Types of Noise and Signal Distortion Quiz
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Questions and Answers

What is the purpose of quantization in the sampling process?

  • To represent digital data in waveform format
  • To convert analog signals to their digital form
  • To enhance the quality of the transmission medium
  • To approximate the amplitude of a pulse to the nearest permitted integer (correct)
  • Which modulation technique is associated with converting analog amplitudes to discrete levels?

  • Pulse Amplitude Modulation (PAM) (correct)
  • Frequency Modulation (FM)
  • Amplitude Modulation (AM)
  • Pulse Code Modulation (PCM)
  • What defines attenuation in communication signals?

  • The increase in signal strength with distance
  • The conversion of digital signals into binary code
  • The introduction of unwanted signals into a desired signal
  • The decrease in signal strength as it travels along a transmission medium (correct)
  • Which type of noise is caused by natural atmospheric phenomena?

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

    What process converts discrete signals into highs (1) and lows (0)?

    <p>Pulse Code Modulation (PCM)</p> Signup and view all the answers

    What is the frequency of violet light with a wavelength of 400 nm?

    <p>7.5 × 10^14 Hz</p> Signup and view all the answers

    What does the term 'modem' refer to?

    <p>Modulator and demodulator</p> Signup and view all the answers

    What is the primary source of solar noise?

    <p>The sun</p> Signup and view all the answers

    In amplitude modulation (AM), which aspect of the carrier signal varies?

    <p>Carrier amplitude</p> Signup and view all the answers

    What causes thermal noise in electrical conductors?

    <p>Thermal agitation of charges</p> Signup and view all the answers

    If a sampling signal has a frequency of 50 Hz, what is its period?

    <p>0.02 sec</p> Signup and view all the answers

    Which modulation technique involves varying the frequency of the carrier?

    <p>Frequency modulation (FM)</p> Signup and view all the answers

    Which type of noise is particularly noticeable in semiconductor devices?

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

    What does distortion refer to in data transmission?

    <p>The alteration of the signal's form</p> Signup and view all the answers

    What does modulation do to a data signal?

    <p>Adds information to an electronic carrier signal</p> Signup and view all the answers

    How is the signal-to-noise ratio (S/N ratio) quantitatively described?

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

    What is the relationship between frequency and wavelength in a wave equation?

    <p>Inversely proportional</p> Signup and view all the answers

    In the formula $S/N ratio = 10 log_{10} (P_s / P_n)$, what does $P_s$ represent?

    <p>Signal power</p> Signup and view all the answers

    When converting an analog signal to a digital signal, what process is commonly used?

    <p>Pulse Amplitude Modulation (PAM)</p> Signup and view all the answers

    What is the S/N ratio when a signal of 2.5 volts rms is corrupted by 10 mV rms of noise?

    <p>48 dB</p> Signup and view all the answers

    What is the S/N ratio of a signal with 350 watts transmitted through a cable medium with 60 watts of noise?

    <p>7.66 dB</p> Signup and view all the answers

    What is the main difference between analog and digital signals?

    <p>Analog signals have an infinite number of values, while digital signals are binary.</p> Signup and view all the answers

    Which formula correctly represents the relationship between wavelength, wave speed, and frequency?

    <p>$𝜆 = rac{c}{𝑓}$</p> Signup and view all the answers

    How is frequency expressed in terms of measurement?

    <p>Cycles per second</p> Signup and view all the answers

    What describes a periodic signal?

    <p>It has a cycle that repeats over time.</p> Signup and view all the answers

    How is amplitude defined in terms of a wave?

    <p>The height of the crest from the equilibrium point.</p> Signup and view all the answers

    If a signal has a period of 0.00235 seconds, how is its frequency calculated?

    <p>$f = rac{1}{0.00235}$</p> Signup and view all the answers

    Which of the following is NOT true about nonperiodic signals?

    <p>They always consist of discrete values.</p> Signup and view all the answers

    What is the unit for measuring frequency?

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

    Study Notes

    Types of Noise in Signals

    • Solar Noise: Originates from the sun.
    • Cosmic Noise: Generated by distant stars.
    • Thermal Noise: Results from thermal agitation of charges in electrical conductors.
    • Shot Noise: Caused by fluctuations in electrical current, noticeable in semiconductor devices.

    Signal Distortion

    • Distortion: Refers to the alteration of a signal during data transmission.
    • Delay Distortion: A phenomenon in guided transmission media where different signal frequencies travel at different speeds.

    Signal-to-Noise Ratio (SNR)

    • Definition: A quantitative measure of signal quality, representing the ratio of signal power to noise power.
    • Formula:
      • ( \text{S/N ratio} = 10 \log_{10} \left( \frac{P_s}{P_n} \right) ) in dB
      • ( \text{S/N ratio} = 20 \log_{10} \left( \frac{V_s}{V_n} \right) ) in dB
    • Example Calculations:
      • For a 2.5 volts rms signal with 10 mV noise: SNR = 48 dB.
      • For a 350 watts signal with 60 watts noise: SNR = 7.66 dB.

    Types of Signals

    • Analog Signals: Continuous values, represented by a sine wave, e.g., speech and audio.
    • Digital Signals: Binary values (0 and 1), represented by a square wave, having discrete levels.
    • Periodic Signals: Repeated patterns within measurable time frames, called cycles.
    • Nonperiodic Signals: Random changes without a repeating pattern.

    Signal Properties

    • Wavelength (( \lambda )): Related to frequency; ( \lambda = \frac{c}{f} ) where ( c ) is the speed of light.
    • Frequency (( f )): Number of waves passing a point each second; ( f = \frac{1}{T} ) where ( T ) is the period.
    • Amplitude: Height of the wave, measured from equilibrium to peak or trough.

    Modems

    • Definition: A combination of "modulator" and "demodulator" for converting digital data into a signal compatible with transmission media.
    • Modulation Types:
      • Amplitude Modulation (AM): Varies carrier amplitude based on the information signal.
      • Frequency Modulation (FM): Varies carrier frequency based on the information signal.
      • Phase Modulation (PM): Varies carrier phase based on the information signal.

    Analog-to-Digital Conversion

    • Sampling: Converts analog signals into discrete levels via ADC.
    • Pulse Amplitude Modulation (PAM): Initial step in converting analog signals.
    • Quantization: Approximates amplitude values of pulses to the nearest integer.
    • Pulse Code Modulation (PCM): Represents discrete signals as binary equivalents.

    Channel Impairments

    • Attenuation: Decrease in signal strength with distance traveled along the medium.
    • Noise: Unwanted signals superimposed onto desired signals.
      • Atmospheric Noise: Arises from natural phenomena (e.g., lightning).
      • Man-made Noise: Generated by human activities and electrical equipment.
      • Extraterrestrial Noise: Includes solar and cosmic noise, originating from outside Earth.

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    Description

    Test your knowledge on various types of noise in signals, including solar, cosmic, thermal, and shot noise. Additionally, explore concepts of signal distortion, and the critical signal-to-noise ratio (SNR) calculations that affect signal quality. This quiz is essential for students studying communication systems and signal processing.

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