JP2644070B2 - Remote loopback test method for echo canceller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a remote loopback test method of an echo canceller using a test signal from a game.

[Conventional technology]

Conventionally, as shown in FIG. 3, a remote loopback test method of this type receives a remote loopback control signal and a band-compressed signal composed of encoded data of a voice signal from a remote station as shown in FIG. 8, a remote loopback control signal is detected. On the other hand, the coded data of the audio signal is decoded by the decoding circuit 6, and then the analog audio signal 13 is decoded by the A / D and D / A conversion circuit 4.
Is converted to This analog audio signal 13 is
The signal is looped back by the loopback circuit 3 driven by the remote loopback control signal detected by the loopback signal detection circuit 8. The folded analog audio signal 14 is A / D, D /
The signal is converted into a digital signal by the A conversion circuit 4, passes through the echo canceller 5, is subjected to predetermined band compression by the encoding circuit 7, and is transmitted to the opposite terminal via the transmission line 9. Thus, the remote loopback test of the echo canceller is performed from the game.

[Problems to be solved by the invention]

In the above-described remote loopback test, two input signals for operating the echo canceller, that is, the level of the received voice signal that is folded back by the folding circuit 3 and input via the A / D and D / A conversion circuits, are combined with the composite signal. Since the received voice signal level input through the circuit 6 is the same (no echo margin), the echo canceller 5 detects double talk and does not perform a normal echo cancellation operation. Therefore, the remote loopback test in this case is
There is a disadvantage that a comprehensive system test including the echo canceller 5 cannot be performed only by testing the decoding circuit, the coding circuit A / D, the D / A conversion circuit, and the transmission line.

[Means for solving the problem]

The remote loopback test method of the echo canceller of the present invention is as follows: 1. After decoding the band-compressed received voice signal received from the game and converting it to an analog signal, the signal is converted to 2 lines by a 2 / 4-wire circuit. Output to a telephone, inputting the transmitted voice signal and the decoded received voice signal after converting the transmitted voice signal from the telephone into a 4-line by the 2/4 line conversion circuit and then converting it to a digital signal; A remote loopback test method of an echo canceller for canceling an echo generated by a 2/4 wire conversion circuit and an echo canceller of a system for compressing a band of a transmission voice signal from which an echo has been canceled and transmitting it to a station, When a remote loopback test signal is received from a game, a band-compressed audio signal included in the remote loopback test signal or an equivalent pseudo signal (hereinafter referred to as an audio signal) is received. ) Is attenuated to a predetermined level at which the echo canceller can perform a normal echo canceling operation, and then the return means is connected back to the echo canceller in place of the voice signal transmitted from the telephone. Features.

2. A 2 / 4-wire conversion circuit connected to a telephone, an A / D conversion circuit for converting a transmission voice signal from the telephone converted into a 4-wire by the 2 / 4-wire conversion circuit into a digital voice signal, A decoding circuit for restoring a band-compressed telephone digital audio signal received from a game station, a D / A conversion circuit for converting a received digital audio signal decoded by the decoding circuit into an analog audio signal, and the A / D The transmission digital audio signal converted by the conversion circuit and the reception digital audio signal output by the decoding circuit are input, and the echo cancellation operation is performed.
An echo canceller for canceling an echo generated when the analog audio signal converted by the A conversion circuit is converted to two lines by a 2 / 4-wire conversion circuit; and a transmission digital audio signal from which the echo has been canceled by the echo canceller. This is a remote loopback test method for an echo canceller of a system comprising a coding circuit for compressing and transmitting to a station via a transmission path, wherein a control signal for the remote loopback test and a band for a predetermined compression ratio are provided. A remote loopback control signal detection circuit for detecting a control signal when a remote loopback test signal comprising a compressed audio signal or an equivalent pseudo signal (hereinafter referred to as an audio signal) is received from a game; 2/4 wire conversion circuit, the A / D conversion circuit, and the D /
It is located between the A / A conversion circuit and operates with the control signal detection information output by the remote loopback control signal detection circuit, disconnects the 2/4 wire conversion circuit, and outputs the D / A conversion circuit. A loop-back circuit for loop-connecting the analog audio signal to the A / D conversion circuit for a remote loop-back test, and the D / A
An audio signal attenuating circuit for attenuating the analog audio signal output from the conversion circuit for a remote loopback test to a predetermined level at which the echo canceller can perform a normal echo cancellation operation. I do.

3. A 2 / 4-wire conversion circuit to be connected to the telephone, and a transmission analog voice signal from the telephone and a reception analog voice signal received from a game terminal, which are converted into 4-wires by the 2 / 4-wire conversion circuit, are input. , Performs an echo cancellation operation, and converts the received analog voice signal received from the opposite station into a 2 / 4-wire conversion circuit.
A remote loopback test method for an echo canceller of a system comprising an echo canceller for canceling an echo generated when converting to a line, wherein a control signal and an analog voice signal or an equivalent pseudo signal for the remote loopback test are provided. A remote loopback control signal detection circuit for detecting the control signal when a remote loopback test signal comprising a signal (hereinafter referred to as an audio signal) is received from a game station, the 2 / 4-wire conversion circuit, and the echo canceller And operates with the control signal detection information output by the remote loopback control signal detection circuit, disconnects the 2/4 wire conversion circuit, and receives the control signal for the received remote loopback test. A loopback circuit for looping back and connecting an analog audio signal to the echo canceller; And an audio signal attenuating circuit for attenuating the analog audio signal for the remote loopback test to a predetermined level at which the echo canceller can perform a normal echo cancellation operation.

〔Example〕

Next, the present invention will be described with reference to the drawings. 1 and 2 are block diagrams showing an embodiment of the present invention. FIG. 1 shows a 2 / 4-wire conversion circuit 2 for converting an audio input / output signal 1 into a 2-wire type or a 4-wire type, and a remote loopback control signal from a received signal from a game received via a transmission line 10. Remote loopback signal detection circuit 8 for detection
A decoding circuit 6 for decoding the encoded data of the audio signal received from the game, a digital audio signal 12 output from the decoding circuit 6 into an analog audio signal 13, and a 2 / 4-line conversion circuit 2. An A / D and D / A conversion circuit 4 for converting the transmission voice signal converted into a digital voice signal into a digital voice signal, and a remote loopback signal detection circuit 8 for detecting and controlling a remote loopback control signal 11 Operated by A / D, D /
A return circuit 3 for returning the received voice signal converted into an analog signal by the A conversion circuit 4 to a transmission path, a voice signal attenuating circuit 15 for attenuating a predetermined level when the received voice signal is returned, and 2/4
An echo canceller 5 for removing the received voice signal from entering the transmitted voice signal by the line conversion circuit 2, and a transmission voice signal output from the echo canceller 5 is band-compressed to a predetermined compression and transmitted via a transmission line 9. And an encoding circuit 7 for transmitting to the opposite station. FIG. 2 is a block diagram of FIG.
The coding circuit 7, the A / D, and the D / A conversion circuit 4 are removed.

In FIG. 1, description of a normal call is omitted, and an operation at the time of a remote loopback test will be described. When a remote loopback control signal is received from a game station via the transmission line 10, the remote loopback control signal is detected by the remote loopback signal detection circuit 8. On the other hand, the encoded data of the band-compressed audio signal received via the transmission path 10 is decoded by the decoding circuit 6, for example.
64Kbps received voice signal is decoded to 16Kbps, A / D, D / A
The signals are output to the Rin terminals of the conversion circuit 4 and the echo canceller 5, respectively. The received voice signal 12 input to the D / A converter of the A / D and D / A conversion circuit 4 is converted into an analog voice signal and output to the loopback circuit 3. The loopback circuit 3 is activated by the remote loopback control signal 11 detected by the remote loopback signal detection circuit 8, and the analog reception voice signal 13 output by the A / D, D / A conversion circuit 4 is a predetermined voice. The signal is sent back to the A / D conversion unit of the A / D and D / A conversion circuit 4 through the signal attenuating circuit 15 and the transmission voice signal from the 2/4 line conversion circuit. The received voice signal 14 returned to the transmission path is converted into a digital signal and input to the Sin terminal of the echo canceller 5. The echo canceller 5 operates according to the received voice signal input to the Rin terminal and the received voice signal that is turned back to the Sin terminal via the signal attenuating circuit 15 and both correspond to the loss due to the signal attenuating circuit 15. Since there is a level difference (echo margin), a normal echo cancellation operation is performed. The received voice signal from which the echo has been removed by the echo caster 5 is band-compressed to a predetermined compression ratio (for example, 16 Kbps) and transmitted to the opposite terminal via the transmission line 9. The game receives this return signal (there is no sound during normal operation) and completes the loopback test.

Note that the amount of attenuation of the signal attenuating circuit 15 inserted at the time of the return is normally 6 dB or more. (CCITT recommendation G-165) The description of the analog system in FIG. 2 is omitted, but it goes without saying that the same operation as the digital system in FIG. 1 is performed.

In addition, white noise is often used as an audio signal transmitted by a game during a remote loopback test.

〔The invention's effect〕

As described above, according to the present invention, the received voice signal received from the game at the time of the remote loopback test is input to the return echo canceller of the transmission path by giving a predetermined attenuation to the received voice signal. This has the effect of enabling a comprehensive remote loopback test of the system.

[Brief description of the drawings]

1 and 2 are block diagrams showing an embodiment of the present invention.
FIG. 3 is a block diagram showing a conventional example of a remote loopback test system for an echo canceller. 1 ... Audio input / output signal, 2 ... 2/4 wire conversion circuit, 3 ...
Folding circuit, 4 ... A / D, D / A conversion circuit, 5 ... Echo canceller, 6 ... Decoding circuit, 7 ... Encoding circuit, 8 ...
Remote loopback signal detection circuit, 9, 10, transmission line, 11, remote loopback control signal, 13, analog voice signal, 14, loopback voice signal, 15 voice signal attenuation circuit.

Claims (3)

(57) [Claims] 1. A band-compressed received voice signal received from a game station is decoded and converted into an analog signal, then converted into two lines by a 2 / 4-wire circuit, output to a telephone, and transmitted voice from the telephone. The transmission voice signal converted into a digital signal after converting the signal into four lines by the 2/4 line conversion circuit and the decoded reception voice signal are input, and an echo generated by the 2/4 line conversion circuit is input. This is a remote loopback test method of an echo canceller for canceling, and an echo canceller of a system for compressing the transmission voice signal from which the echo has been cancelled and transmitting it to a station, and a remote loopback test signal is received from the station. At this time, the echo canceller normally converts the band-compressed audio signal included in the remote loopback test signal or an equivalent pseudo signal (hereinafter referred to as an audio signal) into a normal echo canceller signal. And a return means for returning to the echo canceller in place of the transmitted voice signal from the telephone after attenuating to a predetermined level at which the operation of the echo canceller is possible. Test method. 2. A 2/4 wire conversion circuit for connecting to a telephone,
A / D conversion circuit for converting the transmission voice signal from the telephone converted to 4-wire by the / 4-line conversion circuit into a digital voice signal, and decoding for restoring the band-compressed reception digital voice signal received from the game station Conversion circuit, a D / A conversion circuit for converting the reception digital voice signal decoded by the decoding circuit into an analog voice signal, a transmission digital voice signal converted by the A / D conversion circuit, and the decoding circuit The received digital audio signal output by the input is input and the echo cancellation operation is performed, and the analog audio signal converted by the D / A conversion circuit is
An echo canceller for canceling the echo generated when converting to two wires by a / 4 wire conversion circuit, and a transmission digital voice signal from which the echo has been canceled by the echo canceller is band-compressed and transmitted to the opposite station via a transmission path. A remote loopback test method for an echo canceller of a system comprising an encoding circuit, wherein a control signal for a remote loopback test and a speech signal band-compressed to a predetermined compression ratio or an equivalent pseudo signal ( A remote loopback control signal detection circuit for detecting the control signal when a remote loopback test signal comprising a remote signal is received from a game station; a 2 / 4-wire conversion circuit; and an A / D converter. Circuit and the D /
It is located between the A / A conversion circuit and operates with the control signal detection information output by the remote loopback control signal detection circuit, disconnects the 2/4 wire conversion circuit, and outputs the D / A conversion circuit. A loop-back circuit for loop-connecting the analog audio signal to the A / D conversion circuit for a remote loop-back test, and the D / A
An audio signal attenuating circuit for attenuating the analog audio signal output from the conversion circuit for a remote loopback test to a predetermined level at which the echo canceller can perform a normal echo cancellation operation. Echo canceller remote loopback test method. 3. A 2 / 4-wire conversion circuit for connecting to a telephone,
A transmission analog voice signal from the telephone and a reception analog voice signal received from a game terminal, which are converted into 4-wires by a / 4-wire conversion circuit, are input, and an echo cancellation operation is performed.
A remote loopback test method for an echo canceller of a system comprising: an echo canceller for canceling an echo generated when a received analog voice signal received from the station is converted into two wires by a 2/4 wire conversion circuit. A remote control for detecting a control signal when a remote loopback test signal comprising a control signal for a loopback test and an analog audio signal or an equivalent pseudo signal (hereinafter referred to as an audio signal) is received from a game station;
A loopback control signal detection circuit, which is located between the 2 / 4-wire conversion circuit and the echo canceller, operates on the control signal detection information output by the remote loopback control signal detection circuit, A loopback circuit for disconnecting the 4-wire conversion circuit and connecting the received analog audio signal for the remote loopback test back to the echo canceller, and for operating the loopback circuit for the remote loopback test. And an audio signal attenuating circuit for attenuating the analog audio signal to a predetermined level at which the echo canceller can perform a normal echo canceling operation.