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Ternary Detector for Bidirectional Transmission

IP.com Disclosure Number: IPCOM000077609D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Besseyre, J: AUTHOR

Abstract

The use of a two-wire bidirectional loop allows redundancy of path and permits opening of the loop anywhere without disturbing communication. With such a configuration the two wires of the loop are connected through driver-receiver circuits 1 and 2, as shown in Fig. 1.

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Ternary Detector for Bidirectional Transmission

The use of a two-wire bidirectional loop allows redundancy of path and permits opening of the loop anywhere without disturbing communication. With such a configuration the two wires of the loop are connected through driver- receiver circuits 1 and 2, as shown in Fig. 1.

Driver-Receiver circuit 2 on the loop receives a digitally coded message S1 on line L1 and simultaneously transmits a coded message S2 on line L2. Consequently, a detector is provided at the input of the receiver in order to separate the received signal from the emitted one.

Voltage at the input of the receiver depends on the received signal on L1 and the emitted signal on L2. According to the possible digital values of these signals the input voltage is as follows: S1 S2 Input

Received Emitted Voltage

0 0 -V

1 0 +/- epsilon approx. 0

0 1 +/- epsilon approx. 0

1 1 +V.

From the above truth table, one deduces that when the input voltage is equal to -V or +V, the receives signal is identical to the emitted one and when the input voltage is +/- epsilon the received signal is the complement of the emitted one. Thus, knowing the emitted or local signal it is possible, by using the detector represented in Fig. 2, to deduce the received signal film the emitted one and the input voltage.

A receiver-driver, for example receiver-driver 2 in Fig. 1, on the two-wire loop comprises two resistors R and two current generators G1 and G2. Comparators 3 and 4 provide a...