Types of Communication

Question 1

What is data transmission?

Answer 1

• the transfer of data between two or more digital devices.

Question 2

What is serial data transmission?

Answer 2

• is where data is transmitted one bit at a time along a single data cable.

Question 3

What is parallel data transmission?

Answer 3

• where data is transmitted more than one bit at a time along separate data cables.

Question 4

What is the difference between serial data transmission and parallel data transmission?

Answer 4

• Serial data transmission sends bits in sequence
• Parallel data transmission sends bits all together.

Question 5

What are some advantages of serial data transmission?

Answer 5

• It can cover longer distances
• requires fewer channels/wires to transmit data
• cheaper

Question 6

what are features of serial data transmission?

Answer 6

• Serial data cable includes the USB (Universal Serial Bus)
• They have more wires for the control signals
• A PC has several USB ports for connecting peripherals
• they are reliable over shorter distances
• faster when transmitting data

Question 7

Which is better in speed? Serial or parallel?

Answer 7

• If a parallel data bus had eight cables it would, in theory, transmit data eight times faster than the single data cable used in a serial bus.

Question 8

Which is better of interference? Serial or parallel?

Answer 8

• There is interference between the parallel wires which reduces the bandwidth of parallel connections, so parallel transmission bit rate is limited by interference.

Question 9

What are connections like in serial and parallel?

Answer 9

• Connecting cables are short to minimise the interference effect with parallel transmission, whereas in the serial connection there is no interference or noise problem so connecting cables can be as long as 300 feet

Question 10

Which one uses more cables? Serial or Parallel?

Answer 10

Parallel data transmission uses more cables than serial data transmission: therefore, they are larger, more expensive to produce and more complex than serial cables.

Question 11

What are the advantages and disadvantages of serial data transmission?

Answer 11

• Cheaper (only one wire needed)
• For two way communication an
  extra wire needed
• Reliable but slow
• Serial transmissions is reliable over very long distances at very high frequencies
• Serial connectors such as USB connectors are much smaller and cheaper than parallel connectors

Question 12

What are the advantages and disadvantages of parallel data transmission?

Answer 12

• For two way communication, twice the number of lines are required
• Data is sent faster
• If data is sent in the wrong format, it has to be sent faster
• As speeds of transmission got higher and higher, parallel connection developed problems.
• Parallel transmission can be used only very short distance distances of up to about 2m

Question 13

What are the two types of data transmission?

Answer 13

• skew
• crosstalk

Question 14

What is skew data transmission?

Answer 14

• happens when the bits that are transmitted across parallel links travel at different speeds.
• Data can fall out of sync with the clock signal and therefore not being read correctly.

Question 15

What is Cross talk data transmission?

Answer 15

• occurs when electromagnetic interference between wires that are in proximity results in transmitting corrupted data that needs to be resent.

Question 16

What is the problem with cross talk data transmission?

Answer 16

• The problems of cross talk – refers to the electromagnetic interference between two adjacent channels or parallel wires
• It gets more pronounced at the frequency (speed of transmission) increase
• If data is corrupted, it has to be re transmitted.
• Cables last longer if they are not damaged as easily
• More re sending of data – the worst the performance

Question 17

What is synchronous data transmission?

Answer 17

• where a block of data is transmitted along with a computer-clock-generated timing signal; this will ensure that the data transmitter and receiver are synchronised.

Question 18

What is asynchronous data transmission?

Answer 18

• is where a data stream is not synchronised and transmitted at fixed time intervals

Question 19

What are features of synchronous data?

Answer 19

• The transmitter and the receiver using a common clock signal
• There is no need for start and stop bit – so more information can be send per unit of time
• Data sent at specific intervals
• Data is send at rising edge
• Acts as a unit of memory

Question 20

What are features of asynchronous data?

Answer 20

• There is no clock signal, so additional data is used to control communication
• Data is transmitter when available, rather than at certain intervals
• A start bit is send at the beginning of transmission so that the receiver can prepare for the incoming data,
• Stop signals are typically longer than one bit – so it’s ready for the arrival of the next data

Question 21

What is a start bit?

Answer 21

sent at the beginning of a transmission which means the receiver can prepare for the incoming daa

Question 22

What is a stop bit?

Answer 22

• receiver can recognise the next set of bits.