Abstract: An optical device (7) for use in optical write, read, inspection or measuring apparatuses comprising a diode laser (8) for generating a radiation beam (11) and an optical system (9) for concentrating and guiding the radiation beam. The diode laser is a pulsed laser and a feedback element is arranged in the radiation path at a specific distance (d) from the diode laser. By giving the element a suitable reflection coefficient, a stabilized radiation beam is obtained. The beam direction can be varied by rendering the wavelength adjustable and by making use of a dispersive element.

Abstract: The contents of a digital data file, interspersed as packets of data in a bit stream containing entertainment signals and/or other data files, are quickly identified without a high system overhead for identification of each packet. The data file is divided into packets, and sequential groups of packets making up the file are identified as segments. The first packet of each segment has a prefix containing a service identification number, a block number, a segment number, and possibly segment length information, followed by data contents. The following packets of the segment have only the service identification number and block number, followed by the data contents. Where the file data are transmitted repeatedly, often without change in many segments, receiver processing time or power can be greatly reduced by including a version number or toggle bit in the segment prefix, so that a receiver can ignore the unchanged data.

Abstract: A buffer memory, in which a first signal is written and from which a second signal is read out, and a subtractor which forms the difference between the counts of a read counter and a write counter, which control reading and writing. A justification decision circuit generates a stop signal for the read counter. An accumulator accumulates the difference signal over a predetermined time interval. The accumulator output, delayed by a time interval and weighted with a second factor, and a justification signal denoting the number of stuff bits caused by the justification decision circuit between two stop instants, are added to the subtractor output in the accumulator.

Abstract: A system for recording and/or reading signals on/from information carriers (4) accommodated in cassettes (2) composed of cassettes (2-3A) of a first type and cassettes (2-3B) of a second type, which two types of cassettes have substantially identical dimensions and shapes apart from local identifying distinctive features (22-3A, 26-3A; 22-3B, 26-3B) of a first type and of a second type respectively. Drive apparatus constructed to cooperate with a cassette of the system when inserted in a correct orientation. Drive apparatus of the first type, is constructed for cooperation with cassettes (2-3A) of the first type but not for cooperation with cassettes (2-3B) of the second type, and drive apparatus of a second type, is constructed for cooperation with cassettes (2 3B) of the second type but not for cooperation with cassettes (2 3A) of the first type.

Abstract: Digital data are transmitted as packets within frames, at an average frame rate equal to the sampling rate divided by the number of samples per frame. When, as a result of subband or other coding, the number of packets required per frame would not be an integer, frames containing the next lower integer are transmitted, followed by frames containing the next higher integer. Preferably a first portion of each frame contains synchronization information, a second portion contains allocation information, and a third contains samples of, and scale factor information for, the transmitted signal.

Abstract: In response to a low-frequency superframe signal, the input frames TRA, TRB of each of two digital channels, shifted in time, are applied each to a frame locking circuit which produces sync signals SYA, SYB; and are also applied to a common cyclic addressing double memory. In the write mode each memory location is addressed to contain a block of TRA and a block of TRB of the same rank controlled by write counters which are incremented by the signals SYA and SYB. Each location has a read counter which is shifted to the more delayed signal of the sync signals SYA and SYB by a phase comparator and a coincidence detector. The output signals having information frames TRA' and TRB' are in phase.

Abstract: A data transmission arrangement powered by at least a supply voltage source (U.sub.B), includes a transmitter (11), a receiver (13) and a data transmission path (12) operated in the differential mode and terminated by its characteristic impedance. A reliable detection is possible even upon rupture of one of the two transmission wires (18, 21) by the use of a pure resistance network including the resistors (17, 20) of the transmitter (11), of the data transmission path (12) having the resistors (22, 23) and the resistors (28, 29, 30, 31) of the receiver (13), at least each time one matching resistor (24, 26) being provided on the receiver side connected each to a transmission wire (18, 21) of the data transmission path (12) for producing opposite levels (U.sub.3, U.sub.4) in the receiver (13) and for producing an absolute level in the case of disturbance of a transmission wire (18 or 21).

Abstract: a mass loader (10) stores a plurality of cartridges (14) for loading a selected one of the cartridges (14) into an optical disk reader (12). The loader (10) comprises a magazine carrier (18) and a cartridge loading apparatus (28). The cartridges (14) are stored in a vertical and parallel orientation within slots in a magazine (16) which is then inserted into the magazine carrier (18). The magazine carrier (18) depends from a follower nut (52) which travels along a lead screw (50) in a direction transverse to the parallel orientation of the cartridges (14). As the leadscrew (50) turns, the follower nut (52) travels therealong to move the magazine (16) into the correct position to load the selected one of the cartridges (14) into the reader (12). After the magazine is properly positioned, another lead screw (30) is driven to propel another follower nut (32) therealong. The follower nut (32) has a loading pin ( 40) protruding therefrom which engages the selected one of the cartridges (14) for loading.

Abstract: A device for writing, reading or erasing a record carrier has a coil with a winding arranged between an objective lens and the record carrier. Optical radiation is focused to a spot, the converging beam passing through the coil opening. A core of a transparent material, having an index of refraction which significantly decreases vergence of the focused beam, is placed in the winding opening. As a result the diameter of the coil can be reduced, and permit increase of the generated magnetic field.

Abstract: A receiver for digital information transmitted over a dispersive channel. Where the channel has a storage depth of n bits, memory requirements for an adaptive equalizer are reduced by storing transition states for only 2.sup.n' states, where n'<n, and storing at least n previous bits for 2.sup.n' states in a memory path register. At the same time the equalizer may be based on a reduced state model with 2.sup.n' states. Only n' bits are determined directly by state transitions; the remaining n-n' bits appear from each memory path leading to the respective state, stored in the memory path register.

Abstract: For identifying a preamble or other pattern in a binary bit stream, containing data coded to have a different average number of ones to zeroes from the pattern in question, a pattern detection circuit includes a shift register, a unitary adder and a comparison circuit. The shift register has a sufficient length that there is at least a high probability that the number of ones stored therein is different for the pattern in question from the range of number of ones found in that length of the data stream. The unitary adder counts the number of ones in the register, and this value is compared with the range of values which that length of the pattern should contain. If the pattern to be detected is a preamble used for bit synchronization, and the data are coded in a way which may lead to possibility of synchronization to a subharmonic, a ones-average detector may be used to disable the synchronization circuit for a local clock until the preamble is detected.

Abstract: A diversity receiver having at least two receive branches, and only one equalizer. Each receive branch includes a matched filter and circuits for forming an autocorrelation function for each estimated impulse response of the individual receive branches. A first adder circuit adds the output signals, weighted with weighting factors of the matched filters to form a first sum. A second adder circuit add the autocorrelation functions weighted with weighting factors to form a second sum. The weight factors are approximately inversely proportional to the instaneous noise power in each receive a branch. An equalizer evaluates the two sums.

Abstract: A digital subscriber line circuit for connecting an ISDN subscriber to the trunk side of a digital exchange which comprises an SLD interface operating according to the SLD system. The subscriber line circuit further includes a transfer arrangement for transferring, during a transfer time window, data signals between incoming and outgoing time slots of the SL line of the SLD interface and time slots assigned thereto of outgoing or incoming trunks of the digital exchange. The subscriber line circuit comprises a slip detection means for detecting an incoming or outgoing trunk time slot slipping out of the transfer time window. The slip detection means controls a slip correction means which controls the transfer arrangement in response to the detection of a slip, so that data are skipped in one transfer direction and data are repeated in the other transfer direction.

Abstract: The beginning of a segment within a track of a record carrier, having a plurality of frames in each segment, is identified by detecting the presence of a control mark at a given position near the beginning of a frame, and the absence of a control mark at an adjoining position at which a control mark will be found in all other frames of the segment. The other frames of each segment are free from a mark at the given position. The next bit position containing a mark, after the given position and its adjoining position, is the clock bit position used for bit clock synchronization. An apparatus for reading these marks may include a qualification circuit for evaluating the magnitude of the difference in detector output at the given bit position and the adjoining bit position.

Abstract: A circuit breaker is disclosed having a toggle mechanism in which a desired overlap between the cam link and the sear pin is conveniently, and automatically, achieved. The toggle mechanism also exhibits a relatively small eccentricity, resulting in a circuit breaker which is significantly more sensitive to overcurrents than previous such circuit breakers.

Abstract: A projection television system which adapts automatically between from screen projection and rear screen projection upon insertion of the projector into a rear screen cabinet. A compact projection unit has a quick-disconnect electric connector and optical aligner which mate with connection elements in a projection cabinet upon insertion of the projector into an opening in the front of the cabinet. The cabinet has a two-mirror optical relay which inverts the projected picture. Upon completion of insertion, the electric connections automatically invert the image being projected by the projector. In another embodiment, insertion also automatically connects to audio equipment in the rear screen cabinet.

Abstract: A device for optically scanning a surface (2) with a focal spot (11) formed by an objective lens (10). The objective lens is electromagnetically suspended in a stationary coil system (14) comprising a plurality of coil pairs located one behind the other in a given direction. The coil system can move the objective lens in five or six degrees of freedom. A radiation beam is displaced parallel to itself via a pivotal mirror (22) and a scanning lens (23) so as to track the movement of the objective lens in said direction. A communicator (96) drives only those coils of the coil system which are proximate to the objective system at a given moment.

Abstract: An information transmission system comprises a primary station and a number of secondary stations, information being transmitted from the primary station during traffic time periods which are interspersed in time with control time slots. The control time slots contain control data (CD) which contains a number of identifying indications (CMD1,CMD2,CMD3,CMD4) which each may include an address relating to a secondary station for which succeeding traffic information is intended. The identifying indications may be configured in a number of different ways, for example (E1), it may contain an address (A) and a traffic position identifier (XN). It may also contain, for example (E2), a channel identifier (CH). The information in the control slots allows secondary stations, which may be powered down for substantial periods of time, to prepare for reception of succeeding information if an address identifying that secondary station is included in the control data (CD).

Abstract: A private mobile radio transmission system comprising a plurality of geographically spaced base stations (BS) defining a plurality of overlapping service areas (SA). The base stations are coupled for example by land-line communication links (CL) to a system controller (SC). Mobile stations (MS) equipped with simplex two-way radios are free to roam through the service areas. In order to be able to make a call with or via a base station it is necessary for the mobile station to be registered with the base station concerned. Details of the registration are stored by the mobile station concerned and the base station.

Abstract: The present invention provides a track format for an optical record carrier that is useful in producing a tracking signal with a substantially constant slope at its zero-crossing point for a range of track pitches. The preferred embodiment of track format is also useful in producing a tracking signal that has a substantially constant amplitude over a range of track pitches. The track format, in the preferred embodiment, employs wobbled pits. The sequence in which the wobbled pits occur alternates between adjacent tracks and the offset of the wobbled pits with respect to the center line of a track remain constant regardless of the track pitch. The preferred embodiment of the track format also includes a reference pit that is used to establish the threshold detection level for the read electronics. The location of the reference alternates between tracks to reduce the effect of radial interference on the signal produced using the reference pit and thereby allow an optimal threshold level to be established.