Patent ID: 7178408

Claim:
A method for acoustically sounding the lower atmosphere over an altitude range using acoustic transmitter means and receiver means, the receiver means including a first acoustic transducer, the method comprising the steps of: employing the transmitter means to propagate an acoustic chirp into the lower atmosphere over said range along an axis of propagation, employing the first transducer to detect acoustic echoes of said chirp returned from the atmosphere both during and after the transmission of the chirp, said first transducer thereby also detecting acoustic interference including the direct transmission of the chirp, ambient noise and echo clutter, and employing the first transducer to generate a first analog electronic received signal representative of said detected echoes and interference, sampling said first analog received signal to generate a first input stream of digital samples representative of the instantaneous amplitude of the first analog received signal including signal components due to said interference, generating a complex Fourier transform of said first input stream of digital samples, correlating said complex Fourier transform of said first input stream of digital samples with a complex Fourier transform of the chirp to generate a correlated transform, generating an inverse Fourier transform of the correlated transform so as to generate an output stream of amplitude samples indicative of the strength of reflective or refractive anomalies with respect to range.