RAD 13 – Distance Measuring Equipment (DME) – LMS

📄 Detailed Notes ⚡ Cheat Sheet

Results

📄 Notes ⚡ Cheat Sheet

Q1. *** When a DME transponder becomes saturated:

it goes into a selective response mode of operation

it increases the number of pulse pairs to meet the demand

it reverts to standby

it increases the receiver threshold to remove weaker signals

Q2. % The time taken for the transmission of an interrogation pulse by a Distance Measuring Equipment (DME) to travel to the ground transponder and return to the airborne receiver was 4000 microsecond. The slant range from the ground transponder was?

296 NM

330 NM

324 NM

186 NM

324 NM

Q3. #The design requirements for DME stipulate that, at a range of 200 NM, the maximum systematic error should not exceed:

(+/-3NM)

(+ or -2.75 NM)

(+or-1.25 NM)

(+ or-1.5 NM)

(+or-2.75 NM)

Q4. ** Which of the following will give the most accurate calculation of aircraft ground speed?

A VOR off the flight plan route

A DME on the flight plan route

A VOR on the flight plan route

A DME off the flight plan route

A DME on the flight plan route

Q5. *An aircraft DME receiver does not lock on to its own transmissions reflected from the ground because:

DME uses the UHF band

DME transmits twin pulses

The pulse recurrence rates are varied

They are not on the receiver frequency

Q6. ** If a DME beacon become saturated by interrogations it?

Adjusts the gain to reply to the 100 strongest signals

Adjusts its PRF to cope with all aircraft

Replies to the nearest 100 aircraft

Switches off its identification

Adjusts the gain to reply to the 100 strongest signals

Q7. #Regarding the DME system, which one of the following statements is true?

DME operates in the VHF frequency band

The DME measures the phase difference between the reference and the variable signals to calculate the distance

When passing overhead the DME station the DME will indicate Zero

The transponder reply carrier frequency differs by 63 MHz from that of the interrogation signal

Q8. # The effect of masking the DME antenna of the aircraft from the ground installation is that interruption of reception of DME signals results in?

The airborne installation switching to the memory mode for about 10 to 15 seconds

The signal controlled search circuit (SCS) blanking the DME display

The ground installation not sending any pulse-pairs

The airborne installations switching directly to the search mode

The airborne installation switching to the memory mode for about 10 to 15 seconds

Q9. *The aircraft DME receiver cannot lock on to interrogation signals reflected from the ground because:

DME pulse recurrence rates are varied

Aircraft transmitter and DME ground station are transmitting on different frequencies

Reflections are subject to doppler frequency shift

DME transmits twin pulses

Aircraft transmitter and DME ground station are transmitting on different frequencies

Q10. *% An aircraft at FL 300, with a ground speed of 300 kts, is about to pass overhead a DME station at MSL. The DME receiver is capable of determining ground speed. One minute before the overhead, DME speed and distance indication respectively are?

Less than 300 kts and 7 nm

Less than 300 kts and 5 nm

300 kts and 5 nm

300 kts and 7 nm

Less than 300 kts and 7 nm

Q11. *** A fix obtained by rho-rho navigation is based on information from two?

NDBs

VDFs

DMES

VORS

DMES

Q12. ## In a certain VORTAC installation the VOR station is identified as “STN” and the DME station is identified as “STZ”. This means that the distance between the two beacons is in excess of……

2000 m

100 m

300 m

600 m

Q13. *What is the maximum distance between VOR and DME/TACAN ground installations if they are to have the same morse code identifier?

600 m

60 m

300 m

2000 m

600 m

Q14. *The reason for using different frequencies for the airborne and ground equipment of DME is?

To prevent that DME interrogation pulse pairs from being received by the aircraft after reflection on the earth's surface

That side lobes can be suppressed by the Slide Lobe Suppressor (SLS)

To avoid second trace returns when a DME is more than 200 nm away

That more DME frequencies are available from different beacons

To prevent that DME interrogation pulse pairs from being received by the aircraft after reflection on the earth’s surface

Q15. # 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?

Range of a DME system is always less than 200 NM

Airplane is below the line of sight' altitude

Airplane is circling around the station

Altitude is too high

DME operates on line-of-sight propagation, so its range depends on the aircraft’s altitude.

At FL210, the maximum line-of-sight range is approximately 170–180 NM. Since the DME station is 220 NM away, it lies beyond this range, and the signal cannot reach the aircraft.

Therefore, the aircraft is effectively below the required line-of-sight altitude to receive the signal. The line-of-sight range can be estimated by:

Range (NM) ≈ 1.23 × √height (ft)

Hence, the solution is to fly higher, as increasing altitude increases the line-of-sight range (dependent on both transmitter and receiver heights).

Q16. The DME Line Of Position is a circle with radius?

The slant range and centre the DME station

The slant range and centre the aircraft

The ground distance and centre the aircraft

A ground distance and centre the DME station

Q17. *The airborne DME equipment will transmit pulse pairs at a comparatively high PRF?

When first switched on and after channel change

When the distance presented is above 50 nm

Whenever a stable signal is being received from the selected ground station

At all times, except when the panel control "LO" is operated

When first switched on and after channel change

Feedback

Range Search Pulse rate
► To achieve a rapid lock-on during the range search, the DME interrogator transmits at 150 pulse pairs
per second (pps) for 100 seconds (total 15000 pulse pairs).
► If lock-on is not achieved, it will then reduce the rate to 60 ppps and maintains this rate until there is
a range lock-on.
► After lock-on, the system operates at a random PRF of 27 ppps

Q18. *** In which situation will speed indications on an airborne Distance Measuring Equipment (DME) most closely represent the groundspeed of an aircraft flying at FL400?

When passing abeam the station and within 5 NM of it

When tracking directly towards the station at a range of 100 NM or more

When overhead the station, with no change of heading at transit

When tracking directly away from the station at a range of 10 NM

When tracking directly towards the station at a range of 100 NM or more

Q19. #DME is a radar type of facility and its maximum range (usable range) is limited by?

The height of the airplane

The receiver sensitivity

The transmitter power only

The pulse repetition interval

The height of the airplane

Q20. # What is the function of the Echo Protection Circuit (EPC)?

The EPC has to detect if the interrogator-receiver has been locked on, by reflected pulse-pairs

The EPC has to detect if pulse-pairs reflected by the ionosphere are interfering with directly received pulse-pairs

The EPC has to protect the transponder-receiver against reflected pulse-pairs

The EPC has to detect if unwanted squitter-pulses are interfering with the well functioning of the interrogator-receiver

The EPC has to detect if the interrogator-receiver has been locked on, by reflected pulse-pairs

Q21. % A DME is located at MSL. An aircraft passing vertically above the station at flight level 360 will obtain a DME range of approximately? (use 1NM=6000 feet)

6 nm

11 nm

8 nm

7 nm

6 nm

Q22. ** Airborne DME equipment is able to discriminate between pulses intended for itself and pulses intended for other aircraft because:

aircraft reject pulses not synchronized with its own random pulse recurrence rate

each aircraft has its own frequency allocation

aircraft will only accept unique twin pulses

aircraft transmit and receive on different frequencies

aircraft reject pulses not synchronized with its own random pulse recurrence rate

Q23. Distance Measuring Equipment is an example of………radar operating on a frequency of…..in the…….band.

primary/9375 MHz / SHF

secondary/962 MHz-1213 MHz / UHF

primary/8800MHz / SHF

secondary/1030 MHz-1090 MHz / UHF

secondary/962 MHz-1213 MHz / UHF

Q24. DME and VOR are “frequency paired” because:

both ground transmitter aerials can be placed on the same site if required

the same receiver can be used for both aids

the VOR transmitter is easily converted to the required DME frequency

cockpit workload is reduced

Q25. % A DME station is located 2000 feet above MSL. An aircraft flying at FL200, 10 NM away from the DME station, will have a DME reading of?

11.35 NM

13.44 NM

12 NM

10.44 NM

Q26. #A DME in tracking mode subsequently experiences a reduction in signal strength will switch the equipment in the first instances to:

Standby mode

Signal controlled search

Search mode

Memory mode

Q27. *** The receiver of airborne DME equipment is able to “lock on” to its own “reply pulses” because:

the aircraft receiver only accepts reply pulses which have the same time interval between successive pulses as the pulses being transmitted by its own transmitter

each aircraft has its own unique transmitter frequency and the receiver only accepts reply pulses having this frequency

the reply pulses from the ground transmitter have the same frequency as the incoming interrogation pulses from the aircraft

the aircraft receiver only accepts reply pulses which arrive at a constant time interval

the aircraft receiver only accepts reply pulses which have the same time interval between successive pulses as the pulses being transmitted by its own transmitter

Q28. *For a conventional DME facility ‘Beacon Saturation’ will occur whenever the number of simultaneous interrogations exceeds:

200

100

Q29. # The DME ground transponder has PRF of…………

150 pulses per second

2700 pulses per second

27 pulses per second

1500 pulses per second

2700 pulses per second

Q30. *** How can a DME interrogator distinguish between its own reply pulse-pairs and the reply pulse-pairs of other aircraft in the area, using the same DME station?

The pulse repetition frequency of the pulse-pairs transmitted by the interrogator varies, for each interrogator there is a unique rhythm

The time-interval between both pulses of consecutive pulse-pairs transmitted by the interrogator varies, for each interrogator there is a unique rhythm

On the Y-channel the time interval between the pulses of an interrogator pulse-pair is 36/m-sec an of a transponder pulse-pair 30~m/sec

The DME transponder uses a slightly different, randomly varying, delay for each interrogating aircraft

The pulse repetition frequency of the pulse-pairs transmitted by the interrogator varies, for each interrogator there is a unique rhythm

Q31. % The time taken for the transmission of an interrogation pulse by a Distance Measuring Equipment (DME) to travel to the ground transponder and return to the airborne receiver was 3000 microsecond. The slant range from the ground transponder was?

243 NM

186 NM

330 NM

296 NM

243 NM

Q32. A DME receiver is able to distinguish between replies to its own interrogations and replies to other aircraft because:

DME is secondary radar and each aircraft transmits and receives on a different frequency

each aircraft transmits pulses at a random rate and will only accept synchronized replies

DME transponders reply to interrogations with twin pulses and the airborne equipment ejects all other pulses

when DME is in the search mode it will only accept pulses giving the correct range

each aircraft transmits pulses at a random rate and will only accept synchronized replies

Q33. #A typical frequency employed in Distance Measuring Equipment (DME) is:

10 MHz

100 MHz

1000 MHz

100 GHz

1000 MHz

Q34. #Distance Measuring Equipment (DME) uses radar principles to measure distance?

Plan Range

Vertically

Slant range

Horizontally

Slant range

Q35. #ICAO specifications are that range errors indicated by Distance Measuring Equipment (DME) should not exceed:

(+ or -0.25 NM plus 1.25% of the distance measured)

(+ or -0.25 NM plus 3% of the distance measured up to a maximum of 5 NM)

(+ or -1.25 NM plus 0.25% of the distance measured)

(+ or -0.5 NM or 3% of the distance measured whichever is the greater)

Q36. For a DME and a VOR to be said to be associated it is necessary for:

the aerial separation not to exceed 100 ft in a TMA or 2000 ft outside a TMA

the aerial separation not to exceed 100 m in a TMA or 2000 m outside a TMA

the DME to transmit on the same VHF frequency as the VOR

both beacons to have the same first two letters for their ident but the last letter of the DME to be a 'Z'

the aerial separation not to exceed 100 ft in a TMA or 2000 ft outside a TMA

Q37. * The aircraft DME receiver can accept replies to its own transmissions and reject replies to other aircraft interrogators because?

Transmission frequencies are 63 MHz different for each aircraft

The time interval between pulse pairs is unique to that aircraft

Pulse pairs are amplitude modulated with the aircraft registration

Aircraft interrogation signals and transponder response signals are 63 MHz removed from each other

The time interval between pulse pairs is unique to that aircraft

Q38. ###Groundspeed measurement using DME equipment is most accurate when flying?

Towards the station at short range

From the station at long range

Directly over the station

Past the station at short range

From the station at long range

Q39. * The most accurate measurement if ground speed by DME for an aircraft at 30000 feet will be when the aircraft is?

Tracking away from the beacon at 100 nm

Tracking towards the beacon at 10 nm

Overhead the beacon

Passing abeam the beacon at 50 nm

Tracking away from the beacon at 100 nm

Q40. A DME transponder does not respond to pulses received from radars other than DME because:

DME transmits and receives on different frequencies

it will only accept the unique twin DME pulses

each aircraft transmits pulses at a random rate

DME only responds to the strongest 100 interrogators

it will only accept the unique twin DME pulses

Q41. *A VOR and DME are co-located. You want to identify the DME by listening to the callsign. Having head the same callsign 4 times in 30 seconds the?

DME callsign was not transmitted, the distance information is sufficient proof of correct operation

DME callsign is the one with the lower pitch that was broadcast several times VOR and DME callsigns were the same and broadcast with the same pitch

DME callsign is the one with the higher pitch that was broadcast only once

The VOR IDENT is transmitted three times followed by the DME IDENT transmitted once

DME callsign is the one with the higher pitch that was broadcast only once

Q42. **A VOR/DME share the same first two letters of their respective identifiers; the last identifying letter of the DME is a Z. This means that:

they are co-located

they are more than 600 m apart but serve the same location

they are a maximum distance of 30 m apart

they are widely separated and do not serve the same location

they are more than 600 m apart but serve the same location

Q43. ** The reason for using different frequencies for transmitting and receiving in the DME system is to?

Prevent overload of the system

Avoid the reception in the aircraft of signals referring to other aircraft

Prevent self-triggering of the receiving equipment by the transmitter

Permit more channels in the system

Prevent self-triggering of the receiving equipment by the transmitter

Q44. *Of what use, if any, is a military TACAN station to civil aviation?

It can provide a DME distance and magnetic bearing

It can provide a magnetic bearing

It is of no use to civil aviation

It can provide DME distance

Q45. For a VOR and a DME beacon to be said to be associated the aerial separation must not exceed……….in a terminal area and………outside a terminal area.

30 m 600 m

50 m 200 m

50 ft 200 ft

100 m 2000 m

30 m 600 m

Q46. ### DME pulses are transmitted as pulse pairs. This is done?

So that any radar emissions do not interfere with the DME equipment

To increase the range

So that pulses are square and easily identified

To prevent lock onto the ground

So that any radar emissions do not interfere with the DME equipment

Q47. A DME beacon having a transmit frequency of 962 MHz would have a receive frequency of:

902 MHz

1030 MHz

962 MHz

1025 MHz

Q48. *The aircraft DME receiver is able to accept replies to its own transmissions and reject replies to other aircraft interrogations because:

Transmission frequencies are 63 MHz different for each aircraft

Aircraft interrogation signals and transponder responses are 63 MHz removed from each other

Pulse pairs are discreet to a particular aircraft

Pulse pairs are amplitude modulated with the aircraft registration

Pulse pairs are discreet to a particular aircraft

Q49. The transmission frequency of a DME beacon is 63 MHz removed from the aircraft interrogator frequency to prevent:

receiver accepting replies intended for other interrogators

static interference

the airborne receiver locking on to primary returns from its own transmissions

interference from other radars

the airborne receiver locking on to primary returns from its own transmissions

Q50. ***Which of the following will give the most accurate calculation of aircraft ground speed?

A DME station sited across the flight route

An ADF sited on the flight route

A DME station sited on the flight route

A VOR station sited on the flight route

A DME station sited on the flight route

Q51. %*** Aircraft position 34 15 N 098 00E, magnetic variation 28 W, FL280, PTV VOR/DME position 36 12 N 098 E, magnetic variation 13 E, In order to read the most accurate ground speed given by the DME receiver from his present position, the pilot must fly on which PTC radial?

193 degrees

167 degrees

332 degrees

Aircraft will not receive DME information from PTC due to the line of sight

167 degrees

Q52. **** Aircraft position 52 09 S 024 E, magnetic variation 14 W, FL310, BIT VOR/DME position 54 42 S 024 E, magnetic variation 14 E, In order to read the most accurate ground speed given by the DME receiver from his present position, the pilot must fly on which BIT radial?

166 degrees

266 degrees

194 degrees

346 degrees

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Results

Q1. *** When a DME transponder becomes saturated:

Q2. % The time taken for the transmission of an interrogation pulse by a Distance Measuring Equipment (DME) to travel to the ground transponder and return to the airborne receiver was 4000 microsecond. The slant range from the ground transponder was?

Q3. #The design requirements for DME stipulate that, at a range of 200 NM, the maximum systematic error should not exceed:

Q4. ** Which of the following will give the most accurate calculation of aircraft ground speed?

Q5. *An aircraft DME receiver does not lock on to its own transmissions reflected from the ground because:

Q6. ** If a DME beacon become saturated by interrogations it?

Q7. #Regarding the DME system, which one of the following statements is true?

Q8. # The effect of masking the DME antenna of the aircraft from the ground installation is that interruption of reception of DME signals results in?

Q9. *The aircraft DME receiver cannot lock on to interrogation signals reflected from the ground because:

Q10. *% An aircraft at FL 300, with a ground speed of 300 kts, is about to pass overhead a DME station at MSL. The DME receiver is capable of determining ground speed. One minute before the overhead, DME speed and distance indication respectively are?

Q11. *** A fix obtained by rho-rho navigation is based on information from two?

Q12. ## In a certain VORTAC installation the VOR station is identified as “STN” and the DME station is identified as “STZ”. This means that the distance between the two beacons is in excess of……

Q13. *What is the maximum distance between VOR and DME/TACAN ground installations if they are to have the same morse code identifier?

Q14. *The reason for using different frequencies for the airborne and ground equipment of DME is?

Q15. # 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?

Q16. The DME Line Of Position is a circle with radius?

Q17. *The airborne DME equipment will transmit pulse pairs at a comparatively high PRF?

Q18. *** In which situation will speed indications on an airborne Distance Measuring Equipment (DME) most closely represent the groundspeed of an aircraft flying at FL400?

Q19. #DME is a radar type of facility and its maximum range (usable range) is limited by?

Q20. # What is the function of the Echo Protection Circuit (EPC)?

Q21. % A DME is located at MSL. An aircraft passing vertically above the station at flight level 360 will obtain a DME range of approximately? (use 1NM=6000 feet)

Q22. ** Airborne DME equipment is able to discriminate between pulses intended for itself and pulses intended for other aircraft because:

Q23. Distance Measuring Equipment is an example of………radar operating on a frequency of…..in the…….band.

Q24. DME and VOR are “frequency paired” because:

Q25. % A DME station is located 2000 feet above MSL. An aircraft flying at FL200, 10 NM away from the DME station, will have a DME reading of?

Q26. #A DME in tracking mode subsequently experiences a reduction in signal strength will switch the equipment in the first instances to:

Q27. *** The receiver of airborne DME equipment is able to “lock on” to its own “reply pulses” because:

Q28. *For a conventional DME facility ‘Beacon Saturation’ will occur whenever the number of simultaneous interrogations exceeds:

Q29. # The DME ground transponder has PRF of…………

Q30. *** How can a DME interrogator distinguish between its own reply pulse-pairs and the reply pulse-pairs of other aircraft in the area, using the same DME station?

Q31. % The time taken for the transmission of an interrogation pulse by a Distance Measuring Equipment (DME) to travel to the ground transponder and return to the airborne receiver was 3000 microsecond. The slant range from the ground transponder was?

Q32. A DME receiver is able to distinguish between replies to its own interrogations and replies to other aircraft because:

Q33. #A typical frequency employed in Distance Measuring Equipment (DME) is:

Q34. #Distance Measuring Equipment (DME) uses radar principles to measure distance?

Q35. #ICAO specifications are that range errors indicated by Distance Measuring Equipment (DME) should not exceed:

Q36. For a DME and a VOR to be said to be associated it is necessary for:

Q37. * The aircraft DME receiver can accept replies to its own transmissions and reject replies to other aircraft interrogators because?

Q38. ###Groundspeed measurement using DME equipment is most accurate when flying?

Q39. * The most accurate measurement if ground speed by DME for an aircraft at 30000 feet will be when the aircraft is?

Q40. A DME transponder does not respond to pulses received from radars other than DME because:

Q41. *A VOR and DME are co-located. You want to identify the DME by listening to the callsign. Having head the same callsign 4 times in 30 seconds the?

Q42. **A VOR/DME share the same first two letters of their respective identifiers; the last identifying letter of the DME is a Z. This means that:

Q43. ** The reason for using different frequencies for transmitting and receiving in the DME system is to?

Q44. *Of what use, if any, is a military TACAN station to civil aviation?

Q45. For a VOR and a DME beacon to be said to be associated the aerial separation must not exceed……….in a terminal area and………outside a terminal area.

Q46. ### DME pulses are transmitted as pulse pairs. This is done?

Q47. A DME beacon having a transmit frequency of 962 MHz would have a receive frequency of:

Q48. *The aircraft DME receiver is able to accept replies to its own transmissions and reject replies to other aircraft interrogations because:

Q49. The transmission frequency of a DME beacon is 63 MHz removed from the aircraft interrogator frequency to prevent:

Q50. ***Which of the following will give the most accurate calculation of aircraft ground speed?

Q51. %*** Aircraft position 34 15 N 098 00E, magnetic variation 28 W, FL280, PTV VOR/DME position 36 12 N 098 E, magnetic variation 13 E, In order to read the most accurate ground speed given by the DME receiver from his present position, the pilot must fly on which PTC radial?

Q52. **** Aircraft position 52 09 S 024 E, magnetic variation 14 W, FL310, BIT VOR/DME position 54 42 S 024 E, magnetic variation 14 E, In order to read the most accurate ground speed given by the DME receiver from his present position, the pilot must fly on which BIT radial?

Thank You