Questions and Answers - Communication / Navigation | Aircraft Systems

Questions and Answers - Communication / Navigation

Study Aid Questions

Fill in the Blanks

1. Covalent bonds are created when two or more substances share electrons in their ______.

2. Electron flow occurs when there are ______ in the valence shell due to the atom’s preference to have ______ electrons in all of its shell.

3. A four‐layer diode or ______ has three junctions. The behavior of the junctions can be understood by considering it to be two interconnected ______ transistors.

4. SCRs are often used in high ______ situations, such as switching, phase controls, battery chargers, and ______ circuits.

5. The ______ and amount of voltage applied to the gate can widen and narrow the ______ due to expansion or shrinkage of the depletion area at the junction of the semiconductor.

6. Depletion mode MOSFETs are considered normally ______ while enhanced mode MOSFETZs are normally ______.

7. Forward biased ______ give off energy visible in the ______ characteristic unique to the material of the semiconductor being used.

8. Transistors are rated by the ______ of the collector current to the ______ current, or Beta.

9. Common‐ ______ amplifiers are unique because their construction creates a situation where the base current ______ is than the collector or emitter current.

10. If there is to be an output voltage in a ______ gate, then the inputs cannot both have voltage.

11. The primary flight display displays the attitude indicator in the ______ half of the display and the electronic ______ indicator on the other half.

12. The electronic field component and the electromagnetic field component are oriented ______ to each other and at ______ to the direction that the wave is traveling.

13. 2 common methods of modulating ______ waves are amplitude and ______ modulation.

14. FM is considered ______ to AM for carrying and deciphering information on ______ waves.

15. The information signal is separated from the carrier wave portion of the signal by the ______.

16. Antennas are ______. They radiate and receive waves in certain patterns and ______.

17. ______ wire is used to connect transmitters and receivers to their ______.

18. VORs are marked on aeronautical charts along with their name, the ______ to tune, and a ______ designator.

19. On an RDF system, the only way to determine if the aircraft was flying to or from the ______ was the increasing and decreasing strength of the ______ signal.

20. The combination of a magnetic compass, VOR, and ADF into one instrument is found on an ______.

21. Vertical guidance required for an aircraft to descend for landing is provided by the ______ at an angle of about ______.

22. A ______ transponder provides positive identification and ______ of an aircraft on the radar screen of ATC.

23. Traffic collision ______ systems, or TCAS, are ______ based air‐to‐air traffic monitoring and alerting systems.

24. The ______ covering the antenna must only be painted with approved paint to allow radio signals to pass unobstructed.

25. The GPS receiver measure the time it takes for a signal to arrive from ______ transmitting satellites. This two‐dimensional position is expressed in ______ coordinates.


1. Maintenance of avionics is typically done by a technician with an Airframe license. TRUE/FALSE

2. Analog representations are discontinuous. TRUE/FALSE

3. Diodes act as check valves in AC circuits. TRUE/FALSE

4. Tetrodes are used at higher frequencies than triodes. TRUE/FALSE

5. Semiconductors are thought to be the building blocks of modern electronics. TRUE/FALSE

6. A material is an insulator if the electrons in the valence shell are allowed to move freely from one shell to another. TRUE/FALSE

7. N‐type semiconductor material is also known as a donor material. TRUE/FALSE

8. The amount of current that is allowed to pass through a forward biased diode is indirectly proportional to the amount of voltage applied. TRUE/FALSE

9. A transistor is a sandwich of N‐type material between two pieces of P‐type material and vice versa. TRUE/FALSE

10. Current to the collector‐emitter is turned on and off by the voltage applied to the collector. TRUE/FALSE

11. Photodiodes can carry more current than a photon activated transistor. TRUE/FALSE

12. Rectifiers change AC voltage to DC voltage. TRUE/FALSE

13. Common‐emitter circuits are characterized by high power gains. TRUE/FALSE

14. A sine wave is produced by generators when an conductor is rotated in a uniform electric field. TRUE/FALSE

15. Digital logic is based on the binary numbering system. TRUE/FALSE

16. All gates are amplifiers subject to output fluctuations. TRUE/FALSE

17. The negative OR gate is the same as the NOR gate. TRUE/FALSE

18. The relationship between frequency and wavelength is directly proportional. TRUE/FALSE

19. Ground waves are useful for long distance transmissions. TRUE/FALSE

20. VHF communication radios range from 118.0MHz to 336.975MHz. TRUE/FALSE

21. The distance a carrier wave travels is directly related to the amplification of the signal sent to the antenna. TRUE/FALSE

22. Most radio transmitters generate an unstable oscillating frequency that is stabilized by a mixer. TRUE/FALSE

23. A transceiver is a communication radio that transmits and receives. TRUE/FALSE

24. The strongest signals received align directly with the length of the antenna. TRUE/FALSE

25. The course deviation indicator on an OBS is essentially vertical but moves right and left across graduations each representing 5° of course deviation. TRUE/FALSE

26. The VOR circuitry is still active on an VOR/ILS receiver when the ILS localizer frequency is tuned in. TRUE/FALSE

27. DME distances are slant distances which is longer than ground distance. TRUE/FALSE

28. Transponder code 7700 is used for hijack situations. TRUE/FALSE

29. A radio altimeter indicates altitude in MSL. TRUE/FALSE

30. The accuracy of GPS is within 20 meters horizontally and can be improved to 7.6 meters with the integration of WAAS to the GPS. TRUE/FALSE

Knowledge Application Questions

1. How are analog electric signals modified?

2. Why were vacuum tubes replaced by solid‐state devices in aircraft radios?

3. Why is silicon one of the primary materials used in the manufacturing of semi‐conductors?

4. When is a semi‐conductor said to be reversed biased and what is the resulting effect of the circuit?

5. What does it mean when a diode is designed with a zener voltage and why are they used?

6. What are the advantages of a UJT over a bipolar transistor?

7. What are Shockley diodes useful for?

8. What are the three basic amplifier types?

9. Explain what a NOT gate does in terms of Logic in and out and what this means in relation to voltage.

10. What is the difference between an EXCLUSIVE OR and an OR?

11. Explain the processes of transmitting radio waves.

12. What is demodulation in amplitude modulation?

13. Why is frequency modulation considered superior to amplitude modulation?

14. What are the three frequencies produced when two AC signals are mixed together?

15. What is the purpose of the receiver and what does it do?

16. What are the three characteristics of concern when considering an antenna?

17. How is the use of one‐quarter of the wavelength antenna possible?

18. What is antenna field directivity?

19. Describe the difference between dipole, Marconi, and loop antennas.

20. How does a VOR receiver interpret the signal generated by the VOR station?

21. Describe each of the radio transmissions used on an ILS approach.

22. What does pressing IDENT do for an ATC controller?en is TCAS II required and what does it provide?

23. When is TCAS II required and what does it provide?

24. What are the advantages of ADS‐B over conventional ground‐based radar?

25. What are the three segments of GPS?

Multiple Choices Questions

1. As of 1994, how many satellites currently make up the global positioning system?
a. 15
b. 24
c. 31

2. Which of the follow is an advantage of digital electronics over analog electronics?
a. Continuously voltage modification
b. Easily modified by small inputs
c. Better noise control

3. What happens to electrons when they are heated?
a. Expand their orbit
b. Contract their orbit
c. Nothing

4. What does a triode contain that a diode does not?
a. Heater
b. Grid
c. Screen grid

5. How is the screen grid powered?
a. Positive DC voltage
b. Positive AC voltage
c. Negative AC voltage

6. A negatively doped semi‐conductor is bonded to what type of element?
a. An element with 5 valence electrons
b. An element with 3 valence electrons
c. An element with 4 valence electrons

7. The ease with which electron movement occurs at a give voltage is affected by which of the following?
a. Heat
b. Polarity
c. Conductivity of material

8. Current does not flow through a transistor unless
a. Voltage is applied to the base, narrowing the depletion area at the base‐emitter
b. Voltage is applied to the collector, narrowing the depletion area at the collector‐base
c. Voltage is applied to the emitter, widening the depletion area at the base‐emitter

9. Which of the following is a characteristic of an SCR?
a. has a zener voltage
b. Has a break over voltage rather than a breakdown voltage
c. Limit current flow to one direction

10. A unijunction transistor does not have which of the following?
a. Base material
b. Collector material
c. Emitter material

11. Channel is a material found in which of the following?
a. UJT
b. SCR
c. FET

12. A three‐phase AC circuit is rectified with a:
a. 3 diode circuit
b. 4 diode circuit
c. 6 diode circuit

13. Common‐collector circuits are characterized by
a. High current gain and 180° voltage phase shift from input to output
b. High current gain but practically no voltage gain
c. Attenuates current but causes a high gain in voltage

14. A tank circuit is one with:
a. A capacitor and coil in parallel with one another
b. A capacitor and coil in series with one another
c. A capacitor and resistor in parallel with one another

15. The output of a negative AND gate is the same as a(n):
c. NOR

16. Which of the following is a consolidation of various communication and navigation controls?
a. Audio panel
b. Digital tuner
c. Both A & B

17. What are the frequency ranges and names given to VLF, LF, and MF waves?
a. 3kHZ‐3mHZ, ground waves
b. 2MHz‐25MHz, surface waves
c. 3kHz‐30mHz, sky waves

18. Which of the following frequencies contain the information signal after it comes out of the mixer?
a. Radio frequency
b. Local oscillator frequency
c. Difference frequency

19. How can radio antennas be made effectively shorter?
a. Adding a properly rated capacitor in series with the transmission line
b. Adding an inducer in the circuit
c. Both A & B

20. For optimum performance, the impedance of the transmission line should be equal to the impedance of the antenna, which is often
a. 5 ohms
b. 50 ohms
c. 75 ohms

21. When is the reference signal of a VOR in phase with the variable signal?
a. Magnetic north
b. 90°
c. 180°

22. Where are VOR receivers operationally tested and what is the maximum acceptable error?
a. VOT, ±2°
b. Avionics repair station, ±4°
c. VOT, ±4°

23. NDB signals are modulated with what unique identifying characteristic?
a. Aural identifiers
b. Morse cold pulses
c. Both A & B

24. Which of the following lights represents a marker beacon signal?
a. Blue
b. Amber
c. White

25. Altitude encoders provide what addition information to a radar beacon transponder?
a. Pressure altitude
b. Density altitude
c. Neither A or B

26. According to Title 14 CFR 91 section 91.413, all transponders on aircraft flown in controlled airspace are required to be inspected and tested every
a. 30 days
b. 12 calendar months
c. 24 calendar months

27. Magenta is reserved for which of the following on on‐board weather radar receivers?
a. Heavy precipitation
b. Extreme precipitation
c. Wind shear

28. Which of the following provides an actual return on weather radar?
a. Severe turbulence
b. Wind shear
c. Hail

29. How are ELTs activated?
a. Manually by pilot in an accident
b. As a result of excessive G‐forces
c. Either A or B

30. How are separation minimums reduced for precision approaches?
a. GPS equipped aircraft
b. WAAS equipped aircraft
c. IRS equipped aircraft

Aviation Communication and Navigation
Radio Communication
Inertial Navigation System (INS)/Inertial Reference System (IRS)
Installation of Communication and Navigation Equipment
Reducing Radio Interference
Installation of Aircraft Antenna Systems
Radio Navigation
VOR Navigation System
Automatic Direction Finder (ADF)
Radio Magnetic Indicator (RMI) and Distance Measuring Equipment (DME)
Instrument Landing Systems (ILS)
Area Navigation (RNAV) and Radio Altimeter
Radar Beacon Transponder
Collision Avoidance Systems
Weather Radar
Emergency Locator Transmitter (ELT)
Long Range Aid to Navigation System (LORAN)
Global Positioning System (GPS)