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Paper 2 - Computer Science > Transmission > Flashcards

Flashcards in Transmission Deck (15)
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What is serial transmission

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


What is parallel transmission

Multiple bits of data are sent simultaneously over multiple wires


Disadvantages of parallel

- 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


Example of where parallel transmission can be used

Between components in a computer system
-In integrated circuits and within RAM


What is synchronous data transmission?

- 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.


What is asynchronous data transmission?

- 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.


What is latency?

The time delay that occurs during transmission


When is synchronous data transmission used?

- 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


What is baud rate?
and what is it measured in?

The number of signal changes that occur in a second
Measured in Bd


What is bit rate?

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


How do you calculate bit rate?

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


What does increasing the bit rate mean?

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


What is bandwidth?

The range of frequencies that a communication channel can carry


What is the relationship between bandwidth and bit rate?

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


What is the advantage of using asynchronous transmission?

-Usually used by PC's
-Doesn't require a method of sharing the clock signal