Wednesday, April 11, 2012

Chapter 2

Data Transmission 
How data was transmitted?
It can be transmit by :

– Analog vs digital
– Bandwidth
– Serials Vs Parallel
– Transmission timing
– Transmission directions
– Circuit switched, Packet‐Switched, and Broadcast Connections

Analog transmission uses signals that are exact replicas of a sound wave or image. Signals of varying frequency or amplitude are added to carrier waves with a given frequency of electromagnetic current to produce a continuous electric wave E.g standard phones, fax
machines, and modems.     

Digital transmission the signals are converted into a binary code, which consists of two elements. Digital format is ideal for electronic communication as the string of 1s and 0s can be transmitted by a series of "on/off" signals represented by pulses of electricity or light.

Bandwidth is equal to the amount of data that can be transmitted in a fixed amount of time. Usually, bandwidth is measured in bits per second (bps), Megabits per second (Mbps) and etc. Medium with higher bandwidth can deliver data faster.

Serial vs Parallel Transmission 

Serial Transmission

Serial transmission : data sent one bit at a time, one after another a long a single path

Parallel Transmission 
Parallel Transmission : data is sent at least one byte at a time, each bit in the byte taking separate path

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