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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
Frequency division multiplexing:Frequency slots::time division multiplexing:?(a) Time slots(b) Coded information(c) Pulsed information(d) Band slots |
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Answer» The correct option is (a) Time slots Explanation: In FDM, multiple signals are transmitted over a single channel, each signal being allocated a portion of the spectrum within that bandwidth. In time-division multiplexing (TDM), each signal occupies the entire bandwidth of the channel. However, each signal is transmitted for only a brief time. In other words, multiple signals take turns transmitting over the single channel. |
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| 252. |
What type of satellite TV service uses compressed data transmission to beam signals directly to every home?(a) Direct broadcast satellite(b) Mobile satellite service(c) Broadcasting satellite service(d) Fixed satellite service |
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Answer» The correct choice is (a) Direct broadcast satellite The best explanation: The direct broadcast satellite (DBS) system is an all-digital system. Data compression techniques are used to reduce the data rate in order to produce high-quality picture and sound. They uses special broad coverage satellites with high power to transmit cable-TV-like services direct to homes equipped with the special DBS receivers. |
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| 253. |
A cable TV service uses a single coaxial cable with a bandwidth of 860 MHz to transmit multiple TV signals to subscribers. Each TV signal is 6 MHz wide. How many channels can be carried?(a) 143(b) 123(c) 100(d) 150 |
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Answer» Correct answer is (a) 143 Easy explanation: Total channels = 860/6 = 143.33 or 143. |
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| 254. |
Which of the following is called as UHF connector?(a) PL-259(b) N-type connector(c) SMA(d) BNC |
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Answer» The correct choice is (a) PL-259 To elaborate: The PL-259 is also referred to as a UHF connector, can be used up to low UHF values (less than 500 MHz), although it is more widely used at HF and VHF. It can accommodate both large (up to 0.5-in) and small (0.25-in) coaxial cable. |
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| 255. |
Which type of coaxial cable connector is the least expensive?(a) PL-259(b) F-type connector(c) SMA(d) BNC |
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Answer» Right answer is (b) F-type connector To explain I would say: The least expensive coaxial cable connector is the F-type connector, which is widely used for TV sets, VCRs, DVD players, and cable TV. The cable plug and its matching chassis jack are shown in Fig. 13-6. The shield of the coaxial cable is crimped to the connector, and the solid wire center conductor of the cable, rather than a separate pin, is used as the connection. A hex-shaped outer ring is threaded to attach the plug to the mating jack. |
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| 256. |
Which of the following is not a type of coaxial cable connector?(a) PL-259(b) Banana pin connector(c) SMA(d) BNC |
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Answer» Right option is (b) Banana pin connector Explanation: The most common types of coaxial cable connectors are the PL-259 or UHF, BNC, F, SMA, and N-type connectors. Banana pin connectors are used in power cables. |
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| 257. |
What is used between the two lead wires of a parallel transmission line?(a) Plastic(b) Ceramic(c) Metal(d) Wood |
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Answer» The correct option is (a) Plastic The best explanation: A parallel transmission line is a two-wire balanced line in which insulating spacers have been used to keep the wires separated. Such lines are rarely used today. The spacing between the wires is maintained by a continuous plastic insulator. |
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| 258. |
What is the phase difference between the current flowing in the two wires of a balanced line?(a) 100°(b) 180°(c) 150°(d) 90° |
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Answer» The correct option is (b) 180° Explanation: In a balanced line, the same current flows in each wire with respect to ground, although the direction of current in one wire is 180° out of phase with the current in the other wire. |
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| 259. |
For what purpose was twisted pair cable first used?(a) AM(b) Telephone(c) Wi-Fi(d) Digital data transmission |
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Answer» Correct option is (b) Telephone The explanation is: Twisted-pair cable uses two insulated solid copper wires covered with insulation and loosely twisted together. This type of cable was first used in telephone wiring and is still used for that today. But it is also used for security system wiring of sensors and other equipment. |
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| 260. |
What is the transmission line in which a flat conductor is sandwiched between two ground planes?(a) Microstrip(b) Stripline(c) Coaxial line(d) Balanced line |
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Answer» Correct option is (b) Stripline Explanation: Stripline is a conductor sandwiched between two ground planes. It is more difficult to make than microstrip; however, it does not radiate as microstrip does. |
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| 261. |
A microstrip transmission line is to be used as a capacitor of 4 pF at 800 MHz. The PCB dielectric is 3.6. The microstrip dimensions are h = 0.0625 in, w = 0.13 in, and t = 0.002 in. What is the characteristic impedance of the line?(a) 48.9Ω(b) 12.3Ω(c) 54.3Ω(d) 65.7Ω |
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Answer» Right answer is (a) 48.9Ω Easy explanation: Characteristic impedance of the line = . |
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| 262. |
How are GLONASS satellites differentiated from each other?(a) FDMA(b) CDMA(c) TDM(d) WDM |
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Answer» Right answer is (a) FDMA To elaborate: GLONASS satellites are distinguished and differentiated by radio frequency channel rather than spread spectrum code as in GPS. They use FDMA whereas GPS uses CDMA. |
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| 263. |
What type of modulation is used in L1 Signal of the GPS?(a) Amplitude modulation(b) Phase modulation(c) Frequency shift keying(d) Binary phase shift keying |
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Answer» Correct answer is (d) Binary phase shift keying For explanation: The L1 consists of two components: a precise and a coarse PRN code. The PRN codes and data are modulated onto the carriers using binary phase shift keying. |
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| 264. |
How does troposphere affect the satellite signals?(a) Reduces velocity(b) Reflects the signals(c) Refracts the signal(d) Bit inversion occurs |
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Answer» The correct option is (a) Reduces velocity Explanation: The major sources of errors are when the signal pass through the atmosphere. The troposphere causes the propagation velocity of the signal to be slowed, compressing the signal wavelength. |
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| 265. |
Which of the following position services provided by the GPS require crypto keys?(a) Precise position service(b) Standard position service(c) Ultimate position service(d) Doppler position service |
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Answer» The correct choice is (a) Precise position service To explain I would say: GPS provides two position services, The precise position service and the standard position service. The PPS can be denied to unauthorized users while SPS is free to everyone. Users need crypto keys to access the PPS. These are generally military users. |
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| 266. |
In a current carrying conductor, what happens to the magnetic field produced if the supplied voltage is increased and current is maintained constant?(a) Field strength increases(b) Field radius increases(c) Filed strength decreases(d) Does not change |
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Answer» Right choice is (d) Does not change The explanation: The magnetic field produced by a current carrying conductor is only influenced by the current and not the voltage. Since the current is maintained constant, there is no change in the magnetic field strength or radius. |
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| 267. |
What happens to the electric field between two conductors when the permeability of the material between the plates is increased?(a) Field strength increases(b) Field radius decreases(c) Field strength decreases(d) Nothing happens |
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Answer» The correct answer is (d) Nothing happens To explain I would say: The permeability of a material only affects the magnetic field and not the electric field. Electric field depends upon permittivity of the material between the two conductors. |
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| 268. |
What happens to the satellite signals as the density of the ionosphere is high?(a) Velocity increases(b) Velocity decreases(c) Signal strength increases(d) Frequency reduces |
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Answer» Right option is (a) Velocity increases Best explanation: The velocity of the carrier, the pure sinusoidal wave, is increased in the presence of electrons. Thus the greater the density of electrons in the ionosphere greater the velocity of the signal. |
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| 269. |
Which of the following ensures standardization of ATM services worldwide?(a) FAA(b) ICAO(c) IAO(d) DGCA |
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Answer» Correct option is (b) ICAO For explanation: Standardization of the air traffic management practices internationally is the responsibility of the International Civil Aviation Organization or IACO, which is affiliated with the United Nations and located in Montreal, Quebec, Canada. |
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| 270. |
Which of the following is not true?(a) A conductor carrying alternating current radiates(b) A transmission line must not radiate energy(c) Antennas are transmission lines which are made to radiate energy(d) A parallel wire transmission, when left open, does not radiate |
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Answer» The correct answer is (d) A parallel wire transmission, when left open, does not radiate For explanation I would say: If a parallel-wire transmission line is left open, the electric and magnetic fields escape from the end of the line and radiate into space. This radiation, however, is inefficient and unsuitable for reliable transmission or reception. |
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| 271. |
TEC in the ionosphere is a function of solar radiation.(a) True(b) FalseThe question was posed to me in my homework.I need to ask this question from Atmospheric Effects on Satellite Signals in chapter Satellite Radio Navigation & Inertial Navigation of Avionics |
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Answer» Correct choice is (a) True The best explanation: TEC or the total electron content in the ionosphere is a function of solar radiation. As more radiation falls on Earth, more number of molecules are ionized and hence TEC is more in the daytime than at the night. |
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| 272. |
Where is the localizer antenna placed?(a) Beyond the stop end of the runway(b) Start of the runway(c) Along the runway(d) Air traffic control |
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Answer» Right choice is (a) Beyond the stop end of the runway Best explanation: The localizer antenna is centered on the runway beyond the stop end to provide lateral guidance. The glide slope is located beside the runway near the threshold to provide vertical guidance. |
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| 273. |
The Far field is also known as ______________(a) Fresnel zone(b) Fraunhofer zone(c) Maxwell zone(d) Marconi zone |
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Answer» Correct choice is (b) Fraunhofer zone Best explanation: The far field is also called the Fraunhofer zone. It is named after the Bavarian physicist Joseph Ritter von Fraunhofer. |
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| 274. |
The radiation from an open line can be increased by bending to which of the following angle?(a) 0°(b) 180°(c) 90°(d) 53.76° |
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Answer» Right answer is (c) 90° The best I can explain: The radiation from a transmission line can be greatly improved by bending the transmission line conductors so that they are at a right angle to the transmission line. The magnetic fields no longer cancel and, in fact, aid one another. The electric field spreads out from conductor to conductor. The result is an antenna. |
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| 275. |
The aircraft whose attitude reference is solely based on the natural horizon follow ______(a) VFR(b) IFR(c) Pilot(d) FAA commands |
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Answer» The correct option is (a) VFR The best explanation: VFR flights usually involve small aircraft operated for personal or business purposes. Navigation may be by visual reference to the ground and aircraft attitude control may be based solely on the natural horizon visible through the windscreen of the aircraft. |
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| 276. |
What type of antenna is used in the localizer?(a) Long periodic antenna(b) Helical antenna(c) Dipole antenna(d) Parabolic antenna |
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Answer» The correct answer is (a) Long periodic antenna Easy explanation: Almost all of the localizer antenna is long periodic antenna. It provides unidirectional radiation, can be installed without guy cables and has good broadband characteristics. |
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| 277. |
What is the ratio of the electric field strength of a radiated wave to the magnetic field strength called?(a) Impedance of space(b) Dielectric constant(c) Permittivity(d) Permeability |
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Answer» Correct option is (a) Impedance of space Easiest explanation: The ratio of the electric field strength of a radiated wave to the magnetic field strength is a constant. It is called the impedance of space, or the wave impedance. |
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| 278. |
Who is responsible for the separation of an aircraft from other aircraft in a controlled airspace?(a) ATM operator(b) Pilot(c) Co-pilot(d) Navigator |
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Answer» Right choice is (a) ATM operator For explanation I would say: In controlled airspace, the crew must operate in accordance with instructions received from ATM authorities, and these authorities are responsible for separating the aircraft from all other IFR aircraft. |
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| 279. |
What is the rate of descent when the flare maneuver is executed?(a) 6 ft/sec(b) 12ft/sec(c) 20ft/sec(d) 3ft/sec |
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Answer» The correct choice is (d) 3ft/sec The best I can explain: Land based aircraft are not designed to touch down at the 6 to 16ft/sec sink rate that exists along the glide path. Thus, a flare maneuver must be executed to reduce the descent rate to less than 3ft/sec at touchdown. |
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| 280. |
What is done to reduce the error in localizer as the runway is approached?(a) Gain scheduling(b) Reduce speed(c) Increase angle of attack(d) Flare |
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Answer» Right option is (a) Gain scheduling To explain: The localizer gain must be scheduled to decrease as the runway is approached because the surfaces of constant DDM coverage to make the error signal more sensitive to distant displacement. |
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| 281. |
What is the power radiated by the antenna with gain called as?(a) Critical power(b) Transverse power(c) Effective radiated power(d) Transmitted power |
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Answer» The correct option is (c) Effective radiated power The explanation is: The power radiated by an antenna with directivity and therefore gain is called the effective radiated power (ERP). The ERP is calculated by multiplying the transmitter power fed to the antenna Pt by the power gain Ap of the antenna. |
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| 282. |
What is the minimum visibility when flying below 10,000ft and following VFR?(a) One nautical mile(b) One kilometer(c) One statute mile(d) One mile |
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Answer» Correct answer is (c) One statute mile Explanation: VFR operators below 10,000ft MSL must have a minimum visibility of one statute mile. VFR operators are not required to contact ATM in the controlled or uncontrolled airspace. |
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| 283. |
What frequency does the marker beacon use for fixes along the airways?(a) 50MHz(b) 25MHz(c) 500MHz(d) 75MHz |
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Answer» The correct answer is (d) 75MHz The best I can explain: Marker beacons were developed for better fixes along the airways in addition to directional information. They operate at 75MHz and radiate a narrow pattern upward from the ground. |
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| 284. |
A dipole antenna is also called as?(a) Marconi antenna(b) Yagi antenna(c) Bidirectional antenna(d) Hertz antenna |
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Answer» The correct answer is (d) Hertz antenna The explanation is: One of the most widely used antenna types is the half-wave dipole antenna. This antenna is also formally known as the Hertz antenna after Heinrich Hertz, who first demonstrated the existence of electromagnetic waves. |
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| 285. |
Which are the factors that mach number does not depend on?(a) Static pressure(b) Stagnation pressure(c) Static temperature(d) Thrust produced by the aircraft |
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Answer» The correct answer is (d) Thrust produced by the aircraft Easy explanation: The mach number is computed from the corrected values of static and stagnation pressures. Mach number is comparatively easier to calculate than airspeed in supersonic speeds due to the compression shocks that form in the pitot tube. |
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| 286. |
What does the beam width of an antenna tell us?(a) Signal strength(b) Signal power(c) Directivity(d) Degradation |
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Answer» Right option is (c) Directivity The explanation is: The measure of an antenna’s directivity is beam width, the angle of the radiation pattern over which a transmitter’s energy is directed or received. Beam width is measured on an antenna’s radiation pattern. |
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| 287. |
What altitude does FL540 correspond to?(a) 54,000ft(b) 5.4 ft(c) 54 ft(d) 5400 ft |
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Answer» The correct answer is (a) 54,000ft Best explanation: Pressure altitudes are expressed as flight levels on hundreds of feet using three digits. Hence, FL540 represents a pressure altitude of 54,000 ft. |
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| 288. |
What is the wheel height where flare command is initiated?(a) 75ft(b) 100ft(c) 25ft(d) 5ft |
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Answer» Right option is (a) 75ft To elaborate: The flare command is initiated at a wheel height of about 75ft, well before the runway threshold. However, the radar altimeter may not be used prior to threshold due to uneven terrain or tidal variations. |
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| 289. |
Which of the following can be used to reinforce the upward beam in a marker beacon?(a) Reflector(b) Amplifier(c) Counterpoise(d) Vertical polarization |
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Answer» Right choice is (c) Counterpoise For explanation I would say: The marker beacons use an array of half wave radiators that are aligned in line with the airway. A wire mesh counterpoise below this array can be used to reinforce the upward beam by increasing the signal strength in a particular direction. |
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| 290. |
The area of reduced signal strength in a non directional beacon is called as ______(a) Cone of silence(b) Zero reception zone(c) Zone of silence(d) Non radio zone |
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Answer» Right option is (a) Cone of silence Explanation: The NDB works on an omnidirectional antenna which has the radio pattern of a donut. The zone on the middle which is directly above the antenna is called as the cone of silence. In this region, no signal is transmitted. |
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| 291. |
What is the frequency of rotation of the directional beam in a VOR?(a) 20rps(b) 15rps(c) 30rps(d) 50rps |
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Answer» Correct choice is (c) 30rps The explanation: The VOR sends out two signals. One is a highly directional signal that rotates at a frequency of 30 rps and an omnidirectional signal. The omnidirectional signal is pulsed every time the directional signal coincides with north. |
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| 292. |
What is the range of typical weather radar?(a) 500 nmi(b) 50 nmi(c) 5 nmi(d) 200 nmi |
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Answer» The correct choice is (d) 200 nmi Easiest explanation: The use of airborne weather radar is one method of storm avoidance. A weather radar system can show centers at a distance of up to 200 nmi. |
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| 293. |
Why are retractable pitot tubes used in stealth planes?(a) Aerodynamically efficient(b) Stealth configuration(c) Error values in supersonic speeds(d) Use GPS for speed and altitude |
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Answer» The correct option is (b) Stealth configuration For explanation I would say: Stealth planes, such as the B2 spirit stealth bomber, use retractable pitot tubes to maintain their stealth. When not in stealth mode they extend the probes for air data measurements. |
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| 294. |
What is the height called when the standard temperatures are used?(a) Standard altitude(b) Constant altitude(c) Pressure altitude(d) Total altitude |
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Answer» Correct answer is (c) Pressure altitude The best explanation: The altitude at which the standard temperatures are used is called the pressure altitude. Pressure altitude is the altitude of the aircraft above sea level. It always takes it’s reference as sea level. |
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| 295. |
What does the altitude rate essentially tell us?(a) Vertical speed(b) Rate of climb(c) Rate of glide(d) Rate of decent |
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Answer» Correct choice is (a) Vertical speed For explanation: Air data computers usually provide an output identified as altitude rate which is an outgrowth of the early pneumatic vertical speed indicators which suffer from undesirable lags. Altitude rate combines accelerometer readings and pneumatic readings. |
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| 296. |
Why are pulse pairs used in DME instead of single pulses?(a) Reduce interference(b) Better range(c) Reduced noise(d) Redundancy |
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Answer» Right option is (a) Reduce interference Easy explanation: Pulse systems can easily interfere with each other even if they are of different frequencies. Paired pulses are used in DME to reduce interference with other pulsed systems. |
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| 297. |
The recovery factor for computing the static temperature does not account for _____(a) Friction heating(b) Re-radiation(c) Nonisentropic compression(d) Isentropic compression |
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Answer» The correct answer is (d) Isentropic compression The explanation is: The recovery factor of the probe corrects the original measured temperature readings for frictional heating in the skin, re-radiation from the aircraft to the flow, and nonisentropic compression of air. It is given by η and is measured empirically. |
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| 298. |
Which of the following generates the same field pattern as a vertical dipole antenna?(a) Yagi antenna(b) Helix antenna(c) Alford loop(d) Microstrip antenna |
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Answer» Right option is (c) Alford loop Explanation: Each radiator in the ground station transmitter is an Alford loop. The Alford loop generates a horizontal polarized signal having the same field pattern as a vertical dipole. |
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| 299. |
What is the difference between the static pressure and the stagnation pressure when the aircraft is stationary?(a) Infinite(b) Any random value(c) No difference(d) Static pressure |
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Answer» Correct option is (d) Static pressure To elaborate: when the aircraft is stationary, the pressure sensed by the static port is the free stream air pressure and the stagnation pressure ports are zero. Since the aircraft is not moving stagnation pressure is zero and hence the difference between the two values is the static pressure. |
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| 300. |
How well a target backscatters radar depends on ________(a) The objects RCS(b) Power of radar(c) Speed of the object(d) Heat signature of the object |
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Answer» Correct answer is (a) The objects RCS The best explanation: When radar pulse strikes the aircraft some radio pass through the object whereas some get reflected back. The amount of radio energy that gets reflected back depends upon the Radar cross section of the aircraft. RCS depends on size, material on the surface of the aircraft and many more parameters. |
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