Abstract: In a transmission system a transmitter (12) is coupled to a receiver (13) via a transmission line comprising two wires (1,2). The transmitter (12) generates on said wires two voltages with respect to a reference voltage being opposite in phase. To enable the transmission system to operate in case of a short circuit between the wires (1,2), said two voltages are generated by sources having different short circuit currents.

Abstract: The present invention allows for the simultaneous transmission of two digital signals from one integrated circuit to another. The two digital signals are encoded utilizing a voltage divider circuit and are then transmitted by one transmission line to the second integrated circuit chip. The second integrated circuit chip decodes the first digital signal and then utilizes this decoded digital signal to further decode the second digital signal.

Abstract: A large scale integrated circuit has a first circuit section with input terminals external of the integrated circuit connected to output terminals of a second portion of the integrated circuit for use in an environment not requiring intrinsic safety. When the circuit is to be installed in an environment requiring intrinsic safety the external connectors are disconnected from one another. An excess voltage suppression circuit is connected to the external connections of the second circuit section.

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: The present invention allows for the simultaneous transmission of three digital signals from one integrated circuit to another. The three digital signals are encoded utilizing series resistors of predetermined values and are then transmitted by one transmission line to the second integrated circuit chip. The second integrated circuit chip decodes the first digital signal and then utilizes this decoded first digital signal to further decode the second digital signal, and then utilizes the decoded first and second digital signals to decode the third digital signal.

Abstract: In a data bus with m data bits, electromagnetic interference is produced by polarity switching the data on that data bus. When two consecutive data items result in a change of over half of the data bits, the polarity of the second data item is switched, and a polarity signal is correspondingly switched on the data bus. When the data is received, it is restored to its original polarity by adjusting the polarity of the received data according to the signal on the polarity line. In this way, the total number of bit transitions between any two data items is reduced to a maximum of m/2.

Abstract: The off-state of the binary transitions is used in order to possibly generate symmetrical transitions of the active state of the binary transitions in relation to the off-state, in order to replace the two-state logic of at least one binary transition capable to go to the rest-state by a three-state logic.

Abstract: A method and apparatus 200 for converting dual 4-wire digital data services (DDS-1 and DDS-2) for transmission over a single twisted pair telephone line 205. The present method includes use of a digital data service remote terminal 219 and a digital data service central office terminal 201. Each terminal converts more than one 4-wire digital data services into a 2B1Q signal for transmission over the single twisted pair telephone line 205. The present method provides an efficient and cost effective technique for increasing 4-wire digital data services to a customer premises without a corresponding increase in the number of telephone lines.

Abstract: A network transmitter device and network receiver device is described. The network transmitter device transmits a first voltage potential, a second voltage potential, a third voltage potential and a fourth voltage potential over a first pair of output lines and a second pair of output lines in response to digital signals received over a data input. The network receiver device receives network signals of a first voltage potential, a second voltage potential, a third voltage potential, a fourth voltage potential and a fifth voltage potential over a first pair of output lines and a second pair of output lines. The network receiver device transmits digital signals corresponding to the network signals.

Abstract: A method and system are provided for transmission of m information signal combinations over a known transmission medium at a high rate of speed without crosstalk between data transferred through the transmission medium. The technique employed is to convert each of the m information signal combinations to a unique line signal corresponding to one of n intrinsic orthogonal modes of the defined transmission medium through which the information is to be transmitted (wherein m>n). The encoded line signals, propagated via the orthogonal modes, are received and decoded at a remote location along the transmission medium to restore the original information data. The problem of assigning m unique line signals to each of the m possible information signal combinations is addressed by amplitude modulation of the transmission medium's n intrinsic orthogonal modes.

Abstract: A binary signal encoding technique for reducing the amount of electromagnetic interference (EMI) caused by the transmission of high-speed binary signals over an unshielded twisted pair of conductors. Duobinary modulation, combined with low-pass filtering to confine the signals' frequency spectrum, and stop-band filtering to reduce critically high spectral lines, results in an acceptably low level of electromagnetic emission from the twisted pair. Moreover, duobinary modulation and stop-band filtering to reduce spectral lines avoids the need for signal scrambling to reach acceptable radiation levels by spreading the signal energy across the frequency spectrum.