Abstract: Apparatus for the observation and identification of helicopters by means of an FM-CW radar apparatus provided with transmitter means (1), antenna means (2) and receiver means (3). Blade flashes caused by the rotor blades are digitized by A/D converter (4) and processed by Fourier analysis means (5) and processor (6) in order to determine the range from a helicopter to the radar apparatus and the rotor symmetry characteristics. These symmetry characteristics, together with the blade flash repetition frequency yield a substantially unambiguous indication of the helicopter type.

Abstract: Radar apparatus provided with a transmit generator and antenna means for the transmission of comparatively long, linearly frequency-modulated transmitter pulses. Echo signals are received by antenna means and a heterodyne signal is generated in mixer stage. Propagation time differences for different echo pulses are compensated by means of a dispersive delay element incorporated in the radar receiver. Distortion of the echo pulses in the dispersive delay element is corrected on the basis of a Fresnel ripple correction. A Fourier transformation unit transfers the corrected echo pulses to time domain video with low sidelobes.

Abstract: A search radar system, is provided which includes at least one search radar device (1) having a primary antenna (2) and at least one secondary radar device (3) having an SSR/IFF antenna (4). The radar devices (1, 3) independently supply plot data from which signals are derived that are each suitable for presentation on a radar display. The antennas (2, 4) are oriented in opposite directions so that the said signals are derived from individual plot data representing successive detections by the respective antennas of the same target which can be individually presented. Hence, the data rate of the radar system is doubled relative to a conventional radar system having a conventional secondary radar device and a conventional antenna system.

Abstract: A radar apparatus provided with transmitter means (1), rotating antenna means (2) and receiver means (3) for the transmission per burst and the processing in a video processor of radar echo signals. The video processor includes moving target detection unit (4) provided with a doppler filter bank, for instance an FFT processor, and slow moving target detection unit (6), provided with coherent clutter maps, one map for each radar transmitter frequency used. The coherent clutter maps are also used for reducing the clutter strength of radar echo signals which are applied to the moving target detection unit (4), by subtracting the coherent clutter strengths stored in the clutter maps from the radar echo signals.

Abstract: A communication system comprises a bus system and a number of subsystems which produce and process information, each subsystem being coupled to the bus system by a respective interface. A subsystem makes requests for information of a desired type, including an indication of such type of information, and also produces information which includes an indication of the type of produced information, information request from a subsystem are coupled by its interface to the bus system, the interface also supply the subsystem with information received from the bus system of a type requested by such subsystem and which originated from one or more other subsystems. The interface supplies the bus system with information produced by the subsystem when a request for that type of information has been received from the bus system.

Abstract: Radar apparatus for determining the height of a low-elevation target, the target being illuminated by a transmitter (7) and an antenna (3) via a TR-switch (6). Electromagnetic radiation reflected directly by the target and indirectly by the target via the earth surface is received by the antenna (3) and processed in a sum receiver (9, 10, 11), connected via the TR-switch (6) to the antenna (3), into complex sum signals, and in a difference receiver (12, 13, 14), into complex difference signals. A signal processor (15), receiving the complex sum signals and the complex difference signals, is provided with an algorithm which determines the height of the target. The algorithm enables the determination of the target height while the antenna remains directed at the target.

Abstract: A resonant charging circuit for the charging of a pulse-forming network from a voltage source is provided with a first serial circuit provided with a first switch, an inductor and a first diode for charging the pulse-forming network. The charging circuit is further provided with a second serial circuit provided with a second diode, the inductor, a third diode, and a second switch for feeding excess energy, stored into the inductor, back to the voltage source. Opening and closing of the first and second switches takes place under the control of a control unit.

Abstract: A radar apparatus is provided with a jamming indicator (11), the jamming indicator (11) having the same bandwidth as the preselector filter (15) of the radar receiver (5).

Abstract: An improved power supply device is disclosed where the filament (2) of a transmitter tube (1) is powered by an AC generator (18) via a transformer (12) and a rectifier (24), and where the AC generator (18) receives a feedback via the bifilar winding (5) of a pulse transformer (3).

Abstract: A microwave vector modulator (4) of the reflective type is used to match a microwave load. The adjustable reflection of the vector modulator is obtained by semiconducting surfaces (18, 19, 20, 21), illuminated by light-emitting means (24, 25, 26, 27).

Abstract: The invention relates to a surveillance sensor provided with at least one surveillance radar antenna 1 and at least one co-located and co-rotating electro-optical surveillance sensor 5 mechanically connected to said radar antenna. A combined panoramic picture is compiled by combining information from both sensors using a common track unit 30.

Abstract: An antenna system provided with an adjustable reflection coefficient includes at least one radiation source (1), a reflective surface (12) positioned in the path of the radiation generated by the active radiation source (1) and 9 light-generating means (13, 14). The reflective surface (12) is provided with semiconductor surfaces (2.i.j) with a spacer-therebetween and the light of the light-generating means (13, 14) is used to illuminate the semiconductor surfaces (2.i.j) such that, after reflection of the radiation generated by the active radiation source at the reflecting semiconductor surfaces, a radiation beam is obtained in which the beam width and beam orientation can be varied by adjusting the light intensity so as to adjust the phase of the reflection of the semiconductor surfaces.

Abstract: The antenna system is provided with at least one active radiation source (1) and a reflective surface (2), which is located in at least one part of the radiation (3) generated by the active radiation source (1). The reflective surface (2) is provided with a number of independently adjustable plates (2.j) for generating at least one radiation beam. The antenna system may be provided with means (4) to independently adjust the plates (2.j) for the purpose of (dynamically) orientating the antenna beam.

Abstract: The invention relates to a radar apparatus provided with a detection unit, which determines the positions (12) of objects incorporating fast moving parts, such as helicopters. The detection unit thereto comprises a first range-azimuth area (3), a trend estimation and standard deviation calculation unit (5), a threshold (8), a second range-azimuth area (9) and a clusterer (11).

Abstract: Moving target indication unit provided with a doppler filter bank (1) with n output channels A.sub.i (i=0, 1, 2, . . . , n-1), several threshold circuits (24.i) connected to the output channels, a detection and registration unit (7, 14, 18, 23) provided with means (7, 14, 18) for the determination and registration, per azimuth cell, of a parameter for the amount of clutter in an azimuth cell. The said means are further suitable for determining, based on the output signals of the filter bank (1), k (k.gtoreq.2) parameters per azimuth cell and processing per azimuth cell the combination of k parameters to obtain n threshold values, used to set the n threshold circuits.

Abstract: A pulse radar apparatus is provided with a transmitting unit (4) for the transmission of a modulated transmitter pulse Y.sub.t, a mixer (9), an IF amplifier (11) and a quadrature detector (12) for the reception of signals Y.sub.r and the correlation of signals Y.sub.r with a replica X of the emitted modulated transmitter pulse Y.sub.t, to obtain an in time compressed correlation signal .sigma..sub.xy (.delta.). The pulse radar apparatus is also provided with a pulse discriminator (3) to enable, on the basis of at least one amplitude .vertline.Y.sub.r .vertline. of the received signal Y.sub.r and at least one amplitude .vertline..sigma..sub.xy (.delta.).vertline. of the correlation signal .sigma..sub.xy (.delta.), differentiation between the signals Y.sub.r, possessing modulation, and interference.

Abstract: An FM-CW radar apparatus is provided with: a transmitter unit (1, 2, 3) for the emission of frequency-modulated continuous carrier waves of bandwidth B; a receiver unit (6, 7) for the reception of echo signals reflected by a target, producing target-representing beat signals; a signal processing unit, to which the beat signals are applied, provided with: an A/D converter unit (8) for the sampling and digitization of the beat signals; a first FET processing unit (10) with the object of obtaining at least range information about a target; a second FET processing unit (12) with the object of obtaining at least high resolution information about a target; a control unit (13), which makes the output signals, generated by the first FET processing unit (10) and the second FET processing unit (12), suitable for presentation on a display (14).

Abstract: A sonar system has k acoustic detectors (1) for the detection and conversion of acoustic signals into electrical signals s(k), a beamforming unit (3), a frequency analysis unit (4), which uses the signals s(k) to generate signals s(.phi..sub.i, f.sub.j), representing acoustic signals with n frequencies f.sub.j (j=1 . . . n) received from m beam reception directions .phi..sub.i (i=1 . . . m), and a data processing unit (5). The data processing unit (5) comprises a direction estimator unit (6) which generates, for each of the n frequencies f.sub.j on the basis of at least a selection of the signals s(.phi..sub.i,f.sub.j), a narrowband estimator .OMEGA..sub.NB (f.sub.j) of a direction .OMEGA. of an acoustic source, and subsequently on a selection of these .OMEGA..sub.NB (f.sub.j) a broadband estimator .OMEGA..sub.BB.

Abstract: The invention relates to a course-correction system provided with a transmitting and control device 1 for wireless correction of the course of a launched object provided with a receiving device 2 by transmitting a course-correction signal containing course-correction information C.sub.q and identification codes I.sub.q for individual or collective correction of objects arranged into fixed or variable groups. The receiving device 2 of each object is thereto provided with identification parameter P.sub.k for selecting an identification code I.sub.q=m from the course correction signal, for which I.sub.q=m =P.sub.k. A fixed group is obtained by identical identification parameters P.sub.k for the objects within the group, while variable group is obtained with different identification parameters P.sub.k but identical course-correction information C.sub.q for the objects within the group. The identification parameter P.sub.k of a launched object has a known relation with the trajectory data, such as e.g.

Abstract: A system for determining the angular spin position of a second object (1) spinning about an axis. A first object (7) emits electromagnetic waves. The second object (1) is provided with directional receiving antenna means (10) and with a receiving system (13) which, using the receiving antenna means (10), process in combination the carrier waves received to obtain said angular spin position. The received signals comprise at least one polarized first carrier wave and a second carrier wave which comprises phase information of the first carrier wave.