Electronique Serge Dassault

Dassault Electronique

Bernard J Maitre

Xavier Chazelle

Marie-Francoise Schaub

Xavier Chaella

Thibault De La Fresnaye

Bertrand Augu

A dynamic image is recreated from an observation radar whose extractor supplies an output of blips which are stored. These blips are firstly subject to a range/azimuth processing, which enables the image to be constructed. Then, they are subject to a pre-display processing in order to determine the geometry of the image and its brightness, after which the actual display takes place.

Device for recreating a dynamic image from a radar field of the invention

The surveillance radar device comprises, in combination, a fixed antenna for providing electronic scanning of space in bearing in the horizontal plane, a transmit source and microwave frequency transmit/receive means with a circulator, a transmit channel, a receive channel and means for subdividing the receive channel into a sum signal and at least one difference signal. A first and a second receiver element with frequency change respectively receive the sum and difference signals, and provide numerically coded outputs. Processing means process numerical signals from the first and second receiver elements for the radar detection of objects in the zone under surveillance.

Ground surveillance radar device, especially for airport use

In a process and device for the angular discrimination of targets by airborne radar, the angular position of a point on the ground is ascertained as a function of the Doppler frequency of an echo signal relating to the point under consideration, as determined by passband filtering the echo signals. The Doppler frequencies are selected by a bank of filters and an angular determination is made by analyzing signals including a signal representing the position in the bank of that filter selecting the Doppler frequency of the echo signal, and a reference frequency subject to closed loop control and representing the true Doppler frequency of the ground. Means are provided for maintaining data relating to the position and the range of the target constant during the process of analysis.

Angular discrimination process and device for radar

A coherent pulse radar is activated successively according to at least two pulse repetition frequencies. These frequencies are of values such that (a) the received signal is ambiguous both with regard to distance and with regard to velocity, and (b) their ratio is reducible to the quotient of two integers which are preferably adjacent and have no common factors. For the frequency analysis, a number of samples is taken which depends upon the pulse repetition frequency, the numbers of samples associated with the two pulse repetition frequencies being, in relation to one another, in the ratio of the two integers. The distance/velocity resolution cell is then invariant with respect to the pulse repetition frequency; this permits removal of the ambiguity concerning mean information items appertaining to a long integration time.

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Elancourt, France

Bernard J Maitre