band with requirment

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.

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.

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

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.