GNSS Receiver Biases Due to Non-Linear Phase of Controlled Pattern and Fixed Pattern Antennas

Christopher M. Church and Inder J. Gupta

Abstract:	It is well known that an antenna can introduce direction dependent biases into the code and carrier phase measurements of GNSS receivers. If the antenna has a fixed pattern, these biases can be calibrated and corrected. However, the pattern of an adaptive antenna changes based on the incident signals and, as a result, so do its bias errors. In previous work, we presented a method to predict these biases [1], which assumes that a GNSS receiver finds the true peak of the cross-correlation function. In practice, GNSS receivers use early and late time responses to find the peak of the cross-correlation function, which is assumed to be symmetrical. Due to non-linear phase of GNSS antennas (fixed as well as adaptive antennas) over the satellite signal bandwidth, the cross-correlation function may not be symmetrical, leading to an additional bias. In this paper, we extended our prediction approach to include this receiver induced bias with the antenna bias. The predicted biases are compared with the true biases obtained from computer simulations. We show that the proposed approach works very well in the presence as well as in the absence of jammers. We also demonstrate that for real world antennas, the receiver induced biases due to an asymmetrical cross-correlation function can be quite significant.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	1230 - 1235
Cite this article:	Church, Christopher M., Gupta, Inder J., "GNSS Receiver Biases Due to Non-Linear Phase of Controlled Pattern and Fixed Pattern Antennas," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 1230-1235.
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