Mathematical Problems in Engineering
Volume 2012 (2012), Article ID 595823, 15 pages
Research Article

Signal Transceiver Transit Times and Propagation Delay Corrections for Ranging and Georeferencing Applications

1CRAAM, Escola de Engenharia, Universidade Presbiteriana Mackenzie, 01302-907 São Paulo, SP, Brazil
2Instituto de Matemática e Estatística, Universidade de São Paulo, 05508-090 São Paulo, SP, Brazil
3Laboratório de Geotecnologias e CRAAM, Escola de Engenharia, Universidade Presbiteriana Mackenzie, São Paulo, SP, Brazil
4Instituto de Ciência e Tecnologia, Universidade Federal do Estado de São Paulo, 12231-280 São José dos Campos, SP, Brazil

Received 11 May 2012; Revised 20 July 2012; Accepted 10 August 2012

Academic Editor: Xi-Ming Sun

Copyright © 2012 P. Kaufmann et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The accuracy of ranging measurements depends critically on the knowledge of time delays undergone by signals when retransmitted by a remote transponder and due to propagation effects. A new method determines these delays for every single pulsed signal transmission. It utilizes four ground-based reference stations, synchronized in time and installed at well-known geodesic coordinates and a repeater in space, carried by a satellite, balloon, aircraft, and so forth. Signal transmitted by one of the reference bases is retransmitted by the transponder, received back by the four bases, producing four ranging measurements which are processed to determine uniquely the time delays undergone in every retransmission process. A minimization function is derived comparing repeater’s positions referred to at least two groups of three reference bases, providing the signal transit time at the repeater and propagation delays, providing the correct repeater position. The method is applicable to the transponder platform positioning and navigation, time synchronization of remote clocks, and location of targets. The algorithm has been demonstrated by simulations adopting a practical example with the transponder carried by an aircraft moving over bases on the ground.