JPS6121665A - Trunk circuit - Google Patents

Abstract

PURPOSE:To attain the function similar to that of a relay controller (RC) and scanner (SCN) information lines with the transmission/reception of a DC loop signal of a talking line by eliminating the RC and SCN lines. CONSTITUTION:In applying an incoming transfer service being one of new telephone network services to the titled circuit, when a caller A makes a call to a subscriber B conducting incoming transfer service, a call is incoming to an exchange station 21 accommodating the subscriber B from an exchange station 20 accommodating the subscriber A through an incoming trunk ICT. When the subscriber B makes the incoming transfer service by the incoming numeral analysis of an exchange station 21, the exchange station 21 acquires an incoming transfer trunk TFT and an outgoing trunk OGT, starts an exchange station accommodating the subscriber C as if the subscriber C being a transfer destination were called by the subscriber B to make communication between the subscribers A and C via paths 2, 3 of the network NW of the exchange station 21 and the exchange station 22.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to trunk circuits for telephone exchanges, and more particularly to trunk circuits equipped with audio amplifiers having automatic gain control (AGO) circuits.

In telephone exchanges, audio amplifiers with automatic gain control may be installed in trunk circuits to adjust the level of transmitted signals or audio.

Generally, if the call transmission path is fixed, the gain of the audio amplifier can be set once and the gain will be fixed, but for trunks that are connected to various transmission paths, the gain of the audio amplifier can be changed depending on the connection status. must be done. If the exchange side knows the audio amplifier 1 level setting value when connecting various transmission lines, it may send level setting information to the trunk and set the level accordingly, but from the point of view of economy, it is necessary to detect the level in the audio amplifier. When setting up a circuit, it is common to set the level based on the level of the signal passing through the audio amplifier.

In this case, if the passing signal is a telephone voice, the AG
The system in which the O operates and lowers the level increases the gain when there is no call, giving a natural cine quality with a loud volume at the beginning of each call. For this reason, this type of audio amplifier uses an AGC circuit that detects the average audio level during a call (average over about 1 second) and only makes adjustments to reduce the gain if a level above a certain value is detected. It will be done. Therefore, when such a trunk is acquired and a new call is initiated or the trunk is restored, the AGC circuit must be reset and the audio amplifier must be set to maximum gain.

Conventionally, the trunk circuit equipped with this type of audio amplifier is AG.
Reset information was received from the relay controller (RC) of the exchange to reset the C circuit. The audio amplifier fault signal also sent out fault information from the trunk via a scanning device (say). Therefore, one RO and one BCH information line were required for the interface between the trunk circuit and the exchange.

The purpose of the present invention is to eliminate these Re and SON information lines.
The object of the present invention is to provide a trunk circuit that enables similar functions in direct current loop signal transmission and reception on a telephone line.

The trunk circuit of the present invention includes a voice booster having an AGC circuit that detects the average voice level during a call using a level monitoring circuit, and automatically reduces the gain when a level exceeding a certain value is detected. In the trunk circuit provided, the DC loop of the trunk communication line is monitored, and when either loop intermittent reversal is detected, the circuit is initialized to detect the A.
In order to initialize the GO circuit and prevent the creation of a loop in the communication line within this trunk in the event of a failure in the audio amplifier, a means is provided to detect a failure in the trunk during a trunk continuity test. Next, the present invention will be explained with reference to the drawings.

Figure 1 shows the trunk circuit of the present invention as part of a new telephone network service.
FIG. 2 is a diagram showing an example of a relay method applied to a call transfer service. A is the originating subscriber, B is the subscriber providing the call forwarding service, and C is the subscriber to whom B is forwarding the call. When a call is made from subscriber A to subscriber B, the call is received from the exchange 20 where subscriber A is accommodated to the exchange 21 where subscriber B is accommodated through the incoming trunk OT. When the exchange 21 analyzes the incoming call numbers and finds that subscriber B is in the middle of a call diversion service, the exchange 21 captures the incoming call diversion trunk TPT and the outgoing trunk OGT, and sends the call to subscriber C, who is the forwarding destination, as if it were a subscriber. As if B had made a call, the switching center 22 in which subscriber 0 is accommodated is activated, and the switching center 20. A call between subscriber A and subscriber C is made via paths 2 and 3 of network NW of switching center 21 and switching center 22 .

The transmission line 1o and the switching station 2 between the platform switching stations 2o and 21
The state of the transmission line U1 between U and 22 or the status A, B,
Suppose that C is accommodated in different exchanges, but A and B,
Depending on whether B and C or ABC are accommodated in the same station, the audio amplifier AMP in the call transfer trunk TFT has the function of setting the gain appropriately.

FIG. 2 is a block diagram showing an example of the internal configuration of the audio amplifier installed in the trunk circuit in FIG.
2) The amplifiers 32 . The output of '33 is connected to AGC circuits 36 and 37, and the level detection thereof is adjusted to the attenuator 3 on the input side of each amplifier 3a 33 to set each level.

There is AGCj7 set information 38 and audio amplifier failure information 39 as control signals for the audio amplifier.

FIG. 3 is a basic configuration diagram of the trunk circuit of the present invention and a connection diagram showing the relationship with other trunks. Trunk TRK in the diagram
1 shows the rear side of the switching center 216ECT in FIG. When the network /'NW bus 60 is connected, the current from the TRK battery BAT is Ds1/ --N
W - T F T's A relay - a contact - NW - TRK's D relay - Flows through the earth path, TRK's D relay and T
The FTOA relay is activated and the voice intensifier reset information 38
is input. In addition, in the event of a voice intensifier failure, the TFT AL relay is activated by the AM41W signal 39, and its contact a opens to cut off the TPT 5h channel DC loop. Therefore, although not shown in this figure, when a continuity test is performed during TFT acquisition, the location of the faulty TPT can be easily detected as a continuity test error.

As explained above, the present invention does not provide special Ro and 8ON points between the trunk circuit and the exchange, and the initial settings of the AG and 0 circuits and the failure information of the audio amplifier are transmitted and received through the communication line DC loop. RC! By eliminating the need for SON points, control becomes easier and an economical trunk circuit can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a relay system diagram showing an embodiment in which the trunk circuit of the present invention is applied to a call forwarding service, FIG. 2 is a block diagram showing an example of an audio amplifier in the trunk circuit of the present invention, and FIG. 3 is a diagram of the present invention. FIG. 3 is a basic configuration diagram of the trunk circuit of FIG. 1 and a connection diagram showing the relationship between the other trunks. AI B? C: Subscriber 2.3: Network path, 10.11: Transmission line, 20.21.22: Exchange, 30.31: Hybrid transformer (Oi, 321
3 +, 'l: Amplifier (AMP), 34, 35:
Attenuator 4 36,37 m Automatic gain control (AGO
) Circuit, 3B, 39: Audio amplifier control information line. v-2 diagram AMβ

Claims (1)

[Claims] 1. An audio amplifier having an automatic gain control circuit that detects the average audio level during a call using a level monitoring circuit, and automatically reduces the gain when a level above a certain value is detected. The trunk circuit is characterized in that the trunk circuit is equipped with a circuit that monitors the direct current loop of the trunk communication line and performs initial setting when either one of loop intermittent inversion is detected, and initializes the automatic gain control circuit. circuit. 2. In the trunk circuit according to claim 1, means is provided for detecting a fault in the trunk during a trunk continuity test by not creating a loop of the communication line within the trunk when the audio amplifier is faulty. A trunk circuit featuring: