JPH05244302A - Voice coding decoding device - Google Patents

Abstract

PURPOSE:To attain high speed transmission of a facsimile signal when both a voice signal and the facsimile signal are sent. CONSTITUTION:A voice coder 17, a G3 facsimile demodulator 18, a G3 facsimile signal detector 19, a frame synchronization generator 21, a G3 control frame generator 22 and a multiplexer 23 are arranged in a coding section 12 connecting to an input terminal 11. When a facsimile signal is sent to a digital line 15, a G3 facsimile identification data are integrated in the frame. Furthermore, when G3 facsimile high speed data are sent, a special frame is inserted just before the data and the result is sent. An output of a voice decoder 25 or an output of a G3 facsimile modulator 26 in a decoding section 14 is outputted from a changeover device 29 to an output terminal 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice encoding / decoding device used in a transmission system for transmitting not only voice signals but also facsimile signals.

[0002]

2. Description of the Related Art With the widespread use of digital leased lines, in-house digital networks have been actively constructed. At the same time, the economical efficiency of the line is being pursued, and the voice coding / decoding apparatus is also being reduced in bit rate from this request. However, this reduction in bit rate is performed from the viewpoint of paying attention to the characteristics of the audio signal and not impairing its quality as much as possible. Therefore, there is no particular problem in encoding a voice signal, but there is a problem in that the transmission quality of a non-voice signal such as a facsimile signal is deteriorated. That is, such an encoding is one obstacle when constructing a network that handles telephones and facsimiles without distinction.

In order to solve such a problem, there has been proposed a technique for switching encoders according to a signal to be transmitted. In this proposal, the encoding unit is equipped with a G3 facsimile demodulator in addition to the voice encoder. Where G3
The facsimile demodulator is for converting a G3 facsimile signal defined by CCITT (International Telegraph and Telephone Consultative Committee) into digital data for transmission.

Further, in the proposed apparatus, the decoding section is equipped with a G3 facsimile modulator in addition to the voice decoder.
Then, when the received digital data is G3 facsimile data, the G3 facsimile signal is transmitted by converting it into a modem signal by the G3 facsimile modulator.

[0005]

However, in such a proposed apparatus, it is necessary to add predetermined information to the frame data sent from the transmitting side and transmit the frame data. The information includes information for identifying whether the frame data is voice parameter data or G3 facsimile data, and in the case of G3 facsimile data, information indicating its type (for example, CCITT V21 or V29 / V27ter). , There is information indicating the number of data. Due to the addition of such information, there is a problem that only high-speed facsimile data of 4800 bps or less can be actually transmitted even if the line speed is 8000 bps (bits / second).

Therefore, an object of the present invention is to provide a voice encoding / decoding device capable of transmitting a facsimile signal at a higher speed.

[0007]

According to a first aspect of the present invention, (a) signal discrimination means for discriminating whether an input signal is a voice signal or a facsimile signal, and a voice code for encoding the input voice signal. Converting means, demodulating means for demodulating the inputted facsimile signal, synchronizing signal generating means for generating a frame synchronizing signal when the coded or demodulated signal is incorporated into a frame of a predetermined length and transmitted, and signal discriminating means. And a data transmission means for transmitting identification data for distinguishing it from a voice signal only when it is determined to be a facsimile signal, and (b)
Frame synchronization detecting means connected to the encoding section through a digital line to detect frame synchronization, detecting means for determining whether or not identification data is incorporated in each frame, voice decoding means, and facsimile modulating means. A frame modulated by the facsimile modulating means is output for a frame whose identification data has been incorporated by the detecting means, and a signal decoded by the voice decoding means for a frame not incorporating this identification data. And a decoding unit having a signal output unit for outputting the speech encoding / decoding apparatus.

That is, according to the first aspect of the present invention, a voice signal or a facsimile signal is incorporated in a frame of a predetermined length for transmission, and with respect to the facsimile signal, identification data indicating this is incorporated as an overhead in the frame for transmission. There is.

According to the second aspect of the present invention, when the high-speed facsimile data is incorporated in the frame to be subsequently transmitted instead of the low-speed facsimile data, the special frame is transmitted as the identification data for starting the high-speed facsimile data transmission. The frame transmitting means for starting high-speed facsimile data transmission is arranged in the encoding section, and the decoding section is provided with the frame determining means for discriminating this special frame from other frames.

That is, according to the second aspect of the invention, immediately before the frame for starting the transmission of the high speed facsimile data,
By sending a special control frame indicating the start of transmission of facsimile high-speed data, the number of bits of identification data incorporated in each frame can be suppressed.

The invention according to claim 3 clarifies that the present invention can be applied to, for example, a G3 facsimile signal.

[0012]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 shows the configuration of a speech coding / decoding apparatus according to an embodiment of the present invention. This device includes an encoding unit 12 connected to an input terminal 11 and an output terminal 1
3, and a digital line 15 connecting the coding unit 12 and the decoding unit 14 is connected.

The encoder 12 includes a voice encoder 17, a G3 facsimile demodulator 18 and a G3 facsimile signal detector 19, which are supplied with a signal input from the input terminal 11, a frame synchronization generator 21, and a G3 control. A frame generator 22 and a multiplexer 23 are arranged. That is, if the signal input from the input terminal 11 is a voice signal, it is encoded into a voice parameter by the voice encoder 17 and input to the multiplexer 23. The input signal is G3
If it is a facsimile signal, G3 facsimile demodulator 1
It is converted into facsimile data by 8 and input to the multiplexer 23.

The G3 facsimile signal detector 19 is a G3 facsimile signal detector.
The facsimile signal is detected, and predetermined control is performed according to the detection operation. That is, first, when the input signal is a voice signal, the multiplexer 23 is controlled so that the input from the voice encoder 17 is output to the digital line 15. In the case of a G3 facsimile signal, the multiplexer 23 is controlled so that the input from the G3 facsimile demodulator 18 is output to the digital line 15. In addition, high-speed G3 facsimile signals (CCITT V29 / V2
7 ter) reception is started or the reception of this high-speed signal is ended, the multiplexer 2 outputs the input from the G3 control frame generator 22 to the digital line 15.
3 is controlled.

The frame synchronization generator 21 includes an encoder 12
And the decoding unit 14 generate a synchronization signal for establishing frame synchronization and supply it to the multiplexer 23.

On the other hand, in the decoding unit 14, the digital line 1
The digital data received by the speech decoder 5
5, G3 facsimile modulator 26, G3 control frame detector 27, and frame synchronization detector 28. A switch 29 is arranged on the output side of the voice decoder 25 and the G3 facsimile modulator 26, and this output is supplied to the output terminal 13.

The frame sync detector 28 detects the frame sync of the digital data received from the digital line 15. Based on this frame synchronization, the voice decoder 25, the G3 facsimile modulator 26 and the G3 control frame detector 27 operate respectively.

When the received digital data is a voice parameter, the switch 29 controls the input from the voice decoder 25 to be output to the output terminal 13. Further, if the received digital data is G3 facsimile data, the input from the G3 facsimile modulator 26 is controlled to be output to the output terminal 13.

Further, the G3 control frame detector 27 is
When the control frame is detected, the G3 facsimile modulator 2
6 is notified of the detection. Upon receiving this notification, the G3 facsimile modulator 26 handles the frame data as G3 facsimile high speed data until receiving the notification of the next G3 control frame detection.

2 to 5 show the structure of various frame data having a fixed length. In these drawings, the symbol "S" represents a frame synchronization signal.

FIG. 2 shows the structure of frame data for audio frames. When a voice frame is received from the digital line 15 shown in FIG. 1, the frame synchronization detector 28 also shown in FIG. 1 detects the frame synchronization of the voice frame 31. Based on this,
The speech decoder 25 shown in FIG. 1 reproduces the original speech signal based on the speech parameters using a built-in synthesis filter (not shown).

By the way, the audio frame 31 is not provided with an overhead for distinguishing it from the other frames shown in FIGS. Therefore, the G3 facsimile modulator 26 shown in FIG. 1 cannot detect the overhead in the voice frame 31, and the switch 29 is used by the voice decoder 25.
Will be selected and output to the output terminal 13.

FIG. 3 shows the structure of a G3 facsimile low speed frame. The G3 facsimile low speed frame 32 is composed of a frame synchronization signal S, G3 facsimile identification data, low speed frame identification data and G3 facsimile low speed data.

Digital line 15 to G3 shown in FIG.
When the facsimile low speed frame 32 is received, as shown in FIG.
The frame sync detector 28 shown in FIG. 2 detects frame sync. However, the G3 control frame detector 27
Detects facsimile identification data and low speed frame identification data. Therefore, in this case, the detection of the G3 facsimile low speed frame 32 is determined.
In this state, the G3 facsimile modulator 26 modulates the received digital data into a modem signal, and the switch 29 selects this and sends it to the output terminal 13.

FIG. 4 shows the structure of the G3 control frame. The G3 control frame 33 is composed of a frame synchronization signal S, G3 facsimile identification data, G3 control frame identification data and control data. The G3 control frame 33 is a frame for processing frame data to be received thereafter as a G3 facsimile high speed data frame. That is, the G3 control frame 33 is inserted only when the low-speed data (CCITT: V21) frame is switched to the high-speed data (CCITT: V29 / V27ter) frame on the encoding unit 12 side shown in FIG. 1 or vice versa. It is supposed to be done.

FIG. 5 shows the structure of a G3 facsimile high speed frame. The G3 control frame 33 includes a frame synchronization signal S, G3 facsimile identification data and G3 facsimile high speed data. As described above, the G3 facsimile high-speed frame 34 itself does not have a data structure that directly indicates that it is a high-speed frame, and the processing of the frame differs depending on whether the G3 control frame 33 is arranged before this.
Also in the case of the G3 facsimile high-speed frame 34, the G3 facsimile modulator 26 modulates the received digital data into a modem signal, and the switch 29 selects this and sends it to the output terminal 13.

In the embodiment described above, the G3 control frame is arranged at the head of the G3 facsimile high speed frame. Therefore, the control overhead of the G3 facsimile high-speed frame can be reduced. In this embodiment, each of the frames 31 to 34 shown in FIGS. 2 to 5 is composed of 160 bits, and the G3 facsimile high speed data is composed of 144 bits. This gives 8000
It has become possible to transmit 7200 bps G3 facsimile high-speed data to a bps line.

[0029]

As described above, according to the first aspect of the invention, since the overhead is not arranged in the voice frame, the voice parameter can be efficiently transmitted.

According to the second aspect of the present invention, if the control frame indicating that the data frame is a high-speed data frame is transmitted only once, all the subsequent data frames are processed as the facsimile high-speed frame.
The control overhead in the high-speed facsimile frame can be reduced, and the high-speed facsimile data can be transmitted at high speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a circuit configuration of a speech encoding / decoding device according to an embodiment of the present invention.

FIG. 2 is a frame configuration diagram showing a configuration of an audio frame in the present embodiment.

FIG. 3 is a frame configuration diagram showing a configuration of a G3 facsimile low speed frame in the present embodiment.

FIG. 4 is a frame configuration diagram showing a configuration of a G3 control frame in the present embodiment.

FIG. 5 is a frame configuration diagram showing a configuration of a G3 facsimile high speed frame in the present embodiment.

[Explanation of symbols]

 11 Input Terminal 12 Encoding Unit 13 Output Terminal 14 Decoding Unit 17 Voice Encoder 18 G3 Facsimile Demodulator 19 G3 Facsimile Signal Detector 22 G3 Control Frame Generator 23 Multiplexer 25 Voice Decoder 26 G3 Facsimile Modulator 27 G3 control frame detector 28 frame synchronization detector 29 switcher

Claims (3)

[Claims] 1. A signal discriminating means for discriminating whether an input signal is a voice signal or a facsimile signal, a voice encoding means for encoding the input voice signal, and a demodulating means for demodulating the input facsimile signal. , A sync signal generating means for generating a frame sync signal when a coded or demodulated signal is incorporated in a frame of a predetermined length for transmission, and a voice signal only when the signal discrimination means discriminates a facsimile signal Of the identification data of the frame signal and a data transmission means for transmitting the frame data, a frame synchronization detecting means for detecting frame synchronization, which is connected to the encoding portion through a digital line, and a frame synchronization detecting means for each frame. Detection means for determining whether or not the identification data is incorporated, voice decoding means, facsimile modulation means, For the frame judged by the detection means to incorporate the identification data, a signal modulated by the facsimile modulation means is outputted, and for the frame in which the identification data is not incorporated, it is decoded by the voice decoding means. And a signal output means for outputting the signal. 2. When a high speed facsimile data is incorporated in a frame to be subsequently transmitted instead of the low speed facsimile data, a special high speed data transmission for transmitting a special frame using the identification data as identification data for starting the high speed facsimile data transmission is started. 2. The speech coding according to claim 1, wherein the frame transmission means is arranged in the coding section, and the decoding section is provided with frame judgment means for distinguishing between the special frame and other frames. Decoding device. 3. The voice encoding / decoding apparatus according to claim 1, wherein the facsimile signal is a G3 facsimile signal.