Addressing in radio paging

A technique of batching calls in radio paging reduces pager power consumption and increases performance with no increase in decoder complexity.     

Digital signaling for radio paging

Some of the factors affecting the design of a binary signaling format for high capacity wide area digital radio paging are discussed. Topics considered are synchronization, battery economy techniques, error control coding to ensure acceptable success and false call rates, and the choice of bit rate. Paging successful and false call rates of typical format are predicted for moving and stationary pagers in environment of multipath propagation and shadowing.     

UHF radio propagation characteristics in straight open-groovestructures

The imperfect waveguide method is used to study UHF radio propagation characteristics in open-groove structures with particular interest being devoted to the frequency characteristics of the propagation attenuation constant. Attenuation of propagation has been characterized by the surrounding media absorption, the roughness of the sidewall, and the sidewall tilt. Our study shows that attenuation due to the surrounding media absorption is inversely proportional to the square of the frequency, whereas that due to the roughness on the sidewall surfaces is inversely proportional to the frequency and that due to the sidewall tilt is directly proportional to the frequency. The imperfectness of the actual open groove structures will cause additional electromagnetic mode conversion, thus increasing the propagation loss. The theoretical results are in agreement with the experimental data     

跨省寻呼信号大"串连"

安徽省滁州市位于安徽省东部，比临江苏省的南京市和扬州市。 近几年来，由于寻呼发射机数量的不断增加，在108MHz167MHz频段，电磁环境比较复杂，用户投诉干扰的现象也时有发生。不久前，我市来安县公安局多次反应其无线调度通信网所用中转台频率（收158．625MHz／发164．325MHz）受不明信号干扰严重，无法使用，要求我站予以排查。干扰现象 接到申诉报告后，我们带着HP8920A综合测试仪，IC—R7000扫描接收机驱车赶到现场。在四楼机房，打开中转台的监听开关，听到的是一片寻呼编码基带信号的音调（码率为1200bps，同步码近似一60…     

查找无线寻呼频率干扰二例

视屏幕上为何出现网纹 前不久，我处接到石家庄市有线电视台的反映，一电视节目受到长时间强干扰，致使较大范围内用户电视屏幕上形成严重的网纹，甚至有的电视用户基本不能正常收看。市有线电视台经过长时间检查、维护，仍未能解决问题。 电视接收机受干扰的现象早已引起人们的重视，但以前这方面的投诉主要集中在受到工厂、大功率无绳电话等设备的影响。受干扰的用户一般数量较少，影响区域也不大。但这次近十万用户同时受到同一严重干扰，范围之大，涉及用户之多都是前所未有的。 受干扰的电视节目频点为185．925MHz。用户反映网纹干扰…     

一种简易无线寻呼链路方案

在无线寻呼不断发展的今天，寻呼台的覆盖范围已经不再局限于大小城市，而是向城市的边缘地区、山区甚至农村延伸。在市场经济占主导地位的形势下，链路方案的经济性已不得不在考虑之列。我们经过一年多的实验和使用，摸索了一套低成本、简单易行的链路方案，使用效果较好。基本原理见图1和图2。　　链路主发射机原理见图1。用普通的100MHz对讲机（与寻呼台的寻呼机频率一致）接收寻呼台发射的数据信号，经过简单的整形后处理成规则的方波，用400MHz（或其他链路频率）大功率发射出去，供链路接收机接收。　　链路接收端也是用普通的400M…     

910 MHz urban mobile radio propagation: Multipath characteristics in New York city

Small scale statistics of multipath propagation in a heavily built-up urban mobile radio environment are presented. The statistics cover vehicle travel distances on the order of 30 m along streets. Measuring equipment time delay resolution is about 0.1 µs. In some locations, paths with significant amplitudes are observed with excess delays of 9 to 10 µs. The delay spreads (√second central moment of power delay profile) in this environment are on the order of 2 µs. Often the signal at fixed delays has a Rayleigh-distributed amplitude but large departures from the Rayleigh distribution also occur. From the measurements it appears reasonable to model the urban mobile radio channel as a Gaussian quasi-wide-sense stationary uncorrelated scattering channel within a bandwidth of 10 MHz and for intervals along the street of up to 30 m.     

新型高速寻呼编码

ERMES是ESTI规定的一种新型高速寻呼编码规程，具有传送速率高、通道容量大、频率分配模式效率高、省电等优点。本文介绍该系统的编码原则，编码结构、频率分配模式等。     

Analysis of radio paging errors in multitransmitter mobile systems

Many mobile telephone and personal paging systems require signaling simultaneously from multiple transmitters. This paper analyzes the factors that cause paging errors due to interference when the signaling format consists of audio tones sent simultaneously from two FM transmitters. The factors considered are: drift in carrier and modulation frequencies, and misequalization of land-line amplitude and audio delay. The following results are shown: 1) the interference errors are eliminated if the land lines are amplitude and phase equalized, 2)if the lines are not equalized but the modulation frequencies are equal, then the interference errors can be decreased by an order of magnitude if the transmitters are mistuned such that their difference carrier frequency is just greater than the modulation tone filter bandwidth in the receiver, and 3) if the modulation frequencies are slightly different, then the interference errors can be decreased somewhat by misequalizing the modulation indicies. It is then concluded that if the land lines are not equalized and the signaling tones are not exactly equal, the interference errors cannot be eliminated, but can be decreased by properly aligning the system.     

Theoretical studies of a simulcast digital radio paging system using a carrier frequency offset strategy

In a multistation simulcast digital radio paging system, each base station transmits the same RF signal simultaneously with the resulting efficient frequency utilization and simplified receiver design. In this system a paging receiver in the overlapping area receives several RF signals transmitted from different base stations. When frequency-shift keying (FSK) is used as a modulation method, experimental test results have already shown that the timing of each RF signal should be synchronized as closely as possible, but that the carrier frequency of each transmitter should be set following a certain offset assignment. The signal transmission performance in a multipath fading environment can then be markedly improved. The cause of this improvement effect is theoretically analyzed. It is clarified that the improvement effect is caused by transforming the probability distribution of time-averaged signal power.     

无线电波传播中的随机射线及其应用

对建模无线电波传播的随机射线进行了详细的阐述,从随机网格信道引出随机射线的概念,介绍了随机射线的产生背景和分类,并给出一种产生随机射线的数学模型随机桥过程。使用最大熵原理得到发生后次反射随机射线的概率分布。最后介绍使用随机射线建模超宽带室内信道的多径传播轨,在此基础上可以得到信道特性建模的基本随机变量,以及无线电波传播的概率模型等应用。     

CS优先寻呼机制应用与效果

为了缓解数据业务集中区域CCCH信道资源不足,根据CS和PS业务需求的特点的不同,提出了改变使用CCCH信道的优先级的解决方案.即CS寻呼消息在遇到明显拥塞时可以优先于PS业务的立即指派消息发送,从而解决CS寻呼拥塞的问题.     

Tropospheric radio propagation assessment

The status of tropospheric radio propagation assessment is reviewed and recent advances in this area are described. Special emphasis is given to anomalous propagation in a marine environment. Modeling and measurements of ducting phenomena caused by the oceanic evaporation duct and by elevated refractive layers are discussed. The modeling involves extensive numerical calculations of waveguide propagation, ray-tracing techniques, and empirical relationships. Effects such as sea-surface roughness and horizontal inhomogeneity are also addressed. The models have been compared with extensive measurements in a variety of geographic locations. Worldwide radio refractivity climatologies have been compiled. A propagation assessment system, called the "Integrated Refractive Effects Prediction System" (IREPS), has been developed and successfully tested. It uses a small computer with interactive graphic displays and provides the user with performance assessment of communications and radar equipment based on prevailing atmospheric conditions. Environmental inputs into the system consist of surface measurements and profiles of atmospheric refractivity either calculated from radiosonde balloon data or measured by microwave refractometers. Status and shortcomings of direct and remote sensing techniques for measurement of atmospheric refractivity are also discussed.     

综合呼叫中心系统的建设与应用

绍了综合呼叫中心的系统架构和组网情况,阐述了系统的主要特点,并结合黑龙江铁通的网络情况,重点分析了呼叫中心系统采用的几种关键技术.     

Computer model for paging system coverage

A simple model for estimating propagation coverage in a multiple-transmitter sequential paging system is described. The results of previous single-transmitter propagation studies are employed in a computer program where the resultant is a grid plot of hypothetical receiver locations, each with the expected number of transmitter signals exceeding the paging receiver threshold. The resulting plots readily show the areas where potential coverage problems may exist.     

A comparison of indoor radio propagation characteristics at 910 MHzand 1.75 GHz

The results of temporally and spatially distributed wideband (impulse response) propagation experiments in the 900 MHz and 1.7 GHz radio frequency bands in two different buildings on fixed indoor radio links are reported. Results from the temporal experiments show that, for a specific location in either of the two buildings, the dynamics of indoor channels are slightly less random at 910 MHz than at 1.7 GHz. It is believed that this would result in marginally better performance on a given transmit/receive link in the 900 MHz band. The spatially distributed measurements showed that the structures of average impulse-response envelopes differed for channels in the two buildings. In one building, RMS delay spreads were slightly greater in the 1.7 GHz band for over 90% of transmit/receive link configurations. In the other building, RMS delay spreads were marginally greater in the 900 MHz band for 70% of the configurations     

战术无线电系统及数据通信规程国外短波通信技术最新进展

在互联网和移动通信这两大主流业务称雄信息化领域的今天,世界发达国家始终没有停止过对短波通信技术的研究与发展.近几年来,西方国家从全球战略的高度研制了联合战术无线电系统和一系列保证不同供货商的产品设备能无缝连接的通信规程,在技术上不断取得重大突破.为此介绍国外短波通信发展动态供我国同类企业参考.     

The indoor radio propagation channel

In this tutorial survey the principles of radio propagation in indoor environments are reviewed. The channel is modeled as a linear time-varying filter at each location in the three-dimensional space, and the properties of the filter's impulse response are described. Theoretical distributions of the sequences of arrival times, amplitudes and phases are presented. Other relevant concepts such as spatial and temporal variations of the channel, large-scale path losses, mean excess delay and RMS delay spread are explored. Propagation characteristics of the indoor and outdoor channels are compared and their major differences are outlined. Previous measurement and modeling efforts are surveyed, and areas for future research are suggested     

On radio propagation through earth

The electromagnetic fields of a vertical electric dipole in a conducting half-space are considered. A numerical method for predicting the transfer between two receiving sites is outlined and the results are applied to a configuration used in an experimental test over the frequency range from 1 to 10 MHz.