JPH0683249B2 - Modem pool response return method - Google Patents

Description

DETAILED DESCRIPTION [Outline] In a digital exchange equipped with a modem pool, when a data terminal device connected to a digital line makes an outgoing connection to a data terminal device connected to an analog line through the modem pool, A 2100 Hz signal or a carrier detection signal returned from a data terminal device on the call side is detected by a modem pool, and a response signal is returned to the data terminal device on the call side, thereby making it possible to reliably notify the communication start time.

[Industrial application field]

The present invention relates to a digital exchange having a modem pool for connecting a data terminal device connected to a digital line and a data terminal device connected to an analog line. The present invention relates to a modem pool response returning method that can surely transmit a response of a called data terminal device to a calling data terminal device when an outgoing connection is made to the terminal device.

[Conventional technology]

FIG. 2 is a diagram showing an example of a conventional modem pool response returning method.

In FIG. 2, a data terminal device 2 is connected to a digital subscriber line 4 via a digital interface device (DIF) 3, and a data terminal device 8 is dedicated to an analog format via a modulator / demodulator device (MD) 7. It is housed in a switching network (TN) 6, and the digital switching system 1 is connected to the dedicated switching network 6 via an analog dedicated line 5.

The data terminal devices 2 and 8 each transmit and receive a data signal of 2.4 kilobits per second.

Further, it is assumed that the digital subscriber line 4 and the communication network (NW) 12 of the digital exchange 1 transmit a digital signal of 64 kilobits per second.

The digital interface device 3 is the data terminal device 2.
Divides the data signals transmitted by the
An 8-bit envelope is formed by adding a bit synchronization bit and a signal bit, and the envelope is repeatedly transmitted 20 times to convert it to a digital signal of 64 kilobits per second and send it to the digital subscriber line 4. Further, the digital interface device 3 inversely converts the digital signal of 64 kilobits per second arriving from the digital subscriber line 4 into the data signal of 2.4 kilobits per second by the reverse procedure described above and transmits it to the data terminal device 2. The signal bit is used for transmitting the transmission request signal RS after entering the data communication phase.

The modulation / demodulation device 7 transmits a modulated wave in an analog format, which is a carrier wave in the voice band, to the dedicated exchange network 6 by the data signal transmitted from the data terminal device 8 as is well known, and receives it from the dedicated exchange network 6. The wave is demodulated into a data signal and transmitted to the data terminal device 8.

Further, the digital exchange 1 is provided with a modem pool (MP) 15 in order to enable communication between the data terminal device 2 transmitting / receiving a digital signal and the data terminal device 8 transmitting / receiving a modulated wave.

The modem pool 15 includes a modulator / demodulator (MD) 152 having a function equivalent to that of the modulator / demodulator 7, a digital interface unit (DI) 151 for connecting a data signal transmitting / receiving terminal of the modulator / demodulator 152 to the communication network 12, and a modulator / demodulator 152. Of the analog interface (A
I) 153 and.

Now, the data terminal device 2 makes a call to the data terminal device 8,
When the calling number for the leased line 5 (for example, "7") and the subscriber number for the data terminal device 8 for the dedicated switching network 6 (for example, 77-1111) are sent, the central controller (CC) 13 of the digital exchange 1 Dedicated line calling number "7" transmitted via the digital interface device 3, digital subscriber line 4 and digital subscriber circuit (DLC) 11
And determines that it is necessary to connect via the modem pool 15, selects and seizes the vacant leased line trunk (PVT) 14 and puts it in the outgoing state to the leased line 5, and the subscriber number of the data terminal device 8 "77-1111" is sent to the private switched network 6 via the private line 5, while the empty modem pool 15 is selected / captured, the communication paths p1 and p2 are set in the communication network 12, and the modem pool is set. Connect 15 to digital subscriber line 4 and leased line 5.

When the private switching network 6 calls the data terminal equipment 8 and when the data terminal equipment 8 responds, it sends back a reply signal to the private line 5 and the central control unit 13 detects the reply signal via the private line trunk 14 A response signal is returned to the data terminal device 2 via the subscriber circuit 11, the digital subscriber line 4 and the digital interface device 3, and the response of the data terminal device 8 is sent to the lamp or the display provided in the data terminal device 2. Display it. The data terminal device 2 that has received the response signal starts data communication with the data terminal device 8.

When the called data terminal device responds, the dedicated switching network 6 does not return a response signal to the leased line 5 due to the signal format, that is, the leased line does not have a control channel capable of returning a response signal only through the communication channel. In the case of a configuration, the central control unit 13
Has already been detected when analyzing the leased line calling number 7,
The central control unit is from the leased line trunk 14 to the data terminal unit 8
After the subscriber number has been transmitted, the time counting section (TM) 131 starts time measurement, and when the elapse of a predetermined time is detected, the digital subscriber circuit 11 and the digital subscriber line 4 are detected.
Also, the response signal is forcibly returned to the data terminal device 2 via the digital interface device 3.

In this way, in the configuration in which the dedicated switching network 6 does not return the response signal to the dedicated line 5 in the signal format, even when the called data terminal device 8 is connected to another terminal and is in use, the signal in use is not returned. Therefore, the data terminal device 2 receiving the response signal,
Data communication is started as described above, but the data terminal device 8
It is also assumed that the private switched network 6 has not completed the connection between the private line 5 and the data terminal device 8 because it is in use, etc., and despite the compulsory response signal being returned from the central control device. There is also a risk that data communication will be impossible.

[Problems to be solved by the invention]

As is clear from the above description, in the conventional modem pool response return method, when the digital exchange 1 sets up a connection via the modem pool 15, a predetermined time elapses if the response signal is not returned from the called side. After that, the response signal was forcibly returned to the calling side.

Therefore, even if the calling side receives the response signal, the data communication may not be surely executed, and the serviceability may be deteriorated.

On the other hand, even if the response signal is not returned to the leased line due to the signal format, when the called data terminal device 8 responds, the terminal side modulation / demodulation device 7 uses the half-duplex communication method for a certain period of 2100.
The Hz signal, or in the case of the full-duplex communication system, the carrier wave is transmitted to the modulation / demodulation device 152 via the call channel of the leased line 5, the leased line trunk 14 and the speech network 12, and can be detected by the device 152. However, the central control unit of the digital exchange can detect the control signal via the control channel in the signal format, but cannot detect the 2100 Hz signal or the carrier wave via the communication channel. No response could be detected.

[Means for solving problems]

According to the present invention, the above-mentioned problem is that the calling side data terminal equipment connected to the digital line is connected to the modem pool via the digital subscriber circuit and the communication network in the digital exchange controlled by the central control unit. In the configuration in which the modem pool is provided with a response detecting means in addition to the modulation / demodulation device, in the configuration in which it is connected to the called data terminal device via the communication network, the leased line trunk, the analog line and the terminal side modulation / demodulation device. When the device responds, for example, when a modem pool modulator / demodulator receives a 2100 Hz signal or carrier transmitted from the terminal modulator / demodulator via an analog communication channel, the modulator / demodulator generates a data set ready signal DR or carrier detection signal CD. When the response detection means detects this, the response signal is transmitted to the central control device, and the central control device This is solved by a modem pool response returning system characterized in that a response signal is transmitted to a data terminal device on the calling side through a control line and a digital subscriber circuit.

[Action]

The data set ready to be sent when the data terminal equipment on the calling side controls transmission to the data terminal equipment on the called side via the modem pool, and when the modem device in the modem pool receives the 2100 Hz signal returned from the modem device on the terminal side. When the response detection means detects either the signal DR or the carrier detection signal CD sent when the modulation / demodulation equipment receives the carrier wave returned from the terminal side modulation / demodulation equipment, the response detection means sends the response signal to the central control unit. To do.

As a result, the central control unit returns a response signal to the calling data terminal unit via the control line and the digital subscriber line.

Therefore, the fact that the called data terminal device has actually responded is transmitted to the calling data terminal device that has received the response signal, data communication can be started, and the serviceability is improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a modem pool response returning method according to an embodiment of the present invention. The same reference numerals denote the same objects throughout the drawings.

In FIG. 1, a modem pool (MP) 15 according to the present invention.
Inside the modulation / demodulation device 152, a response detection means (CTL) 154 is provided.

In FIG. 1, the data terminal device 2 is a data terminal device 8
To the dedicated switching line ("7") and the subscriber number (77-1111) of the data terminal equipment 8 to the dedicated switching network (TN) 6, the central control unit of the digital exchange 1 ( The CC) 13 selects and seizes the vacant private trunk (PVT) 14 as in the above to put it in the calling state to the leased line 5, and the subscriber number “77-1111” via the leased line 5 to the dedicated switching network. 6), selects / captures an empty modem pool 15, sets call paths p1 and p2 in the call path network (NW) 12, and connects the modem pool 15 to the digital subscriber line 4 and the leased line 5. .

When the dedicated switching network 6 calls the data terminal device 8 and the data terminal device 8 responds, if the modulation / demodulation device (MD) 7 is a half-duplex communication system, a predetermined frequency (for example, 2100
(Hertz) response signal sound is returned, and if the modulation / demodulation device 7 is a full-duplex communication system, the carrier wave is started to be returned.

The 2100Hz signal or carrier wave is sent to the dedicated switching network 6, dedicated line 5,
It is transmitted to the modulator / demodulator (MD) 152 via the leased line trunk 14, the speech path p1 in the speech network 12, and the analog interface section (AI) 153 in the modem pool 15.

The modulation / demodulation device 152 that has received the 2100 Hz signal is
The data set ready signal DR returned to 54 is changed from the logic "0" to the logic "1", and the modem 15 which has received the carrier wave
2 changes the carrier detection signal CD returned to the response detection means 154 from logic "0" to logic "1".

When the response detection means 154 receives either the data set ready signal DR or the carrier detection signal CD, it transmits a response signal to the central controller 13.

The central control unit 13 to which the response signal is transmitted from the response detection means 154, the control line, the digital subscriber circuit (DL
C) 11, a response signal is sent back to the data terminal device 2 via the digital subscriber line 4 and the digital interface device (DIF) 3, and the opposite data terminal device 8 is displayed on the lamp or display provided in the data terminal device 2. Display the response. Data terminal device 2 that received the response signal
Starts data communication with the data terminal device 8.

As is clear from the above description, according to the present embodiment, when the data terminal device 8 responds, the modulation / demodulation device 7 returns it.
The response detecting means 154 detects that the modem device 152 has received the 00 Hz signal or carrier wave, and transmits a response signal to the central control unit 13, and the central control unit transmits the response signal via the control line and the digital subscriber circuit 11. Since it is returned to the device 2, the data terminal device 2 that has received the response signal can reliably start data communication with the data terminal device 8.

It is to be noted that FIG. 2 is merely an embodiment of the present invention, and the called data terminal device 8 is not limited to being accommodated in the dedicated switching network 6, and many other modifications are possible. Although considered, the effect of the present invention does not change in any case.

〔The invention's effect〕

As described above, according to the present invention, in the digital exchange, the calling-side data terminal device that has received the response signal is surely notified that the called-side data terminal device has actually responded, and the certainty Data communication can be started, improving serviceability.

[Brief description of drawings]

FIG. 1 is a diagram showing a modem pool response returning system according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a conventional modem pool response returning system. In the figure, 1 is a digital exchange, 2 and 8 are data terminal equipment, 3 is a digital interface equipment (DI
F), 4 is a digital subscriber line, 5 is a dedicated line, 6 is a dedicated switching network (TN), 7 and 152 are modulators / demodulators (MD), 11 is a digital subscriber circuit (DLC), and 12 is a channel network ( NW), 1
3 is the central control unit (CC), 14 is the private line trunk (PVT),
Reference numeral 15 is a modem pool (MP), 131 is a time limit unit (TM), 151 is a digital interface unit (DI), 153 is an analog interface unit (AI), and 154 is a response detecting means (CTL).

Claims (1)

[Claims] 1. A calling side data terminal device connected to a digital line is connected to a modem pool via a digital subscriber circuit and a communication line network in a digital exchange controlled by a central control unit, and the communication line network is connected from the modem pool. , A leased line trunk, an analog line and a terminal side modulator / demodulator connected to the called side data terminal device, the modem pool is provided with a response detecting means in addition to the modulator / demodulator
When the data terminal device on the called side responds, the data is transmitted from the modem device on the terminal side through the analog communication channel.
When the modem pool modulator / demodulator receives the 2100 Hz signal or carrier wave, the modulator / demodulator generates a data set ready signal DR or carrier detect signal CD, and when the response detecting means detects this, it transmits the response signal to the central controller, The control device sends a response signal to the data terminal device on the calling side through a control line and a digital subscriber circuit.