Abstract: A transceiver capable of transmitting and receiving current-driven communication signals is implemented within a communication system, for example a subscriber loop associated with the public-switched-telephone-network (PSTN). By utilizing current drivers having high source impedance the load across a communication connection servicing the transceiver is significantly reduced such that additional transceivers may be bridged to the communication connection without substantially affecting the quality of the communication signals.

Abstract: An adaptive interface controller including a plurality of MII ports operable at either one of the first and second transmission rates, a corresponding plurality of Manchester ports operable at the first transmission rate and an MII interface operable at the second transmission rate. The adaptive interface controller includes first select logic that provides data from an active one of the MII ports for one of the Manchester ports or to the MII interface depending upon the transmission rate. Manchester encoding logic is provided to receive data from the first select logic for an active port, to convert the data to Manchester format and to provide the encoded data to a corresponding one of the Manchester ports. Second select logic provides data transmitted to the MII interface for a selected one of the MII ports. Manchester decoding logic detects Manchester encoded data transmitted to any of the Manchester ports and converts the encoded data a serial to bit stream.

Abstract: A noise suppression circuit for a two-wire communications channel comprises a hybrid device, for example a hybrid transformer or circuit, for providing a differential mode signal corresponding to a differential signal received from the two-wire channel. A summing device extracts from the two-wires of the channel a common mode signal and supplies it to a noise estimation unit which derives from the common mode signal an estimate of a noise level in at least one frequency band having a bandwidth considerably narrower than an operating bandwidth for the channel. The noise estimation unit adjusts the amplitude of the noise estimate to correspond to the residual noise in the differential mode signal and subtracts it from the differential mode signal to produce a noise-suppressed output signal. A noise detection and control unit scans the operating band, identifies a frequency band having an instant highest noise level, and sets the noise estimation unit to the detected noisy band.

Abstract: A high frequency video isolation circuit comprising: a modulating signal source for producing a modulating signal having a frequency of several hundred megahertz; an input multiplier for multiplying the modulating signal with an input video signal having frequency components in a frequency range from about several hertz to about one hundred or more megahertz, to produce a modulated video signal having frequency components in a frequency range from about one hundred megahertz to about several hundred megahertz; a first isolation transformer having an input and an output, for transforming the modulated video signal from the input to the output; and an output multiplier for multiplying the transformed modulated video signal with the modulating signal to produce an isolated output video signal having the frequency components of the input video signal.

Abstract: A network interface for receiving both high speed signals and low speed signals includes a passive filter manufactured entirely from passive electronic elements. The filter filters the low speed signal when a low speed signal is received, and does not distort a high speed signal transmitted to an encoder/decoder device when a high speed signal is received.

Abstract: The present invention provides an overhead balanced electricity distribution and/or power transmission network (1201), the network including input means (1301) for the input onto the network of a telecommunications signal having a carrier frequency greater than approximately 1 MHz from an unbalanced source and output means (1301) for removing said telecommunications signal from the network, wherein said input means and said output means provide impedance matching between said network and said source. Thus, propagation of HF communication signals over such networks is optimised, and the input and output means ("conditioning units") provide for interconnection between a source e.g. a relatively low impedance unbalanced HF (possibly coaxial) termination and a high impedance balanced OH EDN, and provide efficient unbalanced to balanced impedance transformation and termination.

Abstract: Method and device for generating bit information in a subscriber station of a bus system, in particular of the bus of the EIBA, essentially symmetrical AC voltage information being superposed as bit information on a DC voltage of the bus in that a DC voltage potential (19) of a line under inductive loading (9) is pulled, in each case in an active pulse (20) to the potential of another line and an equalizing pulse (22, 23) is formed with subsequent energy recovery. It is provided that the active pulse (20) of the bit information at a bit frequency is formed from individual pulses (17) of higher frequency.

Abstract: A bidirectional communications interface employs the same path for transmitting and receiving. The bidirectional communications interface includes one two winding transformer for both transmit and receive and an integrated circuit having a transmitter and a receiver each connected to the same pair of input/output pins. The interface enables a communications node in a communications network to transmit data to and receive data from other nodes in the network.

Abstract: A magnetic communication system includes a transmitter have a single coil transducer, and a receiver having a three orthogonally oriented coil transducers. The signal processing circuitry in the receiver adjusts the phases of the signals received by the three transducers to produce signals which are in-phase. The signals are then summed to provide an output signal from the receiver. The processing circuitry adjusts the phases of the incoming signals either serially or in parallel. Transmissions from the receiver to the transmitter are also phase adjusted in accordance with the same adjustments used in reception.

Abstract: An electronic apparatus capable of transmitting data at two or more different data rates contains transmitter circuitry, a cable connection mechanism, and an isolation transformer having a primary winding and a secondary winding. The transmitter circuitry low-pass filters digital data which the transmitter circuitry transmits to the primary winding at a first data rate. The transmitter circuitry also transmits digital data to the primary winding at a second data rate different from, typically greater than, the first data rate. The cable connection mechanism provides outgoing data from the secondary winding to the communication cable. Importantly, the transmitter circuitry is operable to generate current-sourced data signals at both data rates and then to convert the current-sourced signals into impedance-produced voltage signals that constitute the outgoing data. Current-source amplifier circuitry normally generates the current-sourced signals.

Abstract: A differential line driver having a pair of transistors arranged as a differential pair for driving a transmission line with a differential logic output signal produced in accordance with a differential logic input signal fed to the base electrodes of the pair of transistors. The differential line driver includes circuitry for suppressing EMI emissions generated by common mode voltage switching transients produced at the collector electrodes of the pair of transistors in response to changes in the differential logic input signal. The common mode voltage switching transient suppression circuitry includes a pair of additional transistors. The differential logic input signal is fed to base electrodes of the additional transistors, and through such additional transistors, to the base electrodes of the pair of transistors of the differential pair. In one embodiment of the invention, the additional transistors are connected in a Darlington pair arrangement with the pair of transistors of the differential pair.

Abstract: An isolation circuit is disclosed for isolating ground interference from a wideband transmission signal. The ground isolation circuit of the present invention is constructed using a pair of matched mixer circuits, each of which receives a carrier signal from the same oscillator circuit. The first mixer circuit also receives the baseband signal input after appropriate conditioning, and modulates the baseband signal onto the carrier signal. In the preferred embodiment, the carrier signal has a predetermined frequency which is at least two times the frequency of the baseband signal. The modulated signal (which preferably comprises an rf signal) is transmitted via an rf transmission line to the second mixer, which demodulates the rf signal to recover the baseband signal. Each port of the mixer circuits connects to an isolation transformer to insure isolation from ground interference.

Abstract: A new improved all monolithic transceiver may be manufactured on a single semiconductor die for operation from a single +5 v power supply. The transceiver includes a transmitter of novel design which provides zero output current for a zero signal input. The transmitter may include a linear feedback operational amplifier driver, wherein the driver bias current is enabled only in the presence of a driver input signal. The transceiver is designed to meet the requirements of both MIL-STD 1553 as well as the McDonnell Douglas(MACAIR) A3818, A4905, A5232 and A5690.

Abstract: A differential amplifier (40) receives a low level ADSL signal IN- and IN+ and produces an amplified differential signal. A pair of differential amplifiers (42, 44) receives the differential signal and provides phase shifting and further amplification to the differential signal. A set of differential pairs (46, 48, 50, 52) are coupled to the pair of differential amplifiers (42, 44) and provide further amplification and drive capability to the differential signal. A pair of driver pairs 54 and 56 are coupled to the differential pairs (46, 48, 50, 52) to provide a fully differential output signal OUT- and OUT+ with high linearity. A common mode feedback stage (58) and gain feedback stage (98) provide feedback.

Abstract: A signal transmission circuit for transmitting signals having a wide frequency spectrum over a cable. The circuit includes an isolating transformer having a high pass filtering function; a low-pass filter, the input of the low pass filter being common with the input of the high pass filter; and means for summing the output voltages of the low-pass filter and the high-pass filter.

Abstract: A receiver for a LAN which uses a transformer for isolation. Base line wander is prevented by use of a positive feedback path which provides a signal that compensates for low frequency loss through the transformer. The feedback path connects the output of the receiver to the secondary winding of the transformer. The time constant of the transformer and terminating resistor L/R equals the RC time constant in the feedback path.

Abstract: A repeater for use in a control network includes isolating transformers at its root input/output and at a plurality of branch input/outputs. There is a line receiver and a line driver circuit associated with each of the isolating transformers. To determine the direction of transmission of signals through the repeater, there is a common mode voltage detector which detects a common mode voltage imposed on the wiring to the root side of the root transformer. A corresponding common mode voltage is imposed by the repeater on the branch side of each of the branch transformers. The repeater also includes a logic circuit for testing the validity of signals received from the branches and ensuring that only valid signals are passed to the root transformer.

Abstract: A data transmission method entails differentially transmitting low-pass filtered first outgoing data to and through an isolation transformer at a first data rate. Second outgoing data is differentially transmitted to and through the transformer in the same direction as the first outgoing data but at a second data rate different from, typically greater than, the first data rate. The so-transmitted first and second outgoing data is coupled from the transformer to a communication cable during different time intervals. A related data reception method involves coupling incoming data from a communication cable to and through the isolation transformer and providing the so-coupled incoming data differentially along data transfer paths that extend from the transformer to and through where data moving at the first data rate is received to where data moving at the second data rate is received such that the data transfer paths have a largely constant characteristic impedance.

Abstract: A data received is provided with DC restoration circuitry for correcting the DC level of received multi-level data signals. A DC shift detection circuit detects whether the received DC level multi-level signals has shifted due to a predominance of one of the data levels in the data stream. A correction circuit responds to the shift detection circuit by applying a corrective bias to an isolation transformer. Alternatively, the correction circuit applies a corrective bias to the received signals within the receiver circuit.

Abstract: To go from a coupled high level to a decoupled low level, a source unit (SU) of a transmitter (T) must be decoupled from a transmission line (TL) by a impedance unit (IU). As a result, oscillatory transition phenomena appear in the output signal and this signal possibly goes beyond a prescribed template. To avoid such overshoot problems the present transmitter (T) decreases the signal level during a decrease period before decoupling the source unit (SU) from the transmission line (TL). Therefore a source control circuit (SCC) is included in the control unit (CU) of the transmitter (T) for controlling the source level in such a way that the output signal level is decreasing.

Abstract: A data-transmitting apparatus contains first and second transmitters, a transmit transformer, and a connecting unit for coupling the transformer to an outgoing twisted-pair cable. The first transmitter filters data to produce outgoing data transmitted to the transformer at a first data rate. The second transmitter transmits outgoing data to the transformer at a different, typically greater, second data rate. A data-receiving apparatus contains first and second receivers, a receive transformer, and a connecting unit for coupling an incoming twisted-pair cable to the receive transformer. The first and second receivers receive incoming data from the secondary winding respectively at the first and second data rates. Incoming data is typically provided along data transfer paths that extend from the receive transformer in a daisy chain manner to the receivers. Data moving at either data rate can be transmitted and received without the need for hot switching in the data paths.

Abstract: A transformer system couples a control panel with a power line to support two-way communications over the power line. A first transformer steps-down the power line voltage, supplying power to the control panel. A second transformer and associated capacitors provide a low impedance path at the communication signal frequencies and a high impedance path at the power frequency.

Abstract: A switching arrangement is provided for coupling a transmitting unit to a transmission line. According to the present invention, a transformer is provided, whose secondary winding is a portion of the transmission line and whose primary winding is connected with the transmitting unit and integrated into a parallel resonance circuit, whose resonant frequency is tuned, each time, to the carrier frequency of the transmitted signal. In addition, a tuning unit may be provided for the automatic tuning of the parallel resonance circuit.

Abstract: A method and apparatus for transmitting binary data trains of 0 and 1 data bits, or combinations of these data bits over a communications network. The data bits are converted into pulses whose polarity changes from pulse to pulse, so as to enable an optimal exploitation of the transmission channel with a low error rate. The pulses generated by an apparatus of the present invention have a signal shape that produces a minimum inter-symbol interference. Processing and evaluation of the transmitted pulses are performed by a processor, so that a minimal error rate is attainable even under unfavorable transmission conditions.

Abstract: An improved isolation circuit for protecting data communication equipment from high voltages on a transmission line has two mixers. The first dual balanced mixer (DBMX) translates a data signal on the transmission line to a high frequency and is coupled with an isolation circuit to the second DBMX. The second DBMX then translates the output of the first DBMX to an isolated data signal with the same frequency content as the original data signal.

Abstract: Method and apparatus for cancelling in-band interference in real time. A cancellation circuit is provided where one demodulator circuit provides a demodulated output having interference voltage owing to interference between carrier signals, between a carrier signal and noise, or a combination of both. Cancellation of interference is particularly directed to narrowband applications. Because the interference is within the band of the desired signal, it cannot be filtered without materially harming the quality of the message. A separation circuit is provided for removing the interference voltage component from the message signal. Outputs are provided to a second demodulator for creating a phase-shifted near replica signal of the dominant carrier signal without an interference voltage component. The separation circuit includes an isolation circuit.

Abstract: A cordless headset, requiring very low power using Time Variant Modulation (TVM) for reception of a magnetic signal and TVM of RF or infrared as the transmitter. The headset area or zone of operations is defined by the magnetic field that the headset operates within and uses a handshake protocol that takes advantage of the TVM fixed clock period. The headset communicates with a base station that includes a TVM transmitter and loop for transmitting a TVM signal to the cordless headset, and a RF or infrared receiver capable of receiving TVM signals from the headset. The base station also contains the headset protocol logic for controlling the headset transmission. The headset and base station receiver can both be fixed, mobile or portable and vary with respect to orientation and distance from each other. The receiver circuits in both base station and headset automatically adjust to the variance in signal strength.

Abstract: Bus coupler operates with a transformer and a comparator which is connected downstream in the signal-processing branch. The comparator threshold is raised as a function of the signal in the case of larger signals relative to small signals.

Abstract: A data-transmitting apparatus contains first and second transmitters, a transmit transformer, and a connecting unit for coupling the transformer to an outgoing twisted-pair cable. The first transmitter filters data to produce outgoing data transmitted to the transformer at a first data rate. The second transmitter transmits outgoing data to the transformer at a different, typically greater, second data rate. A data-receiving apparatus contains first and second receivers, a receive transformer, and a connecting unit for coupling an incoming twisted-pair cable to the receive transformer. The first and second receivers receive incoming data from the secondary winding respectively at the first and second data rates. Incoming data is typically provided along data transfer paths that extend from the receive transformer in a daisy chain manner to the receivers. Data moving at either data rate can be transmitted and received without the need for hot switching in the data paths.

Abstract: A method for marshalling an additional outstation (3) of a time division multiple access (TDMA) telecommunications system including a basestation (4) and a plurality of outstations (1, 2), such as a passive optical network (PON). A sequence is transmitted from the additional outstation (3) to the basestation (4) at a level below the noise sensitivity of a receiver (49) of the basestation (4), detected at the basestation and its phase discrimated. From the discriminated phase the loop delay to the additional outstation is determined and the outstation instructed to realign its transmission accordingly. The sequence and its phases are detected by a correlation process. (FIG. 1).

Abstract: A signal coupler includes a transformer having a primary and a secondary winding. Each transformer winding has a pair of associated winding terminals and is also split at an intermediate winding position to form a pair of supplemental winding terminals. Circuitry is provided between each pair of supplemental winding terminals so as to provide different impedances in different frequency bands. In particular, a first circuit, which provides a first impedance in a first frequency range, is connected across the supplemental winding terminals of one winding. A second circuit, is connected across the supplemental winding terminals of the other transformer winding. This second circuit, in combination with the first, provides a second impedance in a second frequency range. In the disclosed embodiment, the first circuit provides an impedance of 600 ohms in the voiceband frequency range. The second circuit in combination with the first provides an impedance of 100 ohms in a frequency range extending above 40 kHz.

Abstract: An apparatus for the wireless transmission of energy and data includes a transformer with two sides for transmitting energy in one direction and data in both directions. A circuit on both of the sides of the transformer controls and evaluates a course of the transmission. In a method for controlling and evaluating the apparatus, a primary-side switching path is interrupted for transmitting energy from the primary side to the secondary side. Data are transmitted from the primary side to the secondary side during an energy storage phase by briefly interrupting a primary-side switching path. Data are transmitted from the secondary side to the primary side in a period during an energy storage phase by a secondary-side load pulse. An information transmission is controlled with a trigger and evaluation device on the primary side and on the secondary side.

Abstract: A single-port network node transceiver that does not draw any substantial current from the network when it is powered-down, enabling it to meet the ISDN powered-down loading specification when built on a CMOS integrated circuit chip. The pull-up transistors of the transmitter output circuit each have means for shorting the well terminal to source terminal connection when the circuit is operating and opening the connection when the power to the transceiver is shut down. The opening of this connection prevents the well-substrate junction of the pull-up transistors from becoming forward biased and drawing current from the network when the power to the transceiver is off and there is voltage present on the network. The transceiver also includes a plurality of ESD overvoltage protection diodes in series between the power supply rail and each input/output terminal.

Abstract: A local area network including cabling interconnecting a plurality of workstations, the cabling including a plurality of data ports and conductors for selectable and removable interconnection between selected ones of the data ports and apparatus for automatically providing an indication of the connection pattern of the data ports.

Abstract: In a terminal coupled to a computer network, a circuit for compensating for the baseline wander of received digital signals. The terminal is AC coupled to the computer network by a coupling transformer. The received digital signal is summed with a correction signal. The resulting summed signal is input to a comparator. This comparator compares the summed signal to a predetermined baseline level. Thus, the output signal from the comparator is fixed at the baseline level. The correction signal is the difference between the summed signal and the output signal from the comparator. The correction signal is filtered and amplified before being fed back to the comparator.

Abstract: A surrounding circuit for the local area network transceiver comprises isolation transformer, electric resistance, Diodes, transmitting circuit, transistor, electric capacitor, and input circuit; in order to slow down the rising time and falling time of the signal, the circuit can effectively improve the output signal waveform at the secondary coil of the isolation transforming and make it similar to sine wave which decreases the possibility of high frequency radiation. The circuit also provides a receiving surrounding circuit connected to the output of the transmitting surrounding apparatus which can eliminate the Common Mode Noise, has the effect of isolation, and at the same time allows the low-frequency collision signal to enter the transceiving circuit and maintains enough high input impedance.

Abstract: Digital termination equipment for use in signal transmission over a 2-wire subscriber line through an interface transformer includes an impedance unit functionally provided between the 2-wire subscriber line and the interface transformer for generating a high impedance when a current more than a predetermined current value flows therein. A power supply unit is provided having first and second terminals. The first terminal is connected to a winding of the interface transformer for supplying a voltage to the impedance unit through the winding. A current path forming circuit is connected to the impedance unit and to the second terminal of the power supply unit for forming a current path between the impedance unit and the second terminal of the power supply unit when a voltage more than a predetermined voltage value is applied. The power supply unit includes a dc power source and a switch connected in series to the dc power source. The switch is turned on when a local loopback testing is executed.