SU515291A1 - Matching device for one-way transmission of signals over the communication line - Google Patents

Description

The invention relates to signal transmission systems for various purposes, in particular, it is intended for the organization of one-way inter-device communication.

A matching device for one-way transmission of signals over a communication line is known, which contains a transmitting cascade with a logic element of transistor-transistor logic and a matching cascade with a transistor connected through a communication line with a receiving cascade, as well as a power source,

However, the known device has a low load capacity, since the matching element consists of passive elements, which reduce the voltage of the useful signal to the magnitude of the voltage drop across them.

The aim of the invention is to increase the load capacity of the device.

For this, a second logic element with a transistor-transistor logic is connected to the transmitting cascade, connected to the first logic element at the input, the output of one logic switch connected to the transistor base of the matching cascade, and through the first resistor to the power supply plus, transistor collector and power supply, the second resistor is switched on the output of another logic element through the third resistor is connected to the emitter of the transistor and to the communication line.

An outline of the electrical device is shown in the drawing.

The matching device for one-way transmission of signals over the communication line contains the transmitting stage 1, consisting of two input-connected logic elements 2 and 3 of the transistor-transistor logic, the matching stage 4 containing the first resistor 5, which is the load of the output stage 1 and 1 sets the base current of the transistor 6, the second resistor 7, which serves as the collector load of the transistor 6, the third resistor 8 which is the load of the output stage of the logic element 3, connected to the emitter of the transistor 6 resistor 8 line

3

connection 9 (for example, a radio frequency cable), connected to the input of the reception stage U of Resisgori 5 and 7, is connected to the positive power source 11.

The device works as follows.

When switching the logic elements 2, 3 from the low-voltage state at the output B, the high-voltage output transistors of these elements are closed and the transmitting stage 1 is disconnected from the rest of the device. The base current, set by resistor 5, opens transistor 6, and a positive voltage drop, equal to the voltage of power supply 11 minus the voltage drop across resistor 7 and the collector-emptter voltage of transistor 6, enters through the link 9 to the input stage 10 and switches it. The link 9 serves as the input impedance of the receiving cascade 10, as a rule, several times higher than the wave resistance of line 9. As a result, a reflected signal is produced, approximately equal to the incoming signal, which propagates along line 9 to its beginnings:; This signal is matched at the transmitting end of the line to which in this mode the equivalent resistance is connected (practically the resistance of resistor 7) equal to the characteristic impedance of the communication line 9, I When switching logic elements 2 and 3 from the low-voltage state at the input to the high voltage at both outputs transmitting cascade. 1 action that low voltage levels. Transistor 6 closes and link 9 is discharged to a low voltage level at the input of the receiving stage 10 through a resistor 8 and the output impedance of logic element 3, the total value of which in this mode is also equal to the characteristic impedance of the link 9.

i L

152914

The use in the transmitting stage 1 of two logic elements 2 and 3, working on communication line 9 only at a low-voltage state at the output, makes it possible for the blocks intended for signal transmission to use the power of standard logic elements having small values of permissible output current in high-voltage output state. On the other hand, inclusion in the matching part

10 of the device of an element intended for matching, based on an active electric element-transistor, provides the necessary amplitude of the signal at the receiving end when operating on a low-ground communication line 15, including a cable with a large kilometric attenuation.

Claims (1)

Invention Formula A matching device for one-way transmission of signals over a communication line, containing a transmitting cascade with a logic element of transistor-transistor logic and a matching cascade with a transistor connected through a communication line with a receiving cascade, as well as with in order to increase the load capacity, a second logic I element with a transistor-transistor logic, connected to the first logic element at the input, is introduced into the transmitting cascade; the output of one logic element is connected to b se transistor matching stage and via a first resistor to the positive power source between the transistor collector and the plus power supply is included a second resistor, and the output of another logic element via a third resistor connected to the emitter of the transistor and to the link.