Hello,(adsbygoogle = window.adsbygoogle || []).push({});

Suppose I have a discrete function of a perfect cosine wave.

So if I will do a DCT on this function I will get one non zero coefficient which corresponds to the perfect cosine wave, and the rest will be zero.

Now I have a pass filter, which filters out anything with a frequency which is different from the original cosine wave.

If I will do this filter on the DCT I did to the cosine wave, then no coefficient should change.

Now, suppose I have a second function which is also a perfect cosine wave of the same frequency as the cosine wave in the first function, but with a different phase.

So the DCT of the second function will give me many non zero coefficients.

If will pass the same filter I did on the first function DCT, then I will loose many coefficient and the result will be some wave which is weaker then the second function original cosine wave.

Is that true?

Basicaly I am trying to find the "obvious" frequency of a discrete wave.

Lets say I have a pure triangle wave. Doing DCT on it will produce a lot of coefficients of different frequencies, but how do I discover the obvious frequency of the triangle wave from these coefficients?

Thanks in advance.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Discrete Cosine Transform

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**