Answers - Communication and Navigation


Fill in the Blanks

1. valence shells
2. holes, eight
3. shockley, three‐layer
4. power, inverter
5. polarity, channel
6. open, closed
7. LEDs, color
8. ratio, base
9. base, larger
10. NAND
11. upper, horizontal situation
12. 90°, 90°
13. carrier, frequency
14. superior, radio
15. detector/demodulator
16. polarized, direction
17. conductive, antenna(s)
18. frequency, Morse code
19. NDB, null
20. RMI
21. glideslope, 3°
22. radar beacon, location
23. avoidance, transponder
24. radome
25. three, latitude/longitude

True or False

1. False, certified repair station
2. False, continuous
3.true
4. true
5. true
6. false; conductor
7. true
8. false; directly proportional
9. true
10. false; base
11. false; less
12. true
13. false high current gains
14. false; magnetic
15. true
16. true
17. false
18. false; inversely proportional
19. true
20. false; 136.975 MHz
21. true
22. false; stable oscillating frequency
23. true
24. false; 90° to the length of the antenna
25. false, 2°
26. false; inactive
27. true
28. false; 7500
29. false; AGL
30. true

Knowledge Application

1. changing signal’s amplitude, frequency, or phase

2. size and inability to withstand vibration made them susceptible to damage.

3. Combines readily with itself and form a lattice of atoms in which adjacent atoms share electrons to fill out the valence shell. Can be easily doped to create N‐type and P‐type semiconductor material.

4. The negative battery terminal is attached to the p‐ material and attracts holes away from the junction in the diode. Positive terminal attached to the N‐ material attracting the free electrons from in the opposite direction. Current cannot flow through the circuit when this occurs.

5. When reversed biased, only leakage current flows through the diode unless it is equipped with a zener voltage. When the zener voltage is reached the diode lets current flow freely through the diode in the direction it is normally blocked. Zener diodes can be used to as a means of dropping voltage or voltage regulation as well as step down circuit voltage for a particular application.

6. Stable in a wide range of temperatures; reduce the overall number of components used saving money and increasing reliability.

7. Switching devices and SCR (with a slight modification)

8. Common‐emitter amplifier; common‐collector amplifier; common‐base amplifier

9. If the input to the gate is Logic 1 then the output is NOT logic 1. A NOT gate inverts the input signal. If there is voltage at the input, there would be no output voltage.

10. In an OR gate if any one of the Logic inputs is a 1 then the output will be a 1. In EXCLUSIVE if both logic inputs are 1 then the output is 0 instead of 1.

11. An AC generator is placed at the midpoint of an antenna. As current builds and collapses in the antenna, a magnetic field does so around it. An electric field also builds and subsides as the voltage shifts from one end of the antenna to the other. Both fields fluctuate around the antenna at the same time. At any point along the antenna, voltage and current vary inversely to each other. Each new current flow creates new fields around the antenna that forces the nottotally‐collapsed fields from the aircraft out into space.

12. Process of removing the original information signal from the carrier wave.

13. FM has a steady current flow and requires less power to produce, since modulating an oscillator takes less power than modulating the amplitude.

14. Original carrier wave, carrier wave plus the modulating frequency, carrier wave minus modulating frequency.

15. A receiver is needed to isolate the desired carrier wave with its information. It separates data signal from the carrier wave. It amplifies the desired frequency captured by the antenna which is weak from traveling through atmosphere.

16. Length, polarization, and directivity

17. A metal fuselage creates a ground plane that acts as the missing one‐quarter length.

18. The orientation of electric and electromagnetic fields remain at 90°, but radiate from the antenna with varying strength in different directions. The strength of the radiated field varies depending on the type of antenna and the angular proximity to it. All antennas radiate a stronger signal in some directions compared to others.

19. A dipole antenna is a conductor and sometimes known as the Hertz antenna. AC transmission current is fed to a dipole antenna. Current is strongest in the middle of the antenna about half the wavelength of the transmission frequency in length. It is horizontally polarized. Common as VOR antenna. Marconi antennas are 1/4 wave for VHF communication. They are vertically polarized and create omnidirectional field. Loop antennas are, as their name implies, fashioned into a loop which alters its field characteristics significantly. It is more compact and less prone to damage. It is used as a receiving antenna and is highly direction‐sensitive.

20. Bearing degrees to or from the station

21. Localizer‐provides horizontal guidance to the centerline of the runway; glideslope‐provides vertical guidance to the touchdown point; compass locator aids in intercepting the approach navigation aid system; marker beacon‐provides distance‐from‐the‐runway.

22. It transmits in such a way that the aircraft’s target symbol is highlighted on the PPI to be distinguishable.

23. Required internationally in aircraft with more than 30 seats or more than 15000 kg. It provides advisories similar to TCAS I but also analyzes the flightpath of approaching aircraft.

24. Entire airspace covered at lower expense. Provides more accurate data as vector state is generated from the aircraft. Weather is a reduced factor. Ultra‐high frequency GPS is not affected. Increased accuracy allows higher density traffic flow. The higher degree of control enables routing for fewer weather delays and optimum fuel burn rates.

25. Space segment, control segment, and user segment


Multiple Choices

1. a
Radio equipment is sensitive to mechanical shock and vibration and is normally shock mounted to provide protection.

2. a
It is advisable to bond radio equipment to the aircraft in order to provide a low impedance ground and to minimize radio interference from static electrical charges. When attaching bonding jumpers, the use of solder should be avoided.

3. b
Radio station license is not required for domestic flights.

4. a
An FCC Restricted Radio Telephone Operator Permit is only required when flying to or communicating with destinations outside the United States.

5. a
The ADF system uses the combination of an omnidirectional sense antenna, and a highly directional loop antenna. In the ADF mode the field patterns of the two antennas are combined into what is known as a cardoid pattern.

6. c
When installing coaxial cable (transmission lines), secure the cables firmly along their entire length at intervals of approximately 2 ft. To assure optimum operation, coaxial cables should not be routed or tied to other wire bundles.

7. b
ELT batteries must be replaced after the transmitter has been in use for more than one cumulative hour.

8. a
The life of the battery is the length of time which the battery may be stored without losing its ability to continuously operate the ELT for 48 hours.

9. b
An emergency locator transmitter may be located anywhere within the aircraft, but the ideal location is as far aft as possible, but just forward of the vertical fin.

10. a To meet the "G" force requirements of TSO-C91, automatic fixed-type inertially activated ELTs must activate at any inertial force, parallel to the longitudinal axis of the aircraft of 5 Gs (+2, -0) and greater for a time duration of 11 (+5, -0) milliseconds or longer.

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