Inclusion of Rotor Blade Modulation in Computer Simulations or Wavefront Simulators

K.A. Griffith, I.J. Gupta

Abstract:	To evaluate the performance of an airborne GNSS receiver using computer simulations or wavefront simulators, one needs to include the platform effects in the simulations. For fixed wing platforms, this can be easily accomplished, however, the task is not as simple for receivers that are mounted on rotorcrafts. We have previously developed an approach to include the rotor blade modulation (RBM) in computer simulations as well as in wavefront simulators. The accuracy of the approach was verified using some numerical data obtained by electromagnetic analysis of an antenna mounted on a model rotorcraft. We have recently built a simple model rotorcraft and measured the response of an antenna mounted on this model rotorcraft. This paper presents the results of these measurements. The results show that the time domain response of the antenna at a given frequency is independent of the blade rotation speed. It is also shown that one obtains the same results when the response of the antenna is measured at discrete blade rotation angles or when the response of the antenna is measured as the rotor blades rotate at a fixed speed. Next, the measured antenna response is compared to the antenna response obtained using a numerical electromagnetic (EM) software package and it is shown that the measured and numerical antenna responses are very similar. Finally, the accuracy of our proposed method for including rotor blade modulation in computer or wavefront simulations is evaluated. It is shown that our method is an adequate approach for including rotor blade modulation in computer or wavefront simulations.
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:	1955 - 1964
Cite this article:	Griffith, K.A., Gupta, I.J., "Inclusion of Rotor Blade Modulation in Computer Simulations or Wavefront Simulators," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 1955-1964.
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