Patent ID: 8180819

Claim:
Apparatus for processing a plurality of real-valued subband signals, the plurality of real-valued subband signals comprising a first real-valued subband signal and a second real-valued subband signal, to obtain a complex-valued subband signal, comprising: a multiband filter for providing a real-valued intermediate subband signal based on filtering the first real-valued subband signal to obtain a first filtered subband signal and the second real-valued subband signal to obtain a second filtered subband signal and based on by combining the first filtered subband signal and the second filtered subband signal to obtain the real-valued intermediate subband signal; and a calculator for providing the complex-valued subband signal by combining the real-valued subband signal from the plurality of real-valued subband signals as a real part of the complex-valued subband signal and a signal based on the intermediate subband signal as an imaginary part of the complex-valued subband signal, wherein the apparatus is operative to assign to each real-valued subband signal according to a center frequency associated with the real-valued subband signal an index m, so that the real-valued subband signals are with an increasing index m, arranged according to the center frequency associated with the real-valued subband signals, wherein the plurality of real-valued subband signals comprises K real-valued subband signals, wherein K is a positive integer and m is an integer in the range from 0 to (K−1).