25% of the distance measured
c) + or – 0.25 NM plus 3% of the distance measured up to a maximum of 5 NM
d) + or – 0.25 NM plus 1.25% of the distance measured

34. Height error has the greatest effect on accuracy when an aeroplane is:

a) over the base line extensions at low altitude
b) at the base line bisector at low altitudes
c) at the base line bisector at high altitude
d) over the base line extension at high altitude

35. A DME and VOR have the same ident, are associated and are:

a) always co-located
b) within 2,000 feet of each other
c) within 100 feet of each other
d) within 600 feet of each other

36. What is the approved frequency band assigned to DME?

a) 960-1215 MHz which is VHF
b) 960-1215 MHz which is UHF
c) 960-1215 MHz which is SHF
d) 960-1215 MHz which is EHF

37. Regarding the DME system, which one of the following statements is true?

a) DME operates in the VHF frequency band
b) The DME measures the phase difference between the reference and variable phase signals to calculate the distance
c) The transponder reply carrier frequency differs by 63 MHz from that of the interrogation signal
d) When passing overhead the DME station the DME will indicate 0

38. The indicated range from a DME station is:

a) slant range
b) ground range
c) 0 when passing overhead the station
d) ground range only if the beacon is co-located with VOR

39. Which one is the most correct statement regarding the range of the DME system?

a) Operates on the principle of phase comparison
b) Operates on VHF
c) Range within “line of sight”, and maximum 200 Nm
d) Has unlimited range due to ground wave propagation

40. Which one of the statements below is correct regarding the DME?

a) Two lines of position obtained from two different DME’s give an unambiguous fix
b) The DME operating frequencies are in the UHF frequency band
c) The indicated distance is the ground distance measured from the aircraft’s projected position on the ground to the DME ground installation
d) The DME ground station is always co-located with a VOR station

41. How many aircraft will DME accommodate before reaching saturation:

a) 50
b) 100
c) 120
d) 150

42. The maximum number of aeroplanes that can be responded to by the DME ground facility is:

a) 100
b) 10
c) 150
d) Unlimited

43. A DME which is listed as operating on an “X” channel is one which:

a) Is paired exclusively with an ILS frequency
b) Is paired exclusively with a TACAN frequency
c) Responds on a frequency 63 MHz higher than the interrogation frequency
d) Responds on a frequency 63 MHz lower than the interrogation frequency

44. The nominal maximum coverage of a DME station is:

a) 150 nm at 20,000 ft
b) 175 nm at 25,000 ft
c) 190 nm at 25,000 ft
d) 200 nm at 30,000 ft

45. Where a DME uses mechanical counters for displaying the range, continuous rotation of the counters means:

a) The DME is in a search mode
b) The DME is in a memory mode
c) The DME is in a tracking mode due to a turn
d) None of the above

46. Which of the following provides distance information:

a) DME
b) VOR
c) ADF
d) VDF

47. A DME beacon will become saturated when more than about ___ aircraft are using the transponder.

a) 10
b) 50
c) 100
d) 200

48. What are the DME frequencies?

a) 1030 and 1090 MHz
b) 1030 – 1090 MHz
c) 960 and 1215 MHz
d) 960 – 1215 MHz

49. DME uses (i) radar in the (ii) band:

a) (i) Primary; (ii) UHF
b) (i) Primary; (ii) SHF
c) (i) Secondary; (ii) UHF
d) (i) Secondary; (ii) SHF

50. An aircraft DME receiver will not lock on to signals reflected from the ground because:

a) DME uses the UHF band
b) DME transmits twin pulses
c) The pulse recurrence rates are varied
d) The reflection are not at the receiver frequency

51. If a DME beacon becomes saturated by interrogations it:

a) It switches off its identification signal
b) Adjusts the gain to reply to the 100 strongest signals
c) Adjusts its PRF to cope with all aircraft
d) Replies to the nearest 100 aircraft

52. The aircraft DME receiver accepts replies to its own transmissions but rejects replies to other aircraft transmissions because:

a) the PRF of the interrogations is unique to each aircraft
b) the pulse pairs from each aircraft have a unique amplitude modulation
c) the interrogation frequencies are 63 MHz different for each aircraft
d) the interrogation and reply frequencies are separated by 63 MHz

53. A category III ILS system provides accurate guidance down to:

a) the surface of the runway
b) less than 50 ft
c) less than 100 ft
d) less than 200 ft

54. In DME interrogation and responses are separated by 63 MHz in order to:

a) Avoid station saturation
b) Differentiate between precision and ordinary DME
c) Facilitate channel selection
d) Prevent self-triggering

55. The accuracy of DME is:

a) ±1nm
b) ±¼ nm + 1.25% of range
c) ±3% of the range
d) ±¼ nm or 1.25% of the range whichever is the greater

56. A VOR and DME are frequency paired. The DME identification ends with Z. This denotes that:

a) The two beacons are co-located
b) The beacons are supporting the same site but are not co-located
c) The beacons are greater than 2000 m apart
d) The beacons are at the same location but are more than 1000 m apart

57. In a certain VORTAC installation the VOR is coding STN and the DME is coding STZ. This means that the distance between the two beacons is in excess of:

a) 600 m
b) 100 m
c) 2000 m
d) 300 m

58. What happens when a DME in the search mode fails to achieve lock-on:

a) it stays in the search mode, but reduces to 60 pulse pairs per second (ppps) after 100 seconds
b) it stays in the search mode, but reduces to 60 ppps after 15000 pulse pairs
c) it stays in the search mode at 150 ppps
d) it alternates between search and memory modes every 10 seconds

59. A DME Transceiver does not lock onto its own reflections because:

a) the PRF of the pulse pairs is jittered
b) it uses MTI
c) the interrogation and reply frequencies differ
d) the reflections will all fall within the fly back period

60. DME pulses are transmitted as pulse pairs. This is done:

a) So that the pulses are square and are easily identified
b) So that stray radar emissions do not interfere with the DME equipment
c) To increase the range
d) To prevent a lock on to the ground

61. How does the DME tell different aircraft apart:

a) By using a jittered PRF
b) By the different frequencies transmitted
c) By the differences in wavelength
d) By the phase of the received pulses

62. DME is a secondary radar operating in the (i) band using frequencies between (ii):

a) (i) SHF; (ii) 962 – 1215 MHz
b) (i) UHF; (ii) 962 – 1215 MHz
c) (i) SHF; (ii) 962 – 1215 MHz
d) (i) UHF; (ii) 962 – 1215 GHz

63. An aircraft at FL 200 is 220 nm from a DME (0 ft amsl). The aircraft equipment fails to lock on, this is because:

a) DME is limited to 200 nm
b) The aircraft is too high to receive the signal
c) The aircraft is too low to receive the signal
d) The beacon is saturated

64. A typical DME frequency is:

a) 1000 MHz
b) 1300 MHz
c) 1000 KHz
d) 113.55 MHz

65. Which of the following would give the best indication of speed:

a) A VOR on the flight plan route
b) A VOR off the flight plan route
c) A DME on the flight plan route
d) A DME off the flight plan route

66. A DME transmitter is operating in the search-for-lock phase. Which of the following statements is correct?

a) the PRF increases, the range counters count down from maximum, the output power is increased
b) The PRF increases and the range counters count up from 300 to maximum
c) The PRF increases and the range counters count down from the maximum
d) The PRF increases and the power is increased

67. If the DME ground transmitter fails

a) the last measured range is frozen for 20 secs
b) all range information is immediately lost
c) the last recorded range is retained until the ground transmitter is restored
d) the counters continue to rotate for 8 to 10 seconds

68. “DME is a ___ radar which provides ___ distances between the aircraft and a ground ___”. Which sequence most accurately completes the above statement?

a) primary; accurate; transmitter
b) secondary; earth; transmitter
c) secondary; slant; transponder
d) primary; slant; transponder

69. If a DME transponder becomes saturated it will:

a) give preference to the nearest 100 aircraft
b) give preference to the furthest aircraft up to a maximum of 70
c) give preference to the aircraft with the strongest transmissions
d) give preference to the first 100 aircraft which interrogated it

70. By using a random PRF the airborne DME can:

a) prevent interference from random transmissions
b) recognise a beacons reply among a mass of ground returns
c) reduce the effect of weather interference
d) distinguish between its own replies and those replies triggered by other aircraft

71. The DME counters are rotating continuously. This indicates that:

a) the DME is unserviceable
b) the DME is trying to lock onto range
c) the DME is trying to lock onto frequency
d) the DME is receiving no response from the ground station

72. On a DME presentation the counters are continuously rotating. This indicates:

a) the DME is in the search mode
b) the DME is unserviceable
c) the DME is receiving no response from the transponder
d) the transponder is unserviceable

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