JPH03234155A - Network controller - Google Patents

Abstract

PURPOSE:To eliminate the need for an exclusive tone signal detection circuit, to suppress the increase in number of components, to improve the reliability and to reduce the cost by sending a tone signal sent from a communication circuit network in the standby mode to a signal transmission reception circuit via a spike noise suppression circuit, and detecting the tone signal therein. CONSTITUTION:A spike noise suppression circuit 4 consists of a series circuit comprising a resistor and a capacitor and a signal transmission reception circuit 6 in the standby mode connects to communication circuit networks L1, L2 via the spike noise suppression circuit 4 and the tone signal is reached to the signal transmission reception circuit 6 through the spike noise suppression circuit 4 and detected therein. Thus, it is not required to separately provide an exclusive use tone signal detection circuit for the detection of the tone signal sent to the signal transmission reception circuit 6 in the standby mode by having only to select the capacitance of the capacitor of the spike noise suppression circuit 4 while taking the frequency of the tone signal sent from the communication circuit networks L1, L2 in the standby mode. Thus, provision of detection circuits in duplicate is avoided, increase in the number of components is suppressed, the reliability is improved and the cost is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a network control device (for public communication lines (telephone lines)).
NCU: Network Control Uni
Specifically, the present invention relates to an improvement in a detection method for a tone signal sent from a communication circuit network (office line) during a so-called standby period when a line is not acquired.

"Prior Art" The network control device is installed between the data equipment and the communication circuit network when performing data communication using a public communication line, and controls the connection of the switching network (starting up the central office switch).・Recovery, sending selection signals, detecting calling signals, etc.)

Such network control equipment may be required to have a function to detect tone signals of a specific frequency sent from the communication network during the so-called standby period when the line is not captured. This problem has been dealt with by constructing a circuit as shown in FIG.

The network control device shown in FIG. 2 is for facsimile/millimeter devices, and in the figure, LAI and LA2 are terminals to which telephones are connected, and Ll and L2 are terminals to which a communication network is connected.

The aforementioned terminals LAI and LA2 are connected to a tone signal detection circuit 8 and a bell signal detection circuit 9 so as to be connected in parallel with the telephone set.
are connected. These circuits 8 and 9 are dedicated circuits for detecting tone signals and hell signals sent from the communication network during standby.

On the other hand, the above-mentioned terminals Ll and L2 are connected to the first switch 7,
a second switch 10, a spike noise suppression circuit 11,
A DC/AC separation circuit 12 and a signal transmission/reception circuit 13 are connected in this order.

Here, the first switch 7 is a two-contact type that serves as a connection switch for connecting and disconnecting the telephone to the communication network, and when the contact is connected to the a side, ,
Cutting off the connection between the signal transmitting and receiving circuit 13 side and the communication circuit network,
When the telephone is connected to the communication network and the contact is connected to side b, the connection between the telephone and the communication network is cut off, and the signal transmitting/receiving circuit 13 side is connected to the communication network. .

In addition, the second switch 10 is a one-contact type that sends out a selection signal using a dial pulse when opened and closed, and the spike noise suppression circuit [1] is a spike noise that is generated when the second switch 10 sends out a selection signal. This is a circuit that suppresses

Further, the DC/AC separation circuit 12 cuts the DC voltage supplied from the communication circuit network and sends only the AC signal necessary for communication to the receiving section of the signal transmitting/receiving circuit 13, or vice versa. The transmission signal (AC signal) formed by the transmitter is superimposed on a DC voltage and sent to the communication network.

As described above, the signal transmitting/receiving circuit 13 includes a transmitter and a receiver for alternating current signals necessary for communication.

Now, in such a conventional device, when on standby, the telephone side is connected to the communication circuit network by connecting the contact of the first switch 7 to side a, and when on standby, the telephone side is connected to the communication circuit network. The incoming tone signal or hell signal is detected by the circuit 8 or 9.

During communication when the line is captured, by connecting the contact of the first switch 7 to the b side, the telephone set and the tone detection circuit 8. Each of the bell signal detection circuits 9 is disconnected from the communication circuit network, and the signal transmitting/receiving circuit 13 side is connected to the communication circuit network instead, and the second switch 10 is opened and closed as appropriate to make the selections necessary for facsimile communication. It enables the transmission of signals (signals indicating dial numbers) and the transmission and reception of procedure signals and image signals.

[Problems to be Solved by the Invention] Normally, the signal transmitting/receiving circuit 13 in a network control device has the ability to detect tone signals.

Therefore, providing a dedicated tone signal detection circuit 8 for detecting tone signals during standby would result in duplication of circuits with the same function, resulting in an increase in the number of parts and a decrease in reliability. This was one of the causes of problems such as high prices and high prices.

The present invention has been made in view of the above-mentioned circumstances, and there is no need to provide a dedicated tone signal detection circuit for detecting tone signals sent from a communication network during standby. It is an object of the present invention to provide a network control device that can avoid duplication of circuits, suppress an increase in the number of parts, improve reliability, and reduce costs.

[Means for Solving the Problems] A network control device according to the present invention includes a signal transmitting/receiving circuit that has a tone signal detection function and transmits/receives an alternating current signal, and a signal transmitting/receiving circuit interposed between the signal transmitting/receiving circuit and a communication circuit network. a switch used to send out a selection signal; a spike noise suppression circuit for suppressing spike noise generated when the switch sends out a selection signal; It is equipped with a switch that connects to the circuit network. Here, the spike noise suppression circuit is constituted by a series circuit of a resistor and a capacitor.

and, during the standby state, is connected to a communication network via the signal transmitting/receiving circuit or the spike noise suppressing circuit,
The tone signal sent from the communication network during the standby period reaches the signal transmitting/receiving circuit through the spike noise suppression circuit and is detected by the signal transmitting/receiving circuit.

[Function] The capacitor, which is a component of the spike noise suppression circuit, has the characteristic of canting a DC signal or allowing an AC signal of a specific frequency corresponding to its capacitance to pass.

Therefore, in the network control device of the present invention configured to connect the signal transmitting/receiving circuit to the communication network via the spike noise suppression circuit during standby, the frequency of the tone signal sent from the communication network during standby is taken into account. By simply selecting the capacitance of the capacitor of the spike noise suppression circuit, the tone signal sent from the communication network during standby can be made to reach the signal transmission/reception circuit, and a dedicated tone signal detection circuit can be installed separately. Even if it is not equipped, the tone signal sent during standby can be detected by the signal transmitting/receiving circuit.

Therefore, duplication of tone signal detection circuits can be avoided, an increase in the number of parts can be suppressed, and reliability can be improved and costs can be reduced.

Embodiment FIG. 1 is a block diagram of an embodiment of a network control device according to the present invention.

The network control device of this embodiment is for Fakunmi+) equipment, and in FIG. 1, LAI and LA2 are terminals to which a telephone is connected, and LL and L2 are terminals to which a communication circuit network is connected. .

A bell signal detection circuit 2, which is a dedicated circuit for detecting a bell signal sent from the communication network during standby, is connected to the terminals LAI and LA2 so as to be connected in parallel with the telephone set. .

Further, the connection of the telephone set and the bell signal detection circuit 2 to the communication network (office line) is controlled by the first switch 1.

Here, the first switch 1 is an L contact type that opens and closes the signal path ρ1 connecting the terminal LAI and the terminal L1,
When the contacts are closed, the telephone is connected to the communication network; when the contacts are opened, the telephone is disconnected from the communication network.

That is, this first switch 1 is used only to switch the connection relationship between the telephone side and the communication circuit network, and is not a circuit that is involved in the connection relationship between the communication circuit network and the signal transmitting/receiving circuit side described later. It is said to be composed of

On the other hand, the above-mentioned terminals Ll and L2 are connected to the second switch 3,
A spike noise suppression circuit 4, a DC/AC separation circuit 5, and a signal transmission/reception circuit 6 are connected in this order.

Here, the second switch 3 is of a one-contact type that sends out a selection signal using a dial pulse when opened or closed.

The spike noise suppression circuit 4 is a circuit that suppresses spike noise generated when the second switch 3 sends out a selection signal, and as shown in FIG.
It consists of a series circuit with.

Capacitor C has a characteristic of cutting DC signals or passing AC signals of a specific frequency according to its capacitance. The capacitance is set so that an incoming tone signal of a specific frequency can be passed to the signal transmitting/receiving circuit 6 side.

Further, the DC/AC separation circuit 5 cuts the DC voltage supplied from the communication circuit network and sends only the AC signal necessary for communication to the receiving section of the signal transmitting/receiving circuit 6, or vice versa. The transmission signal (AC signal) formed by the transmitter is superimposed on a DC voltage and sent to the communication network.

As mentioned above, the signal transmitting/receiving circuit 6 is equipped with a transmitter and a receiver for alternating current signals necessary for communication, and also has a tone signal detection function.

Now, in the network control device of this embodiment, during standby when the line is not captured, the contacts of the first switch 1 are kept closed, and the contacts of the second switch 3 are kept open. Keep it.

In such a standby state where the circuit is connected, either the telephone side or the
The signal transmitting/receiving circuit 6 side is connected to the communication network via the switch 1, and the signal transmitting/receiving circuit 6 side is also connected to the communication network via the spike noise suppression circuit 4.

Here, the capacitor C of the spike noise suppression circuit 4 is
is set in consideration of the frequency of the tone signal sent from the communication network during standby, and the tone signal sent from the communication network during standby is transmitted and received through the capacitor C of the spike noise suppression circuit 4. Since the signal reaches the circuit 6, the signal transmitting/receiving circuit 6 detects it.

Note that the bell signal sent from the communication network during standby is detected by the bell signal detection circuit 2 connected in parallel to the telephone, as in the conventional case.

When the line is captured for communication, the telephone set and the bell signal detection circuit 2 are each disconnected from the communication network by opening the contacts of the first switch 1. Then, as appropriate, the second
The switch 3 is opened and closed to enable transmission of selection signals necessary for facsimile communication and transmission and reception of procedure signals and image signals.

In addition, when sending out the selection signal by a dial pulse, the 2nd switch 3 is closed first, the 1st switch 1 is opened, and the switch 3 is opened and closed.

Furthermore, when transmitting and receiving signals such as tone signals, the switch 1 is opened and the switch 3 is closed.

In the above embodiment, when compared with a conventional network control device,
The tone signal sent from the communication network during standby can be detected by the signal transmitting/receiving circuit 6, and there is no need to separately provide a dedicated tone signal detecting circuit.

Therefore, duplication of tone signal detection circuits can be avoided, an increase in the number of parts can be suppressed, and reliability can be improved and costs can be reduced.

In addition, in the circuit configuration of one embodiment, the first switch 1 that controls the connection relationship between the telephone and the communication circuit network needs only one contact, which simplifies the structure of the switch used and reduces the cost. It can also be promoted.

Note that the network control device according to the present invention is not limited to one for facsimile machines, but can be applied to various data communication devices that use public communication lines, such as modems for personal computer communication, for example.

[Effects of the Invention] As is clear from the above description, in the network control device according to the present invention, the tone signal sent from the communication network during standby is transmitted using a capacitor that is a component of the spike noise suppression circuit. The signal reaches the signal transmitting/receiving circuit and is detected by the signal transmitting/receiving circuit.

Therefore, there is no need to separately equip a dedicated tone signal detection circuit for detecting tone signals sent from the communication network during standby, and it is possible to avoid duplication of tone signal detection circuits. , suppressing the increase in the number of parts,
It is possible to improve reliability and reduce costs.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a conventional network control device, and FIG. 3 is a block diagram showing the configuration of a conventional network control device.
The figure is an explanatory diagram of the configuration of the main part of the above-mentioned embodiment. 1...First switch, 2...Bell signal detection circuit, 3...Second switch, 4...
・Spike noise suppression circuit, 5...DC/AC separation circuit, 6...Signal transmission/reception circuit, R...
...Resistance, C...Capacitor.

Claims (1)

[Scope of Claims] A signal transmitting/receiving circuit having a tone signal detection function and transmitting and receiving AC signals, and a switch interposed between the signal transmitting/receiving circuit and a communication circuit network and used for transmitting a selection signal. and a spike noise suppression circuit for suppressing spike noise generated when the selection signal is sent by the switch, and a switch for connecting the telephone to the communication network during standby when the line is not captured. A network control device comprising:
The spike noise suppression circuit is configured with a series circuit of a resistor and a capacitor, and has a circuit configuration in which the signal transmission/reception circuit is connected to a communication network via the spike noise suppression circuit during the standby period. A network control device characterized in that a tone signal sent from a circuit network reaches the signal transmitting/receiving circuit through the spike noise suppression circuit and is detected by the signal transmitting/receiving circuit.