ecg 50 Hz noise

[burcu]

Should I put lowpass filter for dC offset after bandstop filter? I tried to connect output of bandstop to input of bandstop but I couldn't see a proper signal.

[burcu]

Sorry I wrote wrong. I've connected output of bandstop to input of lowpass.
I also want to learn how to calculate high cut off and low cut off frequencies. Thanks for your reply

[rpursley8]

The best way to see how these filters work is to play with the settings. Take a look at the attached program. It will create a signal with a flat frequency response that you can filter to see how the filtering work. Use the case state to have a case for each filter type and what the response of each filter looks like (Butterworth, Chebyshev, Elliptic, Bessel). See what happens when you change the filter from lowpass, highpass, bandpass, bandstop and change the order. The default for fs is one, but you can change that to whatever you want and scale fl and fh accordingly. You might add code to take the log base 10 of the output and multply it by 20 to see how the response is normally looked at.

[burcu]

Is this for DC offset :You might add code to take the log base 10 of the output and multply it by 20 to see how the response is normally looked at.
Should I take the log base 10 of the lowpass output and multply it by 20 for DC offset?
Thanks for your reply.

[rpursley8]

No, it is just for display purposes. The diagram I sent you is just a little program to 'play' with filters. The 20*log(x) just puts the output in dB. It's 20 instead of 10 because the output of the last vi is in volts instead of watts. Power is directly proportional to the square of the voltage.

[burcu]

Thus, I'm repeating my question again for my ECG 50 Hz noise Should I put lowpass filter for dC offset after bandstop filter? I tried to connect output of bandstop to input of lowpass but I couldn't see a proper signal.

[rpursley8]

The order doesn't matter and one output should feed straight into the input of the other.

[rpursley8]

I'm not sure what you mean by a proper signal. There should be no errors when you tie the output of one to the input of the other. If you are not getting anything on the output of the second one then make sure your sampling frequency is more than twice your fl and fh.

[marp84]

how about if i use notch filter or bandstop filter it's more effective or not?

and what is the frequency cut-off high and low ?

tanx before