Digital Beamforming Monopulse For GPS Attitude Determination

Chun Yang

Abstract:	Array antennas and digital electronics have improved considerably in performance, size, weight, power consumption, and affordability. GPS applications have benefited from progresses in adaptive spatial processing including jammer nulling, signal enhancement, and multipath rejection among others. Along this line of development with array antennas, this paper presents a digital beamforming monopulse technique for attitude determination with GPS signals. GPS attitude determination so far has predominantly relied upon the interferometric technique. As such, two independent baselines are required for three-axis attitude determination. For a given level of phase quality, the angular measurement accuracy of the incident signal’s direction relative to the baseline is proportional to the baseline length and particularly depends upon the ability to reliably resolve phase integer ambiguity and to timely repair cycle slips. In contrast, the monopulse technique presented in this paper has originated from surveillance and tracking radar. For each angular dimension, a pair of sum and difference beams are formed digitally from individual array element outputs. The ratio of the sum beam over the difference beam provides an angular offset measurement of the incident wavefront off the array boresight. This paper describes the concept of a GPS monopulse attitude determination system, alternative implementation schemes, a digital beamforming monopulse angular measurement algorithm, and an integrated attitude estimation algorithm. Computer simulation results are also presented to illustrate the system functionality and noise and dynamic performance.
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:	2037 - 2047
Cite this article:	Yang, Chun, "Digital Beamforming Monopulse For GPS Attitude Determination," 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. 2037-2047.
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