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Multiple > protocol : Quadrantal errors associated with aircraft automatic direction finding adf ?

Question 174-1 : Signal bending by the aircraft metallic surfaces signal bending caused by electrical interference from aircraft wiring misalignment of the loop aerial skywave/groundwave contamination

. quadrantal error .ndb signals may reach the receiver aerial directly and also after being reflected by the aircraft body due to electrical circuits and current flowing through them there is an electromagnetic field surrounding the aircraft in general alignment with its body .this causes the incident radio waves to deflect near the adf receiver aerial the mixed signal affects the null position and the bearing indicated may be with large error.the maximum effect is at quadrantal relative bearings .045° 135° 225° and 315° relative to heading.modern installations are compensated for this error exemple 274 signal bending by the aircraft metallic surfaces.signal bending by the aircraft metallic surfaces.

Errors caused by the effect of coastal refraction on bearings at lower ?

Question 174-2 : Inland and the bearing crosses the coast at an acute angle near the coast and the bearing crosses the coast at right angles inland and the bearing crosses the coast at right angles near the coast and the bearing crosses the coast at an acute angle

. coastal refraction or shoreline effect .low frequency radio waves will refract or bend near a shoreline especially if they are close to parallel to it .least when bearings normal to coastline.radio waves passing the coastline at small angles suffer refraction due to different conducting and reflecting properties over land and sea a false bearing indication is obtained at aircraft flying over sea and taking bearings from ndb located over land the effect is less for an ndb on coast than one inland and on a bearing 90° to coastline then at an oblique angle hence given the choice use beacon at coast and rely on bearings perpendicular to the coastline exemple 278 inland and the bearing crosses the coast at an acute angle.inland and the bearing crosses the coast at an acute angle.

Transmissions from vor facilities may be adversely affected by ?

Question 174-3 : Uneven propagation over irregular ground surfaces static interference night effect quadrantal error

.due to reflections from terrain radials can be bent and lead to wrong or fluctuating indications which is called 'scalloping' exemple 282 uneven propagation over irregular ground surfaces.uneven propagation over irregular ground surfaces.

If vor bearing information is used beyond the published protection range errors ?

Question 174-4 : Interference from other transmitters noise from precipitation static exceeding the signal strength of the transmitter sky wave interference from the same transmitter sky wave interference from distant transmitters on the same frequency

.maximum range and altitude published for a vor guaranteed the reception free from harmful interference from other vors when you are within this airspace exemple 286 interference from other transmitters.interference from other transmitters.

What is the wavelength of an ndb transmitting on 375 khz ?

Question 174-5 : 800 m 8000 m 8 m 80 m

.wavelength m = 300 / f mhz.wavelength m = 300000 / f khz.wavelength = 300000 / 375 khz = 800 m exemple 290 800 m.800 m.

Phase modulation is ?

Question 174-6 : A modulation form used in gps where the phase of the carrier wave is reversed a modulation form used in ils where the navigation phase signal changed from 90° or 150° the cause of an amplitude change of the carrier the cause of polarisation of the modulated signal

.for the ranging codes and navigation messages to travel from the satellite to the receiver they must be modulated onto a carrier frequency by varying the phase of the signal phase modulation as soon as a data signal will be modulated onto the carrier wave the phase of the carrier wave is reversed by 180° the receiver will detect this reversal and is able to reconstruct the data exemple 294 a modulation form used in gps where the phase of the carrier wave is reversed.a modulation form used in gps where the phase of the carrier wave is reversed.

Factors liable to affect most ndb/adf system performance and reliability include ?

Question 174-7 : Static interference night effect absence of failure warning system static interference station interference latitude error height error station interference mountain effect coastal refraction lane slip mountain effect

.navigation using an adf to track ndbs is subject to several common effects. night effect radio waves reflected back by the ionosphere can cause signal strength fluctuations 30 to 60 nautical miles 54 to 108 km from the transmitter especially just before sunrise and just after sunset more common on frequencies above 350 khz. terrain effect high terrain like mountains and cliffs can reflect radio waves giving erroneous readings magnetic deposits can also cause erroneous readings. electrical effect or static interference electrical storms and sometimes also electrical interference from a ground based source or from a source within the aircraft can cause the adf needle to deflect towards the electrical source. shoreline effect or coastal refraction low frequency radio waves will refract or bend near a shoreline especially if they are close to parallel to it. bank effect when the aircraft is banked the needle reading will be offset.it doesn't provide information of failure or malfunction exemple 298 static interference - night effect - absence of failure warning system.static interference - night effect - absence of failure warning system.

Due to 'doppler' effect an apparent decrease in the transmitted frequency which ?

Question 174-8 : The transmitter moves away from the receiver the transmitter and receiver move towards each other the transmitter moves toward the receiver there is no relative movement between the transmitter and the receiver

.because the radio signals travel at a constant speed assuming they are not refracted by the atmosphere the receiver can calculate exactly how far away it is from the transmitter .speed is most often calculated by the receiver using the doppler effect which is the process by which the frequency of a signal changes due to the relative motion of the transmitter frequency decreases when the transmitter moves away from the receiver exemple 302 the transmitter moves away from the receiver.the transmitter moves away from the receiver.

Which one of the following disturbances is most likely to cause the greatest ?

Question 174-9 : Local thunderstorm activity coastal effect quadrantal error precipitation interference

.static emission energy from a cumulonimbus cloud may interfere with the radio wave and influence the adf bearing indication .thunderstorm cause the greatest inaccuracy.coastal effect causes relatively small inaccuracy .the quadrantal error is caused by the refraction from the aircraft's fuselage and is compensated for.precipitation interference is irrelevant exemple 306 local thunderstorm activity.local thunderstorm activity.

The advantage of the use of slotted antennas in modern radar technology is to ?

Question 174-10 : Virtually eliminate lateral lobes and as a consequence concentrate more energy in the main beam simultaneously transmit weather and mapping beams have a wide beam and as a consequence better target detection eliminate the need for azimuth slaving

.the main advantage of a slotted antenna is that it produces a much narrower beam and eliminates most of the lateral lobes therefore more energy can be concentrated in the main beam or you can use less power to transmit exemple 310 virtually eliminate lateral lobes and as a consequence concentrate more energy in the main beam.virtually eliminate lateral lobes and as a consequence concentrate more energy in the main beam.

The frequency which corresponds to a wavelength of 12 cm is ?

Question 174-11 : 2500 mhz 2500 khz 360 mhz 3600 mhz

.frequency mhz = 300 / wavelength m.frequency mhz = 300 / 0 12 m = 2500 mhz exemple 314 2500 mhz.2500 mhz.

A cumulonimbus cloud in the vicinity of an aeroplane can cause certain ?

Question 174-12 : Adf vor weather radar dme

exemple 318 adf.adf.

A radio altimeter employing a continuous wave signal would have ?

Question 174-13 : A directional aerial for transmission and another one for reception an omni directional aerial for transmission and directional aerial for reception a directional aerial for transmission and an omni directional aerial for reception a directional aerial for both transmission and reception

.a radio altimeter is a self contained on board aid which indicates the true height or the lowest wheels with regard to the ground .a continuous wave fm radio beam in the shf band 4200 4400 mhz is directed towards the ground in a 30° cone fore and aft and 30° athwartships across the ship from side to side the signal is reflected back to the aircraft .continuous wave as opposed to pulse radar eliminates minimum target reception range since the time delay for a pulsed signal would be too small to measure properly as well the antennae cannot switch between transmit and receive that quickly as the potential time interval is very small you need separate transmitter and receiver aerial exemple 322 a directional aerial for transmission and another one for reception.a directional aerial for transmission and another one for reception.

Which statement relating to the stabilization of airborne weather radar ?

Question 174-14 : They are stabilized with respect to the pitch and rollaxis but not with respect to the yaw axis they are stabilized with respect to the pitch roll and yaw axis they are stabilized with respect to the yaw axis but not with respect to the pitch and roll axis the pilot can choose the axes of stabilization with the system's stabilization selector switch

exemple 326 they are stabilized with respect to the pitch and rollaxis but not with respect to the yaw-axis.they are stabilized with respect to the pitch and rollaxis but not with respect to the yaw-axis.

Ils transmitters use the ?

Question 174-15 : Uhf and vhf bands vhf uhf and hf bands vhf band only uhf band only

Vor operating frequencies vhf..localiser vhf..marker beacon vhf....dme operating frequencies uhf..glide slope uhf..gnss/gps uhf..l1 and l2 frequencies used by navstar/gps uhf.... ils localiser and glide slope uhf and vhf bands...microwave landing system mls shf..airborne weather radars shf....locator lf/mf exemple 330 uhf and vhf bands.uhf and vhf bands.

The antennae of modern airborne weather radars are stabilized by means of ?

Question 174-16 : Inputs from the aircraft's attitude system artificial gravity switches mercury switches feedback from the antenna accelerometers

.automatic antenna stabilization as employed in today's weather avoidance radar systems consists of an electro mechanical means of maintaining a selected beam scan relative to the earth's horizon during moderate aircraft maneuvers to accomplish this a reference is established by the aircraft's vertical gyro usually a component of the autopilot or integrated flight control system exemple 334 inputs from the aircraft's attitude system.inputs from the aircraft's attitude system.

The type of modulation used for the ils frequency carrier is ?

Question 174-17 : Amplitude modulation frequency modulation phase modulation dual modulation

.amplitude modulation the information that is impressed onto the carrier wave by altering the amplitude of the carrier exemple 338 amplitude modulation.amplitude modulation.

The quadrantal error of an adf ?

Question 174-18 : Is caused by the refraction from the aircraft's fuselage and is compensated for is caused by aircraft magnetism and varies with the deviation as shown on the deviation table is caused by interference from the sky wave may be caused by the interference of vor's within range of the adf receiver and cannot be compensated for

.the quadrantal error is a distortion of the incoming signal from the ndb station by re radiation from the airframe this is corrected for during installation of the antenna exemple 342 is caused by the refraction from the aircraft's fuselage and is compensated for.is caused by the refraction from the aircraft's fuselage and is compensated for.

The skip distance of hf transmission will increase with ?

Question 174-19 : Higher frequency and higher position of the reflecting ionospheric layer lower frequency and higher position of the reflecting ionospheric layer higher frequency and lower position of the reflecting ionospheric layer lower frequency and lower position of the reflecting ionospheric layer

.skip distance the distance between the transmitter and the point on the surface of the earth where the first sky return arrives.it will increase for a higher frequency .it will increase for a higher position of the reflecting ionospheric layer exemple 346 higher frequency and higher position of the reflecting ionospheric layer.higher frequency and higher position of the reflecting ionospheric layer.

Which statement about the errors and effects on ndb radio signals is correct ?

Question 174-20 : The mountain effect is caused by reflections onto steep slopes of mountainous terrain which may cause big errors in the bearing night effect is a result of interference of the surface wave and the space wave causing a reduction in range lightning during atmospheric disturbances may cause a reduction of the signal strength that may result in only slight bearing errors shore line effects may cause a huge bearing error due to reflection of the radio signal onto steep coasts

.mountain effect mountain areas can cause reflections and to a lesser extent diffractions and lead to the error direction reading by adf .this effect similar to night effect is obtained in mountainous areas where the energy received from an ndb consists of two or more waves one of them direct and others by reflection from the mountains bearing indications are found to change rapidly until the affected area is passed.for information night effect radio waves take two paths to the radio compass receiver the first and normal path is along the earth's surface if only these waves were received the compass would point directly to the ndb the second path is via one or more wave refracting layers above the earth the ionosphere returning to earth to mix with direct waves complete changes in the nature of the waves take place on this path and produce errors in direction exemple 350 the mountain effect is caused by reflections onto steep slopes of mountainous terrain which may cause big errors in the bearing.the mountain effect is caused by reflections onto steep slopes of mountainous terrain which may cause big errors in the bearing.

What causes the so called night effect ?

Question 174-21 : A change in the direction of the plane of polarisation due to reflection in the ionosphere the difference in velocity of the em waves over land and over sea at night the absence of the surface wave at distances larger than the skip distance interference between the ground and the space wave

.'night effect' is the influence of sky waves and ground waves arriving at the adf receiver lead at a difference of phase and polarisation which introduce bearing errors at night.night effect predominates around dusk and dawn exemple 354 a change in the direction of the plane of polarisation due to reflection in the ionosphere.a change in the direction of the plane of polarisation due to reflection in the ionosphere.

Comparing a parabolic reflector with a flat plate antenna of the same size ?

Question 174-22 : The flat plate antenna generates less side lobes than the parabolic reflector the parabolic reflector generates less side lobes than the flat plate antenna the flat plate antenna has a considerably smaller beam width the parabolic reflector has a considerably smaller beam width

Parabolic reflector directional but with large loss of energy through side lobes.flat plate antenna directional with side lobe suppresion exemple 358 the flat plate antenna generates less side lobes than the parabolic reflector.the flat plate antenna generates less side lobes than the parabolic reflector.

An amplitude modulation is shown in the figure . 2069 ?

Question 174-23 : A b c d

exemple 362 a.a.

In his basic type a dipole antenna adapted for a frequency of 110 mhz will have ?

Question 174-24 : 136 cm 273 cm 91 cm 205 cm

.wavelength in meter = 300 / frequency in mhz .wavelength in meter = 300 / 110 = 2 72 m 272 cm.a dipole antenna is a wire of length equal to one half of the wavelength.272 cm / 2 = 136 cm exemple 366 136 cm.136 cm.

How is the unit 'hertz' hz defined ?

Question 174-25 : The number of electromagnetic oscillations per second duration of an oscillation the distance covered by a radio wave in one second the number of electromagnetic oscillations per minute

.frequency is the number of cycles occurring in one second in a radio wave expressed in hertz hz frequency is normally given in hertz hz where 1 hz = 1 cycle/second .a cycle is defined as a complete series of values of a periodical process . 2549 exemple 370 the number of electromagnetic oscillations per second.the number of electromagnetic oscillations per second.

An ndb transmits on 427 khz the corresponding wavelength is ?

Question 174-26 : 702 5 m 702 5 cm 7025 cm 70 25 cm

.frequency khz = speed of light / wavelength m.427 khz = 300000 / wavelength m.wavelength m = 300000 / 427 = 702 57 m exemple 374 702,5 m.702,5 m.

An electromagnetic wave consists of an oscillating electric field e and an ?

Question 174-27 : The speed of light the speed of sound for field e and the speed of light for field h the speed of light for field e and the speed of sound for field h the speed of sound

.propagation speed is the speed at which radio wave radiates through space .depending upon the electrical nature of the medium through which it travels the speed varies slightly we can assume a constant 'speed of light' value of 300 000 000 meters 162 000 nm per second exemple 378 the speed of light.the speed of light.

The electromagnetic waves refracted from the e and f layers of the ionosphere ?

Question 174-28 : Sky waves ground waves refracted waves space waves

exemple 382 sky waves.sky waves.

The simplest type of antenna construction is a ?

Question 174-29 : Dipole antenna which is a wire of length equal to one half of the wavelength parabolic antenna used in weather radars slotted antenna used in modern weather radars loop antenna used in old adf receivers

. 2550. dipole antenna exemple 386 dipole antenna which is a wire of length equal to one half of the wavelength.dipole antenna which is a wire of length equal to one half of the wavelength.

An electromagnetic wave consists of an oscillating electric field e and an ?

Question 174-30 : The e and h fields are perpendicular to each other a dipole antenna can only transmit field h the h field is parallel to the wire and field e is perpendicular to the wire when ac current pass through the antenna fields e and h are parallel

exemple 390 the (e) and (h) fields are perpendicular to each other.the (e) and (h) fields are perpendicular to each other.

The frequency which corresponds to a wavelength of 8 25 m is ?

Question 174-31 : 36 36 mhz 3636 mhz 363 6 mhz 3 63 mhz

.frequency mhz = 300 / wavelength m.frequency = 300 / 8 25 m..frequency = 36 36 mhz exemple 394 36.36 mhz36.36 mhz

The frequency which corresponds to a wavelength of 3 km is ?

Question 174-32 : 100 khz 10 khz 1000 khz 1 mhz

.frequency f in khz = 300000 / wavelength m .frequency f in khz = 300000 / 3000 m .frequency f in khz = 100 khz exemple 398 100 khz.100 khz.

Wavelength of frequency 117 95 mhz is ?

Question 174-33 : 2 5 m 25 m 250 m 254 m

.wavelength m = 300000 / frequency khz.wavelength m = 300 / frequency mhz.wavelength m = 300 / 117 95 = 2 54 m exemple 402 2.5 m.2.5 m.

Concerning the wave propagation in the ionosphere we denote three layers those ?

Question 174-34 : D e and f layers and their depth varies with time d e and f layers and their depth does not vary with time a b and c layers and their depth varies with time a c and e layers with equal depth

. 2551.the ionosphere is the ionized component of the earth's upper atmosphere from 60 to 400 km above the surface which is vertically structured in three regions or layers d e and f exemple 406 d, e and f layers and their depth varies with time.d, e and f layers and their depth varies with time.

Radio waves travel at ?

Question 174-35 : The speed of light the speed of sound a speed depending on the type of the electromagnetic waves a speed just below the speed of sound

exemple 410 the speed of light.the speed of light.

In accordance with the itu international telecommunication union a radio signal ?

Question 174-36 : Nature of information to be transmitted type of modulation of the main carrier nature of signal s modulating the main carrier type of modulation of the secondary carrier

.radio signal may be classified by three symbols in accordance with the itu . first symbol indicates the type of modulation of the main carrier . second symbol indicates the nature of the signal modulating the main carrier . third symbol indicates the nature of the information to be transmitted.for information only . you do not have to know that for the exam .a1a telegraphy on off keying without modulation by an audio frequency .a double sideband.1 single channel containing quantized or digital information without the use of a modulating sub carrier.a telegraphy for aural reception exemple 414 nature of information to be transmitted.nature of information to be transmitted.

In accordance with the itu international telecommunication union a radio signal ?

Question 174-37 : Nature of signal s modulating the main carrier type of information to be transmitted type of modulation of the secondary carrier type of modulation of the main carrier

.a radio signal may be classified by three symbols in accordance with the itu radio regulation volume 1 e g a1a . first symbol indicates the type of modulation of the main carrier . second symbol indicates the nature of the signal modulating the main carrier . third symbol indicates the nature of the information to be transmitted exemple 418 nature of signal(s) modulating the main carrier.nature of signal(s) modulating the main carrier.

In accordance with the itu international telecommunication union a radio signal ?

Question 174-38 : Type of modulation of the main carrier nature of signal s modulating the main carrier type of information to be transmitted type of modulation of the secondary carrier

.radio signal may be classified by three symbols in accordance with the itu . first symbol indicates the type of modulation of the main carrier . second symbol indicates the nature of the signal modulating the main carrier . third symbol indicates the nature of the information to be transmitted.for information only . you do not have to know that for the exam .a1a telegraphy on off keying without modulation by an audio frequency .a double sideband.1 single channel containing quantized or digital information without the use of a modulating sub carrier.a telegraphy for aural reception exemple 422 type of modulation of the main carrier.type of modulation of the main carrier.

Vhf very high frequency waves appear in the frequency spectrum ?

Question 174-39 : 30 mhz 300 mhz 3 mhz 30 mhz 300 mhz 3000 mhz 3 ghz 30 ghz

. 1682 exemple 426 30 mhz - 300 mhz30 mhz - 300 mhz

With regard to radio waves propagation a cycle is defined as ?

Question 174-40 : A complete series of values of a periodical process a number of oscillation per second the lenght of the pulse the distance covered by a radio wave in one second

.this is the official easa definition a cycle is any complete round or series of occurrences that repeats or is repeated . 2549 exemple 430 a complete series of values of a periodical process.a complete series of values of a periodical process.

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