Transmission Media

Transmission Media Medium                     Speed                        Cost Twisted Wire            300bps-10Mbps        Low Microwave                 256Kbps-100Mbps  Low Coaxial Cable            56Kbps-200Mbps    Low Fiber Optic Cable     500Kbps-10Gbps     High

PROTOCOL A system of digital rules for data exchange within or between computers.                   EXAMPLE:   Consider   the   communication   between   two individuals. They can only communicate provided they both speak the same language. A little more complex Comm. System Example Electronic Mail In Terms of a little more complex Comm. System ™   SENDER SIDE Input device and transmitter are components of a Personal Computer User of a PC wishes to send a message 'm' User activates electronic mail package e.g. hotmail Enters the message via input device (keyboard) Character string is buffered in main memory as a sequence of bits 'g' PC is connected to some trans system such as a Telephone Network via an I/O Transmitter                    like Modem Transmitter converts incoming stream 'g' into a signal 's' ™   RECEIVER SIDE The  transmitted  signal  's'  is  subject  to  a  number  of  impairments depending upon the                       medium Therefore, received signal 'r' may differ from 's'. Receiver  attempts  to  estimate  original  's'  based  on  its  knowledge  of the medium and                      received signal 'r' Receiver produces a bit stream g'(t) Briefly buffered in the memory Data  is  presented  to  the  user  via  an  output  device  like  printer,  screen etc. The data viewed by user m' will usually be an exact copy of the data sent 'm'