Fundamentals of Radio Communications
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1. What is transmitted, bounced off a target, and received by the same radar’s receiver?
1. RF Wave.
2. What device communicates more elaborate:
– Human voice or machine-to-machine data transmitted and processed in near real time
– Transmits information on a RF carrier wave
– Extracts the information from a compatible receiver
3. For systems to communicate must be compatible in what three areas?
- - Frequency
- - Modulation Type
- - Range
4. Radio frequency communications focuses on what three areas?
- - Modulation Types
- - Radio equipment types
- - Radio network features
5. What are the three modes of communication?
- - Simplex Mode
- - Half-Duplex Mode
- - Full-Duplex Mode
6. Which communication mode does all signals flow in one direction and is often employed in broadcast networks such as Commercial television and radio stations?
6. Simplex Mode.
7. Which communication mode has all signals flow in both directions and is only broadcasted in one direction at a time?
7. Half-Duplex Mode.
8. Which communication device communicates in both directions simultaneously?
8. Full-Duplex Mode.
9. What is an electromagnetic wave that can be modulated, as in frequency, amplitude, or phase, to transmit speech, music, images, or other signals?
9. Carrier Wave.
10. What is the variation of a property of an electromagnetic wave or signal, such as its amplitude, frequency, or phase?
11. What is a type of radio signal in which the amplitude, or strength, of a radio wave is varied in order to carry information from a transmitter to a receiver?
11. Amplitude Modulation.
12. What is a type of radio signal in which the frequency of the radio wave is varied to carry information from the transmitter to the receiver?
12. Frequency Modulation.
13. What is a type of electronic modulation in which the phase of a carrier wave is varied in order to transmit the information contained in the signal?
13. Phase Modulation.
14. What is a system of modulation in which the amplitude, duration, position, or mere
presence of discrete pulses may be so controlled as to represent the message to
14. Pulse Modulation.
15. What are continuous electrical signals that vary in time?
15. Analog Signals.
16. What is the range of the electromagnetic spectrum located either above or below the frequency of a carrier signal?
17. What type of modulation of a carrier wave normally results in two mirror-image sidebands?
17. Amplitude Modulation.
18. What can be represented by shifting the carrier frequency among a set of discrete values, a technique known as frequency-shift keying?
18. Digital Data.
19. What are non-continuous, changing in individual steps where signals consist of pulses or digits with discrete levels or values?
19. Digital Signals.
20. What are the three major classes of Digital Modulation?
- –Phase-shift keying (PSK)
- –Amplitude-shift keying (ASK)
- –Frequency-shift keying (FSK)
21. What are two common examples of Phase-Shift Keying?
21. BPSK (Binary - two phases) and QPSK (Quadrate - four phases).
22. What is a form of modulation which represents digital data as variations in the
amplitude of a carrier wave?
22. Amplitude-shift Keying (ASK).
23. What is a form of frequency modulation in which the modulating signal shifts the output
frequency between predetermined values?
23. Frequency-Shift Keying (FSK).
24. What is a generated signal that is modulated for the purpose of passing information?
24. Carrier Wave.
25. What is a variation of the carrier wave to represent information?
26. What is an integer multiple (exact whole number) of a fundamental frequency?
27. What is a noise gate that only allows signals at a specified strength over a threshold to be played through the speaker?
28. What are five techniques that are commonly used to solve interference problems?
- - Continuous Tone-coded Squelch System (CTCSS)
- - Selective Calling (SELCALL)
- - Digital-Coded Squelch (DCS)
- - Expanded Tone-coded Squelch System (XTCSS)
- - Dual-Tone Multi Frequency (DTMF)
29. The most common squelch control technology and contains 50 low pitch audio tones?
30. What squelch control technique transmits a burst of five in-band audio tones at the beginning of each transmission?
31. What is the newest signaling technique and it provides 99 codes with the added
advantage of silent operation?
32. What is a type of squelch signaling that uses a string of 2-7 tones?
33. Military, paramilitary, and other adversaries are increasing their use of what type of technology?
33. Civilian Commercial-of-the-shelf (COTS).
34. Which Network Radio System requires an FCC License and operates in-between 462 MHz to 467 MHz?
34. General Mobile Radio Service (GMRS).
35. What is an electronic circuit whose output is proportional to its input, but capable of delivering more power into a load?
35. Linear Amplifier.
36. What is a combination of radio receiver and a radio transmitter? Also uses two radio frequencies; input and output?
36. Radio Repeaters.
37. What allows a large number of users to share a relatively small number of radio channels?
37. Trunked Mobile Radio Networks.
38. Two different methods are currently used to control trunking systems?
38. Dedicated and Distributed Control Channels.
39. What is unique and advantageous about a trunked mobile radio system?
39. It has a controlled site controller.
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