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Line Coding

line-coding

September 18, 2016
Published By : Pratik Kataria
Categorised in:

line-coding

Introduction

The process of converting digital data to digital signals. Digital data – sequences of bits.

Characteristics

  • Data rate vs. signal rate
    • Data rate (bit rate) – the number of data elements in a unit time (bps).
    • Signal rate (pulse, modulation rate, baud rate) – the number of signal element in a unit time (baud).
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  • No. of Signal Levels
    • Two data levels,
      Two Signal levels
      line-coding-2
    • Two data levels
      Three signal levels
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  • DC components
    • It is the mean value of the waveform. If the mean amplitude is zero, there is no DC offset.
    • unable to pass a low-pass filter or Over one cycle period if all positive voltage are cancelled by negative volatge then the DC component of the waveform is zero.
    • In line coding, the signal with non-zero dc component is treated as distorted one and it can create errors in the received signal.
  • Bandwidth
    • Although the actual bandwidth of a digital signal is infinite, the effective bandwidth is finite.
  • Self synchronization
    • the clocks at the sender and the receiver must have the same bit interval. If the receiver clock is faster or slower it will misinterpret the incoming bit stream.

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