SU1282338A1 - Device for transmission and reception of information via two-wire communication line - Google Patents

Abstract

Invention m. used in systems for transmitting discrete information via communication lines with galvanic, isolation. The purpose of the invention is to reduce power consumption. The device contains on the transmitter side 1, shunt zl-t 2, output tr-p 3, diode 5, on the receiving side - matching unit 9, input tr-p 10, block 11 comparison. Transistor 4, diode 6, two resistors 7 and 8 were newly introduced, to-rye due to the possibility of working on the load not matched with the characteristic impedance, reducing the power consumption. When the pulse duration exceeds the propagation time of the signal in the communication line, the current in the latter determined by the input resistance of block 9 will decrease by about 10 times. As an additional effect, there is an increase in the reliability of the device due to the reduction in the power of the l-1, a simplification of its operation mode and an increase in the noise immunity of the communication line. 1 il. (I

Description

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The invention relates to the field of transmission of discrete information and May find application in systems of transmission of discrete information over communication lines with automatic communication.

The aim of the invention is to reduce power consumption.

The drawing shows a structural electrical circuit device.

The device contains an amplifier 1, a shunt element 2, an output transformer 3, a transistor 4, a first diode 5, a second diode 6 and two resistors 7 and 8 on the transmitting side, and a matching unit 9 on the receiving side, an input transformer 10 and a comparison block 11.

The device works as follows.

When a pulse is applied to the input of amplifier 1, the amplified pulse through the output transformer 3 is fed through a resistor 8 to the second wire of the communication line (positive pulse). A negative polarity pulse is removed from the second output secondary winding of the output transformer 3, and a current determined by the resistance of the resistance 7 flows through the resistor 7 and the second diode 6. A current also flows through the first terminal 5, resulting in a voltage at the base of transistor 4 equal to zero.

The first and second diodes 5 and 6 must have similar current-voltage characteristics, which is provided in the case when both diodes are used from the same integrated circuit. In this case, the transistor 4 will be closed during the passage of the pulse. The first diode 5 and the second diode 6 prevent the negative discharge of the transformer into the communication line. The impulse through the communication line enters the matching unit 9, the input resistance of which can be significantly (in order) above the wave resistance of the communication line, and through the input transformer 10 enters the comparison unit 11. The pulse reflected from the input of the matching key 9 and falling on the input of the communication line opens the transistor 4, but due to the first diode 5 the reflected pulse does not hit the secondary winding of the output transformer 5, as a result of which the connection line is loaded on the resistance of the resistor 8 you

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biraemy close to the characteristic impedance of the line.

The resistance of the second resistor 7 is selected from the condition that the transistor 4 is saturated, but at the same time it should not be too small so as not to shunt the secondary winding of the output transformer 3 during the passage of a pulse. Transistor

4 can be made as a composite transistor to increase current transfer coefficient. The resistance of the resistor 8 together with the resistance of the open transistor 4 must be equal to the characteristic impedance of the communication line. The opening voltage of the transistor 4 must be greater than the possible difference of the voltage drops on the first and second diodes

5 and 6.

The introduction of resistors, a transistor and a diode allows, by providing: the possibility of operating the load not compatible with the characteristic impedance, to reduce the power consumption of the rotating side and the entire device b in general. Thus, in order to ensure the normal operation of the receiving side, it is sufficient to provide its input impedance of the order of 1-2 kΩ, while the characteristic impedance of the twisted pair line in the screen is 100-150 ohms.

As a result, the current in the communication line when the pulse duration exceeds the signal propagation time in the communication line, which is determined mainly by the input resistance of the matching unit, is reduced by about 10 times.

In addition, the reliability of the device is increased by reducing the power of the amplifier, facilitating its operation, and also increases the noise immunity of the communication line, since in the absence of a pulse from the output transformer 3, the input of the communication line turns out to be closed to a low impedance and any impulses induced on lines of communication, in it is quenched on in, gga resistance.

Claims (1)

Invention Formula A device for transmitting and receiving information over a two-wire communication line, containing an amplifier on the transmitting side, the output of which is connected to the power supply through the primary winding of the output transformer, the first output of the secondary transformer of the output transformer is connected to the cathode under-; The shunt element is connected to the first wire of the communication line, and parallel to the primary winding of the output transformer, a receiving unit is connected to the receiving side, the output of which is connected through the input transformer; Chen to the comparison unit that, with a view reduce the power consumption, a transistor, a second diode and two resistors are inserted on the transmitting side, the second output of the secondary winding of the output transformer is connected to the collector of the transistor and to the first terminals of the transformer; mountains, the second output of one of which is connected to the second. the wire of the communication line, and the second output of the other resistor - with the base of the transistor and the anode of the second diode, the cathode, which is connected to the cathode of the first diode, the anode of which is connected to the emitter of the transistor.