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Flashcards
Thrue Bearing to wie ausrechnen ?
TH + RB = TB to
welches Heading bei den verschiedene ADF
RBI: RB MDI = MH RMI/Radio magnetic indicator) => CH ==> Jedoch dev = 0 ==> im grunde MH
Fehler bei den ADF ?
1. mountain effect:=> reflection (Spiegelung) => +/- 10 - +/- 30 degrees
2. Costal (Shorline Effect): => refraction (Brechung von Strahlen) => angle at which teh radio wave passes teh coastline and teh cruising altitude of teh aircraft determine teh amount of refraction
3. Night- and Twilight Effect: D-layer verschwindet in der nacht => keine absorbation mehr => reflected sky waves
4. Atmospheric Disturbances / statics: charges and discharges ( statics) => lightning
5. Dip error
6. quadrantal error
7. Ansence of failure of warning system, when the ADF doesn't work
Dip error
teh incoming radio wave is not located within this plane an erroneous bearing may result => the orientation of the antenna system is changed due to bank or pitch altitude
=> most noticeable when the aircraft is banked and the station is located directly in front or behind teh aircraft
Quadrantal error
waves reaches an aircraft, the wave enters the antenna but also the aircraft fuselage => fuselage reflect the waves and some of these reflected waves also enter the antenna => max. 045, 135, 225, 315 Min 90 => reflection is backward
ADF tolerance
+/- 5 degrees
the information generated by the ADF receiver is an
the information generated by the ADF receiver is an aircraft to sttaion bearing
What is the task of teh NDB during navigation?
Provides (ausgestattet) aircraft - station bearings
Which kind transmissions are used in combination with ADF
N0N/A1A (NDB) N0N/A2A(NDB) A3E(BS)
What is the most likely disturbance to have the gratest impact on ADF bearings
thunderstorms with lightning
The reason for using different frequencies for transmitting and receiving in the DME System...
Is to prevent self-triggering of the receiving equipment by the transmitter
An aircraft DME receiver does not lock on to its own transmissions reflected from the ground because:
they are not on the receiver frequency
In the DME system The receive and the transmit frequency is always split by xy MHz
In the DME system The receive and the transmit frequency is always split by 63 MHz
The aircraft DME receiver is able to accept replies to its own transmissions and reject replies to other aircraft interrogations because...
pulse pairs are discreet to a particular aircraft
On a DME, display counters rotating throughout their range indicates:
the airborne receiver is conducting a range search
In the DME system, responses in the aircraft equipment to answers to other aircraft is prevented...
By an irregular change in pulse-pair PRF (Pulse Repetition Frequency) in every aircraft installation, and by making the receiver sensitive for reception only in a short period of time of around the anticipated time of arrival of the answer from the ground
Distance Measuring Equipment (DME) operates in the...
UHF band and is a secondary radar system
A DME that has difficulty obtaining a "lock-on": (NOTE: PRF = pulse recurrence frequency, PPS = pulses per second)
stays in search mode but reduces PRF to max. 60 PPS after 15000 pulse pairs have been transmitted
What is the maximum distance between VOR and DME/TACAN ground installations if they are to have the same Morse code identifier?
600 m
The aircraft DME receiver cannot lock on to interrogation signals reflected from the ground because:
aircraft transmitter and DME ground station are transmitting on different frequencies
DME Grundprinzip
aircraft transmits an interrogation signal (pulse pair groups) and the DME ground station sends a response
How you can identify a DME
two or three letters of the Morse code ==> with a VOR/ILS => DME is a higher tone pitch (every 40 seconds)
2 Arten DME
DME/N = en route DME/P = for Microwave landing system
when max. 100 aircraft at teh same tiem at the DME what happens
the aircraft interrogation pulses with the least transmitting power receive no answer
Aircraft Interrogator (on board equipment)
from 1015to 1150 MHz => sends out random pulse pairs => as threnody timing of the pulse pairs is unique for wach DME aircraft unit, the aircraft is able to recognize its own signal when transmitted by the ground station and to distinguish it from other DME transmissions
DME receiver works in different modes:
a) Search Phase: DME has been activated, teh interrogator starts the search phase => at a rate of about 120 pulse pairs/s
b) Lock - On Phase: a sufficient quantity of correct response pulses has been received, these pulses are intergrated in teh lock-on phase => if teh signals are correct, teh system switches to the track phase
c) Track Phase: teh warning flags are removed and teh slant distant is measured and indicatd => 25 pulse per/s
d) Memory Phase: is activated when the signal is lost e.g. due to a bank angle
==> If the aircraft equipment receives further signals within 10 seconds, teh track phase re-engages. Otherwise teh search is activated => A failure flag or dashes are displayed
e) standby Phase: if teh interrogator does not receive signals from a DME ground station during teh search phase
Consider a VOR station with a co-operated DME facility. How can you identify the DME ?
The DME emits with the same MORSE code but at a higher tone pitch
Why will teh DME on-board equipment not lock onto its own transmission reflected from the ground?
Because the receiver frequency is different from the transmitter frequency
What happens if a DME ground facility receives more interrogations than it can process?
The system will decrease receiver sensitivity
When do DME interrogations start?
DME interrogations start when pulse pairs emitted by the tuned DME station are received
Which is the accurac (system error) expected when using a DME
0.2 NM
If a VOR station and a DME station, having different locations, are selected to provide a fix...
When using ADF, the sky-wave (night) effect...
Is most dominant around dusk and dawn
When VOR and DME stations are associated...
They may be separated by as much as 600 metres if they are meant for en-route navigation
The indicator of the ADF equipment responds to...
The carrier wave received
Flying in the vicinity of CB clouds and using ADF
If VOR bearing information is used beyond the published protection range, errors could be caused by...
interference from other transmitters
Consider the following statements on horizontal/slant distance when using DME:
The difference between the two distances will be negligible for en-route navigation when the indicated distance in NM is more than the height of the aircraft above the DME site, stated in thousands of feet
In which one of the following circumstances is ground direction finding (VDF) likely to be used to fix an aircraft's position?
The aircraft DME receiver cannot lock on to interrogation signals reflected from the ground because...
aircraft transmitter and DME ground station are transmitting on different frequencies
