Effects of Rotor Blade Modulation on GNSS Receiver Measurements

A.J. O'Brien, K. Hayhurst, I.J. Gupta

Abstract:	When an antenna is mounted on a helicopter or propellor aircraft, the motion of the rotor blades can cause received signals to undergo multipath that is very complex and timevarying. The resulting periodic variation in the amplitude and phase of received signals is known as rotor blade modulation (RBM), and it can have significant effects on the acquisition and tracking of incident global navigation satellite system (GNSS) signals. In this paper, we present an efficient and precise approach for modeling the effects of RBM on GNSS receiver measurements. This approach provides expressions for GNSS performance metrics such as carrier-to-noise ratio (C/N0), carrier phase bias, and code delay bias which completely characterize receiver performance on the rotocraft platform. Results are presented for a simulated antenna on a simple helicopter model with moving rotor blades. It is shown that the receiver measurements exhibit a time variation that is dependent on rotor blade speed and receiver integration period. The consequences of these effects on GNSS signal tracking are shown to depend on the specific receiver implementation.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	2352 - 2361
Cite this article:	O'Brien, A.J., Hayhurst, K., Gupta, I.J., "Effects of Rotor Blade Modulation on GNSS Receiver Measurements," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 2352-2361.
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