Abstract: A method is disclosed for detecting atmospheric turbulence including aircraft induced wake turbulence and/or wind shear within an aperture associated with an aircraft approach or departure corridor around an airport. The method comprises transmitting into the aperture acoustic signals having a waveform suitable for pulse compression and receiving backscattered acoustic echoes of the acoustic signals from the atmospheric turbulence and/or wind shear. The method further includes processing the acoustic echoes in a matched filter receiver to provide a measure of the atmospheric turbulence and discriminating the aircraft induced demise time, being a time taken for the aircraft induced wake turbulence and/or wind shear to fall below a set threshold at least in the aperture. A system for detecting atmospheric turbulence including aircraft induced wake turbulence and/or wind shear associated with an aircraft approach or departure corridor around an airport is also disclosed.

Abstract: A Sodar apparatus is disclosed for sounding the atmosphere. The apparatus includes a transducer for converting an electrical signal to an acoustic wave and/or vice-versa and transferring means associated with the transducer for transferring the acoustic wave towards the atmosphere and/or for transferring a reflected acoustic wave from the atmosphere. The apparatus further includes isolating means or structure for isolating or attenuating the acoustic wave such that energy of the acoustic wave transferred in a substantially horizontal direction is reduced below energy of the acoustic wave transferred in a substantially vertical direction by a factor of at least 45 dB and more preferably by a factor of at least 70 dB. A method for sounding the atmosphere is also disclosed.

Abstract: A monstatic sodar system using long chirps and send-while-listening techniques employs transmitter-receiver pairs (Tw, Rw; Tv, Rv; Te, Re) that have coincident main lobes (Twm, Rwm; Tvm, Rvm; Tem, Rem). The system uses digital time domain matched filters and frequency modulated or digitally modulated (eg, BPSK) chirps. Digital frequency domain matched filtering may also be used. The matched filters generate sample streams indicative of the phase and amplitude of echo signals returned from the atmosphere after the transmission of a chirp into the atmosphere.