JPH10271047A - Monitoring device for echo canceller - Google Patents

Abstract

(57) [Problem] To provide an echo canceller monitoring device that monitors a sounding state during training. SOLUTION: Based on a reference signal output to the signal line at the time of initial operation, an echo amount calculating unit 3 for calculating an echo amount flowing through the signal line, and based on the echo amount calculated by the echo amount calculating unit 3. An echo removing unit 3 for removing an echo component flowing through a signal line, a control signal sending unit 4 for periodically outputting a control signal for a call operation during a normal operation, and a control signal sending unit for a normal operation. And control signal extraction units 6 and 7 for extracting the control signal output from the output signal line 4 from the output side signal line of the echo removal unit 3, wherein the level of the control signal extracted by the control signal extraction units 6 and 7 is set in advance. If the set value exceeds the set value, the echo amount calculation unit 3
To calculate the amount of echo flowing through the signal line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an echo canceller monitoring apparatus for detecting a sounding state in a communication line.

[0002]

2. Description of the Related Art Conventionally, a transmission signal flowing through a dedicated 2-wire communication line is converted so that it can be transmitted to a 4-wire dedicated communication line, and a transmission signal flowing through a 4-wire dedicated communication line is dedicated to a 2-wire dedicated communication line. As a device for converting data so that it can be transmitted to a communication line, there is a 2-wire to 4-wire conversion circuit, that is, an in-band ringer. The in-band ringer has a function of superimposing a predetermined control signal within a communication band. This gives 1
Various signals such as a 6 Hz dial pulse signal and an on-hook signal indicating an on-hook or off-hook state are temporarily
The signal is replaced with a signal in a voice band of 300 Hz to 3 kHz, and is transmitted to a communication terminal on the other side, or a signal is received in a reverse procedure.

FIG. 4 shows an example of a connection state of a conventional in-band ringer. As shown in FIG.
0 and 20 are connected via a communication line L, respectively, and each in-band ringer 10 (20) is connected to the private branch exchange 1
1 (21). Furthermore, each private branch exchange 1
The communication terminals 12 (22), 13
(23) is connected. Here, the in-band ringer 10 (20) is provided with an echo canceller in order to minimize the echo component generated at the time of 2-wire to 4-wire conversion.

That is, in a long-distance telephone line, a voice may be delayed due to a delay of its own voice through a two-wire to four-wire conversion circuit on the other side and may cause a remarkable trouble in a call. A device that prevents this is an echo canceller, which has a memory that stores the impulse response of the reverberation path.By performing a convolution operation of this impulse response and the received signal, the echo canceller is generated just in the reverberation path. The same echo is generated, and the generated echo component is subtracted from the transmission signal to eliminate the echo component.

FIGS. 5 to 7 are diagrams for explaining the operation procedure in the conventional example. FIG. 5 is a flowchart for explaining a main process, and FIG. 6 is a diagram for explaining an initial setting process. FIG. 7 is a flowchart for explaining the normal operation process.

First, when the power is turned on (step S3)
01), the station B (the right half in FIG. 4) is selected (step S302), and an initialization process described later is executed (step S303). Subsequently, the station A (the left half in FIG. 4) is selected (step S304), and the initial setting process is executed similarly to the station B (step S305), and the initial setting of the stations B and A is completed. Then, a normal operation process is performed (step S306).

[0007] Steps S303 and S3 in FIG.
In the initial setting process at 05, as shown in FIG. 6, the filter coefficients are forcibly reset (step S401),
Next, a DSP (Digital Signal Process)
er) generates a training signal (step S40).
2) Re-converge the filter coefficients inside the echo canceller (step S403). Then, the re-converged filter coefficient is updated as a new filter coefficient (step S404), and it is checked whether or not synchronization has been established (step S405).

If it is determined in step S405 that synchronization has not been established (step S40).
5; N), waiting until synchronization is established, while
If synchronization is established in the determination processing of step S405 (step S405; Y), step S405 in FIG.
Proceed to 304 or step S306.

In the normal operation process in step S306 in FIG. 5, as shown in FIG. 7, first, it is confirmed whether or not the current operation is in an idle state (step S501). If it is not in the idle state in this determination process (step S501; N), an error occurs (step S50).
2). On the other hand, in the determination process of step S501, when it is confirmed that the vehicle is in the idle state (step S50).
1; Y), and then confirm whether a dial call has been made (step S503) and, if the call has been confirmed (step S50).
3; Y), and confirm whether there is a response to the call (step S504).

If there is no outgoing call in the determination process of step S503 (step S503; N), it is confirmed whether or not there is an incoming call (step S505). And
If there is no incoming call in the determination process of step S505 (step S505; N), the process returns to step S503. Then, in the determination processing of step 505, if there is an incoming call (step S505; Y), it is confirmed whether or not there is a response to the incoming call (step S506).

If there is no response in the determination processing in step S504 or S506 (step S504; N, step S506; N), the process returns to step S503. On the other hand, in the determination processing of step S504 or S506, if there is a response (step S504; Y, step S506;
Y), a call is made between the stations A and B (step S507), and the presence or absence of the call termination is confirmed (step S50).
8).

If the call is not yet ended (step S508; N), the process proceeds to step S507 to continue the call. On the other hand, if it is determined in the determination processing of step S508 that the call is to be ended (step S508; Y), step S508 is performed.
The processing from 503 is repeatedly executed.

In a closed loop system including an echo canceller, an amplifier for amplifying a signal is generally provided. However, when an echo generated in a telephone line is canceled by the echo canceller, the amount of the echo in the closed loop system is smaller than the canceling amount of the echo. When the amplifier gain of the amplifier becomes large, the echo component is amplified by the loop, so that a so-called sounding state occurs, and communication becomes difficult. For this reason, in the conventional echo canceller, for example, a method of monitoring the training state of the echo canceller by measuring the echo level of a training signal using white noise has been considered.

[0014]

However, in such a conventional monitoring method of the training state of the echo canceller, the level cannot be monitored except during the transmission of the training signal in the echo canceller. For this reason, the echo canceller that performs the training operation only when the power is turned on can monitor the training state only once, and cannot cope with a change in the state of the system after the training. was there.

In addition, since an amplifier other than the echo canceller exists in the closed loop system, when actually monitoring the training state, it is necessary to determine a state other than the echo canceller in order to determine the sounding state. .

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a monitoring apparatus of an echo canceller for monitoring a sound state during training.

[0017]

According to a first aspect of the present invention, there is provided a monitoring apparatus for an echo canceller which calculates an echo amount flowing through a signal line based on a reference signal output through the signal line during an initial operation. Unit, an echo removing unit that removes an echo component flowing through the signal line based on the echo amount calculated by the echo amount calculating unit, and a control signal that periodically outputs a control signal for a call operation during a normal operation. A transmitting unit, and a control signal extracting unit that extracts a control signal output from the control signal transmitting unit from an output signal line of the echo removing unit in a normal operation, and includes a control signal extracting unit that extracts the control signal extracted by the control signal extracting unit. When the level exceeds a preset value, the echo amount calculation unit calculates the amount of echo flowing through the signal line again.

According to a second aspect of the present invention, there is provided a monitoring apparatus for an echo canceller, comprising: an echo amount calculating unit for calculating an echo amount flowing through a signal line based on a reference signal output through the signal line during an initial operation; An echo removing unit that removes an echo component flowing through the signal line based on the echo amount calculated by the amount calculating unit, a control signal sending unit that periodically outputs a control signal for a call operation during a normal operation, During normal operation, a control signal extraction unit that extracts a control signal output from the control signal transmission unit from the output signal line of the echo removal unit, and a peak that detects a peak value of the control signal extracted by the control signal extraction unit A value detecting section, and a comparing section for comparing a peak value detected by the peak value detecting section with a preset reference value. If the click value exceeds the reference value, it is configured so as to calculate the echo amount flowing in the signal line by again echo amount calculation unit.

In this case, as described in claim 3, the control signal extracting section is constituted by a filter that passes a signal in a specific frequency band, and the peak value detecting section is
Preferably, it is constituted by an integrator.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on one illustrated embodiment. FIG. 1 is a diagram illustrating a main configuration of an echo canceller according to the present embodiment. In the figure, an in-band ringer 1 is provided on a terminal side, with a hybrid transformer 2 provided on the line side, an echo canceller 3 connected to the hybrid transformer 2,
The apparatus includes a signal processing unit 4 for processing a reception signal from the echo canceller 3 and a transmission signal to the echo canceller 3, and a level monitoring unit 5 connected to a signal line on the reception side of the echo canceller 3.

The hybrid transformer 2 branches the transmission signal and the reception signal based on the directionality of the reception signal, and converts the reception signal input from the signal line on the line side into an echo canceller 3 and a signal processing unit. 4, and a transmission signal output from the terminal via the signal processing unit 4 and the echo canceller 3 to the line side. This prevents the transmission signal from leaking to the receiving side and prevents the receiving signal from leaking to the transmitting side.

The echo canceller 3 is provided for removing an echo component generated at the time of 2-wire to 4-wire conversion by the hybrid transformer 2, and calculates a filter coefficient which becomes an optimum value during a training operation. To set. The signal processing unit 4 is for processing a signal transmitted and received between the terminal side and the line side,
A control signal transmitting unit 4a for transmitting a control signal to a signal line including the echo canceller 3 is provided. The control signal sent from the control signal sending unit 4a is a sine wave signal.

The level monitor 5 includes a band erasing filter (BEF: Band Erase Filter) 6 for connecting an input terminal to a reception signal line via the echo canceller 3, and a BEF.
6, a band pass filter (hereinafter, BPF: Band Pass Filter) 7 having an input terminal connected to the output terminal side, an integrator 8 for integrating an output value from the BPF 7, and an output from the integrator 8 as a predetermined reference. And a comparator 9 for comparing the value.

The BEF 6 extracts a signal obtained by removing a signal of a specific band from a signal included in the received signal line, and
F7 extracts only a signal of a certain specific band from the output signal of BEF6. By this, BE
The F6 and BPF 7 extract only the control signal from the reception signal line. The integrator 8 obtains the level of the control signal and outputs it to the comparing section 9. The comparing unit 9 includes an integrator 8
The level of the control signal output from the controller is compared with a reference value, and when the level of the control signal exceeds the reference value, a control signal for resetting the device power is output.

Next, an example of the operation of the in-band ringer in the above-described embodiment will be described with reference to FIGS. FIG. 2 is a flowchart for describing main operation processing in the present embodiment, and FIG. 3 is a flowchart for describing sound detection processing.

First, when the power is turned on (step S1)
01), the initial setting process is executed according to the procedure shown in FIG. 6 (step S102), and then the normal operation process is executed according to the procedure shown in FIG. 7 (step S103). Then, it is confirmed whether or not a control signal is output during the normal operation processing (step S104). If no control signal is output (step S104; N), step S103 is performed.
Then, the normal operation process is performed, and if a control signal is output (step S104; Y), a sound detection process described later is performed (step S105). In the sound detection process, if the sound flag is OFF (step S105; N), the process returns to step S103 to execute the normal operation process, and if the sound flag is ON (step S105). S105; Y), the power is reset, and the processing is executed again from the processing in step S102.

In the sound detection processing shown in step S105 of FIG. 2, as shown in FIG. 3, first, a filter value in the BEF 6 is calculated (step S201).
7 (Step S20)
2). Then, the output value of the control signal is calculated in the integrator 8 (step S203), and then the output value of the control signal is compared with the reference value in the comparator 9 (step S204). Here, when the output value of the control signal is smaller (step S204; N), the sounding flag is turned off (step S205), and when the output value of the control signal is larger (step S204; Y), the sounding flag is turned on (step S206), and step S206 in FIG.
It returns to 106.

As described above, in the present embodiment, the canceling amount of the echo and the amplifier gain in the closed loop are measured by using the control signal transmitted from the control signal transmitting unit 4a like a two-wire in-band ringer. , Detect the sounding state. That is, by measuring the echo level of the control signal at the output of the echo canceller 3, the cancellation amount of the echo canceller 3 can be measured. At this time, if the amplifier gain of the system is known, the loop gain can be obtained, and if the loop gain is 0 or more, it can be determined that the sound is in the sounding state. By this determination, if it is determined that the sounding state,
By resetting the monitoring device, the monitoring device returns to the initial state and performs retraining. In addition, this monitoring device can constantly monitor the communication line, so that it can respond to changes in the line system after training.

As described above, in the present embodiment, by constantly monitoring the line, it is possible to immediately cope with a change in the line system, and to prevent deterioration of the communication quality. Also,
Since the device is used in a more stable system, malfunction of the device due to line fluctuation can be prevented. Further, since the control signal is a sine wave, the level of the control signal is more stable than that of the training signal based on white noise, and the determination can be made by a short-time level measurement. The control signal is also sent from a device installed at the opposing position, but by using a frequency different from that of the own station, the two types of filters provided at the input stage of the level monitoring unit 5 can sufficiently control the signal. Is countered.

[0030]

As is clear from the above description, according to the present invention, the echo cancellation state is constantly monitored by the echo canceller based on the control signal flowing during the normal operation. Is changed to a ringing state, the line state is always monitored during normal operation, the ringing state is detected, and retraining is performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of an echo canceller according to the present invention.

FIG. 2 is a flowchart for explaining main operation processing of the present invention.

FIG. 3 is a flowchart for explaining a sound detection process in FIG. 2;

FIG. 4 is a diagram showing a connection state of a conventional in-band ringer.

FIG. 5 is a flowchart for explaining main operation processing of the conventional example.

FIG. 6 is a flowchart illustrating an initial setting process in FIG. 5;

FIG. 7 is a flowchart for explaining a normal operation process in FIG. 5;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 in-band ringer 2 hybrid transformer 3 echo canceller 4 signal processing unit 5 level monitoring unit 6 band-elimination filter (BEF) 7 band-pass filter (BPF) 8 integrator 9 comparator

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Noriaki Nakanishi 2-1-1 Kotani, Samukawa-cho, Koza-gun, Kanagawa Prefecture Toyo Tsushinki Co., Ltd.

Claims (3)

[Claims] 1. An echo amount calculator for calculating an amount of echo flowing through a signal line based on a reference signal output to the signal line during an initial operation, and an echo amount calculated by the echo amount calculator. An echo eliminator that removes an echo component flowing through the signal line; a control signal transmitter that periodically outputs a control signal for a call operation during normal operation; and a control signal transmitter that is output from the control signal transmitter during normal operation. A control signal extracting unit for extracting a control signal to be output from an output signal line of the echo removing unit, and when the level of the control signal extracted by the control signal extracting unit exceeds a preset value, the echo amount A monitoring device for an echo canceller, wherein a calculating unit calculates an amount of echo flowing through a signal line. 2. An echo amount calculating section for calculating an echo amount flowing through a signal line based on a reference signal output into the signal line at an initial operation, and an echo amount calculated by the echo amount calculating portion. An echo eliminator that removes an echo component flowing through the signal line; a control signal transmitter that periodically outputs a control signal for a call operation during normal operation; and a control signal transmitter that is output from the control signal transmitter during normal operation. Control signal extraction unit that extracts a control signal from the output signal line of the echo removal unit, a peak value detection unit that detects the peak value of the control signal extracted by the control signal extraction unit, and a control signal that is detected by the peak value detection unit. A comparison unit that compares the peak value of the control signal with a preset reference value. If the comparison result indicates that the peak value of the control signal exceeds the reference value, the echo amount calculation unit Therefore the monitoring device of the echo canceller and performs echo calculation of the amount of flowing in the signal lines. 3. The echo according to claim 2, wherein the control signal extracting unit is configured by a filter that passes a signal in a specific frequency band, and the peak value detecting unit is configured by an integrator. Canceller monitoring device.