6,981 research outputs found
Autocorrelations of Binary Sequences and Run Structure
We analyze the connection between the autocorrelation of a binary sequence
and its run structure given by the run length encoding. We show that both the
periodic and the aperiodic autocorrelation of a binary sequence can be
formulated in terms of the run structure. The run structure is given by the
consecutive runs of the sequence. Let C=(C(0), C(1),...,C(n)) denote the
autocorrelation vector of a binary sequence. We prove that the kth component of
the second order difference operator of C can be directly calculated by using
the consecutive runs of total length k. In particular this shows that the kth
autocorrelation is already determined by all consecutive runs of total length
L<k. In the aperiodic case we show how the run vector R can be efficiently
calculated and give a characterization of skew-symmetric sequences in terms of
their run length encoding.Comment: [v3]: minor revisions, accepted for publication in IEEE Trans. Inf.
Theory, 17 page
Constructions for orthogonal designs using signed group orthogonal designs
Craigen introduced and studied signed group Hadamard matrices extensively and
eventually provided an asymptotic existence result for Hadamard matrices.
Following his lead, Ghaderpour introduced signed group orthogonal designs and
showed an asymptotic existence result for orthogonal designs and consequently
Hadamard matrices. In this paper, we construct some interesting families of
orthogonal designs using signed group orthogonal designs to show the capability
of signed group orthogonal designs in generation of different types of
orthogonal designs.Comment: To appear in Discrete Mathematics (Elsevier). No figure
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