JPH0612889B2 - Echo canceling 2-wire type bidirectional repeater - Google Patents

Description

The present invention relates to a two-wire type two-way relay apparatus using an echo canceller (echo canceller) provided for a call transfer telephone service provided by a public telephone line.

"Prior Art" Conventionally, in this type of device, a signal from a two-wire type signal input / output terminal 11 connected to a two-wire type transmission line as shown in FIG. It is supplied to an echo canceling circuit (echo canceller) 13 through a two-wire / four-wire converter 12 for converting into a path. The echo canceling circuit 13 cancels the echo signal from the 4-wire receiving side to the 4-wire transmitting side, and the output thereof is passed through the amplifier 14 to the 2-wire 4
The signal is supplied to the line converter 15 and then supplied to the 2-wire signal input / output terminal 16 connected to the 2-wire transmission line. On the other hand, the signal from the 2-wire type signal input / output terminal 16 is a 2-wire / 4-wire converter 15
Is supplied to the echo canceller (echo canceller) 17 through. The echo canceling circuit 17 cancels the echo signal from the 4-wire receiving side to the 4-wire transmitting side, and its output is supplied to the 2-wire type signal input / output terminal 11 through the amplifier 18 and further through the 2-wire / 4-wire converter 12. . In the echo canceling circuits 13 and 17, the outputs of the amplifiers 18 and 14 are branched and supplied to the reception input terminals thereof in order to perform the echo cancellation described above.

"Problem to be solved by the invention" When this relay device fails due to some cause and becomes a failure, there is a risk of erroneously providing the failed relay device for the next call transfer call. .

In general, it is impossible to completely eliminate the occurrence of failures in any device, and a certain failure rate is unavoidable. Even in a two-way relay device for transferring a call, the occurrence rate of failures for the user should be reduced. The two-way relay device has a very long waiting time except when the line is connected, and therefore the self-diagnosis may be performed using this time. When a failure is found as a result of this self-diagnosis, another bidirectional relay apparatus is used and the use of the failed bidirectional relay apparatus is prohibited, so that the failure rate for the user can be reduced. .

As described above, self-diagnosis is a very useful idea, but the scale of faults that can be detected varies depending on the method of self-diagnosis, and if you try to detect various faults, the scale of the self-diagnosis circuit is naturally large. Become. Therefore, it is necessary to detect the failure of the basic function with the smallest circuit scale.

An object of the present invention is to provide a two-wire type two-way relay apparatus for incoming call transfer, which is capable of detecting a failure of a basic function with a small circuit scale.

[Means for Solving Problems] According to the present invention, a test signal generator for outputting a test signal of a predetermined level is provided, and the test signal of the test signal generator and each path of the 4-wire type transmission line are provided. The output of each amplifier can be switched and supplied as the reception input of each echo canceling circuit by the first and second switching circuits. The output level of each amplifier is detected by the first and second level detection circuits. The first and second switching circuits are switched to the test signal generator side during non-operation in which no relay operation is performed, that is, during standby time other than line connection.

According to the first aspect of the invention, the echo canceling circuit is activated while the test signal is being supplied to the echo canceling circuit, and the detection levels of the first and second level detecting circuits at that time are preset in the monitoring circuit. When the detection level exceeds the determination level, a warning signal indicating that this two-wire bidirectional relay device is in a failure state is sent.

According to the second aspect of the present invention, while the test signal is being supplied to the echo canceling circuit, the echo canceling circuit is deactivated and each of the amplifiers is set to the automatic gain control state. The detection level of the second level detection circuit is compared with a preset judgment level range, and if the detection level is out of the judgment level range, an alarm signal indicating that this two-wire bidirectional relay device is in a failure state Is sent.

With such a relatively simple structure, the basic function of the echo canceling circuit of the first invention and the automatic gain control function of the amplifier of the second invention can be diagnosed.

"Embodiment" FIG. 1 shows an embodiment of the first invention. No. 5 in FIG.
The same reference numerals are attached to the parts corresponding to the drawings. In the present invention, a test signal generator 21 for transmitting a test signal of a predetermined level is provided. Further, the output side of the amplifier 14 and the reception input terminal 17a of the echo canceling circuit 17 in one of the four-wire transmission lines.
A switching circuit 22 is inserted between the switching circuit 22 and the switching circuit 22 so that the reception input terminal 17a of the echo canceling circuit 17 can be switched and connected to the output side of the amplifier 14 and the output side of the test signal generator 21. It Further, a switching circuit 23 is inserted between the amplifier 18 and the reception input terminal 13a of the echo canceling circuit 13,
The reception input terminal 13a of the echo canceling circuit 13 is amplified by the amplifier 18
Of the test signal generator 21 and the output side of the test signal generator 21 can be switched and connected.

Level detection circuits 24 and 25 are connected to the output sides of the amplifiers 14 and 18, respectively, and the output levels of the amplifiers can be detected. The detection outputs of these level detection circuits 24 and 25 are supplied to the monitoring circuit 26. The monitoring circuit 26 compares the input detection level with a preset determination level, and outputs an alarm signal to the external alarm terminal 27 when the detection level exceeds the determination level. Switching of the switching circuits 22 and 23 is controlled by an external control signal from the external control input terminal 28. This external control signal is also input to the monitoring circuit 26, and the monitoring circuit 26
Performs a predetermined sequence control while the external control signal is being input. In a certain section, the monitoring circuit 26 gives a control signal to the enable terminals 13b and 17b of the echo canceling circuits 13 and 17 to cancel the echo canceling circuit 13. , 17, the echo canceling function can be stopped.

When the service is not operating, that is, when the line connection is not made, the 2-wire signal input / output terminal 1
1 and 16 are open, and 4 in 2-wire to 4-wire converters 12 and 15
The sneak (echo) signal from the line receiving side to the 4-line transmitting side is 2
The signal is almost completely reflected at the line signal input / output terminals 11 and 16, and reaches the echo canceling circuits 13 and 17 and the transmission input terminals 13c and 17c, respectively. Switching circuits 22 and 23 are test signal generators when not in operation (called self-diagnosis mode) by external control signals.
A test signal of a constant level from 21 is supplied to reception input terminals 13a and 17a of echo canceling circuits 13 and 17, respectively. For example, white noise is used as the test signal. Second in the monitoring circuit 26
As shown in the figure, while the external control signal is in the non-operational state, in the self-diagnosis mode, the three modes of the communication path diagnosis mode a, the echo canceling circuit converging mode b, and the echo canceling circuit diagnostic mode c are sequentially repeated. In the speech path diagnosis mode (section a), the control signal from the monitoring circuit 26 is applied to the enable terminals 13b and 17b to stop the operation of the echo canceling circuits 13 and 17 to cancel the echo canceling circuit.
The echo signals from 13 and 17 are output without being erased. In this case, the level detection circuits 24 and 25 should detect a level almost equal to the output level of the test signal generator 21. That is, in this case, the abnormality of the communication path excluding the two-line portion can be detected.

Next, the canceling ability of the echo canceling circuit is examined for diagnosis. First, in the echo canceling circuits 13 and 17, a certain time (convergence time) is required for the canceling ability to stabilize. Therefore, in the section b in FIG. After waiting, it is confirmed that the detection level of the level detection circuits 24 and 25 becomes lower by about the erasing ability in the section c.

When the detection level exceeds the preset expected value range in each of the sections a and c, the monitoring circuit 26 determines that there is an abnormality and outputs an alarm signal to the external alarm terminal 27. The alarm signal in the section a indicates an abnormality in the communication path, and the alarm signal in the section c indicates an abnormality in the echo canceling circuit.

[Second Embodiment] FIG. 3 shows an embodiment of the second invention in which parts corresponding to those in FIG. In this example, the amplifiers inserted in the respective paths of the 4-wire transmission line are amplifiers 31 and 32 having an automatic gain control (AGC) function, and the amplifiers 31 and 32 are controlled by the monitor circuit 26 at their enable terminals 31a and 32a. When a signal is applied, the AGC function is stopped and the gain is kept constant, for example, 1.

In the monitoring circuit 26, as shown in FIG. 4, in the self-diagnosis mode during non-operation, the echo canceling circuit convergence mode section b, the echo canceling circuit diagnosis mode section c, the AGC convergence mode section, and the AGC amplifier diagnosis mode section. Repeat e sequentially. In the sections b and c, the AGC functions of the AGC amplifiers 31 and 32 are stopped, and the gains of the amplifiers 31 and 32 are held at 1 or a constant value. Next, in the sections d and e, the echo canceling operations of the echo canceling circuits 13 and 17 are prohibited, and the AGC operations of the AGC amplifiers 31 and 32 function. Since a certain time (rising time) is required for the output level of the AGC amplifier to stabilize, in the section d, the AGC operation of the AGC amplifier starts and then waits for the rising time, and then in the section e, the level detection circuits 24 and 25 Confirm that the detection level becomes large enough to correspond to the AGC capability. When the detection level in the section e deviates from the preset expected value range, the monitoring circuit 26 determines that this is abnormal and outputs an alarm signal to the external alarm terminal 27.

In this embodiment, when the echo canceller circuit is diagnosed, the AG
Considering that it may be necessary to set the output level of the test signal generator 21 to be large for the former and small for the latter at the time of diagnosing the C amplifier, control is performed from the monitoring circuit 26 (or other timing circuit). By receiving the output level switching signal through the line 33 and switching the output level of the test signal generator 21 or the type of the test signal, it is more preferable because the detection accuracy is improved and the diagnostic performance is improved. In the monitoring circuit 26, the outputs of the level detection circuits 24 and 25 are compared with the lower limit and the upper limit of the expected value,
An alarm signal is issued when the lower limit is exceeded or the upper limit is exceeded. In FIG. 2 and FIG. 4, the sections of each mode are shown to have the same length, but this is for the sake of convenience of the invention, and it is also possible to set a preferable time if necessary. The echo canceling circuit diagnosis may be omitted in FIGS. 3 and 4, and only the AGC convergence mode d and the AGC amplifier diagnosis mode e may be performed. Also, the speech path diagnosis mode a in FIG.
May be combined, and in that case, the AGC operation function is stopped and the communication path diagnosis is performed. When the echo canceling circuit is not diagnosed, the echo canceling circuits 13 and 17 may be echo samplers that cancel the echo signal and cancel the echo signal, instead of canceling the echo signal.

[Advantages of the Invention] As described above, according to the present invention, the elimination ability of the echo canceller can be self-diagnosed in the first aspect of the communication path with a small number of external circuits, and the second aspect can perform the AGC function of the AGC amplifier. Since the diagnosis can be performed and thus the most basic function can be self-diagnosed, there is an advantage that the reliability of the echo canceling two-wire bidirectional relay device can be greatly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the first invention, FIG. 2 is a time chart showing its operation mode, FIG. 3 is a block diagram showing an embodiment of the second invention, and FIG. 4 is its operation mode. FIG. 5 is a block diagram showing a conventional echo canceling type two-wire bidirectional relay device. 11, 16: 2-wire type signal input / output terminals, 12, 15: 2-wire 4-wire converter, 13, 17: echo canceling circuit, 21: test signal generator, 22,
23: switching circuit, 24, 25: level detection circuit, 26: monitoring circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kiyohisa Wakabayashi 3-9-11 Midoricho, Musashino-shi, Tokyo Inside Nippon Telegraph and Telephone Corporation Musashino Electro-Communications Research Laboratory (72) Inventor Yusuke Maruyama 5th Shiba, Minato-ku, Tokyo No. 33-1 Inside NEC Corporation (72) Inventor Shigeyuki Umi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited

Claims (2)

[Claims] 1. A first and second 2-wire 4-wire converter for converting a 2-wire transmission path into a 4-wire transmission path, and four wires for each of the first and second 2-wire 4-wire converters. The first and second echo canceling circuits for canceling echo signals from the receiving side to the 4-wire transmitting side, and the outputs of the first and second echo canceling circuits are respectively amplified, and the amplified outputs are respectively output to the above-mentioned second and second. An echo canceling type 2 comprising a reception input terminal of a first echo canceling circuit and first and second amplifiers for supplying to the four-wire receiving sides of the second and first two-wire to four-wire converters.
In a wire type bidirectional repeater, a test signal generator for outputting a test signal of a predetermined level, and an output side of the first and second amplifiers and an output side of the test signal generator controlled by an external control signal. The above second,
First and second switching circuits that are switchably connected to the reception input terminals of the first echo canceling circuit; first and second level detection circuits that detect the output levels of the first and second amplifiers respectively; It is determined whether or not the detection level of the first and second level detection circuits exceeds a set determination level in the state where the test signal generator is connected to the first and second echo canceling circuits by the control signal. An echo canceling two-wire type two-way repeater, which is provided with a monitoring circuit for sending an alarm signal when the level is exceeded. 2. A first and second two-wire and four-wire converter for converting a two-wire type transmission line into a four-wire type transmission line, and four lines each of these first and second two-line and four-line converters. The first and second echo canceling circuits for canceling echo signals from the receiving side to the 4-wire transmitting side, and the outputs of the first and second echo canceling circuits are respectively amplified, and the amplified outputs are respectively output to the above-mentioned second and second. An echo canceling type 2 comprising a reception input terminal of a first echo canceling circuit and first and second amplifiers for supplying to the four-wire receiving sides of the second and first two-wire to four-wire converters.
In a wire type bidirectional repeater, a test signal generator for outputting a test signal of a predetermined level, and an output side of the first and second amplifiers and an output side of the test signal generator controlled by an external control signal. The above second,
First and second switching circuits respectively switchably connected to the reception input terminals of the first echo canceling circuit; first and second level detection circuits respectively detecting output levels of the first and second amplifiers; Means for controlling the first and second echo canceling circuits in a state in which the echo canceling operation is not performed; and the test signal generator connected to the first and second echo canceling circuits by the external control signal, and these echo canceling circuits It is determined whether the detection level of the first and second level detection circuits is out of the set determination level range in a state where the echo canceling operation is not performed, and if it is out of the range, an alarm signal is transmitted. An echo canceling type two-wire type two-way repeater, which is provided with a monitoring circuit.