Small Dynamic Antenna Movements Detected From Phase Residual

Ricardo Schaal and Ana Paula Larocca

Abstract:	It is presented a new approach to monitor dynamic centimetric movements of a GPS antenna, based on the analyses of the amplitude and time behavior of the phase residual, obtained from the static double difference processing. The phase residual contains the receivers phase noise, atmospheric noise, the double difference multipath contribution, the double difference antennas phase center spatial distribution and any small movement that occurred in one antenna. All these components are added in a vectorial form and the research about these displacements is based on which satellite should be used as a reference for the double difference processing and which one for the phase displacement measurement. The movement contribution to the residual absolute value will depend on an oscillation amplitude and direction relative to satellites, reference and measuring. In a particular situation, when the oscillation occurs in the vertical direction and performing the measurement with one satellite overhead and choose the reference satellite close to the horizon, the phase contribution from the movement will be maximum. On the other hand, when the oscillation occurs in the horizontal direction, the measurement must be done with one satellite close to the horizon and the reference satellite overhead. To extract the displacement it is necessary to proceed a cleaning of the data. The FTT band pass filtering, in order to remain just the frequencies that describe the displacement can do this. Preliminary field simulation tests were carried out with a 1 Hz data collecting rate receiver allowing detect sub-hertz movements. Applying different amplitudes and directions in one of the antennas, the results showed that it is possible to measure the amplitude with a precision of a few millimeters. As very good results were obtained, several tests were carried out testing collecting rate under 1 Hz until 10 Hz. The final results obtained, which are presented in this work, show that this method is a very promising tool to measure sub-centimetric dynamic movements.
Published in:	Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001) September 11 - 14, 2001 Salt Palace Convention Center Salt Lake City, UT
Pages:	982 - 988
Cite this article:	Schaal, Ricardo, Larocca, Ana Paula, "Small Dynamic Antenna Movements Detected From Phase Residual," Proceedings of the 14th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 2001), Salt Lake City, UT, September 2001, pp. 982-988.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In