Saab Automobile AB

About: Saab Automobile AB is a based out in . It is known for research contribution in the topics: Radar & Antenna (radio). The organization has 760 authors who have published 890 publications receiving 11811 citations.

A method of indicating the time of an acoustic pulse and a device for carrying out the method.

Abstract: Dans un procede d'indication du moment d'une impulsion acoustique lors de sa transmission ou de sa reception, l'impulsion acoustique se presente sous la forme d'un paquet d'ondes, dont l'enveloppe possede une rampe de montee et une rampe de descente. In a method of the time indication of an acoustic pulse when transmitted or received, the acoustic pulse is in the form of a wave packet, whose envelope has a ramp up and a ramp down. Le procede est caracterise par le fait que le debut de la rampe de descente de l'enveloppe d'amplitude est detecte afin de determiner un moment de reference dans le paquet d'ondes, qu'une transition predeterminee de zero dans la paquet d'ondes est identifiee a partir du temps de reference et que le moment de transition de zero identifiee est determine. The method is characterized in that the beginning of the ramp-down of the amplitude envelope is detected to determine a reference time in the wave package, that a predetermined zero transition in the packet of waves is identified from the reference time and the identified zero transition time is determined. Un dispositif pour realiser le procede et destine a etre utilise dans un systeme acoustique (1) comportant un moyen (3) pour engendrer un signal electrique (E1, E2) correspondant a l'impulsion acoustique (P1, P2), est caracterise par un premier moyen (9) dispose pour detecter le debut de la rampe de descente du signal electrique pour la determination du temps de reference du paquet d'ondes et pour engendrer un signal de declenchement (C) correspondant au temps de reference, et un deuxieme moyen (10) dispose pour repondre au signal de declenchement (C) pour identifier la transition predeterminee de zero dans le paquet d'ondes et pour engendrer un signal de temps (D) correspondant a la transition de zero identifiee (D). A device for performing the method and for use in an acoustic system (1) having means (3) for generating an electric signal (E1, E2) corresponding to the acoustic pulse (P1, P2), is characterized by a first means (9) arranged to detect the beginning of the down ramp electrical signal for determining the reference time of the wave packet and for generating a trigger signal (C) corresponding to the reference time, and second means (10) arranged to respond to the trigger signal (C) to identify the predetermined zero transition in the wave packet and for generating a timing signal (D) corresponding to the zero transition identified (D).

Heat sink for an electric circuit board

Abstract: A heat sink (4) intended for mounting along the edge (3) on an electrical circuit board (1) in order to cool heat-generating components (2) on the circuit board. The heat sink (4) is designed with on the one hand a longitudinal slot (5) for mounting on the circuit board (1) and on the other hand a mounting flange (6) located in substantially the same plane as the slot (5). The design of this mounting flange (6) means that a circuit board (1) provided with a heat sink (4) can be mounted in guide tracks or equivalent in the same manner as a circuit board (1) without heat sink (4). The design of the heat sink (4) also means that the same heat sink (4) can be used for different circuit boards (1) and different components (2).

Method and apparatus for measuring the level of a fluent material in a container

Abstract: In a method of measuring the level of a flowing material kept in a container there is employed a microwave signal that is fed from a transmitter through a tubular waveguide (7) that extends vertically downwardly through the container and communicates therewith so that the surface (10) of the material in the waveguide follows the level of the surrounding material. The signal is reflected from the surface back up through the waveguide and is conducted to a receiver to be employed, after signal processing in an electronic unit, for determining the level of material in the container. The microwave signal is fed to the waveguide by way of a mode generator (11) that produces only one dominant propagation mode of the signal, the wavelength of which is smaller than the diameter of the waveguide (7).

Phase compensation of rate limiters in unstable aircraft

Abstract: For a modern aerodynamically unstable fighter, like the JAS 39 Gripen, the flight control system typically provides 45/spl deg/ phase margin. Therefore rate limiting of control surfaces, which may cause large phase shifts, is an important issue. Software rate limiters are placed on the control servo commands in order to prevent the hydraulic servos from rate limiting. When a rate limiter is saturated, the phase shift drastically reduces the stability margins of the closed loop and increases the risk for pilot-induced oscillation (PIO). This paper describes a novel method for compensating the phase shift of a rate limiter. In contrast to earlier phase compensation methods, this method uses feedback instead of logic or feedforward. Open loop and closed loop properties of the method are discussed. The method gives a drastic improvement on stability margins and reduces PIO tendencies.