History of Data Communication 1940-1989
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Questions and Answers

What is the primary consequence of transmission impairment in data communication?

  • Increased speed of signal transmission
  • Alteration of the transmitted signal (correct)
  • Improved signal quality
  • Reduced data transfer rates

    • Which type of transmission media is best suited for industrial networks with high interference?

  • Microwave
  • Shielded Twisted Pair (STP) (correct)
  • Optical Fiber Cable
  • Unshielded Twisted Pair (UTP)

    • What is a common application of optical fiber cable?

  • Long-distance communication (correct)
  • Printed Circuit Boards (PCBs)
  • Local Area Networks (LAN)
  • CCTV surveillance

    • Which transmission medium is primarily used for cable TV and broadband internet?

    <p>Coaxial Cable</p> Signup and view all the answers

    Which of the following is a characteristic application of microwave transmission media?

    <p>Long-distance links</p> Signup and view all the answers

    Which component is responsible for converting a physical input to an electrical signal?

    <p>Input Transducer</p> Signup and view all the answers

    What is the primary purpose of the Source Encoder in digital communication?

    <p>Compression of data</p> Signup and view all the answers

    What does the Channel Encoder do during the transmission of digital signals?

    <p>Adds redundant bits for error correction</p> Signup and view all the answers

    Which of the following stages occurs first at the receiver end of a digital communication system?

    <p>Digital Demodulator</p> Signup and view all the answers

    How does the Channel Decoder contribute to the recovery of the original signal?

    <p>It corrects distortions by using redundant bits</p> Signup and view all the answers

    In digital communication, what is the main advantage of using Time Division Multiplexing (TDM) over Frequency Division Multiplexing (FDM)?

    <p>TDM simplifies the combining process for digital signals</p> Signup and view all the answers

    What role does the Digital Modulator play in the transmission process?

    <p>It converts digital signals into analog signals for transmission</p> Signup and view all the answers

    Which of the following best describes the function of the Source Decoder?

    <p>It recreates the original source output</p> Signup and view all the answers

    What is a characteristic of Binary ASK modulation?

    <p>Logic 1 is associated with a different amplitude other than that of logic 0.</p> Signup and view all the answers

    In 16-ary ASK, how many bits are considered together for modulation?

    <p>4 bits</p> Signup and view all the answers

    Which type of ASK uses multiple carrier waves, each with different amplitudes?

    <p>Non-coherent ASK</p> Signup and view all the answers

    What happens to the ASK wave when it is multiplied by the carrier wave during demodulation?

    <p>It produces an intermediate form that needs to be filtered.</p> Signup and view all the answers

    In Frequency Shift Keying (FSK), how is logic 1 represented in Binary FSK?

    <p>By a frequency of 50MHz.</p> Signup and view all the answers

    What is the bandwidth issue that arises with the ASK waveform?

    <p>It has abrupt changes in amplitude.</p> Signup and view all the answers

    In M-ary FSK, how is the frequency related to the bits?

    <p>Each symbol corresponds to a unique frequency.</p> Signup and view all the answers

    What process is used to convert the digital signal into an analog wave after demodulation in ASK?

    <p>Digital to Analog Converter</p> Signup and view all the answers

    What major advantage do digital signals have over analog signals in terms of signal quality?

    <p>They are less affected by distortion and interference.</p> Signup and view all the answers

    Which of the following is NOT a benefit of digital communication technologies?

    <p>Increased likelihood of security breaches.</p> Signup and view all the answers

    What transition in communication technology is noted to occur starting from 2017?

    <p>From human-triggered to AI-triggered communications.</p> Signup and view all the answers

    What crucial feature of digital signals aids in maintaining the secrecy of information?

    <p>Signal processing functions.</p> Signup and view all the answers

    Which technology opens new communication possibilities for humans and machines?

    <p>5G technology.</p> Signup and view all the answers

    What is the key difference in the nature of the signals used in traditional communication versus digital communication?

    <p>Traditional signals exist in analog form; digital signals are composed of 1s and 0s.</p> Signup and view all the answers

    What is a primary reason for the necessity of digitization in communications?

    <p>To reduce losses from distortion and interference.</p> Signup and view all the answers

    What strategy is employed in digital communication to prevent signal jamming?

    <p>Spread spectrum techniques.</p> Signup and view all the answers

    What is the primary purpose of a Digital to Analog Converter in signal processing?

    <p>To convert digital signals to analog waveforms.</p> Signup and view all the answers

    In Binary Phase Shift Keying (BPSK), which phase shift is used for logic 1?

    <p>90°</p> Signup and view all the answers

    What enables M-ary Phase Shift Keying to transmit multiple bits at once?

    <p>Encoding a group of bits into a single phase shift.</p> Signup and view all the answers

    What is a characteristic of coherent PSK?

    <p>It employs a single carrier wave for modulation.</p> Signup and view all the answers

    What happens to the signal during the modulation process in Phase Shift Keying?

    <p>The digital signal is multiplied by two different carrier waves.</p> Signup and view all the answers

    What is the purpose of the Band Pass Filter in Phase Shift Keying?

    <p>To reduce abrupt changes in phase.</p> Signup and view all the answers

    In M-ary PSK, how many phase shifts are required if 16 possible bits are being transmitted?

    <p>16 phase shifts.</p> Signup and view all the answers

    Which statement best describes the operation of a NOT gate in the context of PSK modulation?

    <p>It inverts the logic level of the input signal.</p> Signup and view all the answers

    What is the main reason for using a Band Pass Filter in Frequency Shift Keying?

    <p>To limit the bandwidth usage of the FSK wave</p> Signup and view all the answers

    In coherent Frequency Shift Keying, how are the frequencies created?

    <p>Using a single carrier wave for all frequencies</p> Signup and view all the answers

    What happens when logic 1 is multiplied with the carrier sine wave in Frequency Shift Keying?

    <p>It results in the original carrier wave signal</p> Signup and view all the answers

    What is the role of the comparator in the demodulation process of FSK?

    <p>To compare outputs from the Band Pass Filters and determine the digital output</p> Signup and view all the answers

    How many different frequencies are required for 16-ary FSK?

    <p>16 frequencies</p> Signup and view all the answers

    When logic 0 is present in the digital signal, what does it get multiplied with?

    <p>A sine wave with frequency f2</p> Signup and view all the answers

    What type of signal is created as the output of the multipliers during the FSK modulation process?

    <p>An FSK wave with abrupt changes in frequency</p> Signup and view all the answers

    Which logic gate is used to provide the opposite input to one of the multipliers during frequency modulation?

    <p>NOT gate</p> Signup and view all the answers

    Study Notes

    History of Data Communication

    • 1940: George Stibitz pioneered networking technology by sending computing commands over a teletype machine.
    • 1943: Teletype technology enabled the transmission of punched cards at 25 bits per second.
    • 1948: Teletype modems facilitated image transmission across the US.
    • 1958: American Telephone and Telegraph (AT&T) improved computer modem speeds to 110 bits per second.
    • 1962: AT&T introduced the Bell 103 Data Phone, allowing digital data transmission on regular phone lines. J.C.R. Licklider led the development of the ARPANET.
    • 1965: Thomas Marill and Lawrence Roberts created the first wide-area computer network, a precursor to the ARPANET.
    • 1977: Dennis Hayes and Dale Heatherington designed the Hayes 80-130A modem.
    • 1981: The Hayes Smartmodem improved modem speed and functions, becoming affordable.
    • Mid 80s: IBM PC clones, and the rise of PCI modem cards expanded network capabilities.
    • 1989: Tim Berners-Lee facilitated advances in web browsing interface and online content.
    • Mid 90s: Modem costs decreased, and speeds increased drastically.

    Home Broadband and Communication

    • 1996: Brent Townshend developed the 56K modem technology.
    • Early 2000s: Analog phone lines (ISDN), ADSL, and Cable TV modems were alternatives to analog systems.
    • 2002: The launch of 3G enabled widespread application services, including mobile internet.
    • Mid 2000s: Wireless access became widely available and less expensive.
    • 2009: 4G/LTE cellular standards provided high-speed data transmission.
    • 2011-2014: High-speed fiber optic communication gained popularity.
    • 2015: Network function virtualization enhanced modem functions through software.
    • 2017 and Beyond: AI triggered communications and 5G advancements are shaping technology.

    Digital Communication - Analog to Digital

    • Signals in everyday life are usually analog in nature.
    • Digital signals utilize 1s and 0s (high and low values) for transmission.
    • Losses in analog signals (such as distortion, interference) are minimized in digital transmissions
    • Digital signals are more reliable, manageable and easier to design and process compared to analog signals.
    • Digital devices utilize common encoding techniques that make them compatible for many purposes
    • Digital signals use less bandwidth
    • Digital signals are easier to encode and decode when distances are long.

    Advantages of Digital Communication

    • Reduced effect of distortion, noise and interference
    • More reliable digital circuits
    • Easier to design and cheaper digital circuits
    • More flexible hardware
    • Reduced cross talk

    Elements of Digital Communication

    • Source: The original information source (e.g., sound).
    • Input Transducer: Converts physical input to electrical signal (e.g., microphone).
    • Source Encoder: Compresses data, removing redundant bits.
    • Channel Encoder: Adds redundant bits for error correction during transmission.
    • Digital Modulator: Converts the digital signal to an analog signal for transmission over a channel.
    • Channel: Physical medium for transmission.
    • Digital Demodulator: Converts the analog signal back to a digital format.
    • Channel Decoder: Removes redundant bits added by the encoder.
    • Source Decoder: Reconstructs the original data from the coded form.
    • Output Transducer: Converts electrical signal to physical output (e.g., speaker).
    • Output Signal: Final reproduced signal.

    Modulation Techniques

    • Pulse Code Modulation (PCM): Converts analog signals into binary sequences (pulses) -The process of varying one or more parameters to make a carrier signal
    • Amplitude Shift Keying (ASK): Changes carrier wave amplitude to represent binary data.
    • Frequency Shift Keying (FSK): Changes carrier wave frequency to represent binary data.
    • Phase Shift Keying (PSK): Changes carrier wave phase to represent binary data.
    • M-ary Encoding: Transmits multiple bits simultaneously by using various modulation schemes (e.g., M-ASK, M-FSK, M-PSK)

    Types of Transmission Media

    • Guided Media (Wired): Signals travel along a physical path.
      • Twisted Pair Cable: Inexpensive, easy to install, but susceptible to interference and limited distance.
      • Coaxial Cable: Higher bandwidth, less susceptible to interference than twisted pair but more expensive and bulky.
      • Optical Fiber Cable: Very high bandwidth, immune to interference and electromagnetic noise, but expensive and difficult to install and maintain
    • Unguided Media (Wireless): Signals travel through the air.
      • Radio Waves: Omni-directional, used for long-distance communication, susceptible to interference, high attenuation.
      • Microwaves: Uni-directional, high bandwidth; used in mobile phone communication, television, and radar systems.
      • Infrared Waves: Short-range, unidirectional, used for remote controls and short-range wireless communications.
      • Stripline / Microstripline:Used in circuits and applications requiring high frequencies, like microwave circuits and antennas.

    Transmission Impairment

    • Attenuation: Loss of signal strength over distance.
    • Distortion: Signal shape changes during transmission/mismatch to the desired bandwidth
    • Noise: Random unwanted signals added to the original signal during transmission.

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    History of Data Communication PDF

    Description

    Explore the pivotal milestones in the history of data communication from 1940 to 1989. Learn about key innovations such as teletype technology, the introduction of modems, and the development of early computer networks like ARPANET. Understand how these advancements shaped modern networking technology.

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