On-the-Fly Estimation of Antenna Induced Biases in SFAP Based GNSS Antenna Arrays

Y.C. Chuang, I.J. Gupta

Abstract:	Adaptive antenna arrays have become the system of choice for interference suppression in GNSS receivers. To increase the interference suppression capabilities the state-of-the-art GNSS antenna arrays are based on Space-Time Adaptive Processing (STAP) or Space-Frequency Adaptive Processing (SFAP). In SFAP, one can carry out suboptimal processing in that individual frequency bins can be processed independently to reduce the implementation requirements. One can make up for the loss in performance due to suboptimal processing by increasing the number of frequency bins. It has been shown [1] that implementation requirements for a 128-bin SFAP are similar to 9-tap STAP, and 128-bin SFAP can provide as good as or sometimes better interference suppression capabilities to a GNSS receiver. SFAP-based GNSS antenna arrays like STAP-based GNSS antenna arrays can lead to interference scenario dependent antenna induced biases in GNSS receiver measurements. Since these biases are interference scenario dependent, one cannot pre-calibrate the antenna induced biases. In this paper, we will describe a very efficient approach for on-the-fly estimation of the antenna induced biases in SFAP based antenna electronics. In the approach, the stored in-situ radiation patterns of the individual elements of the antenna array along with the real time SFAP weights are used to estimate the antenna induced biases. The approach accounts for the window function and sample overlapping in SFAP. The estimated antenna induced biases will be compared with the true antenna induced biases obtained from our computer simulations of a SFAP system. The computer simulations are based on real antenna arrays and include mutual coupling between antenna elements and platform effects. SFAP is applied to the base band digitized signals received by various antenna elements. These signals include satellite signals as well as interfering signals. Interference scenario consisting of multiple strong narrowband as well as wideband signal sources will be considered. [1] T.D. Moore, “Analytical study of Space-Time and Space-Frequency Adaptive Processing for radio frequency interference suppression,” PhD Dissertation, The Ohio State University, 2002.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2577 - 2582
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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