Bg. Ferguson et Bg. Quinn, APPLICATION OF THE SHORT-TIME FOURIER-TRANSFORM AND THE WIGNER-VILLE DISTRIBUTION TO THE ACOUSTIC LOCALIZATION OF AIRCRAFT, The Journal of the Acoustical Society of America, 96(2), 1994, pp. 821-827
The dominant feature in the acoustic spectrum of a propeller-driven ai
rcraft is the spectral line corresponding to the propeller blade rate
that is equal to the product of the propeller shaft rotation rate and
the number of blades on the propeller. The frequency of this line, whe
n measured by a stationary observer on the ground, changes with time d
ue to the acoustical Doppler effect. In this paper, the short-time Fou
rier transform and the Wigner-Ville distribution are used to estimate
the propeller blade rate at short time intervals for a turbo-prop airc
raft flying at a constant altitude and speed over an acoustic sensor l
ocated just above ground level. The temporal variation in the observed
blade rate is then used to estimate the speed and altitude of the air
craft, together with the source (or rest) frequency of the blade rate.
Finally, the estimated values for these parameters are compared with
the actual values recorded onboard the aircraft during each of the eig
hteen transits formed by pairing each element of a set of speeds: 150,
200, and 250 kn, with each element of a set of aircraft altitudes: 25
0, 500, 750, 1000, 1250, and 1500 ft.