Bulletin of the Institute of Space and Aeronautical Science University of Tokyo
Bulletin of the Institute of Space and Aeronautical Science University of Tokyo
Analyses are made, in this paper, on the resolution of the FM-CW (frequency modulation of continuous wave) acoustic sounder Two different types of noises, (1) the gaussian noise, (2) the pure sinusoidal wave, are assumed to be added to the saw-tooth modulating signal. These noises, through the nonlinear demodulation, degrade the distance measuring ability of the acoustic sounder. The relations between the sounding resolution (or accuracy) and modulating noises are made clear by theoretical calculations. Results are obtained showing that the FM-CW type of acoustic sounder can realize 10 times higher resolution compared to the conventional type of pulse acoustic sounder, for the same frequency band and measurement time.