Authors: Jan M. Kelner, Cezary Ziółkowski, Leszek Kachel Title: The empirical veriication o the location method based on the Doppler eect Proceedings: Proceedings o MIKON-8 Volume: 3 Pages: 755-758 Conerence: 7th International Conerence on Microwaves, Radar and Wireless Communications, MIKON-8 Location: Wrocław, Poland Date: 9- May 8 DOI: INSPEC Accession Number: 357 Print ISBN: 978-83-9666-8- Publisher: IEEE Original Source: http://ieeexplore.ieee.org/xpl/articledetails.jsp?arnumber=4635 Copyright Notice 8 IEEE. Personal use o this material is permitted. However, permission to reprint/republish this material or advertising or promotional purposes or or creating new collective works or resale or redistribution to servers or lists, or to reuse any copyrighted component o this work in other works must be obtained rom the IEEE.
THE EMPIRICAL VERIFICATION OF THE LOCATION METHOD BASED ON THE DOPPLER EFFECT Jan M. Kelner *, Cezary Ziółkowski, Leszek Kachel Abstract: This paper deals with the new location method o radio wave sources, based on the Doppler eect. This unique approach was worked out on the ground o analytical solutions, that describe Doppler requency in ree-space propagation. In this method, position o the radio signal source is calculated on the basis o momentary requency measurements taken by mobile receiver. Theoretical and simulating analysis o the presented methodology was made beore empirical veriication process was introduced. This analysis enabled to evaluate technical capabilities, precision and distance working range o this new location method. Following problems are discussed in this presentation: the review o present methods o radio signals sources location, general outline o the method on the basis o the Doppler eect and preliminary empirical veriication results.. Introduction The problem o radio signals sources location inds the more and more wider range o uses. Location service ind application in: radio-navigation, supervision and control over utilization the radio waves resources, location o communication net users, radio-electronic recognition or military and the internal saety uses. In practice six basic methods are used [-5]: Cell ID or Cell o Origin (CoO), Angle o Arrival (AoA), Time o Arrival (ToA), Time Dierence o Arrival (TDoA), Received Signal Strength (RSS), Global Positioning System (GPS). Each o oregoing methods have some advantages and some disadvantages. These methods could be used, when the located signal source is element o the speciic communication system. In these cases, electromagnetic wave sources are located on the basis o knowledge about transmitted signals structures and transmission o indispensable data rom other system elements. I it is located source, that is element o unknown communication system, only Angle o Arrival method could be used. This method takes advantage o amplitude or phase bearing methods. In this case determination direction on electromagnetic radiation source requires usages o complex receiving antenna systems and bearing inders. Disadvantages, that be burdened oregoing methods, make diicult or practical utilization. So, thereore the new and universal methods o location should be worked out. Analytic description o the Doppler eect, creates one o such possibilities. In [6] we show the way how to solve Maxwell equations in the case o a transmitter continually changing location in relation to a receiver. The obtained solution presents the exact description o the received signal parameters that result rom the location change between a transmitter and a receiver. The analytic description o this problem makes it possible to calculate exactly the value o the received signal parameters especially requency oset. It applies to the communication systems whose objects move ast, or example satellite and airto-ground systems. The solution o Maxwell equations, we obtained, makes it possible to locate signal sources on basis o requency oset measurement.. New location method o radio emission sources Dependence o received signal requency ( x,t) in unction o movement measuring receiver trajectory was obtained on basis o the analytic description o Doppler eect [6, 7]. Founding, that receiver moves with constant velocity v = ( v,, ) (ig. ), the Doppler requency is expressed by ollowing dependence: D k x vt x = k + () k (, t) = ( x, t) ( x vt) + ( k )( y + z ) * Military University o Technology, Kaliskiego, -98 Warsaw, Poland, Phone: +48 68398, Fax: +48 683938, E-mail: jan.kelner@wel.wat.edu.pl
where: x = ( x, y, z) co-ordinates o located radio emission sources, k = v c, v measuring receiver velocit, c speed o light, transmitted signal requency, ( x,t) received signal requency. The new location method was worked out on the basis o ormula () [8]. When the mobile station is moving at set altitude ( y = y = const ), as in ig., then is needed to mark only two x and z co-ordinates. Ater elementary transormation o the expression () or two moments t and t the ormulas described x and z co-ordinates are ollowing [8, 9]: where: x t A t ( ) ta( t ) ( ) A( t ) = v, A t z ( k ) v ( t t ) A( t ) A( t ) A( t ) A( t ) = ± y () F () t () =, () t F() t D k A t F = k. (3) k In order to precision valuation o this location methodology ollowing new quality measure Δ r, urther called location error, was introduced [9]: ( Δx) + ( Δz) ( t) Δ r = = x x + z z, (4) where: x and z real position co-ordinates o the radio emission source (in experiment these values were determined on the basis o laser radar measure), x and z source co-ordinates calculated rom ormulas () (on the basis o momentary requency measure). Figure shows graphic explanation o introduced quantities. Fig.. Space structure o the mutually mobile station and transmitter station locations Fig.. The script o numeric calculations the orthographical projection o the movement measuring receiver set trajectory in relation to radio signal source This new location method was processed to dierential test and simulation. The received results were published in many papers and presented on many conerences [among other things in 7, 9]. Theoretical and simulating analysis o the presented methodology were made beore empirical veriication process was introduced. 3. Empirical veriication o this method The empirical investigation was perormed on Military University o Technology grounds. Figure 3 shows measuring rout with characteristic points A E and example course o Doppler requency. In experiment, source (target) was situated in position ( x, y, z ) = (5., 3.4,.4) m relative the begin o the right-handed cartesian co-ordinate system in point B. On rout section A B vehicle with receiver was speeded up to 36km/h, on section B D vehicle moves with constant velocity 36km/h (in this interval were made momentary requency measurements) and on section D E vehicle stopped. The vehicle average velocity on rout section B D was calculated on the basis o the riding time measurements. Curses o Doppler requency in unction o the time or covered path were obtained out o momentary requency measurements using the Universal Frequency Counter Agilent 533A. Average values o the source co-ordinates were calculated on the basis o Doppler requency courses. Table shows results o measuring and calculation.
Table.. Results o measuring and calculation Fig. 3. Measuring rout with characteristic points A E and example course o Doppler requency in unction o time (or measuring 4)
4. Summary and conclusion The experiment results give possibility to do initial opinion o location method precision. Possibility o these results comparison with dierent location methods [4, 5] is basis o this opinion. This comparison permits to iner about large eectiveness o the new method. Errors estimation o individual co-ordinates Δx, Δ z and location errors Δ r in presented method amounted below m (table ). It is needed to emphasize, that this method is dedicated irst o all to location in open area, where it occurs so-called: down-to-earth space propagation or ree space propagation. The measuring rout in this experiment could be classiied as suburban terrain. On this stage o empirical veriication, the test rout was choice by possibilities o test realization. The measuring rout in section B D (ig. 3) was chosen to conditions which were reminding down-to-earth space propagation (direct visibility o antennas on whole measuring rout section). There are buildings beside the section B D, which cause the signals relections. It is visible in disturbance o the Doppler requency course on sections A B and D E (ig. 3). This empirical test is initial useulness veriication o this new location method. Many tests in dierent space conditions should be conducted, to get the ull inormation o method eectiveness. Reerences [] An Introduction to Mobile Positioning, Mobile Liestreams Limited, 999. [] Gupta I. J.: Stray signal source location in ar-ield antenna/rcs ranges, IEEE Antennas and Propagation Magazine, vol. 46, issue 3, June 4, pp. -9. [3] Hata M., Nagatsu T.: Mobile Location Using Signal Strength Measurements in a Cellular System, IEEE Transaction on Vehicular Technology, vol. 9, no., May 98, pp. 45-5. [4] Vossiek M., Wiebking L., Gulden P., Weighardt J., Homann C.: Wireless local positioning concepts, solutions, applications, IEEE Radio and Wireless Conerence, RAWCON 3, Boston, 3 August 3, pp. 9-4; IEEE Microwave Magazine, vol. 5, issue 4, December 3, pp. 77-86. [5] Zhao Y.: Standardization o mobile phone positioning or 3G systems, IEEE Communications Magazine, vol. 4, issue 7, July, pp. 8-6. [6] Raa J., Ziółkowski C.: Inluence o transmitter motion on received signal parameters Analysis o the Doppler eect, Wave Motion, Elsevier, vol. 45, issue 3, January 8, pp. 78-9. [7] Ziółkowski C., Raa J., Kelner J. M.: Practical aspects o the Doppler eect in mobile communication systems, 7 th International Conerence on Microwaves, Radar and Wireless Communications MIKON 8, 9 4 May 8, Wroclaw, Poland, 9 4 May 8, Proceedings & CD-ROM. [8] Ziółkowski C., Raa J., Kelner J. M.: Method o bearing and location o the space radio wave sources using Doppler eect (original title: Sposób namiaru i lokalizacji źródeł przestrzennych al radiowych z wykorzystaniem eektu Dopplera), number o patent application: P 3854, 7 November 6, Polish Patent Oice, Warsaw, Poland. [9] Gajewski P., Kelner J. M., Ziółkowski C.: Location o the subscriber in radio communication nets, nd Military Communication and Inormation Systems Conerence MCC'8, Bonn, Germany, 5 6 September 7, CD-ROM.