Flashcards
4. Automatic Direction Finding
Cards in this deck (97)
- 1NDBNon Directional Beacon
- 2define ADFAutomatic Direction Finder
- 3what is the difference between an NDB and an ADFThe ADF is the airbourne part of the system, the NDB is the ground part
- 4which frequency band is assigned to NDB190 Khz -1750 Khz
- 5what is measured by the ADFThe relative bearing
- 6define a locatora short range, low powered NDB
- 7what is the approximate range of a locator10-25 nm
- 8define the cone of silenceconical area at the vertical of the NDB where no wave propagates
- 9what frequency bands are normally associated with NDBsLF and MF
- 10what wave are NDBs usually propagated assurface waves
(note sky waves may cause interference) - 11what are the common uses of NDBsenroute navigation, homing and let down in terminal areas
- 12what sort of power do NDBs usually propagate with25 -10000 watts
- 13what can you say about the range in relation to powerthe range is proportional to the square root of power
- 14what is the total range of a typical NDB10 nm to 500 nm
- 15what is the type of emission usually associated with NDBsamplitude modulated or unmodulated
- 16how is the transmission from the NDB polarised?vertically polarised
- 17what type of aerials are used to identify the direction of the NDBloop and sense antennas
- 18what part of a loop antenna is designed to pick up the radio wavethe vertical part
- 19in order for the antenna to pick up the signal correctly, how should it be orientatedthe plane of the loop should be parallel to the incoming radio wave
- 20why should a loop antenna have the plane of the loop parallel to the incoming radio waveone vertical section will be closer to the incoming wave than the other, and therefore a difference in phase will be detected
- 21what is induced in the loop aerial when there is a phase difference in the wave being receiveda current is induced, as the difference in voltage at each of the vertical sections creates a potential diffference
- 22what happens when the plane of the loop aerial is perpendicular to the incoming radio wavethere is no phase difference and therefore there is no current induced
- 23what does the polar diagram of the loop aerial look likea figure of 8
- 24what can be said about a sense aerialit is omnidirectional
- 25what is the polar diagram of a sense aerial look likecircular polar diagram
- 26what is the signal strength of a sense aerial equal tomaximum value from the loop aerial
- 27what is the shape of the polar diagram created when a sense and loop aerial are combinedCardioid
- 28what is the advantage of a Cardioidit only has one direction for zero signal strength
- 29what is the position where there is zero signal strength called in a cardioid polar diagramthe null position
- 30what is ambiguity associated with a sense antenna180˚
- 31what are the two NDB modulationsNON A1A
NON A2A - 32what is NON A1Aindent modulated keying
- 33what is NON A2Aindent modulated by amplitude modulation
- 34what are the 4 factors affecting NDB range-power
-terrain
-frequency
-modulation - 35in regards to terrain, when is the NDB range at its highestover sea or ice , comparative to land
- 36in regards to frequency when is the range of the NDB the highestwhen there is a lower frequency, and therefore a longer wavelength
- 37what type of NDB modulation gives the biggest rangeNON A1A has a better range than NON A2A
- 38how does the propagation of the NDB differ over night ?ionospheric d level absorbs the NDBs frequencies, therefore at night the wave can propagate as both ground AND skywave
- 39what are the 7 errors affecting the NDBnight effect
multipath
quadrantal error
coastal refraction
static interference
thunderstorm interference
dip error - 40define the night effectfading due to interference between the sky and ground waves - predominates at dusk and dawn
- 41what is multipath error also referred to asmountain effect
- 42define the quadrantal errorerrors caused by reflections of the incoming radio wave from the fuselage and wings
- 43when is quadrantal error at its maximumRelative Bearings of
045˚ 135˚ 225˚ 315˚ - 44how is coastal refraction caused?when a wave speeds up over water and bends
- 45define static interferencecaused by high humidity
water droplets on the surface of the aircraft cause static interference - 46define thunderstorm interferencestrongest point of error, worsens as aircraft gets closer to a thunderstorm
- 47dip erroroccurs when the loop/sense aerials are covered by the aircraft during manoeuvres, and the a/c is not in straight and level flight
- 48when is coastal refraction null (2)1. when the propagation direction of the wave is 90˚ to the coastline
2. when the NDB station is sited on the coastline - 49when does the coastal refraction error increase (2)1. when the incidence angle increases
2. when the NDB is further inland - 50what is the angle of incidence referring to when talking about coastal refractionthere is no warning flag
- 51what is the accuracy of an NDB/ADF system6.9˚
- 52what are the three analog instruments used to read the ADF1. RBI - fixed card
2. RBI - moving card
3. RMI - 53RBIRelative Bearing Indicator
- 54RMIRadio Magnetic Indicator
- 55what is always readable on the ADFthe relative bearing by measuring the angle, turning clockwise, from the top of the instrument to the head of the needle
- 56define homingflying to radio aids keep the RB at 0˚
- 57what is the relationship between HDG, RB and BRGHDG + RB = BRG
all in reference to the same north - 58what is the effect of a left wind on homingaircraft turns counter clockwise
- 59what is the effect of a right hand wind on hominga/c turns clockwise
- 60what is the wind from the right also referred to asleft drift
- 61what is wind from the left also referred to asright drift
- 62define trackingflying along a constant radial to radio aids
- 63what is the effect of wind on trackingpilot has to counter the wind effect, hence the relative bearing is equal to the drift (same direction and magnitude)
- 64what does the angle of incidence in reference to coastal refraction refer to ?angle between the normal to the coastline and the direction of propagation
- 65CRCurrent Radial
- 66DRdesired radial
- 67when there is less than 10˚ between the CR and DR and the time to the station is less than 3 minutes, how to you find your angle of interception2 x (CR -DR)
- 68when there is less than 10˚ between the CR and DR and the time to the station is more than 3 minutes, how to you find your angle of interception3 x (CR - DR)
- 69When there is between 10˚-20˚ between the DR and the CR, at what angle do you intercept the DR at?45˚
- 70when there is more than 20˚ between the CR and DR, how do you intercept the DR correctlyyou intercept the radial 20˚ prior to the DR at 90˚, then you intercept the DR with an angle of 45˚
- 71what are the three sectors of entry to a holding pattern1. reciprocal or parallel
2. offset
3. direct - 72define the inbound leg of a holding patternthe straight leg pointing directly to the NDB reference
- 73define the outbound leg of an NDBthe straight leg pointing away from the NDB reference
- 74describe a standard procedure turninitial turn at 45˚ then rejoin the same track as before, usually initial turn is to the left
- 75describe a teardrop procedure turnno standard direction of turn, shape of teardrop rejoining the same path but in an opposite direction
- 76describe a holding patterna reference point that you orbit onto.
- 77what is the ADF selection procedure1. check a/s is within published area
2. turn up the gain
3. select frequency
4. select 'ANT'
5. select BFO as required
6. check indent
7. select ADF - 78when would tracking and homing be the same thingwhen there is no wind
- 79what does the RMI give youQDM
- 80what is the difference between the QUJ and QTE180˚
- 81what is the length of the loop in a loop aerial1/6 wavelength
- 82what is the fixed loop theoryinstead of a rotating loop, there is a pair of fixed loops at 90˚ to each other
- 83in the fixed loop theory in which planes do each of the fixed loops operate inlongitudinal plane
lateral plane - 84in the fixed loop theory how is the current flow createdby the radio wave as it passes the loops, sets up a magnetic field as it passes through the field coils
- 85in the fixed loop theory how is the search coil powereddriven by the motor
- 86what can you say about the search coilit is null seeking
- 87when will the search coil have no voltagewhen it lies 90˚ to the magnetic field
- 88is there any ambiguity associated with the search coilyes, as there are two null positions
- 89how is the ambiguity overcome in the fixed loop theoryby using a sense aerial
- 90When OFF...ADF is not in use, equipment switched off
- 91when ADF...both sense and loop aerials are in operation. the ADF should give a continuous indication of the bearing to the station that has been tuned
- 92when ANT...only sense aerial in operation
- 93when is the ANT setting usedtuning and station identification
- 94what can you say about the audio quality in the ANT position compared to the ADF positionbetter audio quality in the ANT position
- 95what can the ANT switch also be calledREC
ONMI
SENSE - 96when at BFO...the BFO is used to hear unmodulated transmissions
- 97BFOBeat Frequency Oscillator
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- RNAV Flashcards on 4. Automatic Direction Finding , created by Ella Davies on 06/03/2018.
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- Ella Davies
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