Suppose i have a wave with 20kHz, 100kHz and 300kHz.Sampling frequency used is 1000kHz. i apply the discrete wavelet transform on the wave like dwt(wave,'db2'). i will get one level of approximation and detail coefficients. according to the basics, the detail coefficient will have the 100k and 300k components and approximation coeff will have 20k. But when i did fft on the output(on approx nd detail), i didnt get as expected. Could anyone post some matlab code with which i can verify it. And also tell whether i am doing the procedure correctly? Also if anyone could explain the practical side of this tool?