Thales

Thomson-csf

Thomson Marconi Sonar, S.a.s.

Yves Doisy

Laurent Deruaz

Guy Le Parquier

Louis Raillon

Pierre Alinat

Jean-Pierre Baudoux

Marc Masoni

Andre Le Gall

Edmond Noutary

Pierre Metivier

Francedillaois Chalaron

Laurent Deruaz-Pepin

A method for achieving omnidirectional transmission using of a towed linear antenna of length L greater than the wavelength &#x3bb; of the signal transmitted. The antenna has a plurality of P projectors. The spacing between projectors is substantially less than &#x3bb;/2. The method includes applying, to each projector, a transmit signal coming from a common transmit signal. The common signal is assigned a delay based upon a calculation that includes a non-linear term as a function of the position of the projector in the antenna, thereby allowing the angular aperture of the transmission pattern to be modulated. the method permits sonar detection systems comprising transmit and receive antennas having substantially identical diameters, which thereby can be reeled onto the same winch without it being necessary to separate them.

Method for optimizing the power supply for a towed linear transmit antenna for transmitting in omnidirectional mode

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 disclosure relates to a signal processing method for a towed linear antenna, notably to resolve right-left ambiguity, said antenna comprising a set of hydrophone multiplets each with n&#x2267;3 hydrophones spread over a straight section of the longitudinal axis of said antenna, wherein the roll angle of each multiplet relative to the vertical is measured, the signals of said hydrophones and said roll angles are used to synthesize p&#x2267;3 linear sub-antennas, then M azimuth channels are formed with each sub-antenna and 2 adaptive right-left channels are formed from said p sub-antennas for each direction corresponding to each azimuth channel. The invention resolves right-left ambiguity with optimal performance in detection and for long antennas.

Signal processing method for a towed linear antenna

A process for making it possible to detect moving objects by an active sonar operating by the Dopper effect. The process uses, as a transmission signal, a burst of N pulses encoded so as to present a spectrum having a comb-of-lines structure. In this way, the &ldquo;signal/reverberation&rdquo; ratio of the useful signal intensity to the reverberated intensity is increased, thereby increasing the efficiency of the sonar. The process allows objects moving in a reverberating transmission medium to be detected more easily.

Method for detecting mobile objects with active sonar

Method for measuring the doppler shift in a sensor system using

Method for compensating for the movement of the antenna for a sonar

A sonar that enables an already localized object to be found again uses a transmission antenna fitted out to transmit only the two .+-.first order secondary lobes. This antenna is supplied with a set of frequencies tiered so that each of these lobes determines a series of channels at transmission corresponding to these frequencies and filling two sub-sectors located to the right and to the left of the antenna. The reception is done by forming two wide channels, each of which covers one of the two transmission sub-sectors. The discrimination in bearing at reception is done by the discrimination of the frequencies. To cover a more extensive sector, including especially the central part located between two sub-sectors, the antenna can be made to rotate mechanically. This enables the construction of a simplified sonar which can be used in a consumable way.

Method for the formation of channels for sonar

Growing community of inventors

Grasse Plascassier, France

Yves Doisy