data transmission

Data communication

1. DATA TRANSMISSION 2.1 CONCEPTS AND TERMINOLOGY 2.2 ANALOG AND DIGITAL DATA TRANSMISSION 2.3 TRANSMISSION IMPAIRMENTS

2. DATA TRANSMISSION

3. The successful transmission of data depends principally n two factors; Quality of the signal being transmitted The characteristics of the transmission medium ( Bandwith , cost, ease of installatio , etc …)

4. Concepts and Terminologies Data transmission and terminologies occurs between transmitter and receiver over some transmission medium.

5. Direct link used to refer to the transmission path between two devices in which signals propagate directly from transmitter to receiver with no intermediate devices , other than amplifiers or repeaters used to increase signal strength. This term can apply to both guided and unguided media.

6. Multipoint guided configuration , more than two devices share the same medium.

7. Electromagnetic signals is use as a means to transmit data. The signal is a function of time, but it can also be expressed as function time, but it can also be expressed as a function of frequency; that is the signal components of different frequencies. It turns out that the frequency-domain view of signal is far more important to understanding of data transmission than a time-domain view .

8. Analog and Digital Data Transmission The terms analog and digital corresponds roughly to continuous and discrete , respectively. These two terms are frequently in data communications in at least three context. Data Signaling Transmission

9. We can define data as entities that convey meaning. Signals are electric or electromagnetic encoding data. Signaling is the act of propagating the signal along a suitable medium. Finally transmission is the communication of data by the the propagation and processing of signals.

10. Transmission Impairments The impairment is caused by the strength of signals that degrades with distance over a transmission link.

11. The most significant impairments are: Attenuation Delay distortion Noise

12. ATTENUATION refers to lose energy by a signal time When a signal, sample or composite, travels through a medium it loses some of its energy in overcoming the resistance of the medium. It compensate for this lose, amplifier are used.

13. DISTORTION Distortion means signal changes its form and shape. Distortion can occur in a composite signal made of different frequency. Each component have its own propagation sped through a medium and therefore its own delay in arriving at the final signal.

14. Noise maybe devided into four categories: Thermal use Intermodulation Crosstalk Impulse noise