Device and digital signal transformation method

The invention concerns the filtering of digital signal analysis. original samples of the digital signal are processed by successive calculation steps in samples of low and high frequency output, any calculated at a given stage sample being calculated by a predetermined function of the original samples, and / or samples previously calcules.Le signal is processed by successive input blocks of samples (BE1, BE2), calculations in a relevant input block taking into account that the original samples or calculated owned .Two consecutive input blocks (BE1, BE2) are overlapped over a predetermined number of samples of origine.Des output blocks (BS1, BS2) are formed, each output block corresponding to an input block. two consecutive output blocks overlap over output samples having the same rows as the original samples that overlap the corresponding input blocks the output blocks considered.