Maximizing Parallel Testing in an FM Receiver

High volume production environments create great challenges for production testing and verification of Radio Frequency (RF) devices. In this environment, much emphasis is put on parallel testing, or the ability to test multiple devices at the same time using a single tester. In order for this parallelism to become a reality, there is a need for production RF tests to be simplified and reduced to requiring only the simplest test stimulus and analysis. In this paper, we present a new method of measuring the performance of a Frequency Modulation (FM) receiver that requires only a continuous wave signal input in order to eliminate the more costly Signal-to-Noise Ratio test. Using this new technique we will then demonstrate how simplifying this test and adding frequency diversity enables testing of up to 8 devices in parallel using a single tester.     

Associations Between Message Features and Subjective Evaluations of the Sensation Value of Antidrug Public Service Announcements

The effective targeting of high sensation-seeking adolescents, who are most at risk for drug abuse, requires the creation of high sensation value messages. Whereas previous research has focused on subjective reactions of receivers as the primary way to define message sensation value (MSV), we conceptualize message sensation value as the formal and content features (audio, visual, and format) of a message that contribute to subjective message sensation evaluations. The three objectives of this study were (a) to identify message design features that would aid in the development of effective prevention messages targeting high sensation seekers, (b) to develop an objective measure of message sensation value based on formal and content features of messages, and (c) to determine whether high message sensation value messages were associated with higher subjective evaluations of message sensation value. In the present study, 418 undergraduates each viewed 10 PSAs selected at random from a pool of 109 PSAs that had been previously coded for message sensation value. Analyses provide support for the central hypothesis of the study, indicating that perceived message sensation value is at least in part a product of the formal and content features of a PSA.     

用于网络视频的单处理器解决方案

网络和视频领域正趋于互相融合,为嵌入式应用提供了新的应用领域。但是直到最近才出现带集成以太网功能并且能处理高质量视频的单芯片处理器。其原因有以下几点：微控制器(MCU)虽然具有以太网功能,但是处理能力的限制使其只能处理比较低的视频分辨率或比特率,另一方面,专用的视频处理器通常不是缺少网络接口(因此依赖于主机的MCU),就是太不灵活了而不能应付不断变化的需求和多样的视频编码解码情况,其高功耗对很多市场来说成本太高。     

手工式模拟设计获得自动化辅助

模拟仿真器与设计捕捉工具在EDA市场已有长久的历史,这个市场一直在为数字仿真器增加某些Spice。不过,当仿真结果要转换为正弦波和硅片时,模拟EDA工具就会远远落后于数字EDA工具的水平。这种情况正在开始改变,传统数字EDA供应商正在出现以纳米尺度数字工艺支持模拟功能晶圆制作的工具。另外,代工厂专用工具包也正在简化用模拟工艺实现模拟、RF大电压功能的过程。     

Non‐Geminate Recombination as the Primary Determinant of Open‐Circuit Voltage in Polythiophene:Fullerene Blend Solar Cells: an Analysis of the Influence of Device Processing Conditions

The physical origin of the open‐circuit voltage in bulk heterojunction solar cells is still not well understood. While significant evidence exists to indicate that the open‐circuit voltage is limited by the molecular orbital energies of the heterojunction components, it is clear that this picture is not sufficient to explain the significant variations which often occur between cells fabricated from the same heterojunction components. We present here an analysis of the variation in open‐circuit voltage between 0.4–0.65 V observed for a range of P3HT/PCBM solar cells where device deposition conditions, electrode structure, active‐layer thickness and device polarity are varied. The analysis quantifies non‐geminate recombination losses of dissociated carriers in these cells, measured under device operating conditions. It is found that at open‐circuit, losses due to non‐geminate recombination are sufficiently large that other loss pathways may effectively be neglected. Variations in open‐circuit voltage between different devices are shown to arise from differences in the rate coefficient for non‐geminate recombination, and from differences in the charge densities in the photoactive layer of the device. The origin of these differences is discussed, particularly with regard to variations in film microstructure. By separately quantifying these differences in rate coefficient and charge density, and by application of a simple physical model based upon the assumption that open‐circuit is reached when the flux of charge photogeneration is matched by the flux of non‐geminate recombination, we are able to calculate correctly the open‐circuit voltage for all the cells studied to within an accuracy of ±5 mV.     

投影产品的新宠——氙灯

色彩方面的优点氙灯的光线可以提供的优异的色彩,得益于其在可见光波长范围内平坦的光谱输出。其它灯的光谱输出通常带有尖峰,要达到氙灯的光谱输出需要做额外的调整。氙,因为它的光谱输出包含所有颜色,只需较小的或不深的色平衡就可以达到优异的颜色投射和高质量的视觉色调。因此在使用氙灯后,消费者可以看到更好的色彩对比度和优质的图象。氙灯的色温是6500K,汞灯的色温约为8000K。由于最佳的色温是6500K(D65),汞灯的光谱输出需要过滤才能适合这个标准。降低汞灯色温过滤的办法也导致发光效率下降。虽然汞灯比氙灯的效率高得多,但是该必…     

使用系统总线性能计数器来测量和改善嵌入式系统的性能

了解系统总线的活动情况可帮助开发工程师显著改善嵌入式应用的性能。过去,由于嵌入式处理器缺乏复杂的软硬件结合特性,因此监测系统总线的活动情况是一项挑战性难题。在系统级了解应用程序的行为对于有效利用系统资源非常关键,这些资源包括外部存储器、DMA控制器、仲裁、系统总线互连等。     

嵌入式操作系统管理汇聚应用

当今许多复杂的嵌入式系统要求信号处理和信号控制两种功能.过去这两种功能一直属于DSP和微控制器(MCU)两种独立的器件.然而,汇聚处理器的推出改变了这种现状,将DSP和MCU两种功能集成到一种灵活体系结构中,典型的代表有ADI公司的B1ackfin处理器系列.     

了解高级处理器特点提高编码效率

如今的数字信号处理器(DSP)在性能、外围设备集成、功耗和成本方面都具备很多优势,很多系统设计人员希望在原有系统设计中利用DSP获得比传统处理器更好的效益。但其中一个