Relationship between ADC performance and requirements of digital-IF receiver for WCDMA base-station

The recent rapid development of digital wireless systems has led to the need for multistandard, multichannel radiofrequency (RF) transceivers. The paper presents the relationship between the performance of a bandpass-sampling analog-to-digital converter (ADC) and the requirements of a digital intermediate-frequency receiver for a wideband code-division multiple-access (WCDMA) base-station. As such, the ADC signal-to-noise ratio (SNR), the derivation of the receiver sensitivity using the SNR/spurious free dynamic range (SFDR) of the ADC, the effect of the ADC clock jitter and receiver linearity, plus the relationship between the receiver IF and the ADC sampling frequency are all analyzed. As a result, when a WCDMA base-station receiver has a data rate of 12.2 kbps, bit error rate (BER) of 0.001, and channel index, k, of 5 (sampling frequency of 122.88 MHz and IF of 92.16 MHz), the performance of a bandpass-sampling ADC was analytically determined to require a resolution of 14 bits or more, SNR of 66.6 dB or more, SFDR of 86.5 dBc or more, and total jitter of 0.2 ps or less, including internal ADC jitters and clock jitters.     

Transmission system using chaotic delays between lightwaves

We report a chaos-based transmission system that uses optical path differences between wavegroups produced by a short coherence source. Chaos synchronization is demonstrated in delay-differential equations involving optical delays larger than the coherence length of the source. The particular feature is all-optical chaos subtraction for message extraction and a very high masking efficiency.     

Low-noise amplifier design for ultrawideband radio

A new theoretical approach for designing a low-noise amplifier (LNA) for the ultra-wideband (UWB) radio is presented. Unlike narrow-band systems, the use of the noise figure (NF) performance metric becomes problematic in UWB systems because of the difficulty in defining the signal-to-noise ratio (SNR). By defining the SNR as the matched filter bound (MFB), the NF measures the degree of degradation caused by the LNA in the achievable receiver performance after the digital decoding process. The optimum noise matching network that minimizes the NF as defined above has been solved. When the narrow-band LNA assumption is made, the proposed optimum matching network simplifies to the published optimum narrow-band matching network, and the corresponding NF value also becomes equivalent. Since realizing the optimum matching network is in general difficult, an approach for designing a practical but suboptimum matching network is also presented.     

Controlled Growth of Layered Silver Stéarate on 2D and 3D Surfaces

This investigation confirms that silver stearate consists of an infinite‐sheet, two‐dimensional, nonmolecular layered structure. Scanning electron microscopy, X‐ray diffraction, and infrared spectroscopy reveal the following: plate‐like morphology is identified from the SEM image, XRD peaks can be indexed to the (0k0) reflections of a layered structure, and infrared peaks show that alkyl chains are present in an all‐trans conformational state with little or no significant gauche population. Based on these structural characteristics, we demonstrate that silver stearate, a prototype of layered organic‐inorganic hybrid material, can be grown not only in a designed two‐dimensional pattern but also in three‐dimensionally ordered ways by using carboxyl‐group terminated nanoparticles as a template.     

Near‐Optimum Blind Decision Feedback Equalization for ATSC Digital Television Receivers

This paper presents a near‐optimum blind decision feedback equalizer (DFE) for the receivers of Advanced Television Systems Committee (ATSC) digital television. By adopting a modified trellis decoder (MTD) with a trace‐ back depth of 1 for the decision device in the DFE, we obtain a hardware‐efficient, blind DFE approaching the performance of an optimum DFE which has no error propagation. In the MTD, the absolute distance is used rather than the squared Euclidean distance for the computation of the branch metrics. This results in a reduction of the computational complexity over the original trellis decoding scheme. Compared to the conventional slicer, the MTD shows an outstanding performance improvement in decision error probability and is comparable to the original trellis decoder using the Euclidean distance. Reducing error propagation by use of the MTD in the DFE leads to the improvement of convergence performance in terms of convergence speed and residual error. Simulation results show that the proposed blind DFE performs much better than the blind DFE with the slicer, and the difference is prominent at the trellis decoder following the blind DFE.     

Correction

The online version of the original article can be found at     

Digital Simulation of an Adaptive System for Long-Term Ventilation of the Lungs

Digital simulation of a model reference adaptive control scheme for long-term ventilation of the lungs is presented. This adaptive scheme is capable of bringing the instantaneous alveolar pressure of the patient to its normal level within one inspiration period, following a possible change in the patient's respiratory parameters (i.e., airway resistances or lung and chest wall compliances).     

Partition characteristics of close-boiling components in a chromatographic column

Partition characteristics of three close-boiling components (dichloromethane, diethylether, and dimethoxymethane) were investigated with dinonylphthaiate-coated Chromosorb A and helium as the carrier. The outlet stream from the Chromatographic column was monitored continuously. Partition coefficients were experimentally determined at various column temperatures for the three components. With the assumption of uniform film thickness, two parameters were estimated by Fourier analysis of the response curves. The Peclet number for particle was expressed in terms of the Reynolds number and the Schmidt number as: $$\frac{1}{{Pe,p}} = \frac{{0.87}}{{\operatorname{Re} \cdot Sc}} + 0.5$$ Intraparticle diffusion coefficient of each component was also determined in the form of the dimensionless group. P_i. The theoretical response curve in time domain was in good agreement with the observed one. From the sensitivity analysis, it is concluded that the liquid film resistance was small and the diffusion in the liquid phase was not a rate-determining step.     

Mass transfer in a stirred transfer cell with a flat interface

A agitated vessel of Lewis cell type was used to investigate the effect of physical properties on the mass transfer coefficient for partially miscible binary systems. Some measurements were performed with ternary systems transferring only one solute across two immiscible solvents. The mass transfer coefficients were measured under the conventional contra-rotating conditions which were behaved as if the interface was not rotating for some combinations of agitation speeds in each of the two phases. The mass transfer coefficient was deduced from solving a steady-state two dimensional convective-diffusion equation with the assumption of sinusoidal motion of eddies. Owing to the complexity of the hydrodynamic conditions near the liquid-liquid interface, theoretical approach was impossible. Thus, the effects of forced turbulence and physical properlies on the effective surface renewal time were experimentally investigated. The relation between the mass transfer coefficients and the relevant variables was obtained by conventional dimensional analysis as follow: 1 $$Sh_w = 1.93 \times 10^{ - 3} Ca^{1/2} Sc_w^{0.5} Re_w^{0.70} exp(1.60 \times 10^{ - 4} \frac{{v_w }}{{v_o }}Re_o )$$