JPS61167259A - Amplifier of two-wire circuit - Google Patents

Abstract

PURPOSE:To amplify signals of any direction as the occasion demands in a simple circuit by providing a changeover switch that switches the direction of an amplifier optionally and switching and controlling the changeover switch according to received signals of a PB receiver. CONSTITUTION:In the case where voice is sent to a talkie equipment from a subscriber side, a specific PB signal is sent from a subscriber's telephone set. The PB signal is received by a PB receiver 3, discriminated in a gate circuit 4, and resets an FF circuit 5. Accordingly, changeover switches 21-24 make connection in the direction to make an amplifier 1 amplify voice from the subscriber and transmit to the talkie equipment. In the case where voice is sent from the talkie equipment to the subscriber, a PB signal different from above-mentioned one is sent from the talkie equipment. The receiver 3 receives the PB signal, and the circuit 4 discriminates this and resets the circuit 5. Accordingly, the amplifier 1 is connected in the direction to amplify sound signals sent out from the talkie equipment and send to the subscriber side.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an amplifier for a two-wire line used in a talkie transmission line or the like.

SUMMARY OF THE INVENTION The present invention provides an amplifier inserted into a two-wire line connecting a telephone station side device such as a talkie device and a subscriber side device such as a telephone set. A PB receiver that receives the PR multiplied signal, and a changeover switch that arbitrarily switches and connects the direction of the amplifier are provided, and the amplifier can be operated in any direction by controlling the changeover switch according to the received signal of the PB receiver. The connection is switched between the two.

BACKGROUND OF THE INVENTION When inserting a repeater into a two-wire line, a bidirectional amplifier is typically used. However, bidirectional amplifiers have a drawback in that they cannot be made to have a high gain in order to prevent oscillation due to signal coupling. Furthermore, it is expensive because it requires additional circuitry such as a balanced circuit network. Conventionally, the bidirectional amplifier is used even when connecting a talkie device and a subscriber, making it impossible to create an economical system.

Problems to be Solved by the Invention The present invention solves the above-mentioned drawbacks of the prior art and provides an economical system that does not need to transmit signals in both directions at the same time, such as a line connecting a talkie device and a subscriber. It is provided to

Structure of the Invention The two-wire line amplifier of the present invention is an amplifier inserted into a two-wire line connecting a subscriber side device and a central office side device. A changeover switch that connects in any direction; a PB receiver that receives PB multiplied signals sent from the subscriber side and the central office side; and a switching control unit that controls switching of the changeover switch according to the received PB multiplied signal. It is characterized by having

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

The figure is a block diagram showing one embodiment of the present invention. That is, changeover switches 21 to 24 are connected to the input side and the output side of the amplifier 1 and switch the amplifier in any direction, and the PB receiver 3 receives the PB multiplied signal sent from the subscriber side and the central office side. It consists of a switching control section. 1
- The switching control unit identifies the output of the PB receiver 3,
A gate circuit 4 and a clip-flop set the flip-flop circuit 5 when a specific PB double signal sent from the telephone office side and reset the flip-flop circuit 5 when receiving another PB double signal sent from the subscriber side. It is constituted by circuit 5. Always (at flip-flop reset)
When the changeover switches 21 and 23 are closed, the changeover switch 23 is closed.
and 24 are open, and the audio sent from the subscriber side is
The signal is input to the amplifier l through the changeover switch 24, and the output of the amplifier l is sent through the changeover switch 23 to the 1-key device side. When the flip-flop circuit 5 is set, by opening the changeover switches 21 and 22 and closing the changeover switches 23 and 24, the sound sent from the talkie device is input to the amplifier l through the changeover switch 22, and the sound is input to the amplifier l through the changeover switch 22. The output of l is the changeover switch 2! It is sent to the subscriber side through.

Next, the operation of this embodiment will be explained. When transmitting audio from the subscriber side to the talkie device, when a specific PB multiple signal is sent from the subscriber telephone, the PB multiple signal is received by the PB receiver 3, identified by the gate circuit 4, and sent to the flip-flop circuit 5. Reset (if the flip-flop circuit 5 is always reset, the state remains unchanged). Therefore, the changeover switches 21 to 24 are connected in the direction in which the amplifier 1 amplifies the voice from the subscriber and sends it to the talkie device side.

When transmitting audio from a talkie device to a subscriber, it is first sent from a separate PB double signal talkie device. P
The B receiver 3 receives the PB multiplied signal, the gate circuit 4 identifies it, and sets the flip-flop circuit 5.

Therefore, the amplifier 1 is connected in the direction of amplifying the audio signal sent from the talkie device and sending it to the subscriber side.

It is desirable that the flip-flop circuit 5 be reset when the subscriber finishes listening to the talkie tone and goes on-hook.

In addition, when multiple amplifiers similar to the above are inserted in a two-wire line, the flip-flop circuits 5 of the multiple amplifiers are
Especially when reset to J town from a power or close to the subscriber,
Each A-/I is connected in the direction of amplifying the voice from the subscriber and transmitting it to the telephone office side. Conversely, if a specific P
When the B-fold signal is sent out, the flip-flop circuits 5 are set in order from the one closest to the telephone office, the direction of the amplifier 1 is changed, and the PB-fold signal is sent to the next amplifier, and multiple amplifiers 1 Turn to the subscribers one after another.

In this example, even if the gain of amplifier 1 is increased, oscillation does not occur,
This has the advantage of not requiring additional circuits such as a balancing network.

Effects of the Invention As described above, in the present invention, it is possible to amplify signals in any direction as necessary with a simple circuit,
This has the effect of realizing an economical system with a large amplifier gain.

[Brief explanation of drawings]

The figure is a block diagram showing one embodiment of the present invention. In the figure, l: amplifier, 3: PB receiver, 4:
Gate circuit, 5: Flip-flop circuit, 21-24:
Su1 department switch.

Claims (1)

[Claims] In an amplifier inserted into a two-wire line connecting a subscriber side device and a central office side device, a switching device connected to the input side and output side of the amplifier to switch and connect the amplifier in any direction. 2, characterized in that it comprises a switch, a PB receiver that receives PB signals sent from the subscriber side and the central office side, and a switching control unit that controls switching of the changeover switch according to the received PB signal. Wire line amplifier.