Signal Processing on TIVA C launchpad

• posted

Hey, Have anyone done signal processing on TIVA C launchpad???

• posted

I saw your post in c.dsp. Same question here. What do you need help with? This is just a CM4 and does DSP, sort of. Not as efficient as a DSP but can come close for some apps like FIR filters.

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Rick```
• posted

I have got the function for FIR filter from CMSIS library for TIVA C board.

I want to do a high pass filter having cutoff freq 1KHz. after applying function I am getting signal (i.e. array a[1024]) in frequency domain

so my question is from that how would i know that which a[i] is for the 1Khz freq below which i can suppress the signal and agin i can do ifft and get the original signal.??

• posted

If I understand what you're asking, there's no FIR filter that will totally eliminate signal just above the cutoff. So this isn't a programming problem-- it's a matter of understanding how signal processing works.

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If I understand, you are asking how to come up with the coefficients (a[i]) for a high pass filter with a corner frequency of 1 kHz? Or is a[i] the signal data in which case I don't understand your question.

Also, part of your post makes it seem like you think a filter will transform the time input signal to an output frequency signal. That is not the case, both signals will be time signals. Maybe I don't understand your statement about that.

Third possibility... you are asking for a function that will take a time domain signal and turn it into a frequency domain signal? I don't completely understand your post.

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Rick```
• posted

Digital high pass filters are actually band pass filters, since the input frequency should be limited below fs/2

Sounds you have gotten a 1024 FFT of the signal. Knowing the sampling frequency, it should be easy to select which FFT bins are below 1 kHz and which are not. Remove the bins that you do not need and perform an inverse FT to restore the original time domain signal. There are however various windowing issues in this kind of processing...

If you intend to do FFT/IFFT processing, why are you talking about FIR filters ?

• posted

sorry.. I was confused.. now m clear after referring some books.. Yeah my ques was which coefficient represents corner freq of 1 Khz??

• posted

sorry sir.. I was confused.. now I am clear...

• posted

To get that means you need to read more, maybe a *lot* more. Calculating the coefficients of a FIR filter is not a horribly complex job, but it isn't so easy. You need to specify the sample rate, the filter depth, the corner frequency, the transition band width and the stop band attenuation. You might also want to spec the pass band ripple if it is important. There are programs that will then do the math to get the coefficients for you.

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Rick```
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I am coming late to this party, but you start by saying you have a function for a FIR filter, then you finish with a question that's pertinent to doing filtering using FFTs.

They're not the same thing. Even if you already have your answer, I'm curious as to what you're actually dealing with.

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www.wescottdesign.com```
• posted

It may be a badly specified study project in Mumbai, India.

The OP has not said anything of getting the signal into the card or the result out from it.

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-TV```

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