SU1626404A1 - Subscriber line state testing device - Google Patents

Abstract

This invention relates to telephone communications. The purpose of the invention is to increase the reliability of the control. This goal is achieved by introducing a control voltage divider 7, which makes it possible to track current fluctuations in the circuit depending on the load. As a result, a signal appears at the output of the integrator 4, showing the relative change in the signal in the controlled circuit, which is compared with the reference signal in the comparator 6, at the output of which the output signal of the device is formed. 1 il.

Description

The invention relates to telephone communications and can be used in equipment for monitoring and recording the duration of outgoing calls at telephone exchanges.

The purpose of the invention is to increase the reliability of the control.

The drawing shows an electrical block diagram of a device.

The subscriber line condition monitoring device comprises first 1 and second 2 resistors, a power supply 3, an integrating RC circuit 4, a reference voltage source 5, a comparator 6, a controlled voltage divider 7, the drawing also shows a subscriber line 8 including a line 9 and telephone set 10.

The device operates as follows,

In the initial state, the handset of the telephone set 10 is not lifted, the contacts of the lever switch open the loop of the subscriber line 8.

The minus potential at the information input of the device is equal to the voltage of the station power supply 3, the logic zero signal at the output of the comparator 6.

When the handset is removed, a loop is formed through the closed contacts of the switch, the negative potential at the input of the integrating RC circuit 4 increases (the absolute value decreases) due to a drop in voltage on resistors 1 and 2 when current flows through the loop.

The value of this potential is below the threshold of the comparator 6, the latter is turned off, and a logical unit signal is generated at its output, indicating the presence of a loop.

When dialing, a pulse interruption of the loop occurs. In the cycle of interruption of the loop at the input of the integrating RC circuit 4, a potential arises equal to the voltage of the station power supply 3, and at the output of the comparator 6 - a logic zero signal.

When the power supply circuit is interrupted from the cord set in the presence of a loop, the negative potential is removed from the input of the integrating RC circuit 4, the comparator 6 does not work, the logical unit remains at its output, i.e. the loop signal is saved.

Claims (1)

Claim A subscriber line condition monitoring device comprising a first resistor connected between a power supply output and a first subscriber line input, the second input of which is connected to a common bus via a second resistor integrating an RC circuit, the common output of which is connected to a common bus, a reference voltage source connected in series and a comparator, the output of which is the output of the device, characterized in that, for the purpose of reliability of control, a controlled voltage divider is introduced, the control input of which is connected to the power supply, and the outputs are connected respectively to the first and second inputs of the comparator, the second input of which is connected to the output of the integrating RC circuit, the input of which is connected to the first input of the subscriber line. Compiled by V. Kurkov Editor V. Danko Tehred M. Morgenthal Corrector S. Lisina Order 286 Circulation 382 Subscription VNIIIPI of the State Committee for Inventions and Discoveries at the State Committee for Science and Technology 113035, Moscow. Zh-35, Raushskaya nab., 4/5 Production and Publishing Plant Patent, Uzhhorod, 101 Gagarin St.