The document discusses different modes of data transmission: parallel transmission, serial transmission, asynchronous transmission, and synchronous transmission. Parallel transmission transmits data simultaneously over multiple wires, allowing for high speed but requiring many wires. Serial transmission transmits data over a single wire, reducing costs but resulting in lower speeds. Asynchronous transmission uses start and stop bits but does not require synchronization, while synchronous transmission operates under a common clock, transmitting data as blocks without start/stop bits but requiring precise timing.

1. Data Communication and Networking
(DCN)
Practical External:-Presentation
“Transmission Modes”
Submitted To:-
“Ms. Mansi Dangarwala”
Submitted By:-
Manaswi Sharma (185)

2. 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.

4.  Transmitted simultaneously on separate wires.
 Multiple circuits for connection.
 Devices close to each other.
 E.g. Data transmission between computer and
printer.

6. Advantages of parallel transmission:
1. Time required is only one clock cycle.
2. Clock frequency can be kept low.
Disadvantages of parallel transmission:
1. Number of wires.
2. Too many wires.

7.  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.

9. 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.

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

11.  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.

13. 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.

14.  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.

16. 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.