JP3326846B2 - Terminal network controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal network controller connected to a telephone line and performing no-ringing reception.

[0002]

2. Description of the Related Art A conventional terminal network control device will be described with reference to FIG. Conventionally, a terminal network control device 1 that performs no-ringing communication includes a first impedance matching unit 3 connected to a telephone line 2 for forming an impedance at the time of incoming no-ringing, and an impedance matching unit connected to the telephone line 2 at the time of no-ringing communication. A second impedance matching section 4 to be formed, and a reception section connected to the first and second impedance matching sections 3 and 4 for amplifying a signal received from the telephone line 1 and passed through each impedance matching section. An amplifier unit 5, a signal receiving unit 6 for modulating an analog signal of the receiving amplifier unit 5 into a digital signal, a polarity inversion detecting unit 7 for detecting polarity inversion of the telephone line 1, a polarity inversion detecting unit 7, and signal reception The signal from the section 6 is input, the first and second impedance matching sections 3 and 4 are controlled, and the signal is output to the signal transmitting section 8. That the control unit 9
It is composed of

[0003] First, the sequence for performing no-ringing incoming call and communication will be described, and then the operation of each unit will be described. When a no-ringing incoming call is started, the polarity of the telephone line 1 is inverted, and when the terminal network control device 2 receives the polarity inversion signal, the terminal network control device 2 enters a state of receiving a no-ringing call signal (hereinafter abbreviated as an NRS signal) from the telephone line 1. enter. At this time, the termination condition of the telephone line 1 is as follows.
DC resistance 4kΩ or more, AC impedance 2kΩ or more,
And the technical standards for terminal network control devices (hereinafter referred to as
The termination condition at this time is referred to as a first termination condition.) When the terminal network control device 2 receives an NRS signal addressed to itself from the telephone line 1 in a reception standby state, the terminal network control device 2 sends a response signal (hereinafter abbreviated as an ANS signal) to the telephone line 1 in response to the NRS signal. Transmission and no-ringing termination are completed. At this time, the termination condition of the telephone line 1 is a DC resistance of 4 kΩ or more and an AC impedance of 600 Ω (hereinafter, the termination condition at this time is referred to as a second termination condition). When the no-ringing termination is completed, a no-ringing communication state is entered. At this time, the termination condition of the telephone line 1 is the same as the above-mentioned second termination condition. When communication ends,
The terminal network control device 2 opens the telephone line 1 and returns to the standby state.

[0004] Next, the operation of each unit of the terminal network control device at the time of no-ringing reception and communication will be described with reference to FIGS. 3 and 4. In FIG. 4, a first impedance matching unit 3 includes a switch SW10 for controlling connection and disconnection with the telephone line 1, and a resistor R connected in series with the switch SW10 for realizing a first termination condition.
11, a capacitor C12 and a transformer TR13. Also, the second impedance matching unit 4
SW14 for controlling connection and release with telephone line 1
And a capacitor C12 and a transformer TR13 connected in series with the switch 14 in order to realize the second termination condition. On the other hand, the receiving amplifier unit 5 includes an operational amplifier OP17 and resistors R15 and R16 for determining the gain of the receiving amplifier unit 5.

In a standby state, the control unit 9 controls the SW 10 and S
W14 is in an open state, and the telephone line 1 is in an open state without being terminated. At the time of no-ringing reception, the polarity of the telephone line 1 is inverted, and a signal notifying that the polarity inversion has occurred is output from the polarity inversion detection unit 7 to the control unit 9. Control unit 9
Controls the SW 10 in the first impedance matching unit 3 to the ON state in order to receive the NRS signal transmitted from the telephone line 1 to the terminal network control device 2 next. SW
The telephone line 1 enters the NRS signal reception waiting state in a state where the first termination condition is satisfied by the ON state of 10. When an NRS signal is sent from the telephone line 1 to the terminal network control device 2, the NRS signal is input to the receiving amplifier unit 5 via the diode bridge DB, SW10, resistor R11, capacitor C12, and transformer TR13. . The NRS signal is amplified in the receiving amplifier unit 5 and then input to the signal receiving unit 6, where the received NRS signal is converted into a digital signal. The signal output from the signal receiving unit 6 is input to the control unit 9 to determine whether the NRS signal is addressed to the own terminal. When the NRS signal is not addressed to the own terminal, the control unit 9 sets the S
W10 is turned off, telephone line 1 is opened,
The terminal network control device 2 returns to the standby state. On the other hand, when the NRS signal is addressed to itself, the control unit 9 first turns off the SW 10 to output a response signal to the telephone line 1.
Control to bring the first impedance matching section 3 into an open state. Next, the control unit 9 controls the SW 14 of the second impedance matching unit 4 to turn on to terminate the telephone line 1 under the second termination condition and form a signal output path for transmitting an ANS signal. Then, the control unit 9 outputs a command to output an ANS signal to the signal transmission unit, thereby passing through the signal transmission unit 8 and the second impedance matching unit.
An ANS signal is output to the telephone line 1. The non-ringing termination is completed by the transmission and reception of the above signal, and thereafter, the apparatus enters a no-ringing communication state. When the no-ringing communication is completed, the control unit 9 sets the S
W14 is turned off, and the telephone line 1 is opened.

The above is a description of the operation of the terminal network control device 2 when there is no ringing. There is a case where the terminal network control device 2 terminates the telephone line 1 other than at the time of no ringing incoming call, which is when an incoming call to a telephone (not shown) occurs. Hereinafter, the terminal network control device 2 at the time of incoming call
Will be described.

[0007] The no-ringing incoming call (to the terminal network control device) and the incoming call to the telephone are originally different incoming calls.
The terminal network control device 2 should not respond to an incoming call to the telephone. However, the polarity of the telephone line 1 of the incoming signal sent to the terminal network control device 2 at the time of the incoming call is inverted before the incoming signal of 75 V and 16 Hz is sent. The terminal network control device 2 performs the same control as the above-described non-ringing incoming call in order to regard the polarity inversion signal generated at the beginning of the incoming call as the polarity inversion signal of the no ringing incoming call. However, since the incoming call is not a ringing incoming call but an incoming call, the NRS signal is not sent from the telephone line 1 and the terminal network control device 2 does not output the ANS signal.

That is, when an incoming call arrives, the polarity inversion detecting unit 7 detects the polarity inversion signal at the beginning of the incoming call, and then the control unit 9 receives a signal from the polarity inversion detecting unit 7.
Controls ON of the switch SW10 of the first impedance matching unit 3, and terminates the telephone line 1 under the first termination condition.
However, since it is an incoming call, the specified time (3
Even after 50 ms), the NRS signal is not sent, and the control unit 9 opens the telephone line 1 and returns to the standby state.

[0009]

However, in the above-mentioned conventional configuration, if a call is received in a state where a plurality of terminal network controllers are connected in parallel to one telephone line, the first impedance matching unit is used as described above. Current flows from the telephone line 1 because 3 is closed. On the other hand, the exchange determines that the telephone has gone off-hook when the value of the current flowing through the telephone line is equal to or greater than a certain value. Therefore, when a terminal network control device is connected to one telephone line in parallel, the total current flowing into the first impedance matching unit of the terminal network control device increases when there is an incoming call, and the switching side In such a case, it is determined that the telephone has gone off-hook, and there is a problem that an incoming call to the telephone cannot be made.

In order to reduce the value of the current flowing from the telephone line to the terminal network control device when a telephone call arrives, so that the exchange is not determined to be off-hook, the impedance of the first impedance matching section may be increased. However,
At that time, the NRS signal at the time of no ringing arrival is attenuated by an amount corresponding to an increase in the impedance of the impedance matching unit. For this reason, the level of the NRS signal becomes too small, so that the level does not subside within the dynamic range of the signal receiving unit, and there is a problem that no ringing can be received.

[0011] The present invention solves the above problems, and when a plurality of terminal network controllers are connected to one telephone line,
It is an object of the present invention to provide a terminal network control device that can normally receive a telephone call and can also normally perform a no-ringing incoming call.

[0012]

In order to achieve the above object, a terminal network control device according to the present invention has a first impedance matching section connected to a telephone line and terminating the telephone line, and a first impedance matching section connected to the telephone line. Smaller than the impedance matching part of
A second impedance matching section for terminating the telephone line with an impedance having a small transmission loss, and a gain switching section for simultaneously terminating the telephone line with the first impedance matching section.
The gain of the received signal is increased, and the second impedance matching unit is increased.
When the telephone line is terminated , the gain switching unit switches to a small gain, a reception amplifier unit connected to the gain switching unit for amplifying a reception signal, a first impedance matching unit, and a second impedance matching unit. Either impedance matching part
And a control unit for interlocking the control of a gain switching unit that terminates only the control unit.

[0013]

According to the present invention, the first impedance matching unit controls the gain switching unit at the same time as terminating the telephone line by the first impedance matching unit having a high impedance, that is, a large transmission loss, when there is no ringing. Increase the gain of the signal received from the unit. As a result, the analog signal input from the receiving amplifier unit to the signal receiving unit has a signal level falling within the dynamic range of the signal receiving unit. On the other hand, at the time of no ringing communication, the control unit terminates the telephone line at the second impedance matching unit having low impedance and small transmission loss. When the telephone line is terminated by the second impedance matching unit,
The control unit controls the gain switching unit to switch to a smaller gain that is different from the gain at the time of no-ringing reception. As a result, the signal input from the receiving amplifier unit to the signal receiving unit has a signal level that falls within the dynamic range of the signal receiving unit.

That is, the signal input to the signal receiving unit is
Since the level is always kept at an appropriate level, the signal reception level is always kept at an appropriate level, and the impedance of the first impedance matching section can be set high, the current flowing through the telephone line at the time of an incoming call is reduced. Therefore, even when a plurality of terminal network controllers are connected, incoming calls can be normally performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2, the first impedance matching unit 3, the second impedance matching unit 4, the receiving amplifier unit 5, the signal receiving unit 6, the polarity inversion detecting unit 7, Since the signal transmission unit 8 is the same as the component of the conventional example, the description is omitted. The gain switching section 19 switches the gain depending on whether the telephone line 1 is terminated by the first impedance matching section 3 or the second impedance matching section 4, and is configured by a switch SW21 and a resistor R22. Have been. The control unit 20 receives signals from the polarity inversion detection unit 7 and the signal reception unit 6 and controls the first and second impedance matching units 3 and 4, the signal transmission unit 8, and the gain switching unit 19. I do.

Next, the operation of each unit at the time of no-ringing reception and at the time of no-ringing communication will be described with reference to FIGS. When a polarity inversion signal arrives from the telephone line 1 due to no ringing incoming, a signal is output from the polarity inversion detection unit 7 to the control unit 20. In response to this signal, the control unit 20 turns on the switch 10 of the first impedance matching unit 3 to enter the NRS reception waiting state. At the same time, the control unit 20 controls the switch SW21 of the gain switching unit 19 to be ON so as to increase the amplification factor, and the signal level input from the reception amplifier unit 5 to the signal reception unit 6 falls within the dynamic range of the signal reception unit 6. Set the appropriate gain so that it falls within the range.

When an NRS signal for a no-ringing call arrives from the telephone line 1, the signal is amplified by the receiving amplifier unit 5 via the first impedance matching unit 3 and input to the signal receiving unit 6. The NRS signal converted from the analog signal to the digital signal by the signal receiving unit 6 is transmitted to the control unit 20.
Is input to In the control unit 20, as in the conventional example, NR
When the S signal is addressed to itself, the switch SW10 of the first impedance matching unit 3 is turned off and the switch SW14 of the second impedance matching unit 4 is turned on. In addition, the control unit 20 controls the signal transmission unit 8,
An ANS signal is transmitted to the telephone line 1. further,
The control unit 20 controls the SW1 of the second impedance control unit 4
When 4 is turned on, the gain switching section 19 is also controlled, and the gain of the receiving amplifier section 5 is also reduced. Thereafter, the state shifts to the no-ringing communication state. When the communication is completed, the switch SW14 of the second impedance matching unit 4 is turned off, and the telephone line 1 is opened.

That is, when there is no ringing, the first
Even if the signal is greatly attenuated in the impedance matching unit 3, since the gain switching control is performed by the gain switching unit 19, the reception level of the NRS signal coming from the telephone line 1 is The value is within the dynamic range of the signal receiving unit 6.

When a call is received, the control unit 20 terminates the telephone line 1 at the first impedance matching unit 3 in response to an input signal from the polarity reversal detection unit 7, so that the first impedance matching unit 3 The current flows into. However, unlike the conventional example, even if the signal is attenuated at the time of no-ringing arrival, the signal level input to the signal receiving unit 6 is configured to have an appropriate value. Therefore, the impedance of the first impedance matching unit 3 is increased. be able to. Therefore, even if a plurality of terminal network control devices are connected to the telephone line, the current flowing from the line can be reduced to the extent that the exchange does not erroneously determine that the terminal is off-hook.

As is clear from this embodiment, in the terminal network control device of the present invention, when the telephone line 1 reverses the polarity, the control unit 20 terminates the telephone line 1 by the first impedance matching unit 3. Together with the gain switching unit 19
Is controlled to increase the gain of the receiving amplifier unit 5. That is,
Even if the impedance of the first impedance matching unit 3 is increased, the level of the signal input to the signal receiving unit 6 at the time of no-ringing reception falls within the dynamic range of the signal receiving unit 6, so that normal ringing-incoming reception is possible. I have. Further, since the impedance of the first impedance matching unit 3 can be increased in this manner, even when an incoming signal from the telephone line 1 to the telephone arrives, the current flowing from the telephone line 1 to the terminal network control device can be reduced. Can be suppressed. As a result, even if a plurality of terminal network controllers are connected in parallel to one telephone line, there is an effect that the exchange does not erroneously determine that the terminal is off-hook.

The circuit configuration of the present invention is not limited to the one shown in FIG.
One that controls the reception gain of the input signal is also included.

[0022]

As described above, according to the terminal network control device of the present invention, when the telephone line reverses its polarity, the control unit terminates the telephone line by the first impedance matching unit and controls the gain switching unit. Control to increase the gain of the receiving amplifier. That is, even if the impedance of the first impedance matching unit is increased, the level of the signal input to the signal receiving unit at the time of no-ringing reception falls within the dynamic range of the signal receiving unit, and normal no-ringing reception can be performed. Also, since the impedance of the first impedance matching unit can be increased in this way, even when an incoming signal from the telephone line to the telephone arrives, the current flowing from the telephone line to the terminal network control device can be suppressed to a small value. Even when a plurality of network control devices are connected in parallel to one telephone line, there is an effect that the exchange does not erroneously determine that the hook is off-hook.

[Brief description of the drawings]

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

FIG. 2 is a partial circuit diagram of the device.

FIG. 3 is a block diagram of a conventional terminal network control device.

FIG. 4 is a partial circuit diagram of the device.

[Explanation of symbols]

 3 First impedance matching section 4 Second impedance matching section 5 Reception amplifier section 19 Gain switching section 20 Control section

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masaaki Sakata 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-294664 (JP, A) JP-A-4- 61542 (JP, A)

Claims (1)

(57) [Claims] 1. A first impedance matching section connected to a telephone line and terminating the telephone line, and a transmission loss smaller than the first impedance matching section connected to the telephone line and smaller than the first impedance matching section.
Terminating the telephone line with low impedance
Terminating the telephone line with the first impedance matching unit and the gain switching unit at the same time.
The gain of the received signal is increased and the second impedance matching
A gain switching unit that switches to a small gain when the telephone line is terminated in the unit, a reception amplifier unit connected to the gain switching unit for amplifying a received signal, and the first impedance matching unit. A terminal network control device comprising: a control unit that controls the gain switching unit that terminates only one of the second impedance matching units.