JPS611129A - Multiplex transmission system of voice and data - Google Patents

Abstract

PURPOSE:To attain sure switching from voice transmission to data transmission allowing a comparator to transmit silence detecting information to a data terminal equipment and allowing the data terminal equipment to transmit a data signal to a voice band line when intensity information from a threshold value level is small. CONSTITUTION:Only the intensity information (6-bit) among frame format signals is selected by a serial/parallel converter CONV placed while being branched from a low speed coding section CODER output line, converted into a parallel signal and inputted to a comparator circuit COMP. On the other hand, a threshold level (binary code 6-bit) is set to a threshold value setting panel SET in advance manually and inputted to the circuit COMP. The intensity information being an output of the converter CONV and the threshold level being an output of the set panel SET are compared by the circuit COMP. When the intensity information is smaller than the threshold level, the circuit COMP transmits the silence detection information to the data terminal equipment DTE, which transmits a data signal to a voice band line via a hybrid H of a data multiplex section MPX'.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a communication system that multiplexes and transmits low-speed encoded audio signals and data using a communication line in the audio band (0.3 to 3.4 KHz). The present invention relates to a method for inserting data during silence in a low-speed encoded audio signal.

[Conventional technology]

When an audio signal is digitized into a low-speed encoded signal and transmitted using a voice band communication line, the audio signal naturally has silent parts, so it is necessary to insert other data into these silent parts and transmit it. is being carried out. Statistical multiplexing transmission like this is an effective method for making effective use of lines.

FIG. 2 is a schematic diagram of a conventional transmitting side in the case of multiplexing transmission of a low-speed encoded voice signal and data.

In the figure, DTE is a data terminal, C0DER is a voice low-speed encoder, MPX is a voice/data multiplexer, and L
INE is a railroad track. The same symbols represent the same objects throughout all the figures below.

The analog voice signal output from the telephone device is converted into a low-speed code by the voice low-speed encoder C0DER and sent to the voice/data multiplexer MPX.

The audio/data multiplexing unit MPX has a function of detecting silent parts included in audio, and when detecting a silent part, sends silence detection information to the data terminal DTE, and sends the silence detection information to the data terminal DTP.
Upon receiving this silence detection information, it immediately sends the data to the voice band line via the voice/data multiplexer MPX and modem (not shown).

This method of transmitting data using the silent portion of the audio signal is an economical communication method, especially when the line price is high.

[Problem that the invention seeks to solve]

In the conventional communication system of this type, a function is added to the audio/data multiplexing unit MPX to detect silent parts included in audio, and when a silent part is detected, data is transmitted. When there is a sound part, the audio signal is transmitted sideways.

However, since the level of audio fluctuates from moment to moment, conventional PCs
In the conventional method, which detects that the output of the audio low-speed encoder C0DER consisting of an A-D converter used in M communication equipment is smaller than a specified value and considers it as a silent section, switching is frequently performed. The method to solve the drawback of not being able to send a large amount of data is to transmit the voice as a low-speed encoded signal over the voice band line, and insert other data during silent periods of the call. In the communication method that
A speech analysis device using a linear predictive coding method is used in the low-speed encoding section, and the intensity information output from the speech analysis device using the linear predictive coding method is compared with a threshold value manually set from the outside. This is achieved by a voice/data multiplex transmission method that transmits silence detection information and inserts data when the threshold value is smaller than the threshold value.

[Effect]

According to the present invention, audio intensity information is extracted using a linear predictive coding method, this intensity information is compared with a threshold value manually set from the outside, and silence detection information is transmitted and data insertion begins. Therefore, the switching from voice transmission to data transmission becomes reliable, and the probability of switching back to data transmission immediately after switching as in the conventional method is greatly reduced, resulting in the effect of increasing the stability of the system.

〔Example〕

In the present invention, as the audio low-speed encoding unit C0DER, the most efficient linear predictive encoding method (
LPC method) is used.

This LPC method is a method recently developed in the field of speech recognition. After A'-D converting analog audio, it extracts spectral envelope information and sound source information, and then extracts voiced/unvoiced information from the sound source information. This is one of the voice analysis methods that extracts pitch period information and intensity information.

As is well known, the frame format of the LPC system is spectral envelope information @ (parameter); 34 to 35 bits.
Voiced/unvoiced switching, pitch period information; 5-bit strength information (binary code); 6-bit synchronization signal
;1btt. The voiced/unvoiced switching information consists of 1 bit, and the pinch period information consists of 5 bits.

The frame period is 20 m5 (50 Hz), so the transmission speed of low-speed codes is 2400 bps (48 bits).
t x 50Hz).

In the present invention, as described above, the LPC type voice analysis device is used as the voice low-speed encoder C0DER, and the serial format LPC type frame format signal is sent to the line via the voice/data multiplexing unit according to the present invention. Send to LINE.

FIG. 1 is a schematic diagram showing an embodiment of an audio data multiplex transmission system according to the present invention.

In the figure, MPX' is an audio data multiplexing unit according to the present invention;
C0NV is a serial/parallel converter, COMP is a comparison circuit, S
ET is a threshold setting board, H is a hybrid.

In the audio/data multiplexer MPX' according to the present invention, the serial format LP of the audio low-speed encoder C0DER output
When performing voice communication, the frame format signal of the C system is sent to the other party's station via the hybrid H.

In order to detect silent parts, as shown in Fig. 1, the audio low-speed encoder C
A serial/parallel converter CONV is branched to the 0DER output line.

In the serial/parallel converter C0NV, only the intensity information (6 bits) is selected from the frame format signal, converted into a parallel signal, and inputted to the comparison circuit GOMP.

A threshold level (6-bit binary code) is manually set in advance on the two-way threshold setting board SET, and is input to the comparison circuit COMP.

The comparison circuit COMP is a circuit that compares the magnitude of two parallel binary code 6-bit signals.
Output intensity information @ (6 bits) and Threshold setting board SET output threshold level (6 bits)
are compared in size.

If the intensity information is smaller than the set threshold level, the comparator circuit COMP sends silence detection information to the data terminal DTE, and the data terminal DTE
The data signal is sent out to the voice band line via the hybrid H in the data multiplexer MPX'.

〔Effect of the invention〕

As explained in detail above, according to the present invention, switching from voice transmission to data transmission is ensured, and the probability of switching back immediately after switching to data transmission as in the conventional method is greatly reduced. This has the effect of increasing stability.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of an audio data multiplex transmission system according to the present invention. Figure 2 shows multiplexed transmission of low-speed encoded voice signals and data.
FIG. 2 is a schematic diagram of a conventional transmitting side when In the figure, DTE is a data terminal, C0DER is a voice low-speed encoder, MPX is a voice/data multiplexer, and L
INE is a line, MPX' is an audio/data multiplexer according to the present invention, CON and V are serial/parallel converters, COMP is a comparison circuit, SET is a threshold setting board, and H is a hybrid.

Claims (1)

[Claims] Transmits voice as a low-speed encoded signal to a voice band line,
In a communication method that inserts and transmits other data during silent periods of a call, a voice analysis device using a linear predictive coding method is used in the low-speed encoding section, and the output of the speech analysis device using the linear predictive coding method is used. An audio/data multiplex transmission method characterized by comparing certain intensity information with a threshold value manually set from the outside, and transmitting silence detection information and inserting data when the intensity information is smaller than the threshold value. .