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jay2006
Joined: 30 Sep 2006
Posts: 1
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 30 Sep 2006 15:59 why 3db |
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hi there
I have a very basic question..Why do we always consider 3 db bandwidth of the signal and not 2 db or 1 db ...
hope to get a reply
thanks
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flatulent
Joined: 19 Jul 2002
Posts: 4875
Helped: 324
Location: Middle Earth
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30 Sep 2006 16:12 why -3db |
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| In the old days of lumped circuits, the 3 point was easy to calculate because it was where the magnitudes of the real and imaginary parts of the circuit impedance were equal. Also in the early days there could be ripple in the passband which was usually less than 3 dB.
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PaulHolland
Joined: 15 Jan 2003
Posts: 636
Helped: 59
Location: Holland
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30 Sep 2006 17:58 Re: why 3db bandwidth and why not 2 db or 1 db |
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| The point where the power is only 50% of the inband.
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konarkk
Joined: 10 Jun 2006
Posts: 420
Helped: 110
Location: Mumbai , India
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30 Sep 2006 18:10 Re: why 3db bandwidth and why not 2 db or 1 db |
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| Within this limit useful power is obtained & also some tolerence of non linearity is to consider
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safwatonline
Joined: 19 Nov 2005
Posts: 1418
Helped: 172
Location: EGYPT
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01 Oct 2006 1:15 why 3db bandwidth and why not 2 db or 1 db |
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| w=w(pole) i think if it was 2 dB then we would have made 2-dB BW
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Google
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01 Oct 2006 1:15 Ads |
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crazyeng
Joined: 11 Jul 2006
Posts: 6
Helped: 1
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07 Oct 2006 18:51 Re: why 3db bandwidth and why not 2 db or 1 db |
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a power at that freq decrease 50% from center of freq , try to calculate ...Ex
1W
10log(1)=0 dB,
0.5W => 10log(0.5)= -3dB
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