Abstract: A ship's hull including a first hull part arranged as a hard-chine-hull disposed on a second hull part in the shape of a super-slender float. During in service conditions, only the aft half of the first hull part intersects the water surface so that two separate bow waves develop. By appropriate selection of hull widths and by disposition of the first hull part on the second hull part, the bow waves are in phase opposition. This reduces the wave-induced drag of the ship's hull considerably, especially near the critical speed.

Abstract: A radar apparatus having a phased array antenna with a large number of transmit and receive modules, a control unit and a video processor. The control unit generates a number of pulse bursts per azimuth-elevation direction, all of which shows slight carrier frequency differences. The video processor determines a doppler spectrum and compared successive spectra for each pulse burst. As a result of the frequency differences, clutter does not show much of a shift while targets which are subject to fold-back in the frequency domain will show considerable shift. A threshold based on a mean spectrum therefore enables detection.

Abstract: A radar apparatus which employs a pulse train containing an alternating sequence of first and second groups of pulses. The first group comprises a plurality of identical long pulses and the second group comprises a plurality of identical short pulses. The receiver has a single channel, the processing in which is successively adapted for the pulse returns of a group at any one time.

Abstract: A target detector (1) for detecting targets provided with transmitter means (3, 5) for simultaneous generation of different electromagnetic waves having different frequencies which are transmitted by means of an emission and detection device (2). The target detector is also provided with receiving means (3, 4, 5) for obtaining, by means of the emission and detection device (2), target signals comprising target information received at different frequencies. A signal processing unit (15, 16, 17) is provided for processing the target signals in combination to obtain target-representing signals.

Abstract: A radar system for low-level target tracking comprises a first and a second radar apparatus, both apparatus operating at their own frequency, but employing one and the same tracking antenna. A target being tracked in range and angle coordinates by the first radar apparatus can be tracked in angle coordinates by the second apparatus and in range by the first radar apparatus when the target arrives within the range of the second radar apparatus. A preferred digital embodiment of this system is obtained by utilizing a common signal processing unit including a matched filter.

Abstract: A pulse radar apparatus is provided with a transmitter (1), a transmitting antenna (2) and a receiving antenna system (3) with a first and a second receiving channel (4 and 5) coupled thereto. The receiving antenna system (3) comprises N stacked receiving antennas (A.sub.0, A.sub.1, . . . , A.sub.N-1). The first receiving channel (4) comprises N receiving circuits (B.sub.0, B.sub.1, . . . , B.sub.N-1), each connected to a corresponding receiving antenna (A.sub.0, A.sub.1, . . . , A.sub.N-1) and each processing the particular echo signal into two orthogonally phase-detected and digitized video signal components, and a beamformer (14) to derive from said components the orthogonal components I.sub.k, Q.sub.k of the video signal determined jointly by the N receiving circuits in accordance with a receiving beam pattern k corresponding with a specific elevation interval. The second receiving channel (5) comprises N receivers (B.sub.0, B.sub.1, . . . , B.sub.

Abstract: A pulse radar apparatus is provided with a coherent transmitting and receiving unit (1) for the transmission of radar pulses, the reception of echo signals, and the conversion of the echo signals into signals of an intermediate frequency f.sub.if, which may be shifted through a Doppler frequency f.sub.d. The echo signals with frequency f.sub.if +f.sub.d are fed to a detector (7) for the coherent phase detection with a frequency f.sub.if +f.sub.c. The detected signals are fed to an analog-to-digital converter (10), which operates at a frequency of approximately 4f.sub.c. The pulse radar apparatus further includes accumulators (12, 13), alternately fed with the output signals of the analog-to-digital converter (10) each time for a given period, after which period the output signals of the accumulators (12, 13) are representative of the orthogonally detected components of the echo signals.

Abstract: A pulse radar apparatus is provided with a coherent transmitting and receiving unit with N juxtaposed receiving antennas and N receivers for the reception of echo signals and the processing thereof into two orthogonally phase-detected and digitized video signal components i.sub.r and q.sub.r, where r=0, 1, 2, . . . , N-1. A beamformer is provided to derive from these components the orthogonal components I.sub.k and Q.sub.k of the video signal determined jointly by the N receivers in accordance with a receiving beam pattern k corresponding with a specific elevation interval, where l=0, 1, 2, . . . ,N-1. The orthogonal components I.sub.n, Q.sub.n and I.sub.n+1, Q.sub.n+1 supplied through two adjoining beamformer output channels n and n+1, and derived from the video signals P.sub.n, P.sub.n+1 from echo signals of maximum amplitude received from moving targets, are used for determining the deviation (.DELTA..alpha.) of the elevation value .alpha.

Abstract: A pulse radar apparatus (2) for target (14) tracking is designed to provide angular error data representing the deviations of projectiles, fired from a gun (3) at the target with respect to the target position line. The l.f.-signal processor of said radar apparatus comprises:a. a signal analyzer (17) having a filter bank for determining Doppler spectral components of echo signals received from the fired projectiles within the target range gate (23) and l.f. detected;b. selection means (18) for selecting the projectile Doppler spectral components from the signal analyzer (17) and filter bank; andc. an angular error generator (24) for generating angular error data from the Doppler spectral components selected by the selection means (18) to correct gun aiming values calculated by a fire control computer (9).

Abstract: A monopulse radar comprising a pilot signal generator (20) for injecting phase and amplitude-defined pilot signals into the separate receiving channels (6-12, 3, 16-19) to obtain correction signals through the variation in the mutual phase and amplitude relationship between the separate receiving channels for correcting angle error signals derived from target return signals. The pilot signal generator (20) and the transmitter (1) are tunable and a control circuit is incorporated for adapting the pilot signal generator (20) relative to the frequency of the target return signals.

Abstract: A long-range pulse radar apparatus emitting linear F.M. pulses and coherently detecting radar returns contains a chirp generator with a phase-control unit, a slope-control unit and a timing circuit. The timing circuit, supplied with a voltage resulting from the phase detection of the VCO output signal with reference to the COHO signal, determines the times when the VCO phase control voltage is to be gradually replaced by the slope-control circuit output. The latter output is determined by the period required to generate a given number of periodic variations of the signals obtained through the phase detection of the VCO output signal with reference to a fixed-frequency signal.