Noise in Communication Systems
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What does a higher Signal-to-Noise Ratio (SNR) indicate about the signal and noise?

  • The signal is weak and the noise is strong.
  • The signal and noise are equal in strength.
  • The signal is strong and the noise is weaker. (correct)
  • The noise is stronger and the signal is stronger.

    • Which formula correctly represents the quantity for Signal-to-Noise Ratio in terms of voltage?

  • $S/V_s = N/V_n$ (correct)
  • $S = V_s / N_v$
  • $S/V_s = N/P_n$
  • $S/V_n = N/V_s$

    • If the signal voltage is 4.2 $ ext{μV}$ and the noise voltage is 0.3 $ ext{μV}$, what is the calculated S/N ratio?

  • 10
  • 14 (correct)
  • 1.4
  • 12

    • Why is the S/N ratio typically expressed in terms of power rather than voltage?

    <p>Power provides a more accurate representation of signal strength.</p> Signup and view all the answers

    What is indicated if the S/N ratio is low?

    <p>The signal is weak and the noise is strong.</p> Signup and view all the answers

    What is thermal noise also known as?

    <p>Johnson noise</p> Signup and view all the answers

    Which type of noise is associated with semiconductor components like diodes and transistors?

    <p>Shot noise</p> Signup and view all the answers

    What phenomenon occurs due to the random movement of current carriers in a semiconductor?

    <p>Shot noise</p> Signup and view all the answers

    What does flicker noise refer to in semiconductor materials?

    <p>Minute random variations of resistance</p> Signup and view all the answers

    What is transit-time noise related to?

    <p>Time taken for a current carrier to move through a circuit</p> Signup and view all the answers

    What type of noise is described as filtered or band-limited noise?

    <p>Pink noise</p> Signup and view all the answers

    What does intermodulation distortion result from?

    <p>Generating new signals from circuit nonlinearities</p> Signup and view all the answers

    How does noise affect communication systems?

    <p>It is problematic with low amplitude received signals</p> Signup and view all the answers

    What type of external noise is caused by manufacturing equipment?

    <p>Industrial noise</p> Signup and view all the answers

    Which form of atmospheric noise is commonly associated with lightning?

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

    What is the primary cause of solar noise?

    <p>Signals from the sun</p> Signup and view all the answers

    What typically causes internal noise in a receiver?

    <p>Electronic components</p> Signup and view all the answers

    What is noise in terms of electronic signals?

    <p>An electronic signal with random frequencies and amplitudes.</p> Signup and view all the answers

    How does noise affect digital signals compared to analog signals?

    <p>Digital signals require a higher amount of noise to be confused.</p> Signup and view all the answers

    Which type of noise is affected by a noise cycle from the sun?

    <p>Solar noise</p> Signup and view all the answers

    What is a characteristic of cosmic noise?

    <p>It is generated by stars outside the solar system</p> Signup and view all the answers

    What common household example demonstrates noise during radio tuning?

    <p>Hiss or static between radio stations.</p> Signup and view all the answers

    Which of the following is a common type of internal noise?

    <p>Thermal noise</p> Signup and view all the answers

    What visual phenomenon identifies noise on a television screen?

    <p>Snow on black-and-white screens.</p> Signup and view all the answers

    What happens when noise overshadows the original signal?

    <p>The original signal may be completely lost.</p> Signup and view all the answers

    Which type of noise shows the greatest impact on signals with frequencies below 30 𝑀𝐻𝑧?

    <p>Atmospheric noise</p> Signup and view all the answers

    What defines the difference between noise and interference?

    <p>Noise consists of random frequencies, while interference involves specific conflicting signals.</p> Signup and view all the answers

    What can high levels of noise lead to in electronic communication?

    <p>Unpredictable and possibly damaging results.</p> Signup and view all the answers

    What does the term 'signal noise' refer to?

    <p>Unwanted interference that degrades communication signals.</p> Signup and view all the answers

    What is the calculated S/N ratio if the signal power is 6 𝜇𝑊 and the noise power is 120 𝑛𝑊?

    <p>50</p> Signup and view all the answers

    What is the correct formula for converting S/N ratio to decibels (dB) for power?

    <p>$dB = 10 log(S/N)$</p> Signup and view all the answers

    What is the result of $10 log(50)$?

    <p>16.99 dB</p> Signup and view all the answers

    Which calculation method is used to express the noise quality of a receiver?

    <p>Noise Factor and Noise Figure</p> Signup and view all the answers

    What is the decibel value for the S/N voltage calculated as $20 log(14)$?

    <p>22.92 dB</p> Signup and view all the answers

    Which of the following values represents noise power in the example?

    <p>120 𝑛𝑊</p> Signup and view all the answers

    When calculating the S/N ratio, what is the standard notation for signal power?

    <p>$S$</p> Signup and view all the answers

    Which of the following correctly represents the S/N ratio formula using example values?

    <p>$6 imes 10^{-6} / 120 imes 10^{-9}$</p> Signup and view all the answers

    What does the noise factor (NR) represent?

    <p>The ratio of signal power at the input to noise power at the output</p> Signup and view all the answers

    When expressed in decibels, what is the noise factor called?

    <p>Noise figure</p> Signup and view all the answers

    Which of the following is NOT a factor that causes distortion?

    <p>Signal amplification levels</p> Signup and view all the answers

    What is a characteristic of distortion in audio transmission?

    <p>It can result in harsh and unnatural sounds.</p> Signup and view all the answers

    How is distortion used in a Dolby system?

    <p>To distort audio signals for enhancing certain aspects.</p> Signup and view all the answers

    How does distortion differ from noise?

    <p>Distortion affects the waveform, while noise affects only the amplitude.</p> Signup and view all the answers

    Which instrument commonly uses distortion as an effect?

    <p>Electric guitar</p> Signup and view all the answers

    What is one potential outcome of distortion in audio signal processing?

    <p>Garbled sound quality.</p> Signup and view all the answers

    Study Notes

    Noise

    • Noise is an electronic signal with random frequencies and amplitudes, added to a signal during transmission or processing.
    • It appears as a random AC voltage on an oscilloscope, regardless of the source.
    • Noise differs from interference, which disrupts a signal by adding unwanted signals.
    • Signal noise degrades analog and digital signals.
    • More noise is needed to affect digital signals than analog signals, as digital signals use binary pulses.

    Signal-to-Noise Ratio (SNR)

    • SNR represents the relative strengths of signal and noise in communication systems.
    • High SNR means a strong signal and weak noise; low SNR vice versa.
    • Reception is unreliable with low SNR.
    • SNR can be expressed in voltage or power using formulas.
    • SNR is often expressed in decibels (dB).

    Types of Noise

    • External Noise: Uncontrollable noise sources like industrial, atmospheric, or extraterrestrial.
      • Industrial Noise: From manufacturing equipment (e.g., generators, motors).
      • Atmospheric Noise: Electrical disturbances, often from lightning (static).
      • Extraterrestrial Noise: From the sun (solar noise), with an 11-year cycle of increased intensity.

    Internal Noise

    • Noise from components within a receiver (resistors, diodes, transistors).
      • Thermal Noise (White Noise): Random motion of electrons due to heat.
      • Semiconductor Noise: From diodes and transistors, including shot noise, transit-time noise, and flicker noise.
      • Intermodulation Distortion: From generating new signals and harmonics due to circuit nonlinearities.

    Distortion

    • Distortion is an unwanted change in an information signal (audio/video).
    • Distortion affects signal waveform in electronic devices and communication channels.
    • Causes include environmental factors, channel properties, and transmission distance.
    • Some distortions are desirable, like in noise reduction systems or musical effects (e.g., electric guitar).

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    Noise and Distortion PDF

    Description

    This quiz explores the concept of noise in electronic communication systems, detailing its random nature and impact on signal quality. It covers the Signal-to-Noise Ratio (SNR) and various types of noise, emphasizing the differences between external and internal noise sources. Test your understanding of how noise affects both analog and digital signals.

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