Demodulation of a Gosset lattice code having a spectral null at DC

A rarely used definition of the Gosset lattice is revived to construct codes which (unlike other Gosset lattice codes) have a null at DC in their baseband spectrum. A closed-form expression for the code spectrum is derived, and the bandpass spectrum of this code is compared to the spectrum of an E/sub 8/ construction of the same code. A fast sequential method of demodulation is described. This two-stage demodulator consists of a simplified algorithm that can declare erasures to provide speed in demodulation and a maximum-likelihood algorithm used to maintain error performance.<
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