Algorithm for adaptive distance estimators for echolocation in air

We present an adaptive filtering and echolocator system that is able to adapt to the change in air temperature, pressure and humidity, preserving its capabilities of correctly detecting the echo position. The adaptive system is intended to work in conjunction with an air ultrasonic visualization system working at low frequencies, in the band 50-500 kHz. Topics addressed include: computation of the changes in received spectra due to changes in humidity of the air; determining the required adaptive filters responding to the air humidity changes, compensating for the distance-dependent attenuation, and preserving spectra of the reflected impulse; characterization of the reflecting surface; algorithms for the above. This paper proposes a preliminary algorithm, not yet tested.