Thales

Pierre Alinat

Yves Doisy

Laurent Deruaz

Georges Bienvenu

Marc Masoni

The invention relates to the field of underwater acoustics and more particularly to the field of signal processing in a low frequency (LF) active sonar system. The present invention makes it possible to decrease the false alarm rate while retaining the classification of the objects. The subject of the invention is a method of processing signals received corresponding to a signal emitted comprising by recurrence two pulses, a first Doppler tolerant broadband pulse of HFM type in particular and a second Doppler intolerant broadband pulse of BPSK type in particular, comprising:

Signal-processing method and active sonar implementing same

The present invention is directed to a method of allowing a computational load caused by the implementation of conventional signal processing methods operating by multicopy correlation, by simultaneous correlation of the spectrum of the received signal to copies of the signal, each of the copies having a different Doppler shift. The multicopy correlation operation is a time-frequency transformation of the received signal. Synthetic spectra are found by selection of spectral lines and concatenation, starting from the spectrum of the received signal. An inter-spectral product is computed, in other words by the product of each synthetic spectrum with the concatenated conjugate spectrum of the corresponding Doppler copy. A frequency-time transformation of the inter-spectral products is performed.

Fast coherent processing for codes with periodic line spectra

The invention concerns panoramic audio devices to process the impulsive signals received by passive sonars. It consists in isolating, in each beam, impulsive signals in the frequency and time domains and then filtering them according to the characteristics of the human ear. All left and right signals are then summed in order to be listened to in a headset. It allows rapid processing of impulsive signals.

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Vence, France

Pierre Alinat