High pass filter doubt in matlab

Hi, I have a signal in both time domain and freq domain and would like to use highpass filter to filter out the noise frequencies over 500Hz. I have designed a Highpass filter using SP tool and could not able to go ahead after that. My doubts are that, how can i pass my signal into this highpass filter(time domain or freq domain signal) and after that i would like calculate the power of the out put signal.

Can any one help me, how can i do this. See my picture below.

Answer 1

[Wayne King]

Hi, I don't see any picture.

Once you design your filter, did you export it to the command window? You do this by File -> Export

You have the option of exporting the filter as coefficients or as a filter object.

If you export the filter as coefficients use filter() as follows: (I assume input is your data in the time domain).

output = filter(Num,1,input);  %FIR filter
output = filter(Num,Den,input); %IIR filter

If you export an object, use

output = filter(Hd,input);

Hope that helps,

Wayne

[anil]

Hello,

Thanks for yout help and i want calculate the power of the signal after Highpass filter. My sampling frequency is 10kHz and how can i do this.

Answer 2

[Wayne King]

You need to specify what measure of power you want to calculate. If you just want to calculate the norm squared, you can use

norm(x)

If you want to measure power in a particular frequency interval, you can use a spectrum object to get a PSD measurement and then use the avgpower() method with a specified interval to get the power.

Wayne

[anil]

After highepass filter, I have a signal(time domain)with frequencies over 550hz to 5kHz. So, i need to know the power of this signal. In the same way, i have another signal with noise after highpass and i would like to see the difference in power of these two signals. In same way i will do this process for lowpass filter output that 0 to 550Hz. Please give me some idea or formula.

[anil]

power in DB