Abstract: A circuit for receiving voice and data signals on a balanced line, the data signal being an amplitude modulated form of a carrier signal having a frequency at least twice as high as the highest frequency in the voice band. The circuit matches the input impedance thereof to a first nominal balanced line impedance with respect to voice signals and a second nominal balanced line impedance with respect to data signals, applies the data signals to an unbalanced data output terminal, and applies the voice signals to a terminal connected to a bidirectional unbalanced input/output lead of a PABX.

Abstract: An electrical control system for controlling one or more electrical devices includes a local control station and one or more remote control stations, each station including a transmitter and a receiver, the various stations being interconnected by optical fibers for transmission of information between the stations. The local control station continuously encodes the status of the controlled electrical devices, and optically transmits this information to the various remote stations. Also, the receiver of each remote station is provided with means for determining when a fault in the local to remote station link occurs and determines whether it is receiving valid control information from the local station. An alarm signal is produced when the remote station receiver fails to receive control signal information.

Abstract: Workstations may advantageously be interconnected in a cluster arrangement wherein multiple "slave" stations utilize the database which exists in a "master" unit. The cluster interface has been implemented as a wired system but the latter involves significant limitations as to distance between units, electrical noise restricting data transmission rates and the protection of sensitive data from compromise. The fiber optic interface module of the present invention eliminates the foregoing limitations by translating the electrical signals of the wired system into optical signals for transmission and restoring them to electrical signals at a receiving unit.

Abstract: In a communication system having a plurality of mutually independent subscriber stations, these stations seize a common duplex transmission channel for establishing a connection in accordance with a multiple-access method. To prevent simultaneous access and the resultant access destruction and also in the case of frequent access destruction of the blocking of the common duplex transmission channel, each transmission station, to initiate a transmission therefrom, seizes the duplex transmission channel by means of a signalling character. The signalling character is transmitted by the subscriber station during a time slot allocated for that purpose. To distinguish between reporting subscriber stations, a pulse function from a system of orthogonal or substantially orthogonal pulse functions is used as an identification character.

Abstract: In an optical instrumentation system, sensor units are solely constructed optically and each sensor unit comprises a subcarrier generating section for causing periodic changes in the light intensity of light wave from a light source corresponding to the wavelength sweep of the light source to generate a subcarrier, and a sensor section for modulating the subcarrier by detected information, and at the receiving end of the system a demultiplexing section is provided for demultiplexing detected information by selecting the subcarrier.

Abstract: A receiver is applied to optical communication using an optical pulse signal carrying data which is cyclically updated. The optical signal is converted to a corresponding electrical pulse signal. The data is extracted from the electrical signal. The extracted data from successive cycles are compared. In response to the result of comparison between the data, a determination is made as to the number of cycles in which the extracted data is at a given value. When the determined number of cycles reaches a variable preset number, a previously used data value is replaced by the given value. The amplitudes of the electrical signal pulses are compared with a reference level. The preset number is varied in accordance with the result of comparison between the pulse amplitudes and the reference level.

Abstract: Transmission system for bi-phase modulated signals. Generally receiving filters for these signals will have a frequency response up to twice the bit frequency (twice 1/T) passband. For colored noise whose power increases as the frequency increases this may mean a considerable deterioration of the signal-to-noise ratio compared with the signal-to-noise ratio for unmodulated NRZ-signals. In order to increase the signal-to-noise ratio a receiving filter is used in this case, whose frequency response approximates zero above the bit frequency (1/T) (stopband) and which for lower frequencies is determined such that after filtering a predominantly three-level signal is obtained. The binary data signal can be drived from this signal by rectification and slicing. Use: Optical communication systems.

Abstract: Enhanced availability and survivability of communications between geographically remote locations with a minimum of redundancy of transmission facilities and media is provided by a survivable bus network capable of providing continued interprocessor or other communications in the event of multiple bus outages. It consists of multiple busses, bus isolation device (BIDs) and two types of network interface processors (NIPs). The BIDs electrically isolate bus segments on either side of a connection so that if a fault occurs only the segment containing the fault will be affected. The first type of NIP connects to one bus and performs the usual function of providing an electrical and software interface between the network and one or more subscriber processors. The second type is a bridge which performs these same functions but connects to two busses and has the capability to transfer traffic as it appears on either bus to the other.

Abstract: A method and apparatus for transmitting binary sequential data by the multi-level encoding of grouped selected data bits are disclosed. A first number of data bit sequences of the grouped data bits are translated into uniquely chosen ones of a first group of differing level pairs of a multi-level signal and the remaining data bit sequences of the grouped data bits are translated, in a first mode of translation, into uniquely chosen ones of a second group of differing level pairs of the signal, and, in a second mode of translation, into uniquely chosen ones of a third group of differing level pairs of the signal, the mode of translation changing after the occurrence of any of the remaining data bit sequences.

Abstract: Method and apparatus for reducing the convergence time of an echo canceller including a transversal filter having N adjustable complex coefficients comprises the following steps:transmitting a complex training signal constituted by data d(n) transmitted at instants nT, where T is the data interval, having a period LT at least equal to NT and having the following two properties: ##EQU1## for every integer i such that 1.ltoreq.i.ltoreq.N-1, and ##EQU2## for every integer i such that 0.ltoreq.i.ltoreq.N-1; after the transmission of N data, calculating the coefficients C of the transversal filter from the sequence formed by the next L data transmitted, in accordance with the expression: ##EQU3## where C.sub.o represents the N initial coefficients,e.sub.R (n) is the difference signal between the received signal and the real output signal of the transversal filter,D.sup.* (n) represents the complex conjugate value of the last N data entering the transversal filter, and.sigma..sup.

Abstract: In the disclosed communication system the digital message bits (e.g., data bits) to be transmitted to a particular receiver are individually encoded in the digital address (of K bits) of that receiver. The receiver has a K(stage) correlation circuit which serves to correlate all incoming message information with its own digital address. In the case of a match, autocorrelation peaks appear at intervals determined by the digital message. A feature is to transmit each address sequence a number of times (e.g., 8) so as to reduce the likelihood of error.

Abstract: The device is of the type comprising a circuit for compressing the dynamic of the speech signal before transmission of the signal at constant level and an expander for re-establishing at reception the speech level before compression thereof. A logic filtering circuit controls the compression circuit by constant attenuation steps depending on the speech level. A selector comparator circuit coupled by a first input to an output of the logic filtering circuit and by a second input to the output of a device controlling the expander compares the attenuation values supplied by the logic filtering circuit with those supplied by the device controlling the expander and adjusts the attenuation value of the compression circuit to the greatest of the attenuation values supplied by the logic filtering circuit or by the control device of the expander.

Abstract: Given a bus system comprising an optical waveguide, an electro-optical transmitter, and an opto-electrical receiver, the transmitter is constructed such that the light power coupled into the light waveguide and dependent on the information signal to be transmitted is variable in digital steps. The receiver is comprised of DC-coupled amplifiers without gain control. It contains a preliminary stage for generating a useful signal from the light signal, and has a first comparator stage for generating the information signal from the useful signal. The receiver also includes a second comparator stage to which a reference voltage variable in digital stages is supplied and which samples the level of the useful signal emitted by the preliminary stage. The second comparator stage emits a collision signal when the useful signal moves the reference voltage upwardly and thus indicates that at least two transmitters are coupling light into the optical waveguide.

Abstract: A plurality of transmitters synchronized to a common clock each transmit a data signal spread by a common bipolar pseudo-random code having a different assigned code sequence shift. A receiver, synchronized to the clock, discriminates the signal transmitted by a predetermined transmitter from signals transmitted by the others by generating a first bipolar pseudo-random code that is a replica of the common bipolar pseudo-random code and has a code sequence shift corresponding to that of the predetermined transmitter, and a second bipolar pseudo-random code that is a replica of the common bipolar pseudo-random code and has an unassigned code sequence shift. The difference between the first and second bipolar pseudo-random code sequences, which is a trinary code sequence, is cross-correlated with the incoming signals. The cross-correlation despreads only the signal spread by the sequence having the predetermined code sequence shift.

Abstract: A radiocommunications system for transmitting packets of digitized data between a central station and a plurality of subscriber stations using a common set of frequencies. Each subscriber station and central station has an input circuit for compressing packets of digitized data, and a transmitter for generating a transmitter carrier wave. The carrier wave frequency of the transmitter is varied by steps with predetermined frequency values according to a frequency law assigned to the subscriber station and independent of the laws assigned to the other subscriber stations. The frequency steps are synchronous with the frequency steps of the other subscriber stations and the steps have the same duration. A processing circuit coupled between the input circuit and the transmitter calculates and inserts redundancy data into the succession of digitized data.

Abstract: An optoelectronic switching network comprises a transmit board (10), a receive board (40) and an optical projection system (3). The transmit board is formed by plural transmit units, each including a light source (11). The receive board is formed by plural receive units (41), each including plural optoelectronic cells. The optical system projects an image of the transmit board onto the receive units so that in each receive unit the images of the sources of the transmit board coincide with the optoelectronic cells of the receive units. An optoelectric cell is thus activated by an illuminated light source. In each receive unit, a light source illuminates the receive units when a cell thereof is activated, and a supervision receive unit (60) supervises the optoelectronic cells (62) having projected thereon images of the receive units.

Abstract: The adaptive auto-orthogonalizing equalizer in the discrete frequency domain comprises a filter with N cells operating by the overlap-save method, a decision element which assigns one of the possible levels to the filtered samples, and a control circuit which at each iteration varies the cell gains on the basis of the input samples, the output samples and the decided symbols, and which comprises an estimator (S.sub.A) for estimating the gradient of the mean square error, an estimator (S.sub.B) for estimating a matrix which modifies said gradient such that its direction always passes as close as possible to the minimum to be sought, a projector (P.sub.S) for projecting said corrected gradient into a constraint region, and a circuit for adjusting the filter cell gain vector at each iteration.

Abstract: In a position measurement system having a plurality of redundant pulsed light sources, detectors, control circuits, signal conditioning circuits, and signal processors, but having space available for only a single encoder for measuring the position of a monitored device, the pulsed light sources emitting light of different wavelengths which are combined in wavelength multiplexed fashion at the encoder, the combined light then being split for encoding and recombining in time domain multiplexed fashion, the recombined light then being split for filtering of the different wavelengths at the plurality of light detectors each of which provide signal manifestations indicative of the position of the monitored device according to the encoded light pulses of the particular wavelength monitored to the associated control and signal conditioning circuits for transmittal to an associated signal processor.

Abstract: A multiplexing device for a multiband antenna. It essentially comprises, in series from the coupling input to the antenna: a common guide permitting the passage of a high frequency band and a low frequency band, into which issue by means of two coupling holes staggered with respect to one another along the common guide, two orthogonal guides which constitute the inputs for the two orthogonal polarizations of the lower band; a junction; and a polarization duplexer for the higher band. The coupling holes contain resonators forming a short-circuit for the higher band frequencies.

Abstract: An optical data is transmitted from station to station through an optical T-coupler attached to each station. The optical T-coupler splits the data signals into two paths with identical data being transmitted to the attached station and also the succeeding station. An optical to electronic conversion takes place as the data enters the station. Electronic digital switching within each station selects a "normal" mode of receiving data from the preceding station when data is valid or a "bypass" mode of receiving data from the station which precedes the preceding station. Switching from normal to bypass mode is performed by electronic switching and requires no optical switches.