This paper presents a low-power 128-tap dual-channel direct-sequence spread-spectrum (DSSS) digital matched-filter chip. Design techniques used to reduce the power consumption of the system include latch-based register file filter structure, a high-rate compression scheme, optimized compressor cells, and semicustom layout design. To further reduce the power consumption and the hardware requirem...

Acoustic communications using a direct-sequence spread spectrum modulation with a RAKE receiver was tested during the KauaiEx experiment (in Hawaii). The oceanography was measured along the communications path during this test, so that the propagation of the communications transmissions could be subsequently modeled. Such simultaneous measurements provide a continuous picture of how the ocean w...

In the area of mass production, the products are weighed using load cell based weighing system. A load cell is an uncontrollable weighing device. Improvement in filtering increases the speed of weighing and enhances the measurement accuracy. In this paper, a novel algorithm and architecture is proposed for the weighing system. The algorithm has been verified and implemented in the weight measur...

The performance of direct-sequence spread-spectrum (DS/SS) in packet radio networks suffers from the nearfar problem. This can be mitigated by the use of multiuser receivers. This paper introduces a model for peer to peer communications using a simple parallel interference cancellation (PIC) technique, which requires cancellation of only a few dominant interferers. The system performance is eva...

En este trabajo se trataran las diferencias entre los sistemas FHSS y DSSS spread spectrum. Estos sistemas son la base en el desarrollo de las nuevas tecnologías inalámbricas. El canal de comunicación y las propiedades de ambos sistemas son importantes para determinar la elección de uno u otro en una particular aplicación. Primero, introduciremos ambos sistemas y posteriormente utilizaremos mod...

ACKNOWLEDGMENT I would like to thank Dr. Charles Chien for his abundant amount of technical input in all of my research. I am also grateful for Dr. Chien's guidance and criticism on my scientific language and responsibilities. In addition, I would like to thank my adviser, Professor Rajeev Jain, for giving me the opportunity to work with a tremendous group of researchers. My thanks also extends...

Migration towards a full-digital implementation of modems is currently one of the main trends in transmission systems design. In this paper we describe a non coherent a11digital delay lock loop (DDLL) suited for chip timing synchronization in band-limited direct sequence spread spectrum (DS/SS) systems, and we thoroughly analyze its performance. The key features of this novel scheme are represe...

Applying the particle filter (PF) technique, this paper proposes a PF-based algorithm to blindly demodulate the chaotic direct sequence spread spectrum (CDS-SS) signals under the colored or non-Gaussian noises condition. To implement this algorithm, the PFs are modified by (i) the colored or non-Gaussian noises are formulated by autoregressive moving average (ARMA) models, and then the paramete...

In this paper, we propose a channel estimation procedure that together with a time−frequency Wiener mask permits the design of coherent receivers for direct sequence spread spectrum (DSSS) communication systems. Such a receiver excises intentional or non−intentional jamming signals while detecting the sent bit. Transmission channels spread the message signals in time and frequency and are typic...

This paper proposes an algorithm for the suppression of narrow-band interference in direct sequence spread spectrum (DSSS) systems, based on the open loop adaptive IIR notch filtering. The center frequency of the interference is monitored on-line by the adaptive lattice IIR notch filter in [6] or by time-frequency analysis in [3]. The power of the interference signal is also estimated from the ...