JP3030889B2 - Billing signal transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a billing signal sending system, and more particularly to a billing signal sending system for a public terminal in a PCM time-division electronic exchange.

[0002]

2. Description of the Related Art A conventional billing signal transmission system of this type is a subscriber of a PCM time-division switching system 3 having subscriber circuits 15 and 16, a time switch 13, and a control circuit 31, as shown in FIG. A billing signal transmitting circuit 4 for transmitting a billing signal to the public terminal 2 is separately provided on the line side of the user circuit 16 as an adapter.

Next, the operation will be described.

[0006] When the billing frequency of the call between the public terminal 2 connected to the subscriber circuit 15 and the subscriber circuit 15 connected by the time switch 13 reaches a predetermined value, the control device 31 controls the transmission of the billing signal. The signal CC is generated and sent to the charging signal sending circuit 4. The billing signal sending circuit 4 is a public terminal 2
Send a billing signal to. The public terminal 2 receives this billing signal and stores coins inserted by the user of the public terminal in a coin storage box.

[0005] The billing signal has a frequency of 12KHz and 16K.
Hz or a mixed burst signal of 12 KHz and 16 KHz, and uses a frequency based on the terminal specification from among these.

FIG. 4 is a circuit diagram showing an example of the billing signal sending circuit 4.

[0007] The billing signal sending circuit 4 includes a billing signal oscillator 4
1, a transformer-coupled charging signal transmitter 42, and an LC filter 43.

The exchange 3 sends a charging signal transmission control signal CC
Is input to the charging signal transmitter 42, the charging signal output from the charging signal oscillator 41 is transmitted to the public terminal 2. The LC filter 43 inserted in the series in the voice line is a low-pass filter for preventing the charging signal from being transmitted to the called party at the time of transmission and being heard as noise.

[0009]

The conventional billing signal transmission system described above has a transformer-coupled billing signal transmitter composed of discrete components such as coils and capacitors, and an LC filter, and requires a large amount of hardware. There was a disadvantage. Also, the LC inserted in the series to the voice line
There is a drawback that the filter affects the call loss and the ringing margin, thereby deteriorating the call quality.

[0010]

According to the billing signal transmission system of the present invention, a subscriber circuit includes a codec circuit for PCM encoding a speech signal and decoding the PCM code into a speech signal.
PCM that switches M code by PCM switch
In a charging signal transmission method for a public terminal of a time-sharing electronic exchange, a charging signal of a predetermined frequency is transmitted to a PC by a charging signal transmission control signal for controlling transmission of a charging signal.
Comprising a PCM charging signal oscillator generates a PCM charging signal M coding to input the PCM charging signal to the PCM code input terminal is the receiving side of the codec circuit, wherein
A codec circuit transmits the PCM billing signal to the receiving terminal.
And a band-pass filter for passing the signal .

[0011]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a billing signal transmission system according to the present invention.

As shown in FIG. 1, the billing signal transmission system according to the present embodiment includes an exchange 1 of a PCM time division system and a public terminal 2.

The exchange 1 includes subscriber circuits 11, 15 and P
It comprises a PCM billing signal sending circuit 12 having a CM billing signal oscillator 121, a time switch 13, and a control device 14.

The PCM billing signal oscillator 121 has a billing signal frequency of 12 KHz, 16 KHz, or 12 KH.
PCM which is a PCM-converted burst signal of a frequency set for each terminal specification, out of a mixture of z and 16 KHz
A billing signal CP is generated. The output of the PCM billing signal CP is input to a PCM code input terminal TRX on the receiving side of the codec 112 of the subscriber circuit 11.

The subscriber circuit 11 includes a hybrid circuit 11
1, a codec 112, and a call current supply circuit 113.

Next, the operation of this embodiment will be described.

When the user of the public terminal 2 that is the calling party calls the called party and the call is connected and the call is started, a supervisory signal is generated from the subscriber circuit 11 of the exchange 1. The control device 14 of the exchange 1 counts the duration of the monitoring signal and the charging rate corresponding to the duration and the communication distance.

Each time the duration of the monitoring signal reaches 1 minute, 2 minutes or 3 minutes, for example, every one minute, two minutes or three minutes, the control unit 14 controls the monitoring signal according to the counted billing frequency. A second billing transmission control signal CC is transmitted. The billing transmission control signal CC activates the PCM billing signal transmission circuit 12, and the PCM billing signal CP for about one second is input from the PCM billing signal oscillator 121 to the PCM code input terminal TRX of the codec 112 of the subscriber circuit 11. You. The codec 112 decodes the PCM billing signal CP and sends the billing signal decoded into an analog signal to the public terminal 2 as an output of the subscriber circuit 11. The public terminal 2 receives the billing signal and stores the inserted coin in the storage box.

Here, the charging side of the hybrid circuit 111 of the subscriber circuit 11 is applied to the transmitter side of the hybrid circuit 111 by applying a billing signal outside the audio frequency band.
Generation of a reflected wave due to the return loss characteristic of 1 is expected. However, by selecting an optimal balancing network, this can be suppressed, and the influence on the called party can be minimized.

The level of the PCM billing signal CP may be set according to the loss characteristics of the codec 112 and the hybrid circuit 111 and the specifications of the public terminal 2.

FIG. 2 is a block diagram showing an example of the codec 112. The codec 112 has a basic configuration of a PCM codec that encodes and decodes an audio frequency domain.
D converter 21, D / A converter 22, band-pass filters 23 and 25, low-pass filter 24, and OR circuit 2
6 and a control unit 27. The present embodiment is characterized in that a band pass filter 25 for passing the charge signals of 12 KHz and 16 KHz is provided. Further, the D / A converter 22 can deal with not only the voice band but also the PCM code of 16 kHz which is the highest frequency of the billing signal.

Thus, the PCM audio signal input to the PCM code input terminal TRX on the receiving side of the codec 112 passes through the low-pass filter 24, and the PCM billing signal CP passes through the band-pass filter 25. D
The signal is input to the / A converter 22, D / A converted, and transmitted to the public terminal 2.

The PCM billing signal oscillator 121 provided in the PCM billing signal sending circuit 12 can be constituted by a digital circuit.
And a one-chip LSI integrated with it.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made.

For example, although the embodiment has been described as including a PCM charging signal transmission circuit for each subscriber circuit, this circuit is provided with one PCM charging signal transmission circuit for a plurality of subscriber circuits and a digital switch. It is needless to say that switching control by a circuit can be applied without departing from the gist of the present invention.

[0027]

As described above, the billing signal transmission system according to the present invention employs a PC that generates a PCM-coded billing signal.
An M billing signal oscillator is provided, and the PCM billing signal is input to a PCM code input terminal on the receiving side of the codec circuit and decoded by the codec to transmit the billing signal. The configuration has an effect that the LSI can be easily formed, and the amount of hardware can be greatly reduced. In addition, since it is not necessary to provide an LC filter for suppressing a billing signal inserted in a series in a voice line, there is an effect that deterioration of speech quality does not occur.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a billing signal transmission system according to the present invention.

FIG. 2 is a block diagram illustrating an example of a codec illustrated in FIG. 1;

FIG. 3 is a block diagram showing an example of a conventional billing signal transmission system.

FIG. 4 is a block diagram illustrating an example of a charging signal transmission circuit illustrated in FIG. 3;

[Explanation of symbols]

 1,3 exchange 2 public terminal 4 charging signal transmission circuit 11,15,16 subscriber circuit 12 PCM charging signal transmission circuit 13 time switch 14,31 controller 21 A / D converter 22 D / A converter 23,25 Band-pass filter 24 Low-pass filter 26 OR circuit 27 Control unit 41 Billing signal oscillator 42 Billing signal transmitter 43 LC filter 111 Hybrid circuit 112 Codec 113 Communication current supply circuit

Claims (1)

(57) [Claims] A subscriber circuit has a codec circuit for PCM encoding an audio signal and decoding the PCM code into an audio signal, and has a codec circuit for switching the PCM code by a PCM switch. In the billing signal transmission method, PCM encoding of a billing signal of a predetermined frequency by a billing signal transmission control signal for controlling billing signal transmission is performed.
Comprising a PCM charging signal oscillator generates a CM metering signal inputs the PCM charging signal to the PCM code input terminal is the receiving side of the codec circuit, the codec circuit, the PCM Division to the reception side terminal
Charging signal sending method characterized by Rukoto includes a bandpass filter for passing gold signal.