# Using FFT for data compression step is this a lossy method?

Discussion in 'General Electronics Chat' started by tojeena, Feb 11, 2013.

1. ### tojeena Thread Starter Active Member

May 2, 2009
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Using FFT for data compression step is this a lossy method?

2. ### tshuck Well-Known Member

Oct 18, 2012
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Yes, you aren't going to save the entire spectrum, are you? From -∞ to +∞...

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3. ### crutschow Expert

Mar 14, 2008
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What type of signal are you trying to compress?

4. ### tshuck Well-Known Member

Oct 18, 2012
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Ah, yes, I was assuming a non-trivial signal with many harmonics... if you are recording simple sinusoids, within a restricted range, you shouldn't have any loss.

As crutschow has alluded to, it depends on the types of waveforms you are trying to record....

5. ### tojeena Thread Starter Active Member

May 2, 2009
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I am planning to use this a pre processing step for satellite data transmission

6. ### crutschow Expert

Mar 14, 2008
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I assume this is pre-processing of the analog data. What is the nature of that data?

7. ### tojeena Thread Starter Active Member

May 2, 2009
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Yes ,analog data,after getting the coefficients i will give it to the binary coder.

8. ### crutschow Expert

Mar 14, 2008
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To answer you original question, yes the Fourier transform can be a lossy method of compression, as determined by the number of coefficients. The more coefficients, the more the recovered waveform will match the original. So you trade off accuracy for amount of data transmitted. For example, here's a study that looks at that issue.

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9. ### tojeena Thread Starter Active Member

May 2, 2009
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I have thought of using fft as a pre processing method of the rice codes.

10. ### crutschow Expert

Mar 14, 2008
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I'm not that knowledgeable about various coding/compression schemes so can't advise you on that.

May 2, 2009
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12. ### crutschow Expert

Mar 14, 2008
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Sorry, I know of no one with that expertise.

May 2, 2009
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