JPH0630454A - Central office trunk - Google Patents

Abstract

PURPOSE:To obtain an appropriate central office trunk by compensating the transmission loss of a communication line based upon the detection result of the receiving level of a PB signal dialed-by a subscriber and compensating a transmission loss generated at the time of connecting a private communication network to a public communication network. CONSTITUTION:The public communication network(PCN) for connecting a transmitting subscriber SUB-A to a central office trunk(COT) in an exchange A is held at a talking state and a PB signal sent from the SUB.A arrives at a register sender PBRS through the same transmission line as a voice signal. Since the sending level of the PB signal sent from the SUB.A is regulated to a fixed value, the COT or the PBRS can know a transmission loss by detecting the level of the arrived PB signal. The exchange A can compensate a level drop generated at the time of connecting the SUB.A to the private communication network through the public communication network by means of the COT based upon the level of the private communication network obtained from a subscriber SUB.4 and set up the level to a level required at the time of transmission from the SUB.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trunk line trunk,
In particular, in a communication network in which a public communication network is connected to a plurality of ends of the leased line communication network and can be connected to each other, the transmission loss in the public communication network is compensated at the connection point between the leased line communication network and the public communication network. It relates to a preferred trunk line trunk to be used for.

[0002]

2. Description of the Related Art Conventionally, a connection between a private line communication network and a public communication network via a public communication network, that is, a connection of public communication network-dedicated line communication network-public communication network (hereinafter referred to as public-private public connection)
Was practically impossible due to restrictions such as laws and regulations.
However, if this restriction is released due to economic expansion and communication circumstances, it becomes possible to freely connect the private line communication network and the public communication network via the public communication network.

The above-mentioned public-private public connection is such that after connecting from the public communication network to one end of the private line communication network, the necessary number is dialed to go through the private line communication network to the other end of the private line communication network. Can be performed by connecting to the public communication network again.

[0004] Such a connection can obtain immeasurable economic effects especially to a company having an international leased line communication network.

Incidentally, as a conventional technique relating to a station line trunk usable in this type of communication network, for example, Japanese Patent Laid-Open No. 63-
The technology described in Japanese Patent Publication No. 139493 is known.

[0006]

However, in the public / private public connection according to the above-mentioned prior art, since the transmission loss in the public communication network connected to both ends of the leased line communication network is inserted between the transmitting and receiving terminals, the voice call level is low. Has a problem that it is difficult to put into practical use.

[0007] Therefore, as the use of the private connection, the public exclusive connection or the public exclusive connection for connecting the public communication network to the private line communication network as described above is expanded, the public communication network connected to the private line communication network is expanded. It is necessary to solve the problem of voice call level drop due to the transmission loss of.

It is an object of the present invention to solve the above-mentioned problems of the prior art, and to provide a preferred office line trunk to be used in such a case.

[0009]

According to the present invention, the above object is to provide a caller accommodated in a public communication network to a station line trunk provided at a connection point between the public communication network and the leased line communication network. By detecting the reception level of the PB signal dialed to connect to the leased line communication network and compensating for the transmission loss in the public communication network according to the result, the private line communication network can also be used for public communication. The connection to the network is achieved by providing a function of compensating the transmission loss in the public communication network with a constant value.

[0010]

According to the present invention, when a public communication network is connected to a leased line communication network in a station line trunk connecting the public communication network and the leased line communication network, a caller accommodated in the public communication network is connected to the leased line communication network. It is possible to detect the reception level of the PB signal dialed to connect to the network and compensate the transmission loss in the public communication network based on the result, and when connecting from the leased line communication network to the public communication network, Since the transmission loss in the public communication network can be individually compensated with a constant value, good call quality can be ensured even in the case of public / public connection.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a trunk line trunk according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a communication network to which the present invention is applied, FIG. 2 is a block diagram showing a circuit configuration of an office line trunk according to an embodiment of the present invention, and FIG. 3 is an application of the present invention. FIG. 4 is a diagram showing a level diagram between the subscribers in the case of being set, and FIG. 4 is a diagram showing a level diagram between the subscribers in the case of the conventional technique.

In FIGS. 1 and 2, SUB-A and SUB
-B is a subscriber accommodated in a public communication network, COT is a station line trunk that connects the public communication network and a leased line network, and SUB-
C, SUB / D are extension subscribers accommodated in the leased line communication network, LIF is a line trunk connecting extension subscribers of exchanges installed in the leased line communication network, SW is a switch of exchanges A and B, PBRS is , A register sender for sending and receiving PB signals, BWT for bidirectional trunks, RA and RB for relays, ra and rb for relays RA and RB contacts, DRVA,
DRVB is a relay driver, FTr is a photocoupler, Tr is a transistor, L is a coil, D1 to D6 are diodes, RD is a zener diode, C0 and C1 are capacitors, HYB is a hybrid coil, AMP0 and AM.
P1 is an amplifier and CODEC is a codec.

Generally, in a switching network for making voice calls by telephones, the transmission loss between telephones making telephone calls is two.
It is planned to be in the range of about 5 dB, and when the transmission loss reaches 30 dB, the telephone feels distant. In the leased line communication network, for example, the exchange A and the exchange B shown in FIG. 1 are configured by satellite communication lines, and the loss between the extension subscribers SUB / C and SUB / D of the leased line communication network is reduced. Is generally set to about 12 to 16 dB.

Now, suppose that the above-mentioned leased line communication network is designed to have an internal transmission loss of 13 dB,
It is considered that a public communication network is connected to this private line communication network to make a public exclusive connection. Then, it is assumed that the transmission loss from the calling subscriber SUB-A to the office line trunk COT at the connection point of the leased line communication network is 20 dB. Further, the loss in the connection from the originating side (exchange A) office line trunk COT to the receiving side (exchange B) bidirectional trunk BWT is set to 0 dB, and the SUB is passed through the bidirectional trunk BWT on the receiving side and the line trunk LIF.
・ It is assumed that a loss of 5 dB is applied when connecting to D.

Therefore, in this case, the calling subscriber SUB-A
When a public-private connection is made with the called subscriber SUB-D from, a total transmission loss of 25 dB is inserted between the subscribers. The transmission loss from the calling subscriber to the called subscriber is 25
If it is dB, the call will be disturbed. There is no such thing.

On the other hand, it is assumed that the public-private public connection is established between the subscribers SUB-A and SUB-B.
The transmission loss in the public network from B / A to the office line trunk COT at the connection point of the leased line communication network is 20 dB, the transmission loss in the connection between the office line trunk COT of the exchange A and the bidirectional trunk BWT of the exchange B is 0 dB, and the receiving side The transmission loss of the connection between the bidirectional trunk BWT of the exchange B and the office line trunk COT is 0 dB, and the subscriber SUB is connected from this office line trunk COT.
・ Transmission loss up to B in the public communication network is 20 dB.

In this case, a transmission loss of 40 dB in total is inserted in the connection from the calling subscriber SUB-A to the called subscriber SUB-B. The transmission loss of 40 dB from the calling subscriber SUB-A to the receiving subscriber SUB-B exceeds the transmission loss of 30 dB which is a general practical call range, and causes a trouble in the call.

FIG. 4 is a diagram illustrating the above-mentioned public-private connection and the state of transmission loss insertion described in public-private connection.

Next, the case where the transmission loss at the time of public / private public connection is compensated by the station line trunk COT will be described.

In FIG. 1, the calling subscriber SUB.
In order for A to make a public-private connection or to make a public-private connection, it is necessary to connect after the private-line communication network access number after receiving the call to the central line trunk COT via the direct communication dial line (DID line) through the public communication network. Number from phone P
Send by B signal.

The station line trunk COT which receives an incoming call from the public communication network is connected to the register center PBRS via a switch SW constituting the exchange A by a known technique (not shown), and the register sender PBRS makes a dial tone (DT tone). )
And the number necessary for connection of the leased line communication network from the calling subscriber SUB-A is received by the PB signal.

In this state, the calling subscriber SUB-A
The public communication network connecting the switch and the trunk line COT of the exchange A is in a call state, and the calling subscriber SUB-A
The PB signal from the signal reaches the register sender PBRS through the same transmission line as the voice signal. Calling subscriber SUB
Since the transmission level of the PB signal transmitted from the telephone set of A is regulated to a fixed value, the central line trunk COT or the register sender PBRS detects the level of the PB signal which has arrived, so that the calling subscriber SUB. It is possible to know the level reduction in the public communication network from A to the office line trunk COT, that is, the transmission loss.

Based on the level in the leased line communication network at the time of calling from the subscriber SUB / C directly accommodated in the exchange A, the office line trunk COT is the subscriber S.
The level drop when UB / A is connected to the leased line communication network via the public communication network can be compensated by the central line trunk COT to match the level at the time of calling from the subscriber SUB / C. .

As described above, even if the public communication network and the leased line communication network are connected by the exchange A, it is possible to maintain the same speech conversation level as that of the conversation in the leased line communication network. That is, when the calling subscriber SUB-A makes a call with the subscriber SUB-C or SUB-D accommodated in the leased line communication network, the same call level as that in the leased line communication network is secured. can do.

However, the subscriber SUB-A originating from the subscriber SUB is connected to the private line communication network via the public line communication network, and further connected to another public communication network via the exchange B.
-When talking to B, transmission loss of the public communication network connected to the exchange B side is added. In this case, the exchange B has no means for identifying the transmission loss in the receiving side public communication network. Therefore, in one embodiment of the present invention, this loss is fixedly compensated.

FIG. 3 shows how the transmission loss is compensated in the public communication network described above. In the example shown in FIG. 3, the transmission loss in the leased line communication network is set to 13 dB, and the subscriber SUB
The loss in the line trunk LIF at the time of C call is 8 dB, and the loss at the time of call is 5 dB.

In this case, the subscriber SUB · A of the public communication network
If the transmission loss in the public communication network is 20 dB from the detection result of the level of the PB signal that is transmitted from the subscriber SUB-A and reaches the connection point of the leased line communication network, the subscriber S
By performing 12 dB loss compensation on the signal from UB / A, the signal from subscriber SUB / A is
It can be adjusted to the same level as when originating from UB / C. If the transmission loss from the subscriber SUB-A to the leased line communication network is 10 dB, the loss compensation of 2 dB is performed.

According to the embodiment of the present invention, when the subscriber SUB-A or SUB-C talks with the subscriber SUB-D, the call can be made at the same call level by the above-mentioned configuration. it can.

When the SUB-A accommodated in the public communication network is connected to the leased line communication network for a call with the SUB-B accommodated in another public communication network, the subscriber SUB-A originates the call. Assuming that the transmission loss from the subscriber SUB-A to the connection point of the leased line communication network is 20 dB, the signal from the subscriber SUB-A is compensated for the loss of 12 dB as described above.
Since the transmission loss of the public communication network connected to the other side of the leased line communication network is not known, in one embodiment of the present invention,
The fixed 3 dB is compensated.

In this case, even if the transmission loss up to the subscriber SUB-B of the receiving side public communication network is 20 dB,
The transmission loss from the subscribers SUB-A to SUB-B is 27 dB in total, which can be kept within 30 dB of the call loss within the practical use range of calls, and good calls can be made.

Next, with reference to FIG. 2, a circuit example of the office line trunk COT according to an embodiment of the present invention capable of performing the above-mentioned speech level compensation will be described.

In FIG. 2, when the subscriber SUB-A originates an incoming call from the central office line to the illustrated central line trunk COT, a calling signal arrives at the terminals A and B, and the calling signal is transmitted to the terminal A. -Contact rb-Capacitor CO-Diode D4-Zener diode RD-Photocoupler FT
It is detected by the photocoupler FTr in the circuit of r-diode D1-contact rb-terminal B. As a result, the transistor Tr is brought into a communication state, and an incoming call from the central line is transmitted to the control device via the terminal TER.

When the incoming call from the central office line is transmitted, the control device (not shown) gives signals to the relay drivers DRVA and DRVB from the terminals DRVA and DRVB to operate the relays RA and RB and close the contact ra to close the station. While making a response to the line, the contact rb is switched to disconnect the call signal detection circuit, and further, the register sender PBRS is connected to the office line trunk COT via the switch SW.

The register sender RS is a trunk line trunk CO
When it is connected to T, a dial tone (DT tone) is transmitted, and the subscriber SUB-A is prompted to transmit the next dial signal. The dial tone is transmitted to the calling subscriber SUB-A connected to the public communication network via the codec CODEC-amplifier AMP1-hybrid coil HYB-contact rb-terminals A and B-. When the subscriber who hears the dial tone dials, the calling subscriber SUB-A's telephone sets the PB at the specified level.
The signal is sent out. This PB signal has a contact rb from terminals A and B-hybrid coil HYB-amplifier AMP0-
It is received by the register sender PBRS via a codec CODEC and a switch SW (not shown).

PB by the above-mentioned register sender PBRS
When receiving a signal, the hybrid coil HYB and the amplifier AM
P sent from the calling subscriber's telephone between P0 and
The B signal is drawn into the PB signal level detection control unit, and the PB signal level detection control unit recognizes the level of the PB signal reaching the office line trunk COT. The PB signal level detection control unit identifies how much the PB signal of a certain level sent from the telephone is received after being attenuated, and identifies the loss of the transmission line from the level difference from the reference level.

Then, the PB signal level detection control unit compensates the loss of the transmission line which recognizes the gains of the amplifiers AMP0 and AMP1 which are normally set to the gain of 0 dB,
The signal level from the subscriber SUB-A is set to the same level as when the signal is transmitted from the extension telephone of the leased line communication network.

That is, the PB signal level detection control device, as shown in the level diagram shown in FIG.
Transmission loss in public communication network originated from UB / A is 20 dB
, SUB-C, the subscriber of the leased line communication network
Amplifier AMP to match the same level as the
Amplifier A so that the gain of 0 and AMP1 is 12 dB
Control MP0 and AMP1.

One embodiment of the present invention is a station line trunk COT.
By controlling the gains of the amplifiers AMP0 and AMP1 as described above, the subscriber SUB-A is
When making a call to UB / D, it is possible to make a call while ensuring the same level as that of the subscriber SUB / C accommodated in the leased line communication network to make a call to the subscriber SUB / D.

Next, the operation of the station line trunk COT of the exchange B when the connection destination is extended from the leased line communication network to another public communication network in the above connection will be described.

In this case, the control device (not shown)
Knowing to extend the connection to other public communication networks,
The trunk line COT is captured and the terminal DRVA and the terminal D are acquired.
The relay RA and the relay RB are operated from the RVB via the relay drivers DRVA and DRVB.

When the relay RA operates, a loop circuit of terminal A-coil L-contact ra-terminal B is constructed, and the office line trunk COT activates the public communication network, and also from the register sender PBRS via the public communication network. Subscriber SUB
-Send the connection number required to connect to B. At the same time, the control device controls the gains of the amplifiers AMP0 and AMP1 from the terminal LV to the PB signal level detection control unit, for example,
It is shown to be 3 dB. As a result, the office line trunk COT raises the level of the signal sent from the leased line communication network to the public communication network by 3 dB and transmits the signal.

In the connection from the leased line communication network to the public communication network, the value of the transmission loss up to the called subscriber accommodated in the public communication network cannot be identified. Therefore, the embodiment of the present invention is as described above. A gain is provided to compensate for the minimum value of transmission loss in the public communication network.

As described above, according to one embodiment of the present invention, when a public communication network is connected to a leased line communication network, a subscriber accesses the leased line communication network at a connection point with the leased line communication network. The transmission loss in the public communication network can be identified by monitoring the level of the PB signal dialed in order to compensate the transmission loss in the public communication network to a value suitable for a call. Further, one embodiment of the present invention can compensate the minimum value of the transmission loss in the public communication network when connecting from the leased line communication network to the public communication network.

Thus, according to one embodiment of the present invention,
By connecting multiple public communication networks to a dedicated communication network,
To solve the problem of the conventional technology that the communication range is limited due to the increase of transmission loss when making a public-private connection or public-private connection, and expanding the call-enabled range by public-private connection, private-public connection, or public-private connection It is possible to improve the economic effect.

Further, according to the embodiment of the present invention, since it is only necessary to provide the station line trunk with the function of compensating for the transmission loss, it is possible to construct a more economical system.

[0047]

As described above, according to the present invention, it is possible to compensate for the transmission loss in the exclusive connection, the public exclusive connection or the public exclusive connection for connecting the public communication network to the private line communication network. The range of calls using the connection can be expanded.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a communication network to which the present invention is applied.

FIG. 2 is a block diagram showing a circuit configuration of an office line trunk according to an embodiment of the present invention.

FIG. 3 is a diagram showing a level diagram between subscribers when the present invention is applied.

FIG. 4 is a diagram showing a level diagram between subscribers in the case of the prior art.

[Explanation of symbols]

SUB / A, SUB / B subscribers accommodated in the public communication network COT Station line trunk connecting the public communication network and the leased line network SUB / C, SUB / D Extension subscribers accommodated in the leased line communication network LIF Line trunk SW for connecting extension subscribers within the leased line communication network Switch for switches A and B PBRS PB Register register sender for sending and receiving signals BWT Bidirectional trunk RA, RB relay ra, rb relay RA, RB contact DRVA, DRVB relay Driver FTr Photocoupler Tr Transistor L coil D1 to D6 Diode RD Zener diode C0, C1 Condenser HYB Hybrid coil AMP0, AMP1 Amplifier CODEC Codec

Claims (1)

[Claims] 1. A public communication network is connected to a plurality of ends of one private line communication network to connect from the public communication network to the private line communication network, from the private line communication network to the public communication network, or to public communication. To connect the public network to the public communication network, a so-called public-private public connection that connects the network to the private line communication network and further connects to the public communication network P dialed by the accommodated subscriber
The reception level of the B signal is detected, and based on the result, the transmission loss of the public communication network is compensated, and when connecting from the leased line communication network to the public communication network, the transmission loss is compensated by a fixed value. A station line trunk characterized by comprising means.