Synchronous Systems Flashcards
What is essential in synchronous systems
Their clocks must be synchronised
Why do synchronous systems require an extra element?
To inform the receive terminal where a block of data begins and ends!
How can a synchronous system ensure their clocks are synchronised ?
Provide a separate clock line between terminals, or embed the clocking information into the transmitted data
How do synchronous systems allow the receive terminal to determine the beginning and ending of a transmission ?
Each block of data begins with a preamble but pattern, and ends with a post amble bit pattern.
What can a pre amble and post amble be also known as?
Control information
The data and control information, together, are known as what?
The frame
What two formats can a frame be in ?
Character orientated or bit orientated
In character orientated transmissions, how long is the block of data usually?
8 bits in length
How is the block of data treated within character orientated ?
As a sequence of characters
What character would a frame begin with in a character orientated transmission ?
One or more SYN characters, or synchronisation characters, that is a unique bit patten
How does a character orientated transmission signal it has come to the end of the frame?
By using a unique character referred to as the post amble
How else, other than a post amble, can a character orientated transmission signal the end of a black of data
Include the frame length within the control information
How is the block of data treated within bit orientated transmission?
As a sequence of bits
How does a bit orientated signal signal the beginning and end of a transmission ?
By using a special bit pattern called a flag, using the same flag as the start and stop bits
What must be ensured within a bit orientated transmission ?
That the start and stop flags are not repeated in the rest of the data
