Transmission

Question 1

What is serial transmission

Answer 1

Data is sent one bit at a time over a single wire/cable

Question 2

What is parallel transmission

Answer 2

Multiple bits of data are sent simultaneously over multiple wires

Question 3

Disadvantages of parallel

Answer 3

• skewing means that bits arrive at different times so data can arrive in the wrong order
• crosstalk occurs which can result in data corruption
• skewing and crosstalk mean the data needs to be resent
• So it’s more reliable over shorter distances
• uses more wires so is more expensive than serial

Question 4

Example of where parallel transmission can be used

Answer 4

Between components in a computer system

-In integrated circuits and within RAM

Question 5

What is synchronous data transmission?

Answer 5

• A clock signal (shared by the sender and receiver) is used to time when signals are sent.
• The signals, which are sent at regular intervals, will be
  received in the same order that they were sent.

Question 6

What is asynchronous data transmission?

Answer 6

• Uses start and stop bits to indicate the duration of a transmission.
• The start bit is either 0/1 and the stop bit is always the opposite of the start bit.
• The sender and receiver must use the same Baud rate and need only synchronise their clocks for the duration of data transmission.

Question 7

What is latency?

Answer 7

The time delay that occurs during transmission

Question 8

When is synchronous data transmission used?

Answer 8

• Used within the busses during the fetch-decode-execute cycle.
• Suitable for transmitting data in real-time systems as signals are sent at regular intervals

Question 9

What is baud rate?

and what is it measured in?

Answer 9

The number of signal changes that occur in a second

Measured in Bd

Question 10

What is bit rate?

Answer 10

The number of bits that are transmitted over a channel in a second

Question 11

How do you calculate bit rate?

Answer 11

bit rate = baud rate × number of bits per signal change

Question 12

What does increasing the bit rate mean?

Answer 12

The higher the bit rate, the faster the data arrives.

Question 13

What is bandwidth?

Answer 13

The range of frequencies that a communication channel can carry

Question 14

What is the relationship between bandwidth and bit rate?

Answer 14

They are directly proportional, the higher than bandwidth the higher the bitrate

Question 15

What is the advantage of using asynchronous transmission?

Answer 15

• Usually used by PC’s

- Doesn’t require a method of sharing the clock signal