1 / 17

Types of Digital Signal Encoding for Data Communication

Learn about different encoding types like Unipolar, NRZ, Manchester, Bipolar-AMI, and more used in digital data communication for effective signal transmission.

davidjharris
Download Presentation

Types of Digital Signal Encoding for Data Communication

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 5: Encoding • Information must be encoded into signals before it can be transported across communication media • Information can be either • Digital, or • Analog • Signals can be also of two types: • Digital • Analog CS433 - Data Communication and Computer Networks

  2. Types of Encoding CS433 - Data Communication and Computer Networks

  3. Digital-to-Digital Encoding CS433 - Data Communication and Computer Networks

  4. Unipolar • Uses only one level of value (polarity) • Pros: simple and inexpensive • Cons: DC component direct current component with zero frequency) and synchronization (occur whenever the data stream includes a long uninterrupted series of 1’s and 0’s the solution is another line carrying a clock pulse allow the receiver to resynchronize its timer but cost is high) • Digital Transmission systems work by sending voltage pulses along a medium • Polarity: weather the pulse is negative or positive 1’s are positive values 0’s are 0 values 0 1 0 0 1 1 1 CS433 - Data Communication and Computer Networks

  5. Polar • Uses two levels of amplitude • Each bit consists of both positive and negative voltage • Dc component is totally eliminated CS433 - Data Communication and Computer Networks

  6. Non-Return to Zero (NZR) • The level of the signal is always either positive or negative • NRZ-Level : the level of the signal is dependent on the state of the bit (ex. +  1 and –  0) a problem arises when long stream of 0’s and 1’s in the data so the receiver receives a continuous voltage and cannot determine number of bits its clock cannot synchronize with sender clock. • NRZ-Inverted: The signal is inverted if a 1 is encountered supirur to • Less DC-component and more synchronization than Unipolar CS433 - Data Communication and Computer Networks

  7. 0 1 0 0 1 1 1 0 NRZ NRZ-L NRZ-I CS433 - Data Communication and Computer Networks

  8. Return to Zero (RZ) • Uses three signal values: positive, zero, and negative • There is a signal change for each bit (negative-to-zero for 0 and positive-to-zero for 1 • Excellent synchronization • Disadvantage: It needs more bandwidth since two signal changes per bit CS433 - Data Communication and Computer Networks

  9. 0 1 0 0 1 1 1 0 RZ CS433 - Data Communication and Computer Networks

  10. Biphase • Manchester: negative-to-positive transition represents 1 and a positive-to-negative transition represents 0. • Transition at the middle of the bit is used for both synchronization and bit representation. • Differential Manchester: a transition means 0 and no transition means 1. • Transition at the middle of the bit is used only for synchronization. Bit representation is shown by the inversion or noninversion at the beginning of the bit. CS433 - Data Communication and Computer Networks

  11. 0 1 0 0 1 1 1 0 Biphase Manchester Differential Manchester CS433 - Data Communication and Computer Networks

  12. Bipolar • Uses three signal levels: positive, zero, and negative • Zero level represents binary 0 • Positive and negative levels represent alternating 1s CS433 - Data Communication and Computer Networks

  13. Bipolar Encoding Bipolar AMI B8ZS HDB3 CS433 - Data Communication and Computer Networks

  14. 0 1 0 0 1 1 1 0 Alternate Mark Inversion (AMI) • Zero voltage represents binary 0. • Binary 1s are represented by alternating positive and negative signals. CS433 - Data Communication and Computer Networks

  15. Digital signal encoding formats 0 1 0 0 1 1 0 0 0 1 Unipolar NRZL NRZI RZ Manchester Differential Manchester Bipolar-AMI Pseudoternary CS433 - Data Communication and Computer Networks

  16. Bipolar 8-Zero Substitution (8BZS) • A convention adopted in North America to provide synchronization of long string of 0s • If eight or more consecutive 0s are encountered, enforce violations to the bipolar coding as follows: • if the previous polarity is positive: 000+-0-+ • if the previous polarity is negative: 000-+0+- CS433 - Data Communication and Computer Networks

  17. + 0 0 0 0 + 0 0 0 0 - 0 0 0 0 - 0 0 0 0 + 0 0 0 + + - 0 0 - - 0 0 0 - - + 0 0 + High-Density Bipolar 3 (HDB3) • Adopted in Europe and Japan. Number of 1s since last substitution is odd Number of 1s since last substitution is even CS433 - Data Communication and Computer Networks

More Related