why 3 db point is of great significance in frequency filters?

0 ⤊

2007-09-25 03:43:24 · 3 answers · asked by coolbunty_87 1 in Science & Mathematics ➔ Engineering

yeah thanks ppl...
do we choose just because the gain is gets mutiplied by 1/2
but the thing is why not 4db or 6db???

2007-09-25 04:02:32 · update #1

That is a major drop off in signal strength (because of the logarithmic scale). It represents a drop to half the power,

2007-09-25 03:56:40 · answer #1 · answered by Rich Z 7 · 0⤊ 0⤋

Because 3 db is the half power point.
db = 10 log(P1/P2) so if P2 = 2P1 then
db = 10 log(1/2) = 10 (-.301) = about -3 db

Doug

2007-09-25 03:59:16 · answer #2 · answered by doug_donaghue 7 · 0⤊ 0⤋

-3 dB represents 1/2 of the power of the pass band compared with the stop band.

log(0.30103) = 2

.

2007-09-25 03:58:51 · answer #3 · answered by tlbs101 7 · 0⤊ 0⤋