A device for the transmission of push-pull signals by way of a two-wire line in full duplex operation has a push-pull transmitter for the transmission of the push-pull signals to an opposite station and a push-pull receiver for the simultaneous reception of the push-pull signals transmitted from the opposite station, and a compensation circuit for compensating the push-pull signals transmitted from the associated push-pull transmitter in relation to the inputs of the push-pull receiver. The push-pull transmitter and the push-pull receiver are designed as symmetrical differential amplifiers composed of emitter-coupled transistors and are provided with a constant current feed. The compensation circuit is of symmetrical construction and inputs of the push-pull receiver are connected to the wires of the two-wire line by way of two identical decoupling resistors which form parts of the compensation circuit.
A transceiver inserted between a signal source and a two-wire or one-wire line, designed to transmit balanced or unbalanced digital signals to a remote station at the opposite end of the line while receiving similar signals from the latter station, comprises a first and a second amplifier with inputs connected to the line at a proximal and a distal end of a line-terminating impedance, respectively. Each amplifier has an inverting output connected to a noninverting output of the other amplifier, the two nodes formed between the interconnected outputs being connected to respective inputs of a differential third amplifier feeding a signal receiver. The gain of the first amplifier is half that of the second amplifier whereby the locally generated signals are suppressed in the output of the third amplifier. The several amplifiers are realized in integrated circuitry and may be provided with switches for selective changeover between a balanced and an unbalanced mode of operation.
The present invention provides a digital full-duplex line driver which allows digital information to be transmitted across a single bus simultaneously in both directions. The present invention accomplishes this by using both the voltage level on the bus and the current flowing through either a driver on one side of the bus or through the bus itself to decode the required information.
This invention details a baseband bipolar pulse signaling technique employing only two wires for simultaneous bi-directional communications. A first polarity of pulses is utilized for communication of traffic in one direction; traffic in the return direction utilizes pulses of the opposite polarity. Each end of the communication link has both a sender and a receiver. One sender arbitrarily transmits only positive pulses; the receiver at this end of the system will recognize only negative pulses. The inverse set of conditions is enforced at the opposite end of the link. Means are included for synchronizing the application of pulses to the link at the other end in response to the receipt of pulses at that end to avoid overlap of receive pulses at the originating end of the line.
The invention relates to a device for push-pull transmission of items of binary information, wherein in order to improve the ratio of the information which can be simultaneously transmitted to the number of lines in a line group comprising at least three lines, more than two different potentials are produced on the lines while maintaining a constant potential sum in the line groups. Two or more line groups can serve to form phantom circuits.
This device in which the network includes a transmission cable (4) fitted with a pair of conductors (2, 3), is characterized in that each conductor (2, 3) of the cable is linked at each of its ends to a terminal of a resistor (9, 10) whose value is equal to half the value of the characteristic impedance of the cable (4) and the other terminal of which is linked to a voltage source (11, 12).
