Microwave Radio Communications and System Gain Introduction
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Questions and Answers

Why are microwave frequencies limited to line-of-sight applications?

  • They reflect off surfaces
  • They propagate in a straight line (correct)
  • They are absorbed by the atmosphere
  • They require digital modulation

    • What type of modulation is commonly used in existing microwave radio systems?

  • Phase-Shift Keying
  • Frequency Modulation (FM) (correct)
  • Quadrature Amplitude Modulation (QAM)
  • Amplitude Modulation (AM)

    • Why are digital modulation techniques like phase-shift keying preferred in some microwave systems?

  • They are more efficient in power consumption
  • They offer higher frequencies
  • They have shorter propagation distances
  • They are less affected by nonlinear distortion (correct)

    • What is a primary difference between satellite and terrestrial microwave radio systems?

    <p>Location of signal propagation</p> Signup and view all the answers

    Why is frequency modulation (FM) preferred over amplitude modulation (AM) in microwave radio systems?

    <p>FM signals are less affected by nonlinear distortions</p> Signup and view all the answers

    What is the reason behind using satellite systems for long-distance communication?

    <p>They can carry signals farther distances</p> Signup and view all the answers

    What is the typical range of microwave frequencies?

    <p>$500 MHz$ to $300 GHz$ or more</p> Signup and view all the answers

    What is the significance of dividing a microwave frequency band into a low band and a high band?

    <p>It allows for full-duplex (two-way) communication by using separate bands for transmitting and receiving.</p> Signup and view all the answers

    What is the approximate wavelength of a 100-GHz microwave signal?

    <p>$0.3 cm$</p> Signup and view all the answers

    What was the approximate cost of the first transcontinental microwave radio system built by the Bell System?

    <p>$40 million</p> Signup and view all the answers

    How many relay stations were part of the first transcontinental microwave radio system?

    <p>107</p> Signup and view all the answers

    What was the approximate average distance between relay stations in the first transcontinental microwave radio system?

    <p>30 miles</p> Signup and view all the answers

    What is the purpose of dividing the allocated bandwidth for the system in half?

    <p>To reduce interference between stations placed in a straight line.</p> Signup and view all the answers

    In a high/low microwave repeater system, what happens if a repeater station receives a low-band RF carrier?

    <p>It retransmits a high-band RF carrier.</p> Signup and view all the answers

    What is the significance of ringaround in antenna design?

    <p>It prevents power leakage from transmit antennas interfering with nearby receive antennas.</p> Signup and view all the answers

    When can multiple carriers of the same frequency be received?

    <p>When transmission is received from stations three hops away.</p> Signup and view all the answers

    What is the consequence if a transmission from station B is received by station D?

    <p>The transmission will be rejected in the channel separation network.</p> Signup and view all the answers

    What does a high/low-frequency scheme aim to prevent?

    <p>Power leakage from antennas affecting nearby receivers.</p> Signup and view all the answers

    Which wave path is directly between the transmit and receive antennas in a microwave radio system?

    <p>The free-space path</p> Signup and view all the answers

    What is the sum of the free-space path, ground-reflected wave, and surface wave called?

    <p>The ground wave</p> Signup and view all the answers

    Which wave path is the portion of the transmit signal that is returned (reflected) back to Earth's surface by the ionized layers of Earth's atmosphere?

    <p>The sky wave</p> Signup and view all the answers

    At what frequency range does the surface wave provide the primary coverage, and the sky wave helps extend this coverage at night?

    <p>Below 1.5 MHz</p> Signup and view all the answers

    What factor determines the magnitude of the surface wave in a microwave radio system?

    <p>The characteristics of Earth's surface and the electromagnetic polarization of the wave</p> Signup and view all the answers

    Which of the following wave paths does not exist in a microwave radio system?

    <p>The ringaround wave</p> Signup and view all the answers

    What is the primary function of an IF repeater?

    <p>To down-convert the received RF carrier to an IF frequency, amplify, reshape, up-convert to an RF frequency, and retransmit without demodulating below IF</p> Signup and view all the answers

    Which type of repeater allows for reconfiguration of the baseband signal?

    <p>Baseband repeater</p> Signup and view all the answers

    In the configuration shown in Figure 4c, what is the purpose of demodulating the RF carrier to baseband?

    <p>To amplify and reshape the baseband signal before remodulation</p> Signup and view all the answers

    Which statement is true about the baseband signal in a baseband repeater?

    <p>It is frequency-division-multiplexed voice-band channels</p> Signup and view all the answers

    What is the purpose of up-converting the signal to an RF carrier in a repeater?

    <p>To retransmit the signal to the next repeater or receiver</p> Signup and view all the answers

    In the context of microwave repeaters, what does the term 'reshaped' refer to?

    <p>Filtering and amplifying the signal to reduce noise and distortion</p> Signup and view all the answers

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