True-Power Measurement in Digital Communication Systems Affected by In-Channel Interference

A new cyclostationarity-based method for power measurement in digital communication systems in the presence of in-channel interference is proposed. The new method takes advantage of the signal-selective properties typical of algorithms based on cyclic spectral analysis. The true-power measure is achieved from the noisy data by estimating the cyclic spectrum of the desired signal at a cycle frequency not shared with noise and interference. The performance of the method is evaluated through several experiments on spread-spectrum and pulse-amplitude-modulated signals and with reference to different types of interfering signals. The method exhibits very good performance even when the desired and interfering signals completely overlap in both temporal and spectral domains.      

GPRS无线通讯在计量检测中的应用

本文简介了GPRS无线通讯模式以及与传统有线通讯方式的比较,随着信息技术的发展,测量技术与通信技术的紧密结合使得测量技术领域向远程计量及测量系统控制方向发展,GPRS无线通讯在计量检测领域中也可得到应用。     

Video Transmission for Third Generation Wireless Communication Systems

This paper presents a twin-class unequal protected video transmission system over wireless channels. Video partitioning based on a separation of the Variable Length Coded (VLC) Discrete Cosine Transform (DCT) coefficients within each block is considered for constant bitrate transmission (CBR). In the splitting process the fraction of bits assigned to each of the two partitions is adjusted according to the requirements of the unequal error protection scheme employed. Subsequently, partitioning is applied to the ITU-T H.263 coding standard. As a transport vehicle, we have considered one of the leading third generation cellular radio standards known as WCDMA. A dual-priority transmission system is then invoked on the WCDMA system where the video data, after being broken into two streams, is unequally protected. We use a very simple error correction coding scheme for illustration and then propose more sophisticated forms of unequal protection of the digitized video signals. We show that this strategy results in a significantly higher quality of the reconstructed video data when it is transmitted over time-varying multipath fading channels.     

波分复用系统中功率代价的测试

介绍了波分复用（ＷＤＭ）系统中功率代价的起因、测试方法和测试顺序,指出了各种起因对系统性能的影响,并提出了减小相应功率代价的方法。给出了８×２．５Ｇｂ／ｓ×（３×１５０ｋｍ常规单模光纤）ＷＤＭ系统中第６信道和第８信道的功率代价测试结果,ＣＨ８的总功率代价为１．８ｄＢ,其中色散代价为０．８ｄＢ,ＡＳＥ代价为０．９ｄＢ,串话代价为０．１ｄＢ;而ＣＨ６的总功率代价则仅有０．６ｄＢ。     

交流数字功率表测量不确定度的评定

交流数字功率表作为多用途电子测量仪器,在物理、电气、电子等测量领域得到广泛的应用,如何提高功率表校准的准确度是功率表应用的重要课题之一。本文通过对功率表的校准,对其测量结果进行不确定度评定。     

一种适用于无线通信系统的小型微带天线设计

目前无线通信中的天线设计需要满足通信终端日趋小型化的要求.本文提出了一种新型的适用于无线通信系统的小型微带天线.该天线同时采用贴片左右对称曲流和接地板蚀刻梳状缝隙两种小型化方法,使其尺寸大大减小.测试结果表明,该天线在回波损耗时的工作带宽可达到2.415GHz～2.47 GHz,同时具有较好的辐射增益,是一种具有很好理论参考意义与实用价值的微带天线.     

The Direct Digital Measurement of Low-Pass Noise Power

A direct digital method of measuring the noise power in a low-pass random waveform is described. The input-output relationship and the sensitivity of the digital detector are determined. Direct digital measurement of noise power offers a number of advantages in the instrumentation of radiometers and other noise-measuring systems.     

基于nRF903的无线数传模块设计

本文介绍了采用nRF903和P89LPC932构成的无线数传模块,该模块接口电路简单可靠,并能实现低功耗工作。可适用于无线通信系统。     

Measurement of the Individual Harmonics Reactive Power in Nonsinusoidal Systems

This paper presents a method of individual harmonics reactive power measurement for a load supplied by a nonsinusoidal source. The method consists of transforming the load-voltage and the load-current frequency spectra by multiplying both quantities by the quadrature voltages. Next, the products obtained are filtered with a pair of mutually symmetrical narrow-band filters. The mean value of the filter output voltage product appears to be proportional to the individual harmonics reactive power of the load.     

Monitoring in Industrial Systems Using Wireless Sensor Network With Dynamic Power Management

The advances in wireless communication, microelectronics, digital electronics, and highly integrated electronics and the increasing need for more efficient controlled electric systems make the development of monitoring and supervisory control tools the object of study of many researchers. This paper proposes a digital system for energy usage evaluation, condition monitoring, diagnosis, and supervisory control for electric systems applying wireless sensor networks (WSNs) with dynamic power management (DPM). The system is based on two hardware topologies responsible for signal acquisition, processing, and transmission: intelligent sensor modules (ISMs) and remote data acquisition units (RDAUs). The gateway function of the wired network is carried out by remote servers (RSs) based on the Soekris architecture, which is responsible for receiving the data collected and transmitting it to the supervisory controller (SC). To extend the WSN lifetime, sensor nodes implement a DPM protocol. The basic characteristics of the presented system are the following: 1) easy implementation; 2) low-cost implementation; 3) easy implementation of redundant routines (security); 4) portability/versatility; and 5) extended network lifetime.      

基于小波变换的电力系统谐波测量方法

小波变换具有时-频局部化特性,在电力系统的分析中具有无比广阔的应用前景.本文将小波变换方法应用于电力系统谐波检测中,并提出了同步检测与小波变换相结合的电压闪变测量方法,仿真结果表明此方法适用于电压闪变信号的检测和分析.     

Real-Time Digital Multifunction Instrument for Power Quality Integrated Indexes Measurement

In this paper, the design and implementation of a high-performance, real-time power quality (PQ)-measuring instrument based on a digital signal processor is discussed. The system is realized according to the latest standards about PQ monitoring, and it can be reconfigured for future developments of the standards. The instrument is particularly implemented to operate in stand-alone mode, and it is interfaced with a hardware module that adopts Transmission Control Protocol/Internet Protocol to exchange information and data. The main advantage of the realized device is the possibility to perform a comprehensive PQ monitoring that adopts a single low-cost instrument. Finally, this paper reports some preliminary experimental results of the accuracy characterization of an implemented prototype of the proposed instrument.      

图像处理在MDT测量镜片屈光度中的应用

从莫尔偏折技术(MDT)测量镜片屈光度的原理出发,给出了镜片屈光度与莫尔条纹倾角的关系式.进行了实验采集,获取了MDT实测镜片屈光度的莫尔条纹图.然后,基于莫尔条纹图像的特点,采用合适的图像处理算法对实测镜片的莫尔条纹图进行了灰度均匀化、降噪、图像增强、细化等一系列的数字图像处理操作,得到了镜片测量中莫尔条纹图形的清晰轮廓线.最后,给出了不同镜片屈光度的MDT测量结果,并与焦度计的测量结果进行了比较.结果表明,莫尔偏折技术结合数字图像处理用于测量镜片的屈光度时,具有很高的测量精度.     

Rate-Energy Tradeoff for Wireless Simultaneous Information and Power Transfer in Full-Duplex and Half-Duplex Systems

In this paper, we study the rate-energy tradeoff for wireless simultaneous information and power transfer in full-duplex and half-duplex scenarios. To this end, the weighting function of energy efficiency and transmission rate, as rate-energy tradeoff metric is first introduced and the metric optimization problem is formulated. Applying Karush-Kuhn-Tucker (KKT) conditions for Lagrangian optimality and a series of mathematical approximations, the metric optimization problem can be simplified. The closed-form solution of the power ratio is obtained, building direct relationship between power ratio and the rate-energy tradeoff metric. By choosing power ratio, one can make the tradeoff between information rate and harvested power in a straightforward and efficient way. Using the method similar to the half duplex systems, the optimal power ratio can be obtained in the full duplex systems, so as to balance the information transmission rate and energy transmission efficiency. Simulation results validate that the information rate is non-increasing with harvested power in half-duplex systems and the tradeoff of information rate and harvested power can be simply made. In the full duplex systems, the power ratio solution of the rate-energy tradeoff metric optimization problem can be used as the approximate optimal solution of the optimization problem and the approximation error is negligible.     

CDJL10A型无线温湿度与照度测量系统产品浅析

介绍一种新型的温湿度与照度的无线测量系统产品,详细介绍了其工作原理与电路硬件与系统软件设计。     

Automatic Digital Correction of Errors of Microprocessor Systems for Metering Electrical Power

A universal digital method for automatically correcting errors of analog-to-digital converters is considered which forms the basic functional element of a microprocessor system for metering electrical power. The essence of the operation of an algorithm for automatically correcting errors utilizing the method of standard signals is indicated.     

与图像有关的无线通信标准

有线的Internet与无线的移动通信网络有着截然不同的传输环境。3G虽然也定义了图像标准，但其所支持的视频业务标准并没有确定，这也将影响其普及和应用。