27 citations · 128 across the 26 of their papers we have counts for
24 papers · 1 filter
Efficient Multiplex for Band-Limited Channels: Galois-Field Division Multiple Access
H. M. de Oliveira, R. M. Campello de Souza, A. N. Kauffman
A new Efficient-bandwidth code-division-multiple-access (CDMA) for band-limited channels is introduced which is based on finite field transforms. A multilevel code division multipl…
Wavelets for Elliptical Waveguide Problems
M. M. S. Lira, H. M. de Oliveira, R. J. Cintra +1
New elliptic cylindrical wavelets are introduced, which exploit the relationship between analysing filters and Floquet's solution of Mathieu differential equations. It is shown tha…
Radix-2 Fast Hartley Transform Revisited
H. M. de Oliveira, V. L. Sousa, H. A. N. +1
A Fast algorithm for the Discrete Hartley Transform (DHT) is presented, which resembles radix-2 fast Fourier Transform (FFT). Although fast DHTs are already known, this new approac…
The Discrete Cosine Transform over Prime Finite Fields
M. M. Campello de Souza, H. M. de Oliveira, R. M. Campello de Souza +1
This paper examines finite field trigonometry as a tool to construct trigonometric digital transforms. In particular, by using properties of the k-cosine function over GF(p), the F…
Fourier Codes
R. M. Campello de Souza, E. S. V. Freire, H. M. de Oliveira
A new family of error-correcting codes, called Fourier codes, is introduced. The code parity-check matrix, dimension and an upper bound on its minimum distance are obtained from th…
New Algorithms for Computing a Single Component of the Discrete Fourier Transform
G. Jerônimo da Silva, R. M. Campello de Souza, H. M. de Oliveira
This paper introduces the theory and hardware implementation of two new algorithms for computing a single component of the discrete Fourier transform. In terms of multiplicative co…
Genomic Imaging Based on Codongrams and a^2grams
E. A. Bouton, H. M. de Oliveira, R. M. Campello de Souza +1
This paper introduces new tools for genomic signal processing, which can assist for genomic attribute extracting or describing biologically meaningful features embedded in a DNA. T…
Orthogonal Multilevel Spreading Sequence Design
H. M. de Oliveira, R. M. Campello de Souza
Finite field transforms are offered as a new tool of spreading sequence design. This approach exploits orthogonality properties of synchronous non-binary sequences defined over a c…
Fourier Eigenfunctions, Uncertainty Gabor Principle and Isoresolution Wavelets
L. R. Soares, H. M. de Oliveira, R. J. Cintra +1
Shape-invariant signals under Fourier transform are investigated leading to a class of eigenfunctions for the Fourier operator. The classical uncertainty Gabor-Heisenberg principle…
The Hartley Transform in a Finite Field
R. M. Campello de Souza, H. M. de Oliveira, A. N. Kauffman
The k-trigonometric functions over the Galois Field GF(q) are introduced and their main properties derived. This leads to the definition of the cask(.) function over GF(q), which i…
Spread-Spectrum Based on Finite Field Fourier Transforms
H. M. de Oliveira, J. P. C. L. Miranda, R. M. Campello de Souza
Spread-spectrum systems are presented, which are based on Finite Field Fourier Transforms. Orthogonal spreading sequences defined over a finite field are derived. New digital multi…
Eigensequences for Multiuser Communication over the Real Adder Channel
R. M. Campello de Souza, H. M. de Oliveira
Shape-invariant signals under the Discrete Fourier Transform are investigated, leading to a class of eigenfunctions for the unitary discrete Fourier operator. Such invariant sequen…
A Full Frequency Masking Vocoder for Legal Eavesdropping Conversation Recording
R. F. B. Sotero Filho, H. M. de Oliveira, R. M. Campello de Souza
This paper presents a new approach for a vocoder design based on full frequency masking by octaves in addition to a technique for spectral filling via beta probability distribution…
The Z Transform over Finite Fields
R. M. Campello de Souza, H. M. de Oliveira, D. Silva
Finite field transforms have many applications and, in many cases, can be implemented with a low computational complexity. In this paper, the Z Transform over a finite field is int…
On a Density for Sets of Integers
R. J. Cintra, L. C. Rêgo, H. M. de Oliveira +1
A relationship between the Riemann zeta function and a density on integer sets is explored. Several properties of the examined density are derived.
Fourier Codes and Hartley Codes
H. M. de Oliveira, C. M. F. Barros, R. M. Campello de Souza
Real-valued block codes are introduced, which are derived from Discrete Fourier Transforms (DFT) and Discrete Hartley Transforms (DHT). These algebraic structures are built from th…
A Low-throughput Wavelet-based Steganography Audio Scheme
P. Carrion, H. M. de Oliveira, R. M. Campello de Souza
This paper presents the preliminary of a novel scheme of steganography, and introduces the idea of combining two secret keys in the operation. The first secret key encrypts the tex…
A Matrix Laurent Series-based Fast Fourier Transform for Blocklengths N=4 (mod 8)
H. M. de Oliveira, R. M. Campello de Souza, R. C. de Oliveira
General guidelines for a new fast computation of blocklength 8m+4 DFTs are presented, which is based on a Laurent series involving matrices. Results of non-trivial real multiplicat…
Compactly Supported Wavelets Derived From Legendre Polynomials: Spherical Harmonic Wavelets
M. M. S. Lira, H. M. de Oliveira, M. A. Carvalho +1
A new family of wavelets is introduced, which is associated with Legendre polynomials. These wavelets, termed spherical harmonic or Legendre wavelets, possess compact support. The…
Multilayer Hadamard Decomposition of Discrete Hartley Transforms
H. M. de Oliveira, R. J. Cintra, R. M. Campello de Souza
Discrete transforms such as the discrete Fourier transform (DFT) or the discrete Hartley transform (DHT) furnish an indispensable tool in signal processing. The successful applicat…
A Factorization Scheme for Some Discrete Hartley Transform Matrices
H. M. de Oliveira, R. J. Cintra, R. M. Campello de Souza
Discrete transforms such as the discrete Fourier transform (DFT) and the discrete Hartley transform (DHT) are important tools in numerical analysis. The successful application of t…
Fragile Watermarking Using Finite Field Trigonometrical Transforms
R. J. Cintra, V. S. Dimitrov, H. M. de Oliveira +1
Fragile digital watermarking has been applied for authentication and alteration detection in images. Utilizing the cosine and Hartley transforms over finite fields, a new transform…
Fast Finite Field Hartley Transforms Based on Hadamard Decomposition
H. M. de Oliveira, R. G. F. Távora, R. J. Cintra +1
A new transform over finite fields, the finite field Hartley transform (FFHT), was recently introduced and a number of promising applications on the design of efficient multiple ac…
Introducing an Analysis in Finite Fields
H. M. de Oliveira, R. M. Campello de Souza
Looking forward to introducing an analysis in Galois Fields, discrete functions are considered (such as transcendental ones) and MacLaurin series are derived by Lagrange's Interpol…