# Designing a system of two filers(Band Stop and High Pass)

1. Nov 22, 2012

### coolrp

I do not how am I supposed to proceed/begin as well.

The zip files contain a data collected from an ECG machine and the pdf has the problem statement.

Any kind of help would be much appreciated.

Thanks

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• ###### ecg data 2.zip
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2. Nov 22, 2012

### Kholdstare

It's an assignment! We can't help you right away. You have to follow homework help guideline to show that you have approached a solution yourself.

3. Nov 22, 2012

### coolrp

actually I am not able to understand what am I supposed to do.

I mean, okay, i copied the signal in MATLAB and plotted it, it comes out as shown in the figure. I have to design two filters, band stop and a high pass filter to attenuate the noise in the signal.

I know that the bandstop specifications include first/second pass/stop band frequencies, attenuation gain etc etc, but how do i go about calculating them??

how am i supposed to use the sampling, 12bit A/D, amplification of data etc to find the specifications if at all these are to be used?

i dont know where to begin!

4. Nov 25, 2012

### coolrp

5. Nov 25, 2012

### coolrp

can you please tell me how do I filter a signal? I mean the signal output as given in the attached file is plotted. Now if i design a filter using FDA Toolbox, how am i supposed to test that filter for this signal input?

6. Nov 25, 2012

### coolrp

i didn't ask to help me understand how to read the ECG! I merely asked how are to determine the filter specifications.

As for the my work, I did the following, since the sample includes 150, 000 samples and we dont really need all of them. Since the sampling freq is 1000Hz, we can take up any number of samples above that. I took 1024 samples and took the fft of the sample, and plotted the abs value graph and got the signal in frequency domain and now the powerline is clearly visible at 50Hz.
the graphs:

so the passband and stopband frequencies are around 50Hz as in these graphs?

7. Nov 25, 2012

### coolrp

I have a pretty good idea about filters, what I am not very good is MATLAB and dude, seriously, this post wasn't binding on you to answer!!

Fine, I suck at practical implementation of theoretical concepts but dude, chill! Yeah, I am pretty good at theoritical concepts (and that doesn't mean book learning if you think its anywhere close to that)!

Thanks for your help anyways! I am surprised, you thought that the second diagram was a partial filtered graph of the first. Its an ideal ECG signal!

8. Nov 25, 2012

### coolrp

I meant in MATLAB, the FDA tool is a tool in MATLAB to design filters! But it only creates a filter as per my specifications, how do i test it with an input is what I asked? Any idea about that?

9. Nov 25, 2012

### coolrp

I wasn't the one who was taking personal shots.. I just asked for how do I decide filter specifications from a given graph...You don't even know me and you could were questioning my credibility..