Hey,

I'm at Uni studying Multimedia Technology, I've managed to avoid complex maths so far but now I'm doing a Networking module I can't hide any longer! It seems Logarithm will crop up a few times in this module.

To give you an idea of my ability - I don't know trig, soh cah toa, I'd struggle even to work out speed, distance + time functions. In other words, I need a simple explanation!

I'm reading about the frequency response and amplification of a signal processing system. Here's what it says:

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The input and output signal amplitudes are Si(f) and So(f), repectively. The ratio of the output signal amplitude to the input signal amplitude So(f)/Si(f) is called the system's amplification a(f) at frequency (f). The frequency response of a system is a plot of the systems amplification a(f) against the frequency f...

Amplification, or the ratio of the output to the input amplitude, can be described as a logarithm function also. Logarithm1 to the base 10 of the ratio So(f)/Si(f), multiplied by 20 is called the decibel (dB) value of the amplification. This is expressed in the following formula:

Amplification A(f) in dB = 20 log10 (So(f)/Si(f))

By expressing the amplification as a logarithm function, the range of values that it takes becomes much more managable, as shown in this table:

So(f)/Si(f) as a Ratio | A(f) in dB

1000 | +60

100 | +40

10 | +20

1 | 0

1/10 | -20

1/100 | -40

1/1000 | -60

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Above, the 10 after 'log10' should be subscript but I'm not sure how to do that here. The 1 after Logarithm1 should have been superscript.

I understand how to work out the systems frequency response but not how to work out the dB value of the amplification.

I am really not an expert so please try to explain as simply as possible!

Cheers,

Ian