Unit 1.3 HC: The Code Paradigm Flashcards
What is a cipher?
Set of rules that maps symbols onto another set of symbols
What is a code?
Systems that map a set of meaningful units onto another set of meaningful units
Who is Claude Shannon
Proposed the information Theory in 1948
Book - A mathematical theory of communication
Draw the diagram of the information theory
**See slides
What is the physical channel?
Information theory considers communication as a physical channel.
Signal is sent from transmitter –> receiver.
What is channel capacity?
There is a limit to speed, efficiency and maximum volume of concentrations
What is the conceptual challenge of information theory?
Quantity of info transmitted (not WHAT is being)
Conceptualising info such that it allows quantification and measurement
What is informations role in uncertainty?
Information is a measure of uncertainty reduction
What is the first golden rule? Example?
Information is inversely proportional to the likelihood or frequency of something.
e.g. hebrew/arabic - leave out vowels.
Efficient code
What is efficient code?
assigning simpler signals to the more frequent elements (e.g. morse code)
What is the 2nd golden rule?
when all options are equally probable, you can reduce uncertainty but coding signals in a way that reduces no. of potential options by half
What is compact code?
Every possible combo of signals means something. It is optimally efficient
What is noise?
They are irrelevant data with no information.
They occur alongside signals and can distort them and result in decoding mistakes.
What is redundancy?
Strengthens the signal - allowing the receiver to understand it correctly
PROCESS: Add unnecessary elects, repeat several time & send through several channels.
OUTCOME: This protects from noise
4 requirements of the information theory (also acts as limitations)?
Code should be DIGITAL (not analog)
code should be INFINITE (e.g. sentences, words etc)
Objects should be EQUALLY CODABLE (between speakers/listeners)
code should be AMBIGUOUS
