Pulse Code Modulation (PCM) Fundamentals
12 Questions
0 Views

Pulse Code Modulation (PCM) Fundamentals

Created by
@ScenicHarpGuitar

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Who invented Pulse Code Modulation (PCM) in 1937?

  • Claude Shannon
  • Alec H. Reeves (correct)
  • John Logie Baird
  • Guglielmo Marconi
  • What is a limitation of PPM and PWM that PCM can overcome?

  • Noise susceptibility
  • Bandwidth limitations due to resolution requirements (correct)
  • Low signal-to-noise ratio
  • High power consumption
  • Why is it necessary for the voltage to be relatively constant during ADC conversion in a PCM transmitter?

  • To reduce power consumption
  • To increase the bandwidth
  • So that the ADC can complete the conversion before the voltage level changes (correct)
  • To reduce noise susceptibility
  • What is the main function of a sampling circuit in a PCM transmitter?

    <p>To periodically sample the analog input voltage and convert the samples to pulses</p> Signup and view all the answers

    What is a characteristic of Pulse Code Modulation (PCM) signals?

    <p>A group of pulses that represents the inputted analog data</p> Signup and view all the answers

    Why is PCM the most preferred method in telecommunications?

    <p>Because it offers ease of digitizing voice and digital data with high-speed signal transmission</p> Signup and view all the answers

    What is the main limitation of natural sampling?

    <p>It alters the frequency spectrum and introduces an error called aperture error.</p> Signup and view all the answers

    What is the primary function of a sample-and-hold circuit?

    <p>To periodically sample the continually changing analog input voltage.</p> Signup and view all the answers

    What is the advantage of flat-top sampling over natural sampling?

    <p>It introduces less aperture distortion.</p> Signup and view all the answers

    What is the primary method used for sampling voice signals in PCM systems?

    <p>Flat-top sampling.</p> Signup and view all the answers

    What is the result of the sampling process in natural sampling?

    <p>The frequency spectrum of the sampled output is different from that of an ideal sample.</p> Signup and view all the answers

    What is the purpose of the sample-and-hold circuit in PCM systems?

    <p>To periodically sample the continually changing analog input voltage.</p> Signup and view all the answers

    Study Notes

    Pulse Code Modulation (PCM)

    • A digital encoding modulation technique that converts an analog signal into a digital signal via sampling.
    • PCM signal consists of a group of pulses that represent the inputted analog data.

    History of PCM

    • Invented by Alec H. Reeves in 1937 while working for AT&T.

    Advantages of PCM

    • Most preferred method in tele-communications for digitizing voice and digital data.
    • Offers ease of digitizing voice and digital data with high-speed signal transmission through metallic and optic-fiber cables.

    Limitations of Other Modulation Techniques

    • PPM and PWM have bandwidth limitations due to resolution requirements in transmitting 16-bits and beyond.
    • PAM is susceptible to noise, affecting the recovered signal.

    PCM Transmitter and Receiver

    • Function of a sampling circuit in a PCM transmitter is to periodically sample the continually changing analog input voltage and convert those samples to a series of constant amplitude pulses.
    • Sampling circuit allows for accurate conversion of voltage to a binary code by the ADC.

    Sampling Techniques

    • Natural Sampling

      • Retains natural shape of sample pulses during the sample interval.
      • Makes it difficult for an ADC to convert the sample to a PCM code.
      • Alters the frequency spectrum of the sampled output.
    • Flat-top Sampling

      • Most common method used for sampling voice signals in PCM systems.
      • Accomplished in a sample-and-hold circuit.
      • Introduces less aperture distortion than natural sampling.
      • Can operate with a slower analog-to-digital converter.

    Sample-and-Hold Circuit

    • Periodically samples the continually changing analog input voltage and converts those samples to a series of constant-amplitude PAM voltage-levels.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Learn about the basics of Pulse Code Modulation, a digital encoding technique used to convert analog signals into digital signals. This quiz covers the concept of PCM, its history, and its applications in tele-communications.

    More Like This

    Quantization in Pulse Code Modulation
    10 questions
    Digital Signal Processing Quiz
    22 questions
    Pulse Code Modulation (PCM) Technique
    8 questions
    Introduction to Pulse Code Modulation (PCM)
    5 questions
    Use Quizgecko on...
    Browser
    Browser