Amplitude Modulation and Superheterodyne Receiver Quiz
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Questions and Answers

What is the minimum multiplexing bandwidth required for the 30 signals described in the text?

  • $160 kHz$
  • $188 kHz$
  • $94 kHz$ (correct)
  • $120 kHz$

    • What is the minimum transmission bandwidth required for the 30 signals described in the text?

  • $120 kHz$
  • $188 kHz$ (correct)
  • $160 kHz$
  • $94 kHz$

    • If a 0.7 kHz guard band is allowed between each signal and below the first signal, what is the new multiplexing bandwidth?

  • $188 kHz$
  • $94 kHz$
  • $120 kHz$
  • $100 kHz$ (correct)

    • What is the purpose of the local oscillator in a superheterodyne receiver?

    <p>To convert the received signal to a lower intermediate frequency</p> Signup and view all the answers

    What is the advantage of the superheterodyne principle over the tuned radio-frequency (TRF) receiver?

    <p>Better selectivity</p> Signup and view all the answers

    What is the purpose of the ganged capacitors in a TRF receiver?

    <p>To tune the receiver to the desired station frequency</p> Signup and view all the answers

    In a superheterodyne receiver for AM radio, what is the purpose of the local oscillator?

    <p>To generate a fixed intermediate frequency (IF) by mixing with the incoming modulated signal</p> Signup and view all the answers

    If an AM radio station is broadcasting at 600 kHz and the intermediate frequency (IF) is 455 kHz, what should be the frequency of the local oscillator if it operates above the incoming frequency?

    <p>$1055$ kHz</p> Signup and view all the answers

    What is the main advantage of using a superheterodyne receiver?

    <p>The amplification and filtering are performed at a fixed intermediate frequency, regardless of the incoming carrier frequency</p> Signup and view all the answers

    What is the potential disadvantage of using a superheterodyne receiver?

    <p>The intermediate frequency (IF) amplifiers may be tuned outside the assigned frequency band</p> Signup and view all the answers

    In a superheterodyne receiver, what is the purpose of the mixer?

    <p>To translate the incoming modulated signal to the intermediate frequency (IF)</p> Signup and view all the answers

    What is the potential issue known as the 'image frequency problem' in a superheterodyne receiver?

    <p>An unwanted signal at a specific frequency may also be translated to the intermediate frequency (IF)</p> Signup and view all the answers

    In a superheterodyne receiver, the purpose of the local oscillator is to:

    <p>Convert the received signal to a lower intermediate frequency</p> Signup and view all the answers

    In the given example, if the first local oscillator frequency is 106 MHz, what is the image frequency?

    <p>166 MHz</p> Signup and view all the answers

    What is the minimum intermediate frequency required to prevent image frequency problems in the 2.8-3 GHz radar band?

    <p>100 MHz</p> Signup and view all the answers

    In a superheterodyne receiver with two intermediate frequencies, if the first IF is 30 MHz and the second IF is 10 MHz, what is the frequency of the second local oscillator?

    <p>40 MHz</p> Signup and view all the answers

    Which of the following statements about image frequencies in superheterodyne receivers is true?

    <p>Image frequencies can be either higher or lower than the local oscillator frequency</p> Signup and view all the answers

    In an amplitude modulation (AM) system with additive noise, which component of the received signal contains the desired message?

    <p>Both the carrier and sideband components ($P_C + P_{SB}$)</p> Signup and view all the answers

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