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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.
| 301. |
Which of the following cannot be measured in primary radar?(a) Height of the aircraft(b) Speed of the aircraft(c) Direction of the aircraft(d) Position of the aircraft |
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Answer» Correct option is (a) Height of the aircraft Explanation: One of the major disadvantages of the primary radar is that it cannot provide a three dimensional fix, that is position and altitude. They are radars that can find the height of the aircraft but can only be used for short distances. |
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| 302. |
What are the numbers of non-selective interrogations in mode S system?(a) 5(b) 6(c) 7(d) 8 |
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Answer» Correct option is (b) 6 Explanation: Mode S interrogations are divided into two types: selective and non-selective. The non-selective are the simplest and include familiar techniques. There is a total of 6 non-selective interrogations. |
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| 303. |
Which of the following altitude is measured by the pitot-static tube?(a) Standard altitude(b) Constant altitude(c) Pressure altitude(d) Total altitude |
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Answer» Correct answer is (c) Pressure altitude To elaborate: Pressure altitude, as the name suggests, is the altitude derived from pressure measurements. It is measured from the static port of the pitot-static probe. The static pressure of air varies with altitude with approximately 101Kpa at sea level. |
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| 304. |
What is required to accommodate for the ground effect in swiveling pitot tube below rotor system?(a) Secondary radar(b) Doppler(c) GPS(d) Radio altimeter |
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Answer» The correct option is (d) Radio altimeter Explanation: The principle of the probe is that the horizontal component of the induced flow velocity is a repeatable function of horizontal airspeed but varies with ground proximity. Hence, a radar altimeter is required to accommodate the ground effect. |
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| 305. |
Which is the optimum place for a temperature probe?(a) Landing gear(b) Inside cockpit(c) Exit of engine(d) Tip of vertical tail |
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Answer» Correct choice is (d) Tip of vertical tail For explanation: Probes may be mounted on the wing tips, vertical tail, forward fuselage or other areas where the local mach number is the same as the free stream mach number for all expected flight altitudes and speeds. |
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| 306. |
What is the time gap between each pulse in an interrogation pulse pair for a DME?(a) 12μsec(b) 5μsec(c) 15μsec(d) 10μsec |
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Answer» Right answer is (a) 12μsec Easy explanation: The interrogation pulses are in pairs. Each pulse is placed 12μsec apart with each pulse lasting 3.5μsec. The pulse pair repetition rate ranges between 5 pulse pairs per sec to a maximum of 150 pulse pairs per sec. |
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| 307. |
Which mode is used for selective calling?(a) Mode A(b) Mode B(c) Mode C(d) Mode S |
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Answer» The correct option is (d) Mode S Best explanation: Different modes have its own unique features; mode A gives only identity, mode c gives identity and altitude, mode B is used in European operations and mode S is used for selective calling of transponders. |
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| 308. |
What type of radar is the primary radar?(a) Pulse(b) Continuous wave(c) Low frequency(d) Analog |
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Answer» The correct choice is (a) Pulse To explain: The primary radar uses pulse techniques. It sends out short bursts of pulse and the aircraft surface reflects the radio energy back to the radar antenna. It is possible to measure the elapsed time and determine the range or distance of the aircraft. |
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| 309. |
Which of the following instruments use the pitot-static probe for its input?(a) Airspeed indicator(b) Altitude indicator(c) Vertical speed indicator(d) Attitude indicator |
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Answer» The correct choice is (d) Attitude indicator For explanation: The instruments that use pitot-static probe are airspeed indicator, altitude indicator or the altimeter and the vertical speed indicator. The attitude indicator uses the gyro to measure the orientation of the aircraft. |
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| 310. |
What is the temperature measured by a probe on the exterior of a moving aircraft?(a) Static temperature(b) Stagnation temperature(c) Free stream temperature(d) Constant temperature |
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Answer» Correct option is (b) Stagnation temperature Best explanation: The temperature measured by the temperature probe on the exterior of a moving aircraft is called the stagnation temperature. It is always higher than the static temperature due to the heating effects of compressing air at higher speeds. |
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| 311. |
What is the frequency of interrogation pulse in secondary radar?(a) 1020 MHz(b) 1300 MHz(c) 1030 MHz(d) 1500 MHz |
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Answer» Right option is (c) 1030 MHz Explanation: The interrogation pulse is transmitted at 1030 MHz and the reply pulse by the aircraft transponder is given at 1090 MHz. Since the reply is coded information, it does not interfere with other transponders that are using the same frequency. |
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| 312. |
Which mode of the secondary radar gives only altitude?(a) Mode A(b) Mode B(c) Mode C(d) Mode S |
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Answer» The correct choice is (a) Mode A The explanation: There are two types of interrogations in the ATCRBS: mode A and mode C. Mode A provides identity only and mode C provides identity and altitude of the aircraft. |
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| 313. |
What is the time separation for P1 and P3 for mode A secondary radar?(a) 8 μs(b) 21 μs(c) 6 μs(d) 4 μs |
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Answer» Right choice is (a) 8 μs Easy explanation: The time delay between P1 and P3 determines the type of interrogation. When the Time lag is 8μs, it corresponds to mode A whereas a separation of 21 μs corresponds to mode C. |
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| 314. |
What is the reflected pulse in primary radar called?(a) Reply(b) Return(c) Echo(d) Radio reply |
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Answer» Right answer is (c) Echo Explanation: The reflected or backscattered radio energy that reaches the radar antenna is called an echo. In secondary radar it is called a reply since the transponder replies for the interrogation signal. |
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| 315. |
What is the temperature of the air surrounding the aircraft called as?(a) Stagnation temperature(b) Static temperature(c) Total temperature(d) Overall temperature |
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Answer» Right choice is (b) Static temperature The best explanation: The outside air temperature is also called the static air temperature and is necessary for computing various parameters such as true airspeed, air density and for fire control aiming solutions. |
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| 316. |
What does Omega and Decca have in common?(a) Both measure the phase difference(b) Both measure the time difference(c) Both measure the power difference(d) Both operate in the same frequency range |
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Answer» Correct answer is (a) Both measure the phase difference The explanation: Omega and Decca measure the phase differences between the signals transmitted from pairs of stations while the Loran-C and Chayka measure the time difference between the signal from two or more transmitting stations. |
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| 317. |
The period of time that elapses between the successive passes of the satellite over a given meridian of earth longitude is called as _____________(a) synodic period(b) Lapsed time(c) Time period(d) Sidereal period |
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Answer» Correct answer is (a) synodic period Explanation: Another method of expressing the time for one orbit is the revolution or synodic period. One revolution (1 r) is the period of time that elapses between the successive passes of the satellite over a given meridian of earth longitude. Naturally, the synodic and sidereal periods differ from each other because of the earth’s rotation. |
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| 318. |
Why is there a huge spectrum space between the transmitted and received signal in satellite communication?(a) Reduce interference(b) Maximum efficiency(c) Less attenuation(d) To reduce space occupied by filters |
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Answer» Correct option is (a) Reduce interference For explanation I would say: Because of the close proximity of the transmitter and the receiver in the satellite, the high transmitter output power for the downlink is picked up by that satellite receiver. Naturally, the uplink signal is totally obliterated. Furthermore, the transmitter output fed back into the receiver input causes oscillation. To avoid this problem, the receiver and transmitter in the satellite transponder are designed to operate at separate frequencies. In this way, they will not interfere with each other. |
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| 319. |
What type of transmitter is used in a Decca system?(a) Frequency synthesizer(b) Local oscillator(c) Crystal controlled(d) Digital |
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Answer» The correct answer is (c) Crystal controlled To explain I would say: A typical Decca chain consists of a master station and three slave stations. A station has a 2kW crystal controlled transmitter feeding a 300ft antenna. |
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| 320. |
The time period taken by the satellite to complete one orbit is called ________(a) Lapsed time(b) Time period(c) Sidereal period(d) Unit frequency |
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Answer» Right option is (c) Sidereal period The best I can explain: The period is the time it takes for a satellite to complete one orbit. It is also called the sidereal period. A sidereal orbit uses some external fixed or apparently motionless object such as the sun or star for reference in determining a sidereal period. |
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| 321. |
To use a satellite for communication relay or repeater purposes what type of orbit will be the best?(a) Circular orbit(b) Elliptical orbit(c) Geosynchronous orbit(d) Triangular orbit |
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Answer» The correct choice is (c) Geosynchronous orbit Best explanation: The best solution is to launch a synchronous or geostationary satellite. In a geosynchronous earth orbit. Since the satellite remains apparently fixed, no special earth station tracking antennas are required. The antenna is simply pointed at the satellite and remains in a fixed position. With this arrangement, continuous communication is possible. |
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| 322. |
What is the number of independent constants required to specify the nominal orbit?(a) 6(b) 5(c) 2(d) 7 |
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Answer» Right choice is (a) 6 The best explanation: Six independent constants are needed to specify the nominal orbit. These can be the three components of position and velocity at any instant of time and are used in the orbital mechanics equations. |
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| 323. |
Which of the following is the most fundamental for satellite navigation?(a) Power source in satellite(b) Position and acceleration of satellite(c) Distance from the Earth(d) Total number of satellites in the sky |
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Answer» Correct choice is (b) Position and acceleration of satellite The best I can explain: All of the satellite navigation equations have either satellite position or velocity as a variable. The linear independence of the equations, which dictate the observability of the navigation solution, is a function of the relative position of the satellites in orbit. Thus the position and the velocity of satellites is of primary importance. |
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| 324. |
The line connecting the perigee and apogee is called as?(a) Differential line(b) Line of apsides(c) Line of maximum reception(d) Overhead line |
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Answer» Right answer is (b) Line of apsides The explanation is: The points where the satellite is closest and farthest from the Earth is called the perigee and apogee respectively. The line connecting the apogee and the perigee is called the line of apsides. |
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| 325. |
When is the speed of the satellite maximum in an elliptical orbit?(a) Retrograde(b) Posigrade(c) Perigee(d) Apogee |
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Answer» Right choice is (c) Perigee The explanation is: In an elliptical orbit, the speed changes depending upon the height of the satellite above the earth. Naturally, the speed of the satellite is greater when it is close to the earth than when it is far away. The closest point is called the perigee. |
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| 326. |
The clocks are important in satellite navigation as they are potential sources of error.(a) True(b) FalseThis question was posed to me in a job interview.The question is from Orbital Mechanics and Clock Characteristics topic in division Satellite Radio Navigation & Inertial Navigation of Avionics |
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Answer» Correct option is (a) True To elaborate: The navigational messages from a satellite include parameters describing the satellite’s clock offset and drift, which are predicted by the control segment. Any instability in the satellite’s clock causes this prediction to be in error, thus resulting in range and range rate errors in the user’s navigation solution. |
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| 327. |
Which of the following is not one of the perturbations that make the satellite to vary from its elliptical path?(a) Solar activity(b) Asymmetrical components of Earth’s gravitational field(c) Air drag(d) Motion of a passing comet |
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Answer» Correct answer is (d) Motion of a passing comet The explanation is: Perturbations cause the orbital plane to oscillate and rotate and vary the satellite from its elliptical orbital path. These forces include spherical asymmetrical components of Earth’s gravitational field, Lunisolar perturbations, air drag, magnetic and static electric forces. |
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| 328. |
In an approach, the transition flight path is defined by __________(a) GPS(b) Celestial fix(c) Initial and final approach fix(d) ILS |
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Answer» Correct answer is (c) Initial and final approach fix The best I can explain: Approach altitudes are measured barometrically and the transition flight path is defined by initial and final approach fixes using Tacan and marker beacons. Radar vectors can also be used at times. |
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| 329. |
Aircraft executing missed approach from low altitude is called as ____________(a) Bolter(b) Faultie(c) Ranger(d) Dropper |
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Answer» Correct choice is (a) Bolter To elaborate: An aircraft executing a missed approach from low altitude is called a bolter. Bolters fly to a Tacan- defined holding point that moves with the aircraft carrier. |
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| 330. |
What instrument is used to measure the aircraft’s altitude during the approach phase?(a) Pressure altimeter(b) Radio altimeter(c) Sound altimeter(d) Infrared altimeter |
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Answer» Correct option is (b) Radio altimeter The best I can explain: A radio altimeter can accurately measure the altitude of an aircraft and works on the radar principle. Typically, radio altimeters provide accurate altitude measurements till 5000ft and are used only during takeoff and landing. |
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| 331. |
What is used as a surrounding for the solid center core in a coaxial cable?(a) Plastic dielectric(b) Ceramic(c) Metal(d) Wood |
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Answer» The correct choice is (a) Plastic dielectric Explanation: The coaxial cable consists of a solid center conductor surrounded by a dielectric material, usually a plastic insulator such as Teflon. Outside the insulation, there is a second conductor made of fine wires. |
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| 332. |
The velocity factor of a coaxial cable is typically 0.8. What is the speed of transmission?(a) 0.8 x 10^8 m/s(b) 2.4 x 10^8 m/s(c) 1.7 x 10^8 m/s(d) 0.2 x 10^8 m/s |
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Answer» Right option is (b) 2.4 x 10^8 m/s The explanation is: Velocity of transmission = Velocity factor x Velocity in free space = 0.8 x (3 x 10^8) = 2.4 x 10^8 m/s. |
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| 333. |
Which is the best type of coaxial cable connector in terms of performance?(a) PL-259(b) N-type connector(c) SMA(d) BNC |
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Answer» The correct option is (b) N-type connector To explain I would say: The best-performing coaxial connector is the N-type connector, which is used mainly on large coaxial cable at the higher frequencies, both UHF and microwave. N-type connectors are complex and expensive, but do a better job than other connectors in maintaining the electrical characteristics of the cable through the interconnections. |
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| 334. |
Which of the following uses lens and mirrors for focusing?(a) Refractive(b) Reflecting(c) Catadioptric(d) Orthogonal |
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Answer» Correct answer is (c) Catadioptric Explanation: Telescopes are of three types: refractive, which uses lenses as their primary focusing elements, reflective, which uses a curved mirror for focusing, and catadioptric, which mix mirror and lens systems. |
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| 335. |
Why can we not use sky waves for navigation?(a) Low power(b) More noise(c) Unpredictable path(d) Not economical |
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Answer» Right answer is (c) Unpredictable path The best I can explain: The sky waves makes some types of long range communication possible, but is of less value to navigation system because it’s transmission path is unpredictable. A rough location where the sky waves might get reflected can be determined by Snell’s law. |
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| 336. |
The sky background power does not depend on _______(a) Effective entrance area to the telescope(b) Field of view of the telescope(c) Background radiance(d) Intensity of observing star |
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Answer» The correct answer is (d) Intensity of observing star Easiest explanation: The power from the sky background at the focal plane of a telescope depends on the background radiance, the effective entrance area, and the field of view of the telescope. |
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| 337. |
The star signal power does not depend on _____________(a) Spectral irradiance of stellar light(b) Spectral response of the light detector(c) Brightness of the star(d) Size of the star |
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Answer» Right answer is (d) Size of the star The explanation is: Star signal power is the effective area of the telescope times the irradiance of the star. It depends on the spectral irradiance of the stellar light, the spectral response of the light detector, and the brightness of the star. |
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| 338. |
Which of the following are present in an ESA?(a) Gimbals(b) Electronic motors(c) Phase shifter(d) Potentiometer |
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Answer» Right answer is (c) Phase shifter Explanation: The ESA has no mechanical moving parts, such as antenna gimbals, potentiometers, rotary joints, or hydraulic/electronic motors. It uses phase shifters to electronically steer the beam. |
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| 339. |
Which of the following determines the direction of the antenna beam in ESA?(a) Physical direction of antenna(b) Direction of aircraft nose(c) Slope of the phase taper(d) Mechanical gimbal |
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Answer» The correct choice is (c) Slope of the phase taper The best I can explain: The ESA controls the beam by phase shifters. The slope of the phase taper determines the direction in which the antenna beam will be pointed. |
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| 340. |
How is the radar beam moved in the ESA?(a) Phase shift(b) Mechanical gimbal(c) Mechanical servos(d) Hydraulics |
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Answer» The correct answer is (a) Phase shift Explanation: In ESA, the antenna’s beam is moved electronically by setting the phase angles of phase shifters located at each radiating element to provide a linear phase taper across the array surface. |
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| 341. |
Which of the following does not come under air data computer?(a) Pressure ports(b) Pressure transducers(c) Computer(d) Output drivers for interfacing |
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Answer» The correct option is (a) Pressure ports Explanation: A typical central air data computer is a box containing: the pressure transducers, associated excitation circuitry, and signal conditioning circuitry, the computer, and the output drivers that are compatible with interfacing subsystems. |
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| 342. |
Which part of the transmitter subsystem modulates the baseband signal?(a) Antenna(b) Up converter(c) Power amplifiers(d) Mixer |
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Answer» The correct option is (b) Up converter To elaborate: The transmit subsystem consists of two basic parts, the up converters and the power amplifiers. The up converters translate the baseband signals modulated on to carriers up to the final uplink microwave frequencies. |
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| 343. |
Both AESA and PESA are ________ radars?(a) Pulse(b) Continuous wave(c) Low frequency(d) Analog |
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Answer» The correct option is (a) Pulse To explain I would say: Both AESA and PESA that are currently in use are pulse radars. Its basic principle is that shorts bursts of radio pulse are emitted which reflect off a target and the reflected pulse gives the information about the object. |
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| 344. |
The ESA radar beam can be repositioned in a few _______(a) Microseconds(b) Nanoseconds(c) Milliseconds(d) Seconds |
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Answer» The correct answer is (a) Microseconds The best I can explain: Since the antenna’s phase shifter settings can be changed in a few microseconds, an ESA’s beam can be repositioned almost instantly. |
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| 345. |
The time between the collision of two aircraft on a collision course is called _____(a) Differential time(b) Tau(c) Traffic time(d) Collision time |
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Answer» Right answer is (b) Tau To explain: Tau is the range of the other aircraft with respect to an aircraft divided by range rate. Range divided by range rate is time-essentially the time that would elapse before a collision. |
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| 346. |
Which of the following is not one of the basic components of the MLS system?(a) Azimuth ground station(b) Elevation ground station(c) DME(d) Radar |
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Answer» Correct option is (d) Radar The explanation: A basic MLS consists of azimuth and elevation ground stations and a conventional DME for 3D positioning on approach course to 40° on either side of center line and to 15° elevation above the runway. |
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| 347. |
What is the region in which Omega signals are confined according to VLF wave guide model known as?(a) Earth-Atmosphere wave guide(b) Sea-Ionosphere wave guide(c) Earth-Sea wave guide(d) Earth-Ionosphere wave guide |
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Answer» Correct answer is (d) Earth-Ionosphere wave guide Easiest explanation: In the wave guide model of VLF wave propagation the region in which the Omega signals are confined is known as the Earth-Ionosphere wave guide. |
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| 348. |
What does the MLS use to overcome the weakness of ILS system?(a) Narrow beam width antennas(b) More power(c) Filers for separating noise(d) Array of antennas |
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Answer» The correct answer is (a) Narrow beam width antennas Explanation: The main weakness of the ILS system is eliminated by using narrow beam width antennas which are physically small since the frequency is high. As frequency increases antenna size decreases. |
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| 349. |
The height below which landing may continue in case of equipment failure is called as?(a) decision height(b) Abortion altitude(c) Visibility altitude(d) Alert height |
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Answer» Right option is (d) Alert height The explanation: Alert height is the altitude below which landing may continue in case of equipment failure. To meet alert height restrictions, either the avionics must be fault tolerant or the crew must be able to take over manually. |
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| 350. |
Which of the following techniques reduces the diurnal variation but does little effect on the phase behaviour of signal of equal path length over different environments?(a) Composite Omega(b) Propagation corrections(c) PPC(d) Subtracting the signal phases at two of the frequencies |
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Answer» Correct answer is (a) Composite Omega For explanation I would say: The composite Omega technique reduces the diurnal variation but does little to reduce the wide variation in phase behaviour exhibited by paths of equal length over substantially electromagnetic/geophysical environments. |
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