The multi-disciplinary approach to engineering has become an important factor for the design of many new products, systems and processes. The systems integration of engineering areas in circuits, electronics, controls, signals and computing exploits and exceeds the relative advantages of single disciplines.
This special issue comprises of six selected papers from the 2nd International Conference on Signals, Circuits and Systems (SCS 2008), Hammamet, Tunisia, 7-9 November 2008. The aim of the 2008 International Conference on Signals, Circuits & Systems (SCS’08) is to cope with the rapidly progressing technology. The multi-disciplinary approach to engineering has become the key to many different products and processes. The integration of mechanics, electronics, control and computing exploits and exceeds the relative advantages of single disciplines, and when they are integrated, the synergy ensures that performances reach unprecedented levels. The conference was sponsored by IEEE Signal Processing Society, IEEE Circuits and Systems Society and Association Université et Environnement, and organized by National Engineering School of Sfax (ENIS) and Electronics, Microtechnology & Communication Laboratory (EMC). The proceedings of the SCS 2008 were included in IEEE Xplore.
   The conference received more than 177 paper submissions from 34 countries and regions, of which 67 were selected for oral presentation and 33 papers as posters. From these research papers, through two rounds of reviewing, the guest editor selected six as the best papers of the Conference.
In “Analysis of Chaos-Based Coded Modulations under Intersymbol Interference”, Francisco J. Escribano, Luis López, and Miguel A. F. Sanjuán analyze the behavior of a class of chaos-based coded modulations (CCM’s) in channels with time-invariant intersymbol interference (ISI). The authors use the ISI distance spectrum of the CCM’s to calculte bounds for the bit error rate (BER), and provide the analytical condition a CCM has to comply to stand a limited quantity of ISI. The effect of the main modelling parameter of this class of chaos-based systems was explained, and it was shown that the dynamics of the underlying chaotic map is in each case the main factor to account for the final performance. The results show that CCM systems are of potential interest in this kind of distorting environment.
In “Extraction and Simulation of Intra-gate Defects Affecting CMOS Libraries”, Aymen Ladhar and Mohamed Masmoudi present an automated approach to extract and simulate potential intragate defects in standard cell library, based on the use of verification and simulation CAD tools. As application, the authors used these fault signatures to diagnose different types of intra-gate defects. Experimental results show the efficiency of the approach to isolate injected defects on industrial designs.
   In “Pseudorandom Direct Sampler for Non-Uniform Sub-sampling Architecture in a Multistandard Receiver”, Asma Maalej, Manel Ben-Romdhane, Chiheb Rebai, Patricia Desgreys, Patrick Loumeau, and Adel Ghazel propose a Non- Uniform Sampling (NUS) technique for down-conversion stage in a multistandard radio. For both narrowband and wideband standard processing, NUS promises relaxing system design constraints, decreasing the sampling frequency as well as reducing power consumption. A non-uniform clock generator, called Pseudorandom Direct Sampler (PDS), is described. PDS is used to non-uniformly control the Analog-to-Digital Converter (ADC) performing IF sub-sampling in proposed GSM/UMTS/WiFi multistandard receiver architecture. PDS architecture is based on using modified Direct Digital Synthesizer (DDS) including pseudorandom behavior. A 90-nm CMOS FPGA based prototype of PDS reveals an internal clocking up to 350 MHz and a power consumption lower than 4 mW.
   In “On Digital Filtering of Band-limited Signals Using Lower Sampling Rates”, Kostadin Tzvetkov and Andrzej Tarczynski explore filtering of multi-band bandlimited signals by means of a linear digital filter with one or more stopbands. The main goal of the paper is to demonstrate that such a task can be accomplished using sampling rates lower than Landau rate, where the Landau rate is defined as the total bandwidth of the input signal. In order to reach such low rates Periodic Nonuniform Sampling is employed. The authors show that the proposed filtering method is most efficient when bandpass and multiband filtering is required. Necessary and sufficient conditions for filtering are derived, and an algorithm for designing PNS grids that allow sub-Landau sampling and filtering is proposed. Reconstruction systems are discussed and experimental examples are presented, which confirm the feasibility of the approach.
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