JPS6240836A - Echo erasion type two-wire bidirectional repeater - Google Patents

Abstract

PURPOSE:To diagnose a function of an echo erasing circuit by a small circuit scale, by providing a test signal generator for outputting a test signal of a prescribed level, and a switching circuit. CONSTITUTION:Switching circuits 22, 23 are switched to a test signal generator 21 side by an external control signal at the time of non-operation, when a repeating operation is not operated, namely, at the time of a waiting time except a line connecting time. As a result. a test signal of a prescribed level from the generator 21 is supplied to echo erasing circuits 13, 17, respectively. Subsequently, output levels of amplifiers 14, 18 for amplifying outputs of each echo erasing circuit 13, 17, respectively are detected by level detecting circuits 24, 25, respectively. A monitoring circuit 26 decides whether detecting levels of the detecting circuits 24, 25 have exceeded a set level or not, and sends out an alarm signal in case said detecting levels have exceeded the set level. In such a way, a function of the echo erasing circuit can be diagnosed by a small circuit scale.

Description

[Detailed Description of the Invention] "Industrial Application Field-1 This invention is a two-wire system using an echo canceling circuit (Eco 1--F Jansera) for call forwarding services provided on public telephone lines. This invention relates to a two-way relay device.

[Prior art-1] Conventionally, this type of device has a two-wire transmission line connected to a two-wire transmission line (signals from No. 8 input/output terminal II, as shown in Fig. 5).
The 2-wire/4-wire converter 12 that converts the 2-wire transmission line into a 4-wire transmission line is connected to 1H to create an echo cancellation circuit (x=r-ganceler).
]3. 4-wire reception with echo cancellation circuit 13 (jl
The echo signal to the 4-wire transmitting side is eliminated, and the output ε is passed through the amplifier 14 to 1H and supplied to the 2-wire 4-wire converter 15.
From this, the signal is supplied to a two-wire signal output terminal 7-16 connected to a two-wire transmission line. On the other hand, the signal from this two-wire signal input/output terminal 16 is supplied to an echo cancellation circuit (echo canceller) 17 through a two-wire/four-wire converter 15. The echo canceling circuit 17 cancels the echo signal from the 4-wire receiving side to the 4-wire transmitting side, and its output passes through the amplification 11B and is further transmitted to the 2-wire 4-wire transmitting side.
The signal is supplied to the two-wire signal input/output terminal 11 through the line converter 12 .

In the echo cancellation circuit 13.17, in order to perform the echo cancellation described above, each output of the amplifier 18.14 is branched and supplied to its receiving input terminal.

[Problem to be Solved by the Invention] If this relay device breaks down for some reason and becomes a failure, there is a risk that it will mistakenly provide the failed intermediate device for the next call transfer call. Ta.

Generally, it is impossible to completely eliminate the occurrence of failures in any device, and a certain failure rate is unavoidable. The occurrence rate of failures for users should also be reduced in bidirectional relay devices for incoming call transfer. Since the bidirectional relay device has a very long waiting time when not connected to a line, this time can be used to perform self-diagnosis. If a fault is found as a result of this self-diagnosis, 1! By using the device and prohibiting the use of a bidirectional relay device in which a fault has occurred, the incidence of faults for users can be reduced.

In this way, self-diagnosis is a very useful concept, but the scale of the faults that can be detected varies depending on the method of self-diagnosis, and the scale of the self-diagnosis circuit is naturally required to detect various faults. Become. Therefore, it is necessary to detect basic functional failures with as small a circuit scale as possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a two-wire bidirectional relay device for call transfer that is capable of detecting failures in basic functions with a small circuit scale.

[Means for Solving the Problems] According to the present invention, a test signal generator that outputs a test signal of a predetermined level is provided, and the test signal of the test signal generator and each IL line of the four-wire transmission line are The output of each φg amplifier in the first . A second switched I circuit allows it to be switched to be supplied as a receive input to each echo cancellation circuit.

The output level of each amplifier is the first. It is detected by the second level detection circuit.

1st. The second switching circuit is switched to the test signal generator side during non-operation when relay operation is not being performed, that is, during waiting time other than when the line is connected.

According to the first aspect of the present invention, the echo canceling circuit is put into an operating state while the test signal is supplied to the echo canceling circuit, and the monitoring circuit outputs the first signal at that time. The detection level of the second level detection circuit is compared with a preset judgment level, and if the detection level exceeds the judgment level, an alarm signal is sent out indicating that this two-wire bidirectional relay device is in a fault state. be done.

According to the second aspect of the present invention, while the test signal is being supplied to the echo cancellation circuit, the echo cancellation circuit is rendered inactive, each of the amplifiers is placed in an automatic gain control state, and the monitoring circuit controls the first... The detection level of the second level detection circuit is compared with a preset judgment level range, and if the detection level is within the judgment level range, this does not indicate that this two-wire bidirectional relay device is in a fault state. A police signal is sent out.

With such a relatively simple configuration, it is possible to diagnose the basic functions of the echo cancellation circuit in the first invention and the automatic gain control function of the amplifier in the second invention.

"Embodiment" FIG. 1 shows an embodiment of the first invention. 5 in Figure 1
Parts corresponding to those in the figure are given the same reference numerals. In this invention, a test signal generator 21 is provided which sends out a test signal of a predetermined level. Further, a switching circuit 22 is inserted between the output side of the amplifier 14 on one path of the four-wire transmission line and the reception input terminal 17a of the echo cancellation circuit 17, and the switching circuit 2
2 allows the receiving input terminal 17a of the echo canceling circuit 17 to be connected to the output side of the amplifier 14 and the output side of the test signal generator 21. Also, the amplifier 18
A switching circuit 23 is inserted between the receiving input terminal 13a of the echo canceling circuit 13, and the switching circuit 23 connects the receiving input terminal 13a of the echo canceling circuit 13 to the output side of the amplifier 18 and the output side of the test signal generator 21. It is possible to switch to and connect to.

Level detection circuit 24.25 on the output side of amplifier 14.18
are connected to each other, and the output level of each amplifier can be detected. The detection outputs of these level detection circuits 24 and 25 are supplied to a monitoring circuit 26. The monitoring circuit 26 compares the input detection level with a preset judgment level, and outputs an alarm signal to the external alarm terminal 27 when the detection level exceeds the judgment level. An external control signal from an external control input terminal 28 controls switching of the switching circuits 22 and 23.

This external control signal is also input to the monitoring circuit 26, and the monitoring circuit 26 performs predetermined sequential control while the external control signal is input.
From each enable terminal 13b of the echo cancellation circuit 13.17
, 17b to stop the echo cancellation function of the echo cancellation circuit 13.17.

When the service is not in operation, that is, when the line is not connected, the 2-wire signal input/output terminal 1 is
1.16 is open, and the wraparound (echo) signal from the 4-wire receiving side to the 4-wire transmitting side in the 2-wire 4-wire converter 12.15 is almost completely removed at the 2-wire signal input/output terminals 11 and 16. It is reflected and reaches the transmission input terminals 13c and 17c of the echo cancellation circuits 13 and 17, respectively. Switching circuit 22.2
3 receives a constant bell test signal from the test signal generator 21 during non-operation (referred to as self-diagnosis mode) by means of an external control signal;
17a respectively. For example, white noise is used as the test signal.

In the monitoring circuit 26, while the external control signal is in a non-operating state as shown in FIG. 2, the self-diagnosis mode sequentially repeats three modes: channel diagnosis mode a1 echo cancellation circuit convergence mode b9 echo cancellation circuit diagnosis mode C In the channel diagnosis mode (section a), the control signal from the monitoring circuit 26 is applied to the enable terminals 13b and 17b to activate the echo canceling circuit 13.17.
operation is stopped, and the echo signal is output from the echo canceling circuit 13.17 without being cancelled. In this case, the level detection circuits 24 and 25 should detect a level that is approximately the same as the output level of the test signal generator 21. That is, in this case, abnormalities in the communication path excluding the two-wire portion can be detected.

Next, to diagnose the echo cancellation circuit, its cancellation ability will be examined. First, since the echo cancellation circuit 13.17 requires a certain amount of time (convergence time) for the cancellation ability to stabilize, the interval in Figure 2 is only the convergence time after the echo cancellation circuit 13.17 starts operating. Wait, then level detection circuit 2 in section C
It is confirmed that the detection level of 4.25 becomes f1 lower as the erasing ability increases.

When the detection level exceeds the preset expected value range in 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 fJ. The alarm signal in section A indicates an abnormality in the communication path, and the alarm signal in section C
An alarm signal at indicates an abnormality in the echo cancellation circuit.

Second Embodiment-1 FIG. 3 shows an embodiment of the second invention, with the same reference numerals assigned to parts corresponding to those in FIG. 1. In this example, each i of the 4-wire transmission line
1! The amplifier inserted in the l path has automatic gain control (8GO)
When the amplifier 3+12 receives a control signal from the monitoring circuit 26 to its enable terminals 31a and 32a, its 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 cancellation circuit convergence mode 1
The section C1 of the echo cancellation circuit diagnostic mode, the section d of the AGC convergence mode, and the section e of the AGC amplifier diagnostic mode 1' are repeated in sequence. In section S, C, AGC of AGC amplifier 31.32
The function is stopped, and the gains of the amplifiers 31 and 32 are maintained at 1 or a constant value. Next, in sections d and e, the echo cancellation operation of the echo cancellation circuit 13.17 is prohibited, and the AGC operation of the AGC amplifier 31.32 is enabled. This is because a certain amount of time (rise time) is required for the output level of the AGC amplifier to stabilize.

In interval d, the AGC operation of the AGC amplifier starts, and then waits for a period of time, and then in interval e, the level detection circuit 24.25 detects the level detection circuit 24.25. Make sure that you are reasonably personable. When the detection level in section e falls below the preset expected range (16), the monitoring circuit 26 determines this to be abnormal and outputs a police report to the alarm terminal 27.

In addition, in this example, when diagnosing the echo cancellation circuit and
When diagnosing a GC amplifier, the output level of the test signal generator 21 may need to be set high for the former and low for the latter, so the monitoring circuit 26 (or other timing circuit) is By having a configuration in which the test signal is output from the test signal generator 21 through the control cotton 33 and the type of test signal is switched, the detection product term is further increased and the diagnostic performance is improved. Therefore, it is more preferable. Furthermore, in the monitoring circuit 26, each output of the level detection circuits 24 and 25 is as follows.
It is compared with the lower limit and upper limit of the expected value, respectively, and an alarm signal is issued when the lower limit is below or the upper limit is exceeded.

In FIGS. 2 and 4, the sections of each mode are shown to have the same length, but this is for the convenience of the invention, and they can be set at preferable times if necessary. Figure 3.

In FIG. 4, the diagnosis of the echo cancellation circuit may be omitted, and only the GC convergence mode d and the AGC amplifier diagnosis mode e may be used. Furthermore, the communication path diagnosis mode [a shown in FIG. If the echo cancellation circuit is not diagnosed, the echo cancellation circuit 13.17 cancels the echo signal.
Instead of an echo canceller, it may be an echo suppressor that attenuates and suppresses echo signals.

"Effect of the Invention 1 As explained above, according to the present invention, in the first invention of the communication path, the cancellation ability of the echo cancellation circuit can be self-diagnosed with a small number of external circuits, and in the second invention, the cancellation ability of the echo cancellation circuit can be self-diagnosed. Since the functions can be self-diagnosed and the most basic functions can be self-diagnosed in this way, there is an advantage that the reliability of the echo-cancelling two-wire bidirectional relay device can be greatly improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the first invention, Fig. 2 is a time chart without showing its operating mode, Fig. 3 is a block diagram showing an embodiment of the second invention, and Fig. 4 is its operating mode. FIG. 5 is a block diagram showing a conventional echo-canceling two-wire bidirectional medium-sized device. Il, 16: 2-wire signal input/output terminal completed, +2.15:
2-wire 4-wire converter, 13.174 echo cancellation circuit, 21: test signal generator, 22, 23: switching circuit, 24.25: level detection circuit, 26: monitoring circuit.

Claims (2)

[Claims] (1) First and second 2-wire and 4-wire converters that convert a 2-wire transmission line into a 4-wire transmission line, and each 4-wire receiving side of these first and second 2-wire and 4-wire converters The first and second echo canceling circuits cancel the echo signal from the 4-wire transmitter to the 4-wire transmitting side, and the respective outputs of the first and second echo canceling circuits are amplified, and the amplified outputs are sent to the second and first echo canceling circuits, respectively. An echo-cancelling two-wire bidirectional relay device comprising a receiving input terminal of an echo-cancelling circuit and first and second amplifiers that supply signals to the respective four-wire receiving sides of the second and first two-wire and four-wire converters. a test signal generator that outputs a test signal at a predetermined level; and a test signal generator that is controlled by an external control signal to connect the output sides of the first and second amplifiers and the output side of the test signal generator to the second,
first and second switching circuits respectively switchably connected to the reception input terminals of the first echo cancellation circuit; first and second level detection circuits respectively detecting the respective output levels of the first and second amplifiers; Determine whether or not the detection levels of the first and second level detection circuits exceed a set determination level in a state where the test signal generator is connected to the first and second echo cancellation circuits according to the control signal, and set the test signal generator. An echo-cancelling two-wire bidirectional relay device characterized by being provided with a monitoring circuit that sends out an alarm signal when the level exceeds the level. (2) First and second 2-wire and 4-wire converters that convert a 2-wire transmission line into a 4-wire transmission line, and each 4-wire receiving side of these first and second 2-wire and 4-wire converters The first and second echo canceling circuits cancel the echo signal from the 4-wire transmitter to the 4-wire transmitting side, and the respective outputs of the first and second echo canceling circuits are amplified, and the amplified outputs are sent to the second and first echo canceling circuits, respectively. An echo-cancelling two-wire bidirectional relay device comprising a receiving input terminal of an echo-cancelling circuit and first and second amplifiers that supply signals to the respective four-wire receiving sides of the second and first two-wire and four-wire converters. a test signal generator that outputs a test signal at a predetermined level; and a test signal generator that is controlled by an external control signal to connect the output sides of the first and second amplifiers and the output side of the test signal generator to the 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 the respective output levels of the first and second amplifiers; 1. means for controlling the second echo canceling circuit to a state in which no echo canceling operation is performed;
, is connected to the second echo cancellation circuit, and determines whether the detection levels of the first and second level detection circuits are out of the set judgment level range in a state where these echo cancellation circuits are in a state where the echo cancellation operation is not performed. 1. An echo-cancelling two-wire bidirectional repeater, characterized in that it is provided with a monitoring circuit that makes a judgment and sends out an alarm signal when the range is out of range.