Compiled MCQs in Navigational Aids and Radar Systems Part 1 of the series as one topic in Electronic System and Technologies (Communications Engineering) in the ECE Board Exam.

This is the Multiples Choice Questions Part 1 of the Series in Navigational Aids and Radar Systems as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

### Multiple Choice Questions Topic Outline

• MCQs in Other Navigational Methods
• MCQs in Distance Measuring Equipment
• MCQs in Automatic Direction Finder
• MCQs in Instrument Landing System
• MCQs in Microwave Landing System
• MCQs in Ground Proximity Warning System
• MCQs in Traffic Alert and Collision Avoidance System
• MCQs in Navigation by using Satellites
• MCQs in GPS, GLONASS, Galileo Positioning System
• MCQs in Radar Frequency Bands
• MCQs in Radar Functions and Roles
• MCQs in Radar Parameters: PRT, PRF, the Duty Cycle, Average Power
• MCQs in Doppler Effect
• MCQs in Range Equations

Following is the list of multiple choice questions in this brand new series:

PART 1: MCQs from Number 1 – 50                        Answer key: PART I
PART 2: MCQs from Number 51 – 100                   Answer key: PART II

### Start Practice Exam Test Questions Part I of the Series

1. The minimum range of radar is primarily determined by

• a. The pulse width and the TR cell recovery time
• b. The ATR cell recovery time
• c. The overall height of the antenna
• d. The peak power output of the radar transmitter

2. Bearing resolution is

• a. The ability to distinguish two target of different distances
• b. The ability to distinguish two target of different elevations
• c. The ability to distinguish two adjacent targets of equal distances
• d. The ability to distinguish two targets of different sizes

3. Find the distance in yards to an object if the display of a radar signal measures 4.4 microseconds.

• a. 380
• b. 328
• c. 722
• d. 656

4. What device is located between the magnetron and the mixer and prevents received signals from entering the magnetron?

• a. TR box
• b. ATR box
• c. RF attenuator
• d. Resonant cavity

5. Where is RF attenuator used in a radar unit?

• a. Between the antenna and the receiver
• b. Between the magnetron and the antenna
• c. Between the magnetron and the AFC section of the receiver
• d. Between the AFC section and klystron

6. What radar circuit determines the pulse repetition rate?

• a. Discriminator
• b. Timer/ synchronizer circuit
• c. Artificial transmission line
• d. Pulse-rate indicator circuit

7. Given the pulse width of 8 microseconds and a duty cycle of 8%, determine the pulse repetition time of a radar system.

• a. 100 us
• b. 1 us
• c. 1000 us
• d. 10 ms

8. On runway, an ILS localizer shows

• a. Deviation left or right of runway center line
• b. Deviation up or down from ground speed
• c. Deviation percentage from authorized ground speed
• d. Wind speed along runway

9. Range markers are determined by

• a. CRT
• b. Magnetron
• c. Timer
• d. Video amplifier

10. The characteristic of the magnetron output pulse that relates to accurate range measurement is its

• a. Amplitude
• b. Decay time
• c. Rise time
• d. Duration

11. The minimum range of a radar is determined by

• a. The frequency of the radar transmitter
• b. He pulse repetition rate
• c. The transmitted pulse width
• d. The pulse repetition frequency

12. A circuit to develop AFC voltage in a radar receiver is called the

• a. Peak detector
• b. Crystal mixer
• c. Second detector
• d. Discriminator

13. The echo box is used for

• a. Testing and tuning of the radar unit by providing artificial targets
• b. Testing the wavelength of the incoming echo signal
• c. Amplification of the echo signal
• d. Detection of the echo pulses

14. In a radar unit, the local oscillator is

• a. A hydrogen thyratron
• b. A klystron
• c. A pentagrid converter tube
• d. A reactance tube modulator

15. What is the peak power of a radar pulse if the pulse width is 1.0 microsecond, PRR is 900 and the average plate power input is 45 watts?

• a. 50 kW
• b. 45 kW
• c. 60 kW
• d. 62.5 kW

16. Radar uses what form of energy to detect planes, ships and land masses

• a. Sound energy
• b. Visible light
• d. Electromagnetic energy

17. In a pulse radar system, what component controls the timing throughout the system?

• a. Power supply
• b. Synchronizer
• c. Indicator

18. What radar measurement of an object is referenced to true north?

• a. Height
• b. Surface angle
• c. Vertical angle
• d. One-way distance

19. Surface search radar normally scans how many degrees of azimuth?

• a. 30 degrees
• b. 90 degrees
• c. 360 degrees
• d. 180 degrees

20. What limits the maximum range of a surface search radar?

• a. Pulse width
• b. Transmitter power
• c. Frequency

21. What IF frequency (ies) is (are) normally used in radar receivers?

• a. 30 or 60 MHz
• b. 455 kHz
• c. 70 MHz
• d. 10.7 MHz

22. What is the typical frequency range about the center frequency of a tunable magnetron?

• a. Plus or minus 5 percent
• b. Plus or minus 10 percent
• c. Plus or minus 15 percent
• d. Plus or minus 8 percent

23. What type of radar provides continuous range, bearing and elevation data on an object?

• d. Doppler shift

24. What radio navigation and determines the distance from a transponder beacon by measuring the length of time the radio signal took to travel to the receiver?

• b. Loran C
• c. Distance marking
• d. Distance measuring equipment

25. Which of the following is a feature of an instrument landing system?

• a. The localizer which shows aircraft deviation horizontally from center of runway
• b. The glideslope or glide path which shows vertical altitude of an aircraft during landing
• c. Provides communications to aircraft
• d. Both a and b

26. What transmission method does not depend on relative frequency or target motion?

• a. Digital transmission
• b. Frequency modulation
• c. Pulse modulation
• d. CW modulation

27. The beat frequency in a swept-frequency transmitter provides what contact information?

• a. Frequency
• b. Travel time
• c. Range
• d. Velocity

28. A self- synchronization radar system obtains timing trigger pulses from what source?

• a. Transmitter
• b. Echo box
• c. Anti-transmit and receive box
• d. Transmit and receive box

29. In externally-synchronized radar, what determines the PRR of the transmitter?

• a. Synchronizer
• b. Master oscillator
• c. Blocking oscillator
• d. Free-running multivibrator

30. Transmitter power readings are most often referenced to what power level?

• a. 1 watt
• b. 1 milliwatt
• c. 1 microwatt
• d. 1 picowatt

31. What type of radiator normally drives a corner reflector?

• a. Half-wave
• b. Despun
• c. Isotropic
• d. Marconi

32. A monopulse receiver has how many separate channels?

• a. One
• b. Two
• c. Three
• d. Four

33. How many major lobes are produced by a paraboloid reflector?

• a. One
• b. Two
• c. Three
• d. Four

34. The Doppler variation is directly proportional to what radar contact characteristics?

• a. Frequency
• b. Velocity
• c. Range
• d. Travel time

35. What is the simplest type of scanning?

• a. Single lobe scanning
• b. Mechanical scanning
• c. Electronic scanning
• d. Electromechanical scanning

36. What term is used to describe the ability of a radar system to distinguish between targets that are close together?

• a. Target resolution
• b. Bearing resolution
• c. Range resolution
• d. Angular resolution

37. Radar altimeters use what type of transmission signal?

• a. Amplitude modulated
• b. Frequency modulated
• c. Phase modulated
• d. Pulsed modulated

38. Tracking radar searches a small volume of space during which phase of operation?

• a. Scanning
• b. Tracking
• c. Searching
• d. Acquisition

39. How many active elements are contained in a magnetron?

• a. Two
• b. Three
• c. Four
• d. Five

40. Transit time might be defined as the time required for

• a. RF energy to travel through the waveguide
• b. A pulse to travel a wavelength inside a waveguide
• c. One cycle of operation to be completed
• d. Electrons to travel from cathode to anode

41. On a basic synchro system, the angular information is carried on

• a. Dc feedback signal
• b. Stator lines
• c. Deflection coils
• d. Rotor lines

42. What circuit element receives the drive voltage in a radar system’s fiber optic signal transmitter?

• a. Filter capacitor
• c. Temperature sensor
• d. Transistor

43. For a range of 10 nautical miles, the radar pulse repetition frequency (PRF) should be

• a. Approximately 8.1 kHz or less
• b. 900 Hz
• c. 18.1 kHz or more
• d. 120.3 microseconds

44. If the operating radar frequency is 3000 MHz, what is the distance between the waveguide and the spark gaps in older radar units?

• a. 10 cm
• b. 5 cm
• c. 2.5 cm
• d. 20 cm

45. Ship raster scan radar has a CRT with the following characteristics: 70 pixels per character, 80 character per line, 25 lines per screen and it scans 100 screen per second. What is the minimum required bandwidth for the electron beam control signal?

• a. 210 MHz
• b. 0.21 MHz
• c. 2.1 MHz
• d. 21 MHz

46. Continuous wave radar is frequency modulated with a 50-Hz sine wave. At the output of the receiver phase detector, a phase delay of 36 degrees is measured. This indicates a target range of

• a. 15 km
• b. 75 km
• c. 150 km
• d. 300 km

47. A target pulse appears on the CRT 100 microseconds after the transmitted pulse. The target slant range is

• a. 30 km
• b. 93 miles
• c. 15 km
• d. 15, 000 yards

48. A gated LC oscillator operating at 12.5 kHz is being used to develop range markers. If each is converted to a range, the range between markers will be

• a. 120 km
• b. 12 km
• c. 1.2 km
• d. 210 km

49. What type of tube best meets the requirements of a modulator switching element?

• a. Thyratron
• b. Magnetron
• c. Klystron
• d. Phanotron

50. What type of transmitter power is measured over a period of time?

• a. Peak
• b. Return
• c. Average
• d. Reciprocal

### Complete List of MCQs in Communications Engineering per topic

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