Detection of Millimetric Periodic Displacement Amplitude using one GPS Receiver

R.E. Schaal, A.P.C. Larocca

Abstract:	This paper presents the results of an approach to determine the value small displacements of a GPS antenna fastened to a structure. Vibrations, periodic or not, are common behavior of large structures, such as bridges, footbridges, tall buildings and towers under to dynamic loads. The behavior in time and frequency will lead into structural analysis studies. The hypothesis of article is that any large structure that presents vibrations in the centimeter range down to millimeters can be monitored by the phase measurements of a single receiver with high data rate, as far as the direction of the displacement is pointing to a particular satellite. In this scenario, the carrier phase will be modulated by antenna displacement. During a period of a few tens of seconds, the relative displacement to the satellite, the satellite clock and the atmospheric phase delays can be assumed as a polynomial time function. The residuals from a polynomial adjustment contain the phase modulation due to small displacements, random noise, receiver clock short time instabilities and multipath. The results showed that is possible to detect centimeters displacements in the phase data of a single satellite and millimeters in the difference between the phases of two satellites. Applying a periodic non sinusoidal displacement in the antenna with a span of ten millimeters appears clearly in the difference of the residuals. The FFT exhibited a defined peak of the third harmonic well over the random noise.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	1540 - 1544
Cite this article:	Schaal, R.E., Larocca, A.P.C., "Detection of Millimetric Periodic Displacement Amplitude using one GPS Receiver," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 1540-1544.
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