Design and implementation of a computerized data base system for outpatient

CHAPTER ONE

1.1 INTRODUCTION 
A Geographical Information System (GIS) is a system of hardware, software and procedures to facilitate the management, manipulation, analysis, modeling, representation and display of geo‐referenced data to solve complex problems regarding planning and management of resources. Functions of GIS include data entry, data display, data management, information retrieval and analysis. The applications of GIS include mapping locations, quantities and densities, finding distances and mapping and monitoring change. There are mainly three categories of geographic positioning systems to determine or track a user’s location, which have been designed and proposed over the years. These systems are mainly three categories: 

 Global Positioning System, Wide-area Location System and Indoor Positioning System. Global Positioning System (GPS) receives signals from multiple satellites to determine the physical location of a user. 

The limitation for this system is that it is inefficient for indoor use; alongside in urban areas it often possesses difficulties in receiving signals where high buildings shield the satellite signals. 

Wide-area location systems are mainly based on cellular networks that involve measuring the signal strength, the angle of signal arrival and/or the time difference of signal arrival. The positioning information in wide-area location systems is highly limited by the cell size or cell coverage. 

Several approaches have been proposed for indoor location sensing or indoor positioning system such as infrared sensing, radio frequency, ultrasonic and scene capture analysis. There are also a few technologies to use within indoor areas, such as GPS psudo lite, ultrasonic and cellular-based systems, which need considerable supporting devices and facilities. Each of these methods has their own advantages and disadvantages. Some are expensive to implement, while others are not very accurate. The Active Badge is the first location system. Radar, well-known approach, is an RF (Radio Frequency) system for locating and tracking users within large structures. The approach is an empirical method and a signal propagation model. This procedure determines user location by combining signal strength measurements with signal propagation models. RF signal strength within building is affected by multipath propagation effects and absorption, resulting in non-linear behavior. The results show that the empirical method is superior in terms of accuracy with median resolution in the range of about 3m and the signal propagation model has 4.3m accuracy (median), but it makes deployment easier. The applications of indoor positioning are many, for instance, location-finding, indoor robots, inventory tracking, security, etc. 

Geographic Information (GI) represents information that can be associated to a location on Earth, information about nature phenomena, natural, cultural and human resources in general. A GIS (Geographic Information System) represents an ensemble of hardware-software for capturing stocking, validating, managing, analyzing and visualizing data that have a geographic reference. 

1.2 BACKGRAOUND

Function of an Information system is to improve one’s ability to make decisions. An Information system is a chain of operations starting from planning the observation and collection of data, to store and analysis of the data, to the use of the derived information in some decision making process. A GIS is an information system that is designed to work with data referenced to spatial or geographic coordinates. GIS is both a database system with specific capabilities for spatially referenced data, as well as a set of operation for working with data. There are three basic types of GIS applications which might also represent stages of development of a single GIS application