On Sun, 18 Dec 2011 13:32:30 -0600, wongjowo wrote:

> Hi every one..
>
> I has designed a bandstop IIR filter to removed 60 Hz Sinus Noise at ECG
> signal.
> The step of I have done are :
>
> 1. Designed a bandpass filter (frequency domain) -> it will be H

2. Do FFT to the ECG Signal -> it will be X
3. Do the circular convolution -> Y = X.*H

>
> But my question is : the output of Y is WRONG, because the result of X
> by FFT is SYMMETRIC , but H is not symmetric. Please help to let me know
> how to apply the bandstop to the signal???

Huh?
You've said nothing at all about Y, only about the symmetry of X and H.
Yes, the impulse response of an IIR filter is not symmetric -- so?
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

Reply by mnentwig●December 18, 20112011-12-18

>> but H is not symmetric.

it should be, otherwise you'll get a complex-valued output time domain
waveform from real-valued input.

Reply by wongjowo●December 18, 20112011-12-18

Hi every one..
I has designed a bandstop IIR filter to removed 60 Hz Sinus Noise at ECG
signal.
The step of I have done are :
1. Designed a bandpass filter (frequency domain) -> it will be H
2. Do FFT to the ECG Signal -> it will be X
3. Do the circular convolution -> Y = X.*H
But my question is : the output of Y is WRONG, because the result of X by
FFT is SYMMETRIC , but H is not symmetric.
Please help to let me know how to apply the bandstop to the signal???
Thanks in advance