Thread Subject: Frequency weighted Acclereration

Hello Everybody,

   I have an accleration time history. I need to convert it to frequency weighted accl time history.

By that I mean I have a plot wherein certain weights are specified for each frequency upto 80 HZ.

How can I obtain the frequency weighted accl time history ? One way to do it is to take the FFT of the original time history, multiply it with appropirate weights and then do an inverse fft to convert it back to time history. Now the problem is with multiplying the weights with FFT ?

Is this the only way, or is there another strategy to get the frequency weighted accl time history.

Thanks and Regards
Madhu V. Shurpali

Madhu wrote:
> Hello Everybody,
>
> I have an accleration time history. I need to convert it to frequency
> weighted accl time history.
>
> By that I mean I have a plot wherein certain weights are specified
> for each frequency upto 80 HZ.
>
> How can I obtain the frequency weighted accl time history ? One way
> to do it is to take the FFT of the original time history, multiply it
> with appropirate weights and then do an inverse fft to convert it
> back to time history. Now the problem is with multiplying the weights
> with FFT ?
>
> Is this the only way, or is there another strategy to get the
> frequency weighted accl time history.
>
> Thanks and Regards Madhu V. Shurpali

If you can convert your frequency weighting to a set of filter
coefficients, you can filter your time history directly. You can look at
the filtfilt command for filtering. I'm sure there's a filter design
tool in Matlab to design the filter coefficients based on your desired
frequency response, but I'm not familiar with that tool. Perhaps someone
else here can help with that part.

--
Dave
dvt at psu dot edu