Estimation of aircraft angular coordinates using a directional-microphone array--An experimental study.
Ground reflections cause problems when estimating the direction of arrival of aircraft noise. In traditional methods, based on the time differences between the microphones of a compact array, they may cause a significant loss of accuracy in the vertical direction. This study evaluates the use of first-order directional microphones, instead of omnidirectional, with the aim of reducing the amplitude of the reflected sound. Such a modification allows the problem to be treated as in free field conditions. Although further tests are needed for a complete evaluation of the method, the experimental results presented here show that under the particular conditions tested the vertical angle error is reduced ∼10° for both jet and propeller aircraft by selecting an appropriate directivity pattern. It is also shown that the final level of error depends on the vertical angle of arrival of the sound, and that the estimates of the horizontal angle of arrival are not influenced by the directivity pattern of the microphones nor by the reflective properties of the ground.
Acoustics Research Center, Department of Electronics and Telecommunications, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
Meritxell
M
Genescà
Acoustics Research Center, Department of Electronics and Telecommunications, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
U Peter
UP
Svensson
Acoustics Research Center, SINTEF Information and Communication Technology, N-7465 Trondheim, Norway.
Gunnar
G
Taraldsen