Problems DWT levels

[Andre1982]

Hello everyone,

I have problem with the advanced signal processing toolbox, especially with the DWT and the level of the coefficients. I am not sure but I think there might be a mistake, using the WA Discrete Wavelet Transform VI. First of I think the example program Get and Set Single Level Detail Coefficients.vi. I think if I want the Level 1 Coefficients, that I get the Coefficients of level 2, because if I use almost the same part in a different program I get out of a data set of 10000 at level 1 only 2500 Detailed Level 1 Coefficients. I think there should be 5000 data points. I get 5000 data points, if I use level 0, but there are no level zero coefficients. The same thing happens with the WA Get Single-level Coeffs and Reconstruction.vi . It seems like there is a shift to the Coeffs array. I understand this array like this: Example Level 5 analysis

[A5, D5, D4, D3, D2, D1]

Level 1 gets the D2 Coefficients and should get the D1.

I would be very thankful for any help!

With Regards

André

[Philipp R.]

Dear André

When I run Get and Set Single Level Detail Coefficients.vi, I
cannot specify a level of 0, the lowest level is 1.

I also found this explanation of the coefficients according to level
specified: When processing waveforms using discrete wavelet transform
based multiresolution analysis, 2 "coefficients" are produced depending on
the "level" chosen. These coefficients are known as the "approximation"
and the "detail." The approximation at level 1 is the summation of the
approximation and detail at level 2. The approximation at level 2 is the
summation of the approximation and detail at level 3 and so forth. (cp.
p.4-6 of the WA_User_Manual.pdf).

The bottom line of all this is, I think we're only seeing a disagreement
in labeling here, what you have known as level 0 is called level 1 in
LabVIEW etc.

Best regards

Philipp R.