# Designing Bandpass Filter

Discussion in 'General Electronics Chat' started by aliarosemary, Jan 4, 2013.

1. ### aliarosemary Thread Starter New Member

Jan 4, 2013
3
0
I am doing the calculation for designing the bandpass filter.Somehow, i am stuck how to find the stopband frequency(fc1). I only can find passband frequency (fp1 and fp2) and stopband frequency(fc2). Below is the question that i am working on now:

A signal is sampled at the sampling rate of 10kHz. The signal has useful signal content
between 1kHz and 2.4kHz, and distortion of not more than 1dB is required for this range. It
is known that the signal is corrupted with noise above 3.6kHz. This noise needs to be
attenuated by at least 40dB. You are required to proposed a design for the FIR bandpass
filter. Justify your choice. Obtain the impulse response for the filter

I dont know how should i find the fc1 is it related the third /fifth harmonic?

2. ### Brownout Well-Known Member

Jan 10, 2012
2,375
998
Can the lower cutoff frequency be extrapolated from fp1 and the fliter order? Is the filter order determined by the upper stop band and the distortion spec?

3. ### aliarosemary Thread Starter New Member

Jan 4, 2013
3
0
Lower cutoff frequency can be find if we have fc1. the formula is
lower cutoff frequency=(fp1+fc1)/2

since i do not know how to find the fc1, how can i find the lower cutoff frequency.

4. ### Brownout Well-Known Member

Jan 10, 2012
2,375
998
Can fc1 not by found by considering the filter order and fp1? If you know fp1 and the rolloff (determined by the filter order ) then can you not calculate fc1????? I'm trying to think back 20 years to my fliters classes. Work with me.

5. ### aliarosemary Thread Starter New Member

Jan 4, 2013
3
0
okey thanks,i got it. sorry im quite blur .now i got it

6. ### naspek Member

Feb 17, 2010
45
0
hey alia.. mind sharing how did u get the value?