Vayudoot Aviation

1. DME is a …………. radar operating in the …. band and uses………… in order to obtain range information. The correct words to complete the above statement are

primary UHF pulse pairs

secondary UHF twin pulses

primary SHF CW signals

secondary SHF “jittered pulses”

2. When a DME transponder becomes saturated

it increases the receiver threshold to remove weaker signals.

it goes into a selective response mode of operation.

it reverts to standby.

it increases the number of pulse pairs to meet the demand.

3. 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 a maximum distance of 30m apart.

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

they are widely separated and do not serve the same location.

4. 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.

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.

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

5. 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.

6. Referring to DME during the initial stage of the “search” pattern before “lock-on”

the ground receiver maintains the ground transmitter pulse transmission rate at no more than 150 per second

the aircraft transmits 24 pulses per second and the receiver checks a maximum of 150 pulses per second

the airborne transmitter transmits 150 pulses each second

the airborne receiver checks 150 pulses each second.

7. An aircraft flying at FL250 wishes to interrogate a DME beacon situated 400ft amsl. What is the maximum range likely to be achieved?

210 nm

198 nm

222 nm

175 nm

8.
The VOR in an aircraft is correctly tuned and set to define the centre line of an airway within UK airspace which you intend to fly. The indication received on the VOR/ILS deviation indicator is shown in the diagram alongside. At the same time the DME gave a range of 40 nm from the facility. Use the above information to answer the next two questions. Use the 1 in 60 rule and assume 1 dot equals 2°. Assuming still air conditions, on regaining the centreline, it will be necessary to make the following alteration of heading:

left onto 045°

left onto 225°

right onto 048°

right onto 225°

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

aircraft reject pulses not synchronised with its own random pulse recurrence rate.

aircraft transmit and receive on different frequencies.

each aircraft has its own frequency allocation.

aircraft will only accept unique twin pulses.

10. 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 synchronised 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.

11. DME operates in the frequency band, it transmits which give it the emission designator of

EHF twin pulses A9F

UHF double pulses J3E

SHF double size pulses PO1

UHF twin pulses PON

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

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

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

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

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

13. 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.

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

static interference.

interference from other radars.

14. 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

30m 600m

100 m 2000 m

50 feet 200 feet

50 m 200 m

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

902 Mhz

1025 Mhz

962 Mhz

1030 Mhz

16. The range indicated by DME is considered to be accurate to within

3% of range

1.25 % of range

0.5 nm

+/-0.25 nm +/-1.25% of range

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

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.

DME transmits and receives on different frequencies.

18. A DME receiver is able to distinguish between replies to its own interrogation pulses and those intended for other aircraft using the same transponder because

DME transponders reply to interrogations by means of twin pulses and the airborne equipment rejects all single pulses.

when DME is in the range search mode it will accept only pulses separated by + or - 63 MHz from the interrogation frequency.

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

each aircraft transmits pulses at a random rate(“jittering”) and will only accept replies that match this randomisation.

19.
The VOR in an aircraft is correctly tuned and set to define the centre line of an airway within UK airspace which you intend to fly. The indication received on the VOR/ILS deviation indicator is shown in the diagram alongside. At the same time the DME gave a range of 40 nm from the facility. Use the above information to answer the next two questions. Use the 1 in 60 rule and assume 1 dot equals 2°. At the time of the observation, the aircraft was on the

042° radial

228° radial

048° radial

222° radial

20. The accuracy associated with DME is

+ or - 3% of range

+ or - 1.25% of range

+ or - 3% of range, or 0.5nm, whichever is greater

+/-0.25 nm +/-1.25% of range

21. Distance Measuring Equipment is an example of _________ radar operating on a frequency of _______ in the __________ band

secondary 1030 MHz UHF

primary 8800 MHz SHF

primary 9375 MHz SHF

secondary 962 MHz UHF

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