RU2013003C1 - Device for matching of two- and four-wire paths - Google Patents

Abstract

FIELD: electric communication. SUBSTANCE: device relates to digital telephone sets used in electric communication equipment. For matching of two-wire and four-wire paths output of first winding of transformer and output of third resistor are connected to collector of transistor which emitter is coupled to second output of resistor and is linked via capacitor to other output of second winding of transformer. Device includes transistor 1, output wire 2 of four-wire path, first resistor 3, supply wire 4, second resistor 5, transformer 6, having first, second and third windings 7, 8, 9, third resistor 10, capacitor 11, input wire 12 of four-wire path, first and second wires 13 and 14 of two-wire path, common wire 15. EFFECT: enhanced transient attenuation between two-wire and four-wire paths with simultaneous simplification of device. 1 dwg

Description

 The invention relates to techniques for electrical communication, in particular to devices for matching two-wire and four-wire paths, and can find application in digital telephone communication systems in which a transition from a two-wire line to a four-wire is necessary, and vice versa.

 The aim of the invention is to increase the transient attenuation between two-wire and four-wire paths while simplifying the device.

 The drawing shows a structural diagram of a device for matching two-wire and four-wire paths.

 The device comprises a transistor 1, an input bus 2 of a four-wire path, a first resistor 3, a power bus 4, a second resistor 5, a transformer 6 having a first, second, and third winding 7, 8 and 9, a third resistor 10, a capacitor 11, an output bus 12 of a four-wire path, the first and second bus 13 and 14 of the two-wire path, a common bus 15.

 The operation of the device is as follows.

 The device provides the transmission of communication pulses from the input bus 2 to the buses 13 and 14 with the simultaneous compensation of the transmitted signal on the output bus 12. The device also allows you to receive communication pulses from the buses 13 and 14 to the output bus 12 with full isolation from the input bus 2.

 In the device, the first resistor 3 sets the bias in the transistor 1, which operates in non-saturation mode. The third resistor 5, together with the resistance introduced through the first winding 7 of the transformer 6, forms the collector load of the transistor 1. The third resistor 5, in addition, plays the role of a matching resistance and wave impedance of the line and input resistance along the buses 13 and 14. Transistor 1 together with the second resistor 3 forms a source of current pulses, where the second resistor 3 determines the amplitude of the current pulses in the load of the transistor 1.

 The amplitude of the pulses on the output bus 12 is made up of the EMF induced on the second winding 8 of the transformer and the EMF pulses induced on the second resistor 3. The capacitor 11 eliminates the constant component of the pulses taken from the second resistor 3.

 When transmitting pulses from the input bus 2 to the buses 12 and 13, the EMF values taken from the chain consisting of the second resistor 3 and the capacitor 11, and from the second winding of the transformer 6 are in antiphase and compensate one another. Therefore, during transmission and in reception mode, only pulses appear on the output bus of the four-wire path, which are transformed from the third winding 9 of the transformer to its second winding 8. For optimal compensation of the transmitted pulses on the output bus 12, the ratio of the resistance of the second resistor 3 and the load of transistor 1 should be equal the ratio of the second and first windings 8 and 7 of the transformer 6.

Claims (1)

 A device for matching two- and four-wire paths, comprising a transistor, a first, second and third resistors, a capacitor and a transformer, the first terminal of the first winding of which is connected to a common bus and connected to the first terminal of the third resistor, the terminals of the second transformer winding are connected to the buses of the two-wire path, the first terminal of the third winding of the transformer is connected to the output bus of the four-wire path, the base of the transistor is connected to the input bus of the four-wire path and is connected through the first resistor to a power bus connected to the first output of the second resistor, characterized in that, in order to increase the transient attenuation between the two- and four-wire paths while simplifying the device, the second terminals of the first winding of the transformer and the third resistor are connected to the collector of the transistor, the emitter of which is connected to the second output the second resistor and is connected through a capacitor to the second terminal of the third winding of the transformer.