Spectrum shaping with parity sequences.
For certain types of digitally generated holographic memories, it is important that the Fourier components to be stored have a constant, or nearly constant, modulus. It is shown that by interlacing two sequences of complex numbers, one a data sequence representing the information to be stored and the second a parity sequence, derivable from the data sequence, the discrete Fourier transform of the combined sequence can be made to have a constant modulus. A slight variation of the method leads to a spectrum with varying modulus but only a discrete set of phases. The sequences may be one-dimensional or multidimensional.
Chu
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Goodman
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