Marek Pola

Model comparison of bistatic radar clutter

Bistatic radars are parts of coherent multistatic radar systems for air targets positioning and tracking in various systems including the Air Traffic Control. The signal processing in the bistatic radar invariably encounters with a competitive signal, reflected from terrain objects - the land clutter. In this paper a research in the area of bistatic radar clutter modeling is presented. After the bistatic clutter scenario is defined two land-clutter models, based on a common general geometry are described. The bistatic radar clutter power equation derived here ([9]) is used for computation of interesting parameters like a bistatic radar effective clutter cross section, a total clutter power and a clutter reflectivity. In the end the two models are compared with actually measured bistatic radar clutter with use of a real terrain profile around the radar.

Accuracy of spectral analysis methods for precision indoor positioning system

At the University of Pardubice there is currently developed a modern positioning system for localization of fire brigade and members of rescue corps. The TDOA based system use an OFDM wideband signal to separate direct propagated signal from mixture of its replicas created in a multipath channel. In the paper, the model of a received signal is presented and this signal is processed by spectrum analysis methods to estimate the direct propagated signal delay. The accuracy of nonparametric, parametric and subspace methods is compared and new insights into application of spectral analysis methods are presented.

Effects of signal distortion in a FMCW radar on range resolution

Frequency Modulated Continuous Wave (FMCW) radars are used in many range measurement applications. The effects of phase errors in radar antenna, circuit dispersion and of frequency modulation nonlinearity on FMCW radar resolution have been analyzed using computer simulation and experiments with a radar prototype in the 10 GHz band.

A proposal of radio ultrawideband systems for precision indoor localization

Indoor localization systems have been used in many divers application of commercial, public service and military sectors. This paper presents a proposal of system for ultra-wideband (UWB) radio system allowing Real Time Localization (RLTS) in indoor environment. Accurately tracking people in indoor locations is a very difficult technical problem that has not yet been completely solved. UWB transmission technology is primary attractive in GPS denied environments such as buildings. In this paper will be described important parameters of ultra-wideband radio system that depends on complicated conditions especially in buildings. Another goal of this paper is to examine the basic positioning principle and various approach of realizations of UWB systems which would be used for tracking people in complex indoor environments. This application has been recently researched in many scientific papers and experimentally studied. The UWB localization system is especially suitable in this context because it allows centimeters accuracy in ranging, as well as low-power and low-cost implementation.

Ultra Wide Band receiver design

This paper deals with our Ultra Wide Band (UWB) receiver which is designed for precise indoor localization of fire fighters and members of the rescue teams. The purpose of this indoor positioning system is to search for UWB transmitters in a given area and to determine their position. This article describes not only the hardware design of the UWB receiver but also the FPGA firmware development. The described hardware is also focused on the development of algorithms and creating signal records used during the real positioning system development. The design of our UWB receiver considers many requirements such as wide bandwidth, high ADC sampling rate, high speed digital buses, high speed digital interfaces and being made of low cost parts. The results of our simulations show that UWB receiver we proposed is suitable for this application and the hardware and firmware is able to fulfill our requirements. New functions and new signal processing algorithms can be easily added to the FPGA firmware in the future.

Measurement on precise indoor positioning system in the real environment

At the University of Pardubice there is currently developed a precise indoor positioning system intended for fire fighters and robotic platforms. In this paper the measurement on such a system on the test HW signal chain is presented. Signal developed in the late paper [2] had been generated and sent to two receiver stations. Cables and air was used for the signal transmission. Signal from the both receivers stations was processed and the Difference of distances (DOD) was estimated. There were two ways of obtaining the DOD - a cross correlation method with the known signal pattern (Corr) and a spectral analysis method (SAM) [2]. The signal processing was shown to be highly robust leading to the system sub-meter accuracy. When measuring with cables, an average DOD error of 24.5 cm was demonstrated using the Corr method. For the measurement through the air the maximum average DOD error of 34 cm was reached by the SAM method.

Analysis of short - base multistatic systems receiving aircraft transponders signals

In the paper a mathematical model of a short-base multistatic system using aircraft transponder signals is presented. Several system modifications, combining a hyperbolic TDOA system, elliptical system using its own interrogator, angle measurement system and system exploiting the altitude information from the aircraft are simulated and analyzed. Their horizontal and vertical position estimation RMS errors are compared and possibilities of ADS-B based positioning system reliability enhancement are proposed.

OFDM signal bandwidth selection for indoor positioning system

In GPS denied environments like buildings there was unimaginable to wirelessly and electronically track members of rescue squads still few years ago. With today technologies the situation changed but there are still sever challenges to such system. Perhaps the most serious one is a direct signal separation from a bunch of its replicas caused by a multipath propagation. The aim of this article is to assess the problem of accurate direct signal time of arrival measurement in this situation. In the article the model of broadband transmitted and received signals modulated by OFDM are presented and methods of the direct signal delay estimation are described. Later the proper bandwidth for a sub meter accuracy of the range estimation is proposed based on modeling.

Pseudorange error analysis for precise indoor positioning system

Abstract There is a currently developed system of a transmitter indoor localization intended for fire fighters or members of rescue corps. In this system the transmitter of an ultra-wideband orthogonal frequency-division multiplexing signal position is determined by the time difference of arrival method. The position measurement accuracy highly depends on the directpath signal time of arrival estimation accuracy which is degraded by severe multipath in complicated environments such as buildings. The aim of this article is to assess errors in the direct-path signal time of arrival determination caused by multipath signal propagation and noise. Two methods of the direct-path signal time of arrival estimation are compared here: the cross correlation method and the spectral estimation method.