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aamir sher khan
Joined: 30 May 2009
Posts: 2
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 30 May 2009 8:40 band with requirment |
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hi
I am using FSK technique to transmit data through air using RF.The data rate is 50Kbps and Frequency deviation is 90KHz.The receiver uses phase lock loop PLL method to demodulate the signal.Can anyone tell me how can i calculate the bandwidth of IF filter in receiver.Does the PLL method reduces the bandwidth requirement.
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vfone
Joined: 10 Oct 2001
Posts: 2328
Helped: 327
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30 May 2009 10:31 standard if band |
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280kHz
http://en.wikipedia.org/wiki/Carson_bandwidth_rule
PLL demodulator doesn't reduce the BW requirements but may perform better than a standard FM demodulator.
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FvM
Joined: 22 Jan 2008
Posts: 5160
Helped: 767
Location: Bochum, Germany
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30 May 2009 10:49 IF band width requirment |
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| Yes, but according to the source, the bandwidth rule applies to GFSK rather than simple FSK.
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30 May 2009 10:49 Ads |
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aamir sher khan
Joined: 30 May 2009
Posts: 2
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30 May 2009 11:34 Re: IF band width requirment |
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| FvM wrote: |
| Yes, but according to the source, the bandwidth rule applies to GFSK rather than simple FSK. |
i am using BFSK and the carson rule for that is
B = 2 * ( frequency deviation + symbol rate )
do you think that this rule is not applicable so FSK
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FvM
Joined: 22 Jan 2008
Posts: 5160
Helped: 767
Location: Bochum, Germany
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30 May 2009 11:46 IF band width requirment |
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I think, you should calculate some overhead rather than designing the bandwidth too small.
P.S.: Or accept a smoothening of the received waveform. You have to consider also the modulation, e.g. manchester or direct coding.
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