JPS63292865A - Charging signal transfer circuit - Google Patents

Abstract

PURPOSE:To improve call quality, by interrupting currents on a line (a) and a line (b) for a time t1 or a time t2 by using a detecting signal generated by detecting the input or the interruption of a charging signal, and transferring the information of the input or the interruption of the charging signal by switching connection between a line and the lines (a) and (b) within the above time. CONSTITUTION:When the charging signal is inputted, it is detected by a charging signal detector 2, and the detecting signal is added on a first timing generator 31 and a second timing generator 41. And since the second timing generator generates a negative pulse with width t1 and adds it on a current controller 42, the current controller 42 turns OFF a transistor Q1 for the time t1 by using the pulse. Also, when the detecting signal is inputted, the first timing generator 31 operates a contact rl3 by driving a relay winding RL3 for the time t1, and switches the connection of a power source to the lines (a) and (b). In other words, since switching is performed while no currents flow to coils L1-L4, noise is suppressed, then, deterioration in the call quality can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] In the billing signal transfer circuit, a detection signal generated by detecting the input or disconnection of the billing signal is used to control the current flowing through the a line and the b line for a time t3.

Or, it is designed to improve call quality by cutting off for t2 time, switching the connection between the A line and B line and the power supply within this time, and transferring information on input or disconnection of billing signal. It is.

[Industrial application field]

The present invention relates to an improvement in a billing signal transfer circuit 2, for example, a billing code transfer circuit inserted into a PCM line for transmitting a billing signal for toll collection on a public telephone line.

FIG. 5 shows an explanatory diagram of billing signal transfer. The diagram will be explained below assuming that C is talking to D using a public telephone.

First, the voice of C is digitized by the signal converter in the transmission terminal equipment via the handset (not shown), the exchange in the A office, the A line and the B line, and converted into a PCM signal by the multiplexing/demultiplexing circuit. This PCM signal is multiplexed with a PCM signal obtained using a signal digitized by another signal converter and sent to the B station.

At station B, the received multiplexed PCM signal is separated by a multiplexing/demultiplexing circuit in the transmission terminal equipment, and converted into an audio signal by a signal converter. However, when the call time has elapsed, for example, 3 minutes, a billing signal indicating a request to insert coins is sent from station B to station A.

At station A, a multiplexing/demultiplexing circuit separates the billing signal and sends it to a signal converter. Therefore, the potential of the a line is changed from Ov to 1, for example -48V, and the potential of the b line is changed from -48V to Ov.
By switching to , the input of the billing number 5 is sent to the public telephone via the exchange.

When a coin is inserted into a public telephone, the 1-charging code is cut off, so the potentials of the a-line and b-line go back to the original OV and -48V.
1 call continues.

Here, it is necessary that the call quality does not deteriorate even if the potentials of the a-line and b-line are switched by a billing signal.

[Conventional technology]

FIG. 6 shows a block diagram of a conventional example. In the figure, when a response signal indicating that a call has been entered is sent from station B to station A, the response signal is separated by the multiplexing/demultiplexing circuit (not shown) in station A and converted into a signal, as described above. The response signal is added to the response signal detector 1 in the device. Therefore, the relay winding RL is driven by the detection output, and the contact rlI moves from the solid line to the dotted line.

The A line is switched to OV and the B line is switched to 148V, making it possible to make a call.

After that, the audio signals that have passed through the a & 1 and b lines are multiplexed via the capacitor C1 and the 2-wire/4-wire converter T.
The signal is sent to a separate circuit (not shown) and the call is initiated.
For example, after three minutes have elapsed from the start of the call, a billing signal from station B is applied to billing signal detector 2 of station A.

Therefore, the relay winding RL is driven by the detection output from the billing signal detector 2, and the contact r4z moves from the solid line to the dotted line, so the a line changes from Ov to -48V.

The b line is switched from 148V to Ov, but the potential with reversed polarity, that is, the information on the billing signal input is passed through a balanced low-pass filter consisting of the line ring, ~L4, and capacitors C+ and Cz. , contact r12. ．． A line.

The signal is sent to the A office exchange (not shown) via the B line.

Note that when the charging signal is disconnected, the charging signal detector 2 detects this and stops driving the relay winding RL, so the contact r
f2 is restored as shown by the solid line, the a line is Ov, and the b line is -48V.
Switch to .

[Problem that the invention seeks to solve]

Here, the potentials of the a-line and b-line are switched by the input of the billing signal, but a low-pass filter is inserted so that the noise generated at this time does not enter the audio signal.

However, this filter has the problem that voice components contained in noise cannot be sufficiently removed, resulting in deterioration of speech quality.

Means for Solving Problem C] The above problem is solved by the billing signal transfer circuit shown in FIG.

Here, 4 utilizes the detection signal generated by detecting input or disconnection of the charging signal to connect the a line and the b line to the power supply during the current interruption caused by the operation of the a line control means. This billing signal transfer means transfers information on input or disconnection of billing signals by switching connections and inverting or restoring the potentials of the a-line and b-line.

[Effect]

In the present invention, when the potentials applied to the a-line and b-line are reversed by switching the contacts, the duration is 1.5 mm as shown in FIG. 2 due to the transient phenomenon of the current flowing through the wire ring ~L4. Or, a waveform shorter than t2 was generated, and it was experimentally confirmed that this was the cause of deterioration in speech quality. Therefore, in order to prevent this waveform from occurring, the contacts were switched while the current flowing through the coil was turned off, and the current was allowed to flow once the switching was completed.

That is, a pulse generated using a detection signal generated by detecting input or disconnection of a charging signal.

The current passing through the current control means 4 is turned on or off, and during the off period, another pulse generated using the above detection signal is used to connect the a line and b line in the billing signal transfer means 3 to the power supply. Switch connections.

As a result, even if the potentials of the a-line and b4m are switched, no noise is generated, and the quality of communication is improved.

〔Example〕

FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is an explanatory diagram of the operation of FIG. 3. In addition, the number on the left side of Figure 4 is the third
The waveforms of the portions with the same symbols in the figure are shown. Further, the low-pass filter 32 and the first timing generator are the constituent parts of the billing signal transfer means 3, and the transistor Q, the second timing generator 41, and the current controller 42 are the constituent parts of the current control means 4. . Here, the same reference numerals indicate the same objects throughout the figures.

The operation shown in FIG. 3 will be explained below with reference to FIG.

First, when a billing signal as shown in the first half of FIG. 4-2 is input, it is detected by the billing signal detector 2.

A detection signal is applied to the first timing generator 31 and the second timing generator 41.

Therefore, the second timing generator configured with a monostable multipipe rake, for example, generates a negative pulse with a width of t, which coincides with the rising edge of the charge signal, as shown in Fig. 4-■, and controls the current. The current controller 42 uses this pulse to turn off the transistor Q for a time t1.

On the other hand, when the detection signal is input, the first timing generator 31 composed of a delay circuit and a monostable multivibrator, for example, drives the relay winding RL3 to operate the contact rf3 during time t8, and connects the power supply. Switch the connection between the A line and B line.

Note that even when the billing signal is disconnected, no current flows through the a-line and b-line as described above.1. Switch the connection back and forth in time.

That is, since the connection is switched in a state where no current is flowing through the wire ring .about.L4, noise is suppressed and deterioration in speech quality is improved.

〔Effect of the invention〕

As explained in detail above, the present invention has the effect of improving the deterioration of call quality.

[Brief explanation of drawings]

Fig. 1 is a principle block diagram of the present invention, Fig. 2 is a waveform diagram that occurs during switching, Fig. 3 is a block diagram of an embodiment of the present invention, Fig. 4 is an explanatory diagram of the operation of Fig. 3, and Fig. 5 The figure is an explanatory diagram of billing signal transfer, and FIG. 6 is a block diagram of a conventional example. In the figure, 3 indicates billing signal transfer means, and 4 indicates current control means. -t77%F, clear 1; main tear punishment picture 2 Kuchimoto Hiaki/) Yasaki A? 1 block 2 嘱 3 decoy

Claims (1)

[Claims] Using the detection signal generated by detecting input or disconnection of the billing signal, the current flowing through the a line and the b line is reduced to t_
Current control means (4
), and during the current interruption caused by the operation of the current control means, the a
Switch the connections between the A line and B line and the power supply, and
A billing signal transfer circuit comprising a billing signal transfer means (3) that transfers information on input or disconnection of a billing signal by inverting or restoring the potential of a line.