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Abstract
Multipath is one of the prominent error sources in Global Positioning System (GPS), which adversely affects the accuracy of the user’s position. This paper describes the estimation of frequency components of multipath error signal using spectral analysis and its effective mitigation using time-varying digital Alters. Four types of 2nd order Alters, namely, Butterworth, Type I and II Chebyshev and Elliptic filters, are examined for mitigation of multipath and their performance is compared. It is observed that by applying digital filters of different cut-off frequencies over the spectrum of the multipath, one can significantly reduce the multipath errors. The designed filters are applied to GPS data acquired from a typical urban environment site and found that Butterworth filter reduced the error most effectively. To extract the magnitude of error contribution in low and medium multipath frequency ranges, its mitigation is carried out with Butterworth filter. The performance of the filter is validated by the spectral analysis for multipath signals before and after filtering process. However, this spectral analysis followed by digital filtering is different from the approaches reported elsewhere in the open literature. This new approach is very useful in identifying least-affecting multipath sites for GPS applications.
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Notes on contributors
Yedukondalu Kamatham
Yedukondalu Kamatham was born in July, 1976 at Biradawada, India. He obtained his B.Tech. (Electronics and Communication Engineering) from Nagarjuna University, Guntur, Andhra Pradesh, India in 1998 and M.Tech, with specialization of Opto Electronics and Laser Technology from International School of Photonics, Cochin University of Science and Technology, Cochin-82, India in 2001. He is pursuing Ph.D. at Dept of ECE, University College of Engineering, Osmania University, Hyderabad, India. His areas of interest include GPS signal processing, Adaptive signal processing, Optical, Analog and Digital Communications. He has been guiding several B.Tech. /M.E student projects in these areas. He has published more than 22 research publications. Presently he is an Associate Professor in ECE department, ACE Engineering College, Ankushapur, Ghatkesar Mandal, Ranga Reddy Dist -501 301, Andhra Pradesh, India. He has 14 years of teaching experience in various Engineering Institutions with different academic positions. He is member of IEEE and life member of ISTE. E-mail: [email protected]
A. D. Sarma
A. D. Sarma (M’11) was born in Achanta, India, in August 1953. He received the Ph.D. degree in electronic and electrical engineering from London University, London, U.K., in 1986. He was associated with Defence Electronics Application Laboratory, Defence Research and Development Organization, Dehradun, India; Electrical Engineering Department, Indian Institute of Technology Delhi, New Delhi, India; Defence Electronics and Research Laboratory, Defence Research and Development Organization, Hyderabad, India; Telecommunications Division, Electrical Engineering Department, Eindhoven University of Technology, Eindhoven, The Netherlands; andWave Propagation Laboratories, National Oceanic and Atmospheric Administration, Boulder, CO. He has about 30 years of experience in the areas of GPS, radio-wave propagation, and mobile communication. He has been guiding several Ph.D. students in these areas. He is currently the Director of the Research and Training Unit for Navigational Electronics (NERTU), Osmania University, Hyderabad. He has more than 200 papers to his credit. E-mail: [email protected]
Ashwani Kumar
Ashwani Kumar was born in June 1959 at Arrah, India. He obtained his B.Sc. (Hons) in Physics from BHU, Varanasi in 1978 and M.Sc. from M.U., Bodh Gaya in 1980. He obtained his Ph.D. from Osmania University, Hyderabad. He is working as Scinetist ‘G’ in Defence Electronics Resaearch Laboratory (DLRL), Hyderabad. Since 1984 he is in the field of design, development and production of various types of wide band antennas, antenna systems and Radomes for communication and radar Electronic Warfare applications. His present areas of interest include Multibeam Phased arrays, Shared apertures, Wide band Printed Circuit antennas,Fractal antennas, Reflectors and antennas for GNSS applications. He has 32 technical papers and 2 patents to his credit. He is Fellow of IETE, India and Member AOC, India Chapter. E-mail: [email protected]
K. Satyanarayana
K. Satyanarayana obtained bachelor’s degree in ECE from Osmania University, Hyderabad in the year 1976 and Masters Degree in 1984 from the same university. He worked as Assistant Engineer in the state owned SCC Ltd from November 1977 to April 1985. He joined the University College of Engineering in May 1985 as Lecturer. He is presently an Associate Professor in the Department of BME, UCEOU. His academic responsibilities at the college included Chairman, Board of Studies in BME, Head BME. He was also Systems Analyst, Network Administrator OU, Director, Computer Centre, UCE OU. He designed the Campus wide networks for the College of Engineering and Osmania University. His present areas of research and development interests include Design and Development of GPS based systems, Embedded systems, Medical Instrumentation, Solar power systems, RFID based Inventory and instrument tracking systems, Automated test instrumentation, Computer Networks, Cloud computing and DSP. E-mail: [email protected]