JPH0371833B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a videotex terminal control device.

(Prior art) The Videotex communication network, which transmits image information in response to requests from an information center to subscriber terminals via the public telephone network, currently has two types of user terminals: dedicated user terminals and general-purpose user terminals. Various types of terminal devices are available.
The former connects a dedicated terminal to the subscriber line from the network central office to the telephone, while the latter connects a general-purpose processing device, such as a personal computer, to the subscriber line via a videotex adapter. It is something to do. The latter include those to which a telephone is connected separately and those that have a built-in telephone function.

Conventional general-purpose terminals include those described in "Captain Adapter PC-CM301 for Personal Computers," NEC Technical Report, Vol. 38, No. 5, pp. 96-100 (1985). However, in conventional devices, all connections to the telephone network and videotex communication network and switching from a telephone to a terminal device were performed manually.

For example, as shown in Figure 5, when the calling subscriber dials the special identification code ``166'' of the Videotex network from a telephone and receives a second dial tone (SDT) from the central office of the telephone network, the calling subscriber hears this on the telephone. Listen to the information on your device and dial the information center number or service identification code "112". Further, when a videotex switching instruction signal is subsequently received from the videotex communications network (VCP), the originating subscriber hears and operates the videotex button on the videotex terminal. Then the data terminal (DTE)
You can then manually switch the connection and receive video text services from then on. During this time, if the subscriber encounters a busy call, he or she hears the busy tone and performs a recovery operation. Operation points where such manual operations are performed are indicated by ★ in FIG.

(Problems to be Solved by the Invention) In such conventional videotex terminal devices, connection and switching between the telephone network and the videotex communication network depends on the user's manual operations and the audibility of various signal tones. ing. Therefore, there is a heavy operational burden on the user until the videotex start screen is received from the videotex communication network.
Another problem was that the waiting time for this was long.

The present invention solves these drawbacks of the prior art,
It is an object of the present invention to provide a videotex terminal control device that can reduce the user's operational load and reduce waiting time.

(Means for Solving the Problems) According to the present invention, a videotext system connected between a subscriber line of a switching network and a data terminal equipment, and controlling a videotext connection to the data terminal equipment via the switching network. The terminal control device includes a signal tone identifying means for identifying a signal tone received from the subscriber line, and a connection control means for controlling the connection between the subscriber line and the data terminal device in response to the signal tone identifying means. have

(Function) According to the present invention, the signal tone identification means, for example,
Identifying dial tones for videotex connections, busy tones, and instruction signals for connecting to data terminal equipment received from subscriber lines. The connection control means requests video text service from the switching network when a dial tone is detected, restores the connection to the switching network when a busy tone is detected, and restores the connection to the switching network when an instruction signal is detected. connect to the switching network.

(Embodiment) Next, an embodiment of the videotex terminal control device according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2, in a typical videotex system configuration, a videotex communication network 12 housing an information center 10 that provides videotex information is connected to a subscriber telephone network 14; Videotex terminals 18 and 20 are available, connected via public line 16.

The videotex terminal device 18 is a dedicated use terminal, and is connected to the subscriber line 16 along with a telephone set 22. On the other hand, the videotex terminal device 20
is a general-purpose user terminal, such as a data terminal equipment (DTE) 24 such as a personal computer.
is connected to the subscriber line 16 via a videotex adapter or videotex terminal controller 26. In this embodiment, the adapter 26 has a built-in telephone function. Note that the telephone function is indicated by the dotted line 28.
As shown in , it may take the form of a normal subscriber premises device independent of the data terminal device 24.

The videotex adapter 26 has an automatic calling function to which the present invention is applied, and includes an adapter function section 50 that realizes various functions such as communication protocol conversion, modem, line switching, and interface with the data terminal device 24. have In this embodiment, this means detecting various tones received from the central office of the telephone network 14 at each stage of the outgoing connection, such as a second dial tone, a busy tone, and a videotext switching indication signal. It also has an automatic signal tone detection function that clearly identifies the signal.

In this embodiment, this signal tone automatic detection function is
This is realized by the tone detection section 30 and control circuit 40 shown in the figure. The tone detection section 30 includes two tone detection circuits 32 and 34 and an AND gate 3.
6 are connected as shown in the figure. Note that the adapter function section 50 is controlled by the control circuit 40.

The inputs of the tone detection circuits 32 and 34 are both connected to an input terminal 42 into which the signal arriving at the subscriber line loop 16 from the central office of the telephone network 14 is input. This signal includes various tones. For example, according to the signal tone standards used in current videotex systems, the information center 10 for videotex connections
The second dial tone (SDT), which requests an identification signal from the calling subscriber, has a frequency of 400±19Hz and an intermittent rate of 240±
The signal tone is 7.2 IPM (interruptions per minute), and the busy tone (BT) is a signal tone with a frequency of 400 ± 19 Hz and an intermittent rate of 60 ± 7.2 IPM. Further, the videotext switching instruction signal for instructing connection to the data terminal device 24 is a continuous signal with a frequency of 2100±7 Hz.

Therefore, the tone detection circuit 32 is configured to detect a signal having a frequency of 2100 Hz among the signal sound frequencies arriving at the input terminal 42 with a predetermined tolerance. Its output 38 is input to one input of AND gate 36. Also, the tone detection circuit 34
is a tone decoder circuit that detects a signal with a frequency of 400 Hz among the signal sound frequencies arriving at the input terminal 42 with a predetermined tolerance, and its output 39 is
It is input to the other input of AND gate 36.
Both detection circuits 32 and 34 are advantageously constructed of, for example, a filter circuit consisting of a resistor and a capacitor, or a digital filter. A (Tone Detect) signal as shown in FIG. 3 is output to the output 44 of the AND gate 36.

More specifically, when the tone detection circuit 34 detects the second tone, it generates a square wave (of logic levels 0 and 1) with a pulse width of 125 ms and a repetition period of 250 ms.
is output from terminal 44. When the tone detection circuit 34 detects a busy tone, a rectangular wave with a pulse width of 0.5 seconds and a repetition period of 1 second is output from the terminal 44. Similarly, when the tone detection circuit 32 detects the video text switching instruction signal, the logic level 0 continues to be output from the terminal 44.

Such detection signals are input to the control circuit 40, and the control circuit 40 identifies each signal by determining its duration. For example, the second dial tone and the busy tone are distinguished by the length of their high and low levels, and the busy tone and the video text switching instruction signal are distinguished by monitoring the level for a period of one second or more.

More specifically, control circuit 40, in this embodiment, is comprised of a processing system that periodically scans various input ports at predetermined time intervals, such as 10 millisecond intervals, to capture input information. In FIG. 1, in order to avoid complication of the drawing, portions that are not directly related to understanding the present invention are omitted from illustration and explanation thereof will be omitted.

Therefore, the control circuit 40 controls the predetermined number of times, e.g.
When it is detected that the input 44 continues to be at a high or low level for 10 to 14 scans and is alternately repeated for a minimum of 3 seconds, it is determined that the second beep has arrived. Similarly, the control circuit 40 controls the input 4 at a predetermined number of scans, e.g.
When it is detected that the high level or low level of 4 continues and is repeated alternately for a minimum of 3 seconds, it is determined that a busy tone has arrived. In addition, in the scanning of the control circuit 40, the low level of the input 44 is continuously increased by at least 2 times.
If it is detected that the signal continues for seconds, it is determined that a video text switching instruction signal has arrived.

Referring to FIG. 4, the operating procedure of the videotex user using the device of this embodiment is shown in FIG.
4, is shown in conjunction with the operation of the VideoText Communication Network (VCP) 12 and the information center 10.
Note that in the same figure, ★ marks indicate operations that were conventionally performed manually, but are automatically performed in this embodiment. An example of identification of a signal tone in automatic transmission from the videotex terminal device 20 and associated connection control operation will be described with reference to FIG. 4 and FIGS. 6A to 6D.

The calling subscriber first enters a dialing command from the data terminal 24, ie an information center number (eg 5 digits) or a service identification code (eg 3 digits). videotex adapter 26
When the control circuit 40 receives this dial command (100), it controls the adapter function section 50 to close the loop of the subscriber line 16 and waits for a dial tone (DT).

Upon receiving the dial tone, the control circuit 40 controls the adapter function section 50 to output it to the speaker (102). Therefore, the control circuit 40 controls the adapter function section 50 to dial out a special number (for example, "116") for identifying the videotex service to the subscriber line 16 (104). Therefore, in this embodiment, time monitoring for 47 seconds is started (106), and a response from the telephone network 14, that is, reception of a signal tone is waited for (108).

The control circuit 40 is connected to the input port 4 by the above-described operation.
4 and determines whether the received signal tone is a second dial tone (112), a busy tone (136), or a videotex switching instruction signal (122).

In the normal sequence, a second tone is now received. Therefore, the control circuit 40
0 and enter the number of the Videotex information center 10 or the Videotex service code "112"
is sent to the subscriber line 16 (114). In response to this, the station facilities of the electric arm network 14 establish a connection to the videotex communication network 12. Control circuit 40 now monitors the level at input port 44 and begins 47 second time monitoring 116 of signal tone detection 118.

When a connection with the information center 10 is established via the videotex communication network 12, a videotex switching instruction signal is sent back from the communication network 12 (122). When the control circuit 40 determines the arrival of the switching instruction signal as described above, the adapter function section 50
and transmits a response, that is, a connection enable signal, to the data terminal device 24 (124). Therefore, the control circuit 40 controls the adapter function section 50 to perform automatic switching such as extending the subscriber line 16 to the data terminal device 24, and sends a terminal response signal, that is, a built-in modem (Backward Request to Send).
is transmitted to the videotex communication network 12 (126), and the terminal profile is transmitted three times in succession (128).

In response, the videotex communication network 12 sends out the screen information of the start screen that had been received from the information center 10 (130), and from then on, the data terminal device 24 and the videotex communication network and information center The screen information and request signals are exchanged between the terminal and the terminal. This allows users to enjoy Videotex communication services in an interactive manner.

It should be noted that at each stage, if a busy situation occurs, the control circuit 4
0 detects a busy tone in step 136, it controls the adapter function section 50 to transmit a busy response to the data terminal device 24 (132), and the subscriber loop 1
Performs semi-normal operations such as opening 6 (134).
Also, if it is detected that the signal arriving at the line 16 does not satisfy the specified frequency range and intermittent rate,
After a predetermined time (120), the control circuit 40 similarly sends a busy response 132 and opens the loop.
134 to force a recovery.

As described above, in this embodiment, the operations from transmitting a message from the videotex terminal device to connecting to the videotex communication network and receiving the screen information of the start screen from the communication network are also automated. In other words, the special number for identifying the video text, for example the 3-digit "166".
After sending out the second dial tone or busy tone, and after sending out the information center number, for example, 5 digits or 3 digits, the video text switching instruction signal is automatically detected.

Therefore, the user can receive screen information (start screen) without manually operating the video text adapter 26. Also, the waiting time until then is minimized. Therefore, the operability of the device is improved.

If the constants of the tone detection circuits 32 and 34 and the flow control of the control circuit 40 are appropriately set, various signals other than the second dial tone, busy tone, and video text switching instruction signal, such as an answer tone, can be detected. A signal tone can be detected, for example, the adapter 26
It can be applied to various controls such as the modem, line control unit (NCU), and built-in multifunction telephone included in the device.

(Effects of the Invention) As described above, in the present invention, the operations from sending a message from the VideoTex terminal control device to connecting to the VideoTex communication network and receiving the screen information of the start screen from the communication network are also automated. Therefore, the user can receive screen information without manually operating the videotex terminal device.
Improved device operability and minimized waiting time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a functional unit that realizes the automatic signal tone detection function in an embodiment of the present invention, and FIG. 2 is a typical block diagram of a videotex system to which the videotex terminal control device according to the present invention is applied. FIG. 3 is a waveform diagram showing the waveform of the signal tone detection signal appearing in the circuit shown in FIG. 1, and FIG. 4 is a system configuration diagram showing the system configuration. FIG. Operating instructions for subscriber telephone network,
An operation flow diagram shown in relation to the operation of the Videotex communication network and information center; FIG. 5 is a flow diagram similar to FIG. 4 showing the operation procedure by a conventional device;
FIGS. 6A to 6D are flowcharts illustrating an example of identification of a signal tone in automatic transmission from a videotex terminal control device and connection control operations associated therewith. Explanation of symbols of main parts, 20...Video text terminal equipment, 24...Data terminal equipment, 26...
Video text adapter, 30... tone detection section, 32, 34... tone detection circuit, 40... control circuit.

Claims (1)

[Scope of Claims] 1. A videotex terminal control device that is connected between a subscriber line of a switching network and a data terminal device and controls a videotex connection to the data terminal device via the switching network, comprising: The device is a general-purpose data terminal device, and the videotex terminal control device includes a signal tone identifying means for identifying a signal tone received from the subscriber line, and a signal tone discriminating means for identifying a signal tone received from the subscriber line, and a signal tone discriminating means for communicating with the switching network in response to the signal tone discriminating means. After the call is connected, terminal information is sent and received to and from the switching network until the data terminal device is ready to receive image information, thereby preparing for connection between the data terminal device and the switching network. 1. A videotex terminal control device, comprising: connection control means for controlling connections. 2. The control device according to claim 1, wherein the signal tone identifying means distinguishes between a dial tone for videotex connection, a busy tone and a connection to the data terminal device received from the subscriber line. The connection control means requests video text service from the switching network when the dial tone is detected, and restores the connection to the switching network when the busy tone is detected. and when the instruction signal is detected, sends a connectable signal to the data terminal device, then sends a terminal response signal to the switching network, and further sends terminal information multiple times when a synchronization signal is received from the switching network. 1. A video-tex terminal control device for connecting said data terminal to a switching network.