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Signal Generator (signal + generator)
Selected AbstractsHyperchaotic signal generation via DSP for efficient perturbations to liquid mixingINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 1 2009Zhong Zhang Abstract This paper presents the design, simulation, hardware implementation and an application in liquid mixing of some hyperchaotic circuits, based on the digital signal processing (DSP) technology. The hyperchaotic Chen's system is used as an example to show the system discretization and variable renormalization in the design process. Numerical simulation is given to verify the hardware signal generator. The implemented hardware of Chen's system generates outputs in good agreement with the numerical simulation. The hyperchaotic signal output from the DSP is applied to generate complex perturbations in liquid mixing experiments. Dye dispersion experiments show that the induced hyperchaotic motion effectively helps enhance the mixing homogeneity in the stirred-tank-based mixer in our laboratory. Copyright © 2008 John Wiley & Sons, Ltd. [source] Detection of Nucleic Acids Using Enzyme-Catalyzed Template-Guided Deposition of Polyaniline,ADVANCED MATERIALS, Issue 4 2007Q. Gao An electrochemical procedure for the detection of nucleic acids is realized by utilizing polyaniline as a signal generator for the transduction of nucleic acid hybridization events (see figure). The unique combination of enzymatic amplification and template-guided deposition can be used in conjunction with other detection techniques, and the sensitivity of the biosensor increases with increasing time. [source] Active measurements of antenna diversity performances using a specific test-bed, in several environmentsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2010Moctar Mouhamadou Abstract The diversity performances of the wireless devices operating in a multipath propagation environment are usually presented in terms of correlation coefficient, diversity gain and effective diversity gain. These parameters can be measured in reverberation chamber. This paper presents some active measurements of antenna diversity performances on a small wireless terminal in several realistic environments. The measurements were performed in the WiMax band, i.e. at 3.5 GHz, in a reverberation chamber where the channel is statistically uniform, in a real indoor propagation channel, and in an outdoor-to-indoor environment. The diversity performances are evaluated by using a specific test-bed constituted by an arbitrary signal generator and two radio-frequency digitizers. The effectiveness of diversity is presented in terms of effective diversity gain, signal to noise ratio, bit error rate and frame error rate. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. [source] A fully integrated ultra-low power CMOS transmitter module for UWB systemsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2009Tao Yuan Abstract A fully integrated CMOS ultra-wideband (UWB) transmitter module is proposed for UWB applications. The transmitter module consists of a band-notched UWB antenna and a transmitter IC which integrates a pulse generator, a gating signal generator and driver amplifiers (DAs). The drive amplifier uses a two-stage amplifier,a Class-E amplifier and a Class-A amplifier with switch control, to significantly reduce power consumption (522 ,W/20 Mbps). Fabricated using a 0.18-,m CMOS process, the generated pulse then passes through the DA, which not only drives the antenna but also shapes the generated digital signal to meet the Federal Communications Commission spectral mask specification. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2318,2323, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24632 [source] Electromagnetic Field Treatment of Nerve Crush Injury in a Rat Model: Effect of Signal Configuration on Functional RecoveryBIOELECTROMAGNETICS, Issue 4 2007Janet L. Walker Abstract Electromagnetic fields (EMFs) have been demonstrated to enhance mammalian peripheral nerve regeneration in vitro and in vivo. Using an EMF signal shown to enhance neurite outgrowth in vitro, we tested this field in vivo using three different amplitudes. The rat sciatic nerve was crushed. Whole body exposure was performed for 4 h/day for 5 days in a 96-turn solenoid coil controlled by a signal generator and power amplifier. The induced electric field at the target tissue consisted of a bipolar rectangular pulse, having 1 and 0.3 ms durations in each polarity, respectively. Pulse repetition rate was 2 per second. By varying the current, the coils produced fields consisting of sham (no current) and peak magnetic fields of 0.03 mT, 0.3 mT, and 3 mT, corresponding to peak induced electric fields of 1, 10, and 100 µV/cm, respectively, at the tissue target. Walking function was assessed over 43 days using video recording and measurement of the 1,5 toe-spread, using an imaging program. Comparing injured to uninjured hind limbs, mean responses were evaluated using a linear mixed statistical model. There was no difference found in recovery of the toe-spread function between any EMF treatments compared to sham. Bioelectromagnetics 28:256,263, 2007. © 2007 Wiley-Liss, Inc. [source] Generic UMTS test signal for RF bioelectromagnetic studiesBIOELECTROMAGNETICS, Issue 6 2004H. Ndoumbč Mbonjo Mbonjo Abstract This report outlines the characteristics of universal mobile telecommunications system (UMTS) signals and discusses the signal parameters with respect to their possible biological relevance in order to define a generic UMTS test signal (GUS) for experiments aiming at the investigation of biological effects of weak electromagnetic fields. The GUS includes features of a real UMTS signal and especially the characteristics of UMTS, which differ from those of already applied second generation mobile communication systems (GSM 900, DCS1800, PCS1900, IS-95). It has been specified on the basis of the recommendations of a working group of the German Forschungsgemeinschaft Funk (FGF) with a focus on the mechanisms of UMTS which are responsible for slow term signal contributions, i.e., low frequency variations of the radio frequency (RF) envelope, since the hypothetical possibility of biological relevance of weak electromagnetic fields is often attributed to time variations of the RF envelope with frequencies close to those of natural processes. In this respect, it is also shown that the mandatory power control loop in UMTS gives rise to very strong 1.5 kHz variations on the air interface. Based upon the concept of the GUS, a UMTS test signal generator (GUS6960S) is described. Bioelectromagnetics 25:415,425, 2004. © 2004 Wiley-Liss, Inc. [source] Genotoxicity of radiofrequency signals.BIOELECTROMAGNETICS, Issue 2 2002Abstract As part of a comprehensive investigation of the potential genotoxicity of radiofrequency (RF) signals emitted by cellular telephones, in vitro studies evaluated the induction of DNA and chromosomal damage in human blood leukocytes and lymphocytes, respectively. The signals were voice modulated 837 MHz produced by an analog signal generator or by a time division multiple access (TDMA) cellular telephone, 837 MHz generated by a code division multiple access (CDMA) cellular telephone (not voice modulated), and voice modulated 1909.8 MHz generated by a global system of mobile communication (GSM)-type personal communication systems (PCS) cellular telephone. DNA damage (strand breaks/alkali labile sites) was assessed in leukocytes using the alkaline (pH>13) single cell gel electrophoresis (SCG) assay. Chromosomal damage was evaluated in lymphocytes mitogenically stimulated to divide postexposure using the cytochalasin B-binucleate cell micronucleus assay. Cells were exposed at 37±1°C, for 3 or 24 h at average specific absorption rates (SARs) of 1.0,10.0 W/kg. Exposure for either 3 or 24 h did not induce a significant increase in DNA damage in leukocytes, nor did exposure for 3 h induce a significant increase in micronucleated cells among lymphocytes. However, exposure to each of the four RF signal technologies for 24 h at an average SAR of 5.0 or 10.0 W/kg resulted in a significant and reproducible increase in the frequency of micronucleated lymphocytes. The magnitude of the response (approximately four fold) was independent of the technology, the presence or absence of voice modulation, and the frequency (837 vs. 1909.8 MHz). This research demonstrates that, under extended exposure conditions, RF signals at an average SAR of at least 5.0 W/kg are capable of inducing chromosomal damage in human lymphocytes. Bioelectromagnetics 23:113,126, 2002. © 2002 Wiley-Liss, Inc. [source] | ||||||||||