| In order to successfully demodulate a digitally modulated signal, the receiver must rst synchronize its os-cillators and clocks to the received signal. If direct-sequence spread-spectrum modulation is used, then it is also necessary to synchronize to the code sequence that was used to produce the spectral spreading. Methods used to achieve coarse synchronization to the code sequence, also cal...

Digital chaotic sequence spread spectrum (CSSS) communication systems provide a number of advantages for secure communications due to the apparent bandlimited Gaussian noise-like signal characteristics and non-repeating nature underlying chipping sequence. The Rayleigh magnitude distribution represents challenge, however, transmission through linear high-power amplifiers (HPA), both high peak-t...

In this paper, we study the spectrum usage efficiency by applying wideband methods and systems to the existing analog systems and applications. The essential motivation of this work is to define the prospective coexistence between analog FM and digital Spread Spectrum systems in an efficient way sharing the same frequency band. The potential overlaid Spread Spectrum (SS) system can spectrally c...

In today communication systems the most probable problems are that of channel capacity, jamming and interference or noise. The channel capacity can be maximized by multiplexing the channel. While the jamming problem and for noise reduction the most important technique that we can apply is spread spectrum. That by spreading the spectrum of the original message signal, the impact of noise upon th...

The article is dedicated to direct sequence spread spectrum signals acquisition. Communication channels that use are characterized by significant delay and carrier frequency shift as a rule. That’s why the acquisition most problem in receive equipment design. Suggested approach base on Fast Fourier Transform discussed modeling suggested algorithm’s results.

Nowadays most communication networks like GSM, WLan or WiMAX are based on pre-existing infrastructure. These infrastructures are complicated, costly and difficult to deploy in very short time. Whereas Wireless Ad Hoc Networks are infrastructure-free self organizing networks which consist of cooperating nodes. These networks are highly desirable for various emerging applications for military and...

An evaluation board with FPGA (XC2S15) and 200MHz single-chip Direct Digital synthesizer (AD9857) has been designed to demonstrate a Fast Frequency Hopping CDMA (FFH-CDMA) implementation. The paper shows how the pseudo-random Gold code may determine the frequency hopping of the carrier in FFH-CDMA systems.

A simpIe Anderson transition model, ignoring guest clusterization, excitation lifetime, sensor concentration, excitonphonon coupling and thermalization, appears to be incompatiile with the critical concentrations observed for triplet exciton transport in several ternary crystal systems. Dynamic percolation, involving hopping or tunneling through longrange clusters, remains our suggested modeL

The performance of a direct sequence spread-spectrum land-mobile satellite transmission system, using binary phase shift keying (BPSK) modulation, is analyzed. The satellite channel is modeled as having shadowed Rician fading characteristics. The bit error probability is evaluated, considering both the envelope and the phase variation. Assuming a Gaussian approximation for the interference, num...

The optimal arrival-time distribution that maximizes the delay-capture probability in spread-spectrum packet radio networks is derived. It is shown that using the optimal arrival-time distribution, the capture probability converges to a finite value as the number of contending users increase. Normalized throughput and average delay is computed for slotted ALOHA random access packet radio networ...