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Forward transform processing apparatus and inverse processing apparatus for modified discrete cosine transforms, and method of performing spectral and temporal analyses including simplified forward and inverse orthogonal transform processing
Forward transform processing apparatus and inverse processing apparatus for modified discrete cosine transforms, and method of performing spectral and temporal analyses including simplified forward and inverse orthogonal transform processing
A method for performing a simplified digital spectral analysis on a block of N samples representing an information signal in the time domain, in which the block of N samples is multiplied by a forward transform window to provide a block of N processed samples. The block of processed samples is digitally preprocessed to provide a block of N/4 complex numbers, which is orthogonally transformed, using digital processing equivalent of a Fast Fourier Transform, to provide a block of N/4 transformed complex numbers. The block of transformed complex numbers is then digitally post-processed to provide a block of N/2 spectral coefficients representing the information signal in the frequency domain. In a method of performing a simplified digital temporal analysis on a block of N/2 spectral coefficients representing the information signal in the frequency domain, the block of spectral coefficients is digitally pre- processed to provide a block of N/4 frequency domain complex numbers, which is orthogonally transformed into a block of N/4 time domain complex numbers by digital processing equivalent to a Fast Fourier Transform. The block of N/4 time domain complex numbers is digitally post processed to provide a block of N/2 processed time domain samples, which is re-arrayed and multiplied by an inverse transform window to provide a block of N samples representing the information signal in the time domain.
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