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Thread: Maths/Calculator help please!

  1. #1
    Va Va Voom Lowe's Avatar
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    Maths/Calculator help please!

    I'm severely rusty when it comes some maths and need a bit of help using the old scientific calculator!

    Right I'm working out a bit of stuff with the relationships between decibels and watts.

    So, for my example, 80w = 19dB

    You work this out on the calculator by pressing:

    80
    Log
    x
    10
    =

    Now lets say I want to go the other way... Which button is the opposite of Log?

  2. #2
    The King of Vague Steve B's Avatar
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    its 10^(db/10)
    Code:
    Power in watts = 10^(db/10)
                   = 10^(1.9)
                   = 80W
    Last edited by Steve B; 02-08-2007 at 03:06 PM.

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    Lowe (02-08-2007)

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    Gaarrrrr! Dav0s's Avatar
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    its not quite that easy, but basically...

    10^ is the opposite of log.

    so...

    10log80 = 19

    log80 = 1.9

    to "reverse" this, you would do

    10^1.9 which is roughly 80.


    so in your example, you would take the dB, divide it by 10, and then do 10 to the power of that.

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    Lowe (02-08-2007)

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    Ta

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    The King of Vague Steve B's Avatar
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    my maths skills are as rusty as yours

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    HEXUS webmaster Steve's Avatar
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    Quote Originally Posted by Steve B View Post
    my maths skills are as rusty as yours
    You do an engineering course !!!!111one(lim(x->0,sin(x)/x))
    PHP Code:
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    Va Va Voom Lowe's Avatar
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    I now realise why I couldn't find it - the calculator doesn't have one!

  10. #8
    The King of Vague Steve B's Avatar
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    Quote Originally Posted by Steve View Post
    You do an engineering course !!!!111one(lim(x->0,sin(x)/x))
    i've not done any maths since 2nd year
    i like to stick to the stuff with lots of standards, thats why I like digital comms
    cyclical redundancy coding, yes please. Analogue systems transmission power levels, no thank you!

  11. #9
    HEXUS webmaster Steve's Avatar
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    Then we have similar attitudes towards maths
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