Portable instrument for in-vivo infrared oxymetry using spread-spectrum modulation

Redundant Wavelet Watermarking using Spread Spectrum Modulation

Spread Spectrum modulation has become a preferred paradigm in many watermarking applications. This paper analyzes the performance of such a blind watermarking scheme under discrete wavelet frame rather than a traditional orthonormal wavelet expansion. The over complete representation offered by the redundant frame facilitates the identification of significant image features via a simple correla...

Spatial image watermarking using spread spectrum modulation

The paper presents low cost spatial image watermarking scheme where inherent anti jamming and interference rejection property of spread spectrum modulation is utilized to provide robustness against image distortions and malicious attempts to remove or tamper with the watermark. The use of error correction code allows a trade-off between degree of robustness and embedding rate for a given attack...

Spread-Spectrum Multi-h Modulation

Spread Spectrum Modulation and Signal Masking Using Synchronized Chaotic Systems

Chaotic dynamical systems are nonlinear deterministic systems which often exhibit erratic and irregular behavior. The signals that evolve in these systems are typically broadband, noise-like and similar in many respects to a stochastic process. Because of these properties chaotic signals potentially provide an important class of signals which can be utilized in various communications, radar and...

Direct sequence spread spectrum Walsh-QPSK modulation

In this paper we present Walsh-quadrature phase-shift keying (Walsh-QPSK) pseudonoise (PN) modulation schemes for both coherent and noncoherent direct-sequence code-division multiple-access (DS-CDMA) systems, wherein the PN spreading sequences for in-phase and quadrature data in a conventional QPSK PN modulation scheme are coded by Walsh sequences indexed by a special rule to reduce the envelop...