Transmission modes

Patkar Varde College Of Arts, Commerce & Science

Data Communication and Networking(DCN)

Practical External:-Presentation“Transmission Modes”

Submitted To:-“Ms. Mansi Dangarwala”

Submitted By:-Manaswi Sharma (185)

Data Transmission

Data transmission is the physical transfer of data (a digital bit stream) over a point-to-point or point-to-multipoint communication channel. Communication channel is any physical media like cables etc.

Data Transmission-Modes

Parallel Transmission

Transmitted simultaneously on separate wires.

Multiple circuits for connection.

Devices close to each other.

E.g. Data transmission between computer and printer.

Diagrammatic representation of parallel transmission

Advantages of parallel transmission:

1. Time required is only one clock cycle.2. Clock frequency can be kept low.

Disadvantages of parallel transmission:

3. Number of wires.4. Too many wires.

Serial Transmission

Transmitted serially on same wire.

Requires 1 wire to connect.

Close or far doesn’t create any problem.

E.g. Data transmission between computer and computer.

Diagrammatic representation of serial transmission

Advantages of serial transmission:

1. Only one wire is required.2. Reduced cost due to less number of conductors.

Disadvantages of serial transmission:

1. Speed of data transfer is low.2. To increase speed of data transfer, clock frequency

needs to be increased.

Types of Serial Transmission

In data communication, Timing control of the reception of bits is important. There are two methods of timing control for reception of bits.

Asynchronous data transmission:

Data bytes transmitted at any instant of time.

One byte at a time.

Ideal time between two bytes.

Different clock frequencies.

‘start’ and ‘stop’ bits are used.

Ideal time is not constant, also known as gaps.

Timing of signal is not important.

Diagrammatic representation asynchronous transmission

Advantages of asynchronous transmission:

1. Synchronization not necessary.2. Cheap scheme.

Disadvantages of synchronous transmission:

1. ‘start’ and ‘stop’ bits and gaps makes transmission slow.2. Timing error.

Synchronous data transmission:

Carried out under common master clock.

Transmitted as a block of bits.

Operate at same clock frequencies.

No ‘start’ and ‘stop’ bits required.

No gaps between data bytes.

Timing of signal is important.

Diagrammatic representation synchronous transmission

Advantages of asynchronous transmission:

1. Speed of data is much.2. Timing errors are reduced.

Disadvantages of synchronous transmission:

1. Data entirely dependent on timing.2. Devices should be properly synchronized.