In this paper, the properties of the WalshHadamard codes used as spreading codes in QCDMA cellular systems are analyzed. It is shown that among Walsh-Hadamard codes, obtained from Hadamard Matrix , only k 2 ) , 2 ( k H k 1 + k codes are orthogonal to each other in all phases. Also, the performance of the Walsh Hadamard codes is compared with that of the Gold codes from the average cross-correla...

We consider the cross-correlation of a Costas array with its image under a horizontal and/or a vertical flip. We propose and prove several bounds on the maximal cross-correlation and on its value at the origin, for both general Costas arrays and for algebraically constructed ones.

Elshorbagy et al. (2001) report the presence of chaos in the streamflow series in the Little River and Reed Creek based (only) on the low correlation dimensions of 1.19 and 1.07 obtained when the Grassberger-Procaccia correlation dimension algorithm (e.g. Grassberger & Procaccia, 1983) is employed. Whether or not a low correlation dimension is a proof of chaos is an important question (cf. Siva...

Deep surveys have recently discovered galaxies at the tail end of the epoch of reionization. In the near future, these discoveries will be complemented by a new generation of low-frequency radio observatories that will map the distribution of neutral hydrogen in the intergalactic medium through its redshifted 21cm emission. In this paper we calculate the expected cross-correlation between the d...

Reliable estimates of vertical, inline and crossline components of apparent displacements in time-lapse seismic images are difficult to obtain for two reasons. First, features in 3-D seismic images tend to be locally planar, and components of displacement within the planes of such features are poorly resolved. Second, searching directly for peaks in 3-D cross-correlations is less robust, more c...

[1] Cross correlation of ambient seismic noise is known to result in time series from which station‐station travel‐time measurements can be made. Part of the reason that these cross‐correlation travel‐time measurements are reliable is that there exists a theoretical framework that quantifies how these travel times depend on the features of the ambient noise. However, corresponding theoretical r...

Sequences with very low out-of-phase auto-correlation and cross-correlation function are widely used for synchronization in mobile communication and multimedia systems where reliable data transmissions are required. For optimum detection, synchronization sequences usually have out-of-phase correlation values that are very low or zero. However sequences with ideal correlation function are very r...