May 262010
It’s a jargon engineers or physicists are using.
It’s a promise.
It’s about describing a ratio between two quantities.
How big is the one compared to the other?
For example, Chan’s height is 40 inch and Han’s height is 80 inch.
Han is two times higher than Chan.
Using dB, we say
10 log (p2/p1) = 10 log 2 = 3 dB (where p2 is Han’s height and p1 is Chan’s height)
Note here that base is 10.
Q: Then, the real question is why we are using this complicated thing ?
Logarithm is being used to express too small or too large number in an easy manner.
For example, one million bigger, then
10 log 1000000 = 60 dB
