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    Modulation

    Anyone know anything about amplitude frequency and phase modulation?

    22 Comments

    a bit... going back a while now though. what's the question?

    Original Poster

    Describe what they are lol, google just brings up a bunch of diagrams, i have to fill half a page for each

    to what level are you studying. back when i was at college wikipedia was my friend when it came to stuff like this. i ve had a quick look and it all seems correct. definitely enough information on there to condense to half a page.

    EDIT: SNAP

    A Tip for Wikipedia though, try to cross reference it with say 2 other sources to make sure its reliable. The uni course im doing mentions this as anyone can edit Wiki.

    Original Poster

    Alright lads nice one for that, anyone know were i can find information on these...

    Binary Coded Decimal (BCD)

    Relative Encoding

    Character Suppression

    Huffman Coding/Dynamic Huffman Coding

    Need to get at least 8 lines to do with them and searched google but most of them dont give me much to take from. thanks.

    In what context do you need the answers for,

    Example a ]google search for " Relative Encoding" give results and examples used in many processes

    Original Poster

    This is what i originally had...

    Relative Encoding

    This is an alternative for numerical data and it only sends the difference in size between each value which can be found useful for data logging.


    Character Suppression

    This looks for characters that are repeated 3 or more times. It then sends a control character followed by the actual character followed by the number of actual characters in the run


    Huffman Coding/Dynamic Huffman Coding

    Looks for characters that are repeated more frequently than others and encodes them with fewer bits than the characters which occur infrequently


    Facsimile Compression

    Can achieve greater than 10:1 compression with digitised images simply because there can be long strings of the same data (a particular colour)


    but i need to expand on these to pass

    I don't think there is a need for Colleges and Uni's anymore. Just give everyone a laptop, a broadband connection and a link to Google or Wiki !
    A few virtual tutors and a secure examination site and Bob's your uncle !

    Easy, I just solved the Governments education problems in 3 short sentences !

    Ha, think how boring it is for us poor lecturers when you get 20 copies of wikipedia to mark! :-D

    And students think editing it to make it seem like their own work is just filling it with their own special spelling mistakes hehe

    Give some more examples of where you might use the different compression algorithms, for example huffman encoding will be used in documents such as text files as they can use letter frequency statistics (e is most common letter etc). Wouldn't be as good for binary files as they generally have equal weights, although in advanced compression systems an 'alphabet' can be custom-made to the data it is encoding. Character suppresion is alo known as ]run length encoding and is good for compressing diagrams and drawings (but not photos as adjacent pixels are usually different).

    Leila70;1527091

    Ha, think how boring it is for us poor lecturers when you get 20 copies … Ha, think how boring it is for us poor lecturers when you get 20 copies of wikipedia to mark! :-DAnd students think editing it to make it seem like their own work is just filling it with their own special spelling mistakes hehe



    Hehehehe !...........owned I think is the term they use isn't it ?

    homer_213;1526717

    A Tip for Wikipedia though, try to cross reference it with say 2 other … A Tip for Wikipedia though, try to cross reference it with say 2 other sources to make sure its reliable. The uni course im doing mentions this as anyone can edit Wiki.



    Wiki is great in that most things stated there have plenty of articles linked to from Wiki to back them up... it's improved a lot lately.

    duckmagicuk2;1527189

    Wiki is great in that most things stated there have plenty of articles … Wiki is great in that most things stated there have plenty of articles linked to from Wiki to back them up... it's improved a lot lately.



    its also got better as its got bigger cause for however many people are ********ed enough to change things there are more geeks who are extremely aggitated by this and put it back

    if its a peice of hand in coursework then wilki shouldnt be referenced even if used because uni's frown upon it due to the unrealibility of it

    Text book?;-)

    Original Poster

    Nice one lads, you just saved my life me teacher kept failing my assignments as he doesn't like me but after he failed me today i got another teacher to check and he passed me easily, nice one.

    Original Poster

    Ok need one last bit of help, this is to do with error control.

    this is what i have so far

    Error Control

    The reason we need error control is to make sure that the data that was sent from one end of the transmission is the same data that was received at the other. If an error was to occur then it is usually suspected to have been caused by either EMI or timing errors. There are 2 basic strategies for error control, the first being Forward error control (FEC), this is mainly used when retransmission is either impossible or impractical or if redundant information is transmitted with the original bit stream. The other method of error control is Automatic Repeat Request (ARQ), this is perhaps the most popular strategy used in error control as it uses error detection along with a retransmission of corrupt data.

    I need to provide an example of the part in bold, but i dont remember were i sourced my info from as it was few months ago, thanks if you pull me through again my friends

    Is ]this what you need?

    ]More

    DVB digital television and digital radio etc. are examples of the use of forward error control (the information cannot be resent if there is bad reception etc).

    Edit - by the way, its shouldn't be "the other method of error control", it should be "another method of error control" as the former implies it is the only alternative which it isn't.
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