Engineering Questions with Answers - Multiple Choice Questions
MCQs on Parallel and Serial Transmission
In a parallel communication, each bit requires a transmitter and receiver.
Explanation: In a parallel transmission each bit is transmitted in a separate wire. Since each bit is transmitted individually, each bit requires a separate transmitter and a receiver.
What is the cable that carries the information in parallel transmission called?
a) Parallel line
b) Data bus
c) Data line
d) Data link
Explanation: In a parallel transmission multiwire cables are used. These cables carry a bit in each wire and are referred as data bus.
Which of the following is a false reason for parallel lines not being used for long distances?
a) Cost factor
b) Signal Attenuation
c) Number of transmission channels
d) Low speed
Explanation: One of the major disadvantages of using parallel transmission for long distance is that laying the data bus is costly. To cover a distance of 10km for an 8 bit system, we need a cable of 80km length. Parallel data are usually faster than serial since all the bits are transmitted simultaneously.
Why higher speed communications in parallel transmission require shorter length?
c) Inductive and capacitance effects
Explanation: As the speed of transmission or the frequency of transmission increases the wavelength of transmission becomes comparable with the length of the data bus. This causes inductive and capacitance effects which degrade the signal.
Which bit is transmitted first in a serial communication?
a) Least significant bit
b) Most significant
c) All the bits simultaneously
d) Not in any specific order
Explanation: In serial transmission, the bits are transmitted one after the other in a specific order. The least significant bit is transmitted first and the most significant bit is transmitted in the end.
In serial communication, if the time interval to transmit one bit is 10μs. What is the time to transmit an 8-bit word?
Explanation: Total transmission time = time for each bit x total number of bits = 8 x 10μs = 80μs.
In parallel communication, if the time interval to transmit one bit is 10μs. What is the time to transmit an 8-bit word?
Explanation: Since all the bits are transmitted simultaneously, the time taken for the transmission of one bit is equal to the time taken for the transmission of any number of bits. Therefore the time taken is 10μs.
The devices that convert serial to parallel and parallel to serial are called?
b) Transmission converters
Explanation: Parallel transmission is high speed and serial data can cover longer distances. Hence they are used interchangeably and the devices which convert serial to parallel and parallel to serial transmission is called serializer/deserializer device (SERDES).