Abstract: A direct conversion receiver for FSK modulated digital signals has two quadrature signal paths (I, Q) and an a.f.c. loop for controlling a local frequency generator. A control signal for the a.f.c. loop is produced by an offset frequency detector, and is in the form of a unipolar series of pulses having an average value which is proportional to the offset of the local frequency with respect to the carrier frequency of the signal being received. The offset frequency detector derives such control signal based on the difference between phase-shifted cross-products of the signals in the I and Q paths. This achieves fast a.f.c. loop response, improving the performance of the receiver, and permits a simpler loop filter for achieving the requisite signal averaging. The receiver also includes an out-of-range detector for detecting when the local frequency is outside a predetermined window with respect to the carrier frequency of the received signal, in which case the a.f.c.

Abstract: A communication system comprising a controller (1) arranged for service implementation. The controller (1) is arranged for extracting a service logical program from a data bank (3) after the controller has received parameters transmitted by a terminal unit (6), and for activating a service in response to a service logical program and second parameters and, in response to a service logical program and first parameters, for providing a service for a subscriber and for transmitting at least one service parameter to the terminal unit (6, 8) and/or, in response to a service logical program and fourth parameters, for deleting a subscriber's authorization to use a service.

Abstract: A reference current source for generating a reference current (Irf) includes a bipolar first transistor (2) and a bipolar second transistor (4), the base of the first transistor (2) being coupled to the base of the second transistor (4), a first resistor (6) connected between the emitter of the first transistor (2) and the emitter of the second transistor (4), and a second resistor (8) connected between the emitter of the second transistor (4) and a supply terminal (10).

Abstract: The invention relates to a measuring apparatus used for testing the connections between at least two subassemblies (3, 4, 5), comprising a test system (1) for generating a test signal available on an output of the test system and for evaluating an analysis signal produced by a subassembly (3, 4, 5) from the test signal and received on an input of the test system. The test system (1) is also provided for applying a switch control signal to a controller (10, 11, 12) included in a subassembly (3, 4, 5). A subassembly (3, 4, 5) includes a switching circuit (7, 8, 9) controlled by the assigned controller (10, 11, 12), which switching circuit is provided for directing a test signal or an intermediate signal formed from this test signal to a test input of a subassembly and for receiving at least a further intermediate signal from a test output of a subassembly.

Abstract: In a GRASE magnetic resonance method, most profiles in k-space with a certain k.sub.y value are measured with different magnetic field read gradient polarity and at different time intervals from the excitation RF-pulse. The two resulting sets of measurements, with positive and negative read gradient polarity, respectively, are used to correct read gradient polarity dependent phase errors, in order to obtain reconstructed images in which the effects of these phase errors are greatly reduced. In an improved version the measurements are used to reconstruct images with a predictable T.sub.2 weighting.

Abstract: Adaptive discrete-time filters, as used, for example, in echo cancellers responsive to input signals, more specifically speech signals, which can be modelled with an autoregressive process of the order of p, a control circuit for controlling the coefficients for adjusting a discrete-time transversal filter in accordance with an algorithm which requires the same amount of computation as the Least Mean Square (LMS) algorithm but leads to the same or better convergence results for this type of signals than the Orthogonal Projection (OP) algorithm.

Abstract: The invention relates to an image projection device. This device comprises an illumination system having a lamp for supplying an illumination beam, at least one image display panel for modulating the illumination beam in accordance with an image to be projected to a signal beam, and a projection lens system for projecting the image on a projection screen. To suppress Moire interference between the structure of the image projection screen and the image display panel, an optically transparent beam-displacing element is arranged at an angle with respect to the signal beam axis in at least a portion of the signal beam in the light path between the image display panel and the projection screen at a position where a lamp image is present.

Abstract: An optical scanning device for realizing in a recording layer of an optical tape a longitudinal path (i.e. pattern) of substantially parallel tracks. The device includes an optical system for focusing a radiation beam at the recording layer, which radiation beam causes a scanning spot to develop on the recording layer. The tracks are formed by the optical tape being cyclically scanned, through use of a polygon mirror, via the scanning spot and displaced relative to the optical system in a direction transverse to the scanning direction. The device further includes an optoelectrical measuring unit for deriving a measuring signal indicative of the track pitch of the successively produced tracks. The velocity of the displacement of the optical tape is controlled as a function of the measuring signal.

Abstract: A first object, which comprises organic material, is bonded to a second object by a method whereby both objects are provided with complementary optically smooth surfaces, subsequent to which these surfaces are brought into substantial contact with one another, consequent upon which spontaneous atomic bonds are formed between atoms of the two objects. The strength of the atomic bonds thus formed can be increased by subsequently heating the region of contact of the two surfaces.

Abstract: An echograph of the type involving signal processing in the time domain with correlation-interpolation of the echographic signals is adapted to measure radial displacement velocities of the walls of an artery. A frame is scanned with a period T of a few ms at a rate of one excitation per line, and the correlations-interpolations are performed between collinear excitation lines shifted by the period T (52), enabling velocity values V(x,z,t) to be obtained for storage in a first memory (55) and amplitude values A(x,z,t) for storage in a second memory (57). These values are subsequently processed (60) in order to deduce dilatation and compression curves therefrom.

Abstract: Known in a digital communication system (1) are phase recovery methods for QPSK modulated signals. It is proposed to extend such methods to multi-resolution QAM signals, which can be represented by rotationally invariant signal constellations. To this end, with each received symbol (r.sub.i), a phase reference (.phi..sub.i) for a high priority-bit (HP-bits) constellation is determined, and with respect to this phase reference (.phi..sub.i), a sub-constellation (CLx) for low-priority bits (LP-bits) is constructed, the sub-constellation (CLx) being rotationally invariant. The sub-configuration (CLx) is translated to an origin (O) of the signal constellation, and then the low priority-bits (LP-bits) are determined by determining a minimum squared Euclidean distance (Ed) of the rotated and translated received symbol (b.sub.i ') with respect to the rotated and translated sub-constellation. For a 2R(2,2)-QAM signal constellation a simple detection method is thus provided.

Abstract: An apparatus including at least one input terminal for electrical connection to an external conductor, a ground terminal and a protection circuit connected between the input and ground terminals. The protection circuit comprises at least one transient voltage suppressor. During a test, the transient voltage suppressor can be made inoperative by a switch that interrupts the electrical continuity of the protection circuit. At least the protection circuit and the switch are accommodated in a housing.

Abstract: A display device (1) has a display panel (2) which comprises a first substrate (6) on which a first picture electrode (11-27) is provided as well as a substantially parallel second substrate (7) on which a second picture electrode (20) is provided, both substrates (6, 7) sandwiching an electro-optical medium (8). Said electro-optical medium (8) is capable of switching between an at least substantially transparent state and a scattering state under the influence of an electric field. A transparent insulating layer (10) is provided between the first picture electrode (11-17) and the electro-optical medium (8), said insulating layer reflecting the light (30) which, at least during operation, is emitted by a light source (3) and sidelong captured by the panel (2), so that it does not reach the first picture electrode (11-17).

Abstract: A combination including a recording arrangement and a source selection arrangement. The recording arrangement includes at least two different inputs for receiving different types of signals (e.g., analog, digital and/or optical); a recording unit for recording a digital signal on the record carrier; and a switching unit for coupling one of the inputs to the recording unit. (If the input coupled to the recording unit does receive a digital signal, then recording arrangement includes a conversion device for converting that signal to digital form.) The source selection arrangement includes at least two different outputs for supplying different types of signals (e.g., analog, digital and/or optical) to corresponding inputs of the recording arrangement; and a source selection unit for selecting between different signal sources and thereby enabling the signal source selected to supply a signal to one of the outputs.

Abstract: In a multiple access network, signals transmitted by a plurality of secondary stations to a primary station are to be distinguished by the primary station. One method for realizing this is by the use of Sub-Carrier Multiple Access (SCMA). According to the method of SCMA, a transmit signal is modulated on a subcarrier having its own frequency and then amplitude modulated on a main carrier in each secondary station. To reduce a mutual disturbance by the secondary stations in SCMA, according to the present invention, a transmit signal is converted into high-speed bursts of a transmit signal. As a result, fewer secondary stations on average are active, so that the mutual disturbance by the secondary stations will diminish.

Abstract: A device for optically scanning an information plane (2) having tracks (5). Radiation supplied by a radiation source (7) is focused on the information plane by an objective system (8). The beam reflected by the information plane is incident on a dividing element, for example, a grating (12), which divides the beam into two halves along a dividing line (17). Two sub-gratings (15, 16) at both sides of the dividing line, respectively, each form a sub-beam from one half of the beam, which sub-beams are detected by a detection system (10), which produces detection signals therefrom. A focus error signal is generated from the detector signals. According to the invention, modulation of the focus error signal by the track structure will be minimal if the dividing line (17) is located at an angle between 15.degree. and 80.degree. to the direction of the tracks.

Abstract: Transmitter station for transmitting a plurality of television programs, and receiver for receiving the programs.Transmitter station for transmitting, and receiver for receiving a plurality of television programs via respective transmission channels. A teletext page with tuning data which are representative of the transmission channels used by the transmitter station is transmitted by means of one of the programs, for example a local television program. An installation procedure of downloading the tuning data comprises the search of the local television program. In order to accelerate the procedure, the page header of its teletext pages includes a code (.about.) indicating that the tuning data are incorporated in said television program.

Abstract: An optoelectronic semiconductor device (10) with a radiation-emitting semiconductor diode (3), preferably a diode laser (3), is particularly suitable as a radiation source in optical read and write systems such as bar code readers, laser printers, and optical disc systems. The diode (3) has one or two exit surfaces for radiation (R) which are provided with coatings (4). In such a device (10) it is found that a deposit rich in carbon is formed on the coating (4) of the laser (3), with the result that the output of the diode (3) fluctuates. The deposit may be avoided in that organic impurities are avoided or a selection is carried out in that respect. However, this is cumbersome and expensive.In a device (10) according to the invention is the diode (3) is present within an envelope (20) which is hermetically sealed off from the outer world (40), and a gaseous oxidizing compound (30) is present inside the envelope (20).