Dccn - Digital Transmission
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The document discusses various digital transmission methods, including encoding techniques for converting digital data into signals. It covers line coding types such as unipolar, polar, return-to-zero, and Manchester encoding, as well as modulation techniques like amplitude, frequency, and phase modulation. Additionally, it addresses transmission modes such as asynchronous and synchronous transmission.
![Data Communication
and Computer Networks
[EEE 314]
Mubashir Husain RehmaniMubashir Husain Rehmani
Assistant Professor
Department of Electrical Engineering
COMSATS Institute of Information Technology,
Wah Cantt, Pakistan](https://image.slidesharecdn.com/dccnlecture19compatibilitymode1-170621222722/85/Dccn-Digital-Transmission-1-320.jpg)
Dccn - Digital Transmission
- 1. Data Communication and Computer Networks [EEE 314] Mubashir Husain RehmaniMubashir Husain Rehmani Assistant Professor Department of Electrical Engineering COMSATS Institute of Information Technology, Wah Cantt, Pakistan
- 5. LineLine coding is the process ofcoding is the process of converting digital data to digitalconverting digital data to digital signalssignalssignalssignals
- 6. Line Coding
- 7. Signal Level vs Data Level
- 9. Line Coding
- 10. Unipolar encoding uses only one voltage level. In a unipolar scheme, all the signal levels are on one side of the time axis, either above or below.
- 12. Polar encoding uses two voltagePolar encoding uses two voltage levels (positive and negative).levels (positive and negative).
- 13. Types of Polar Encoding
- 14. NRZ Non Return to Zero NRZ-L Non Return to Zero - Level NRZ-I Non Return to Zero – Inverted
- 15. In NRZIn NRZ--L the level of the signal isL the level of the signal is dependent upon the state of thedependent upon the state of the bit.bit.bit.bit.
- 16. In NRZIn NRZ--I the signal is inverted if aI the signal is inverted if a 1 is encountered.1 is encountered.
- 17. NRZ-L and NRZ-I
- 18. RZ Encoding Return-to-zero (RZ) scheme uses three values: positive, negative, and zero. In RZ, the signal changes not between bits but during the bit. The signal goes to 0 in the middle of each bit. It remains there until the beginning of the next bit.
- 19. Manchester Encoding In Manchester encoding, the duration of the bit is divided into two halves. The voltage remains at one level during the first half and moves to the other level in the second half.
- 20. In Manchester encoding, theIn Manchester encoding, the transition at the middle of the bittransition at the middle of the bit is used for both synchronizationis used for both synchronizationis used for both synchronizationis used for both synchronization and bit representation.and bit representation.
- 22. In differential ManchesterIn differential Manchester encoding, the transition at theencoding, the transition at the middle of the bit is used only formiddle of the bit is used only for synchronization.synchronization.synchronization.synchronization. The bit representation is definedThe bit representation is defined by the inversion orby the inversion or noninversionnoninversion at the beginning of the bit.at the beginning of the bit.
- 23. In bipolar encoding, we use threeIn bipolar encoding, we use three levels: positive, zero,levels: positive, zero, and negative.and negative.and negative.and negative.
- 24. Types of Bipolar Encoding
- 26. B8ZS Encoding
- 28. Analog to Digital Encoding
- 29. Pulse Code Modulation (PCM) The Analog signal is Sampled The Sampled signal is Quantized The Quantized values are encoded as stream of bitsof bits
- 30. Sampling: PAM
- 33. Digital to Analog Encoding
- 35. Bit rate is the number of bits per second. Baud rate is the number of signal units per second. Baud rate issignal units per second. Baud rate is less than or equal to the bit rate.
- 38. ASK In amplitude shift keying, the amplitude of the carrier signal is varied to create signal elements. Both frequency and phase remain constant while the amplitude changes.
- 39. FSK In frequency shift keying, the frequency of the carrier signal is varied to represent data.
- 40. PSK In phase shift keying, the phase of the carrier is varied to represent two or more different signal elements. Both peak amplitude and frequency remain constant as the phase changes.
- 41. PSK Consetllation A constellation diagram can help us define the amplitude and phase of a signal element
- 42. 4-PSK Method
- 44. 8-PSK
- 45. QAM Quadrature amplitude modulation is a combination of ASK and PSK so that a maximum contrast between each signalmaximum contrast between each signal unit (bit, dibit, tribit, and so on) is achieved.
- 46. Table 5.1 Bit and baud rate comparison ModulationModulation UnitsUnits Bits/BaudBits/Baud Baud rateBaud rate Bit Rate ASK, FSK, 2ASK, FSK, 2--PSKPSK Bit 1 N N 44--PSK, 4PSK, 4--QAMQAM Dibit 2 N 2N 88--PSK, 8PSK, 8--QAMQAM Tribit 3 N 3N 1616--QAMQAM Quadbit 4 N 4N 3232--QAMQAM Pentabit 5 N 5N 6464--QAMQAM Hexabit 6 N 6N 128128--QAMQAM Septabit 7 N 7N 256256--QAMQAM Octabit 8 N 8N
- 50. In asynchronous transmission,In asynchronous transmission, we send 1 start bit (0) at thewe send 1 start bit (0) at the beginning and 1 or more stopbeginning and 1 or more stopbeginning and 1 or more stopbeginning and 1 or more stop bits (1s) at the end of each byte.bits (1s) at the end of each byte. There may be a gap betweenThere may be a gap between each byte.each byte.
- 51. Asynchronous here meansAsynchronous here means “asynchronous at the byte level,”“asynchronous at the byte level,” but the bits are stillbut the bits are stillbut the bits are stillbut the bits are still synchronized; their durations aresynchronized; their durations are the same.the same.
- 53. In synchronous transmission,In synchronous transmission, we send bits one after anotherwe send bits one after another without start/stop bits or gaps.without start/stop bits or gaps.without start/stop bits or gaps.without start/stop bits or gaps. It is the responsibility of theIt is the responsibility of the receiver to group the bits.receiver to group the bits.
- 55. Modulation of Analog Signals Amplitude Modulation (AM) Frequency Modulation (FM) Phase Modulation (PM)
- 56. Analog to Analog Modulation
- 57. Types of Analog Modulation
- 58. AM
- 59. FM