Asynchronous and self-organizing radiolocation system — AEGIR

Abstract

Since first travels by land or sea, it was necessary to determine position in an unknown environment. At the beginning methods were simple. They were based on the observation of characteristic points, in the case of shipping additional observations of the coastline. Then came a navigation based on astronomical methods (astronavigation). At the beginning of the XX-century a new way of determining the current location was developed. It uses radiowave signals. First came the radio-beacons, which at fixed intervals, transmitted well-defined sequence of radio signals. Then came ground-based systems. Pulse signals are received from at least three stations operating synchronously. Electronically measured the delay of one signal relative to the other, allows to determine the difference in distance separating the object from the localized sources. According to the principles of geometry allows the plot (or find) on the map hyperbole, which is the object. The newest way to determine your position are satellite systems. They are based on the measurement of arrival time of radio signals from satellites to the receiver. Currently, the most popular system is GPS (Global Positioning System). This system is fully controlled by the Department of Defense, and only the U.S. forces and their closest allies have guaranteed accuracy offered by the system. Armies of other countries can only use the civilian version. Due to the popularity of this system and its worldwide range, terrorist can build bombs with simple GPS receivers to detonate in a specific place. To prevent this, deliberate errors to the civilian version of the system can be introduced. Those deliberate errors will also prevent the use of GPS by the secret services or the armies of other countries than the U.S. This situation has spawned the need for an independent radiolocation system. This article describes the construction and operation of such a technology demonstrator that was developed at the Technical University of Gdansk. It was named AEGIR (according to Norse mythology: god of the seas and oceans). The main advantage of the system is to dispense with the chain organization of the reference station, which work with each other asynchronously. This paper presents results and analysis of its effectiveness.