I need to deisgn a filter that recovers a 40kHz signal in a very noisy system. I think I would need to implement a bandpass filter for this, with passband omega_o = 80pi rad/s. However, I think I need more information to find out the circuit elements/bandwidth/quality factor/cutoff frequencies. Any ideas would be greatly appreciated. ASAP PLEASE! Thanks.

 

Originally posted by roxetz@Mar 6 2006, 06:44 PM
I need to deisgn a filter that recovers a 40kHz signal in a very noisy system. I think I would need to implement a bandpass filter for this, with passband omega_o = 80pi rad/s. However, I think I need more information to find out the circuit elements/bandwidth/quality factor/cutoff frequencies. Any ideas would be greatly appreciated. ASAP PLEASE! Thanks.

[post=14705]Quoted post[/post]​

Sounds awefully much like your are dealing with ultrasonic transducers. I had a similar problem a few years ago and ended up making an active filter using an OP AMP. Unfortunately I don't think I still have this circuit but I will look for it tomorrow. I know we had one hell of a time trying to get it working but in the end it worked well.

 

Originally posted by roxetz@Mar 6 2006, 03:44 AM
I need to deisgn a filter that recovers a 40kHz signal in a very noisy system. I think I would need to implement a bandpass filter for this, with passband omega_o = 80pi rad/s. However, I think I need more information to find out the circuit elements/bandwidth/quality factor/cutoff frequencies. Any ideas would be greatly appreciated. ASAP PLEASE! Thanks.

[post=14705]Quoted post[/post]​

An accessible reference for passive filter design is the Radio Amateurs Handbook. It is published by the American Radio Relay League(ARRL)
ARRL website
It has tables for Butterworth, Chebychef, and Bessel up to 8th order.
You might be surprised by the size of the components that you need: especially the inductors.

Good Luck

 

Originally posted by roxetz@Mar 6 2006, 02:44 AM
I need to deisgn a filter that recovers a 40kHz signal in a very noisy system. I think I would need to implement a bandpass filter for this, with passband omega_o = 80pi rad/s. However, I think I need more information to find out the circuit elements/bandwidth/quality factor/cutoff frequencies. Any ideas would be greatly appreciated. ASAP PLEASE! Thanks.

[post=14705]Quoted post[/post]​

Give this website a look.

Filter Design Tool

hgmjr

 

Thanks guys. I know how to do this now...