JPH09168001A - Composite telephone system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize a frequency by sending a voice signal and an image signal through a same line. SOLUTION: A transmitter side is provided with a VAD section 16 detecting a period of voice/silence of a voice signal and a multiplexer section 18 inserting image data to a non-voice period of voice data based on an identification signal from the VAD section 16 and sending the resulting signal, and a receiver side is provided with a demultiplexer section 22 demultiplexing the voice data and the image data, inserting blank data corresponding to the image data to the voice data, preventing timewise deviation of the voice signal and providing an output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite telephone system for multiplex transmission of voice data and image data, and more particularly, to a composite telephone capable of transmitting voice and images on the same line and effectively using frequencies. Regarding the system.

[0002]

2. Description of the Related Art A composite telephone system is a multiplex transmission system for simultaneously transmitting data such as voice, moving images, still images and facsimiles. In the conventional compound telephone system, the modulation method is different between the voice signal and the image signal of the moving image, the still image, the facsimile, etc. Therefore, each modulator is provided with an independent modulator and demodulator, and different lines are allocated for transmission. It was supposed to do.

[0003]

However, in the above-mentioned conventional composite telephone system, since the voice signal and the image signal are transmitted using different lines, the occupied frequency band is widened, and the frequency is effective in the entire system. There was a problem that it could not be used for.

Further, in the conventional composite telephone system, since a voice signal is transmitted regardless of the presence or absence of voice, there is a problem that useless information is transmitted in the case of no voice.

The present invention has been made in view of the above situation, and it is possible to eliminate wasteful transmission of non-voice information, transmit voice signals and image signals through the same line, and effectively use frequencies. The purpose is to provide a composite telephone system.

[0006]

The invention according to claim 1 for solving the problems of the conventional example is to synthesize transmission data in which a video signal is inserted in a non-voice section of a voice signal in a composite telephone system. The present invention is characterized in that it has a transmitting device for transmitting as described above, and wasteful transmission of a non-voice signal can be eliminated, a voice signal and an image signal can be transmitted on the same line, and frequency can be effectively used.

According to a second aspect of the present invention for solving the above-mentioned problems of the conventional example, in a composite telephone system, a voice signal and an image signal are separated from received transmission data, and a section of the image signal is a blank voice. It is characterized by having a receiving device that outputs the separated audio signal and the separated audio signal and the blank audio signal as a signal, and the audio signal and the image signal are transmitted from the transmission data transmitted through the same line. It is possible to eliminate the time lag of the audio signal when separating and outputting.

According to a third aspect of the present invention for solving the above-mentioned problems of the conventional example, a voice input unit for inputting voice and a voice signal for encoding the voice signal from the voice input unit in a composite telephone system. An encoding unit, an audio signal memory unit for accumulating the encoded audio signal, an audio detection unit for detecting a voiced section and a non-voiced section in the encoded audio signal, and an image are input. An image input unit, an image signal encoding unit that encodes the image signal from the image input unit,
An image signal memory unit that stores the encoded image signal, and an audio signal is read from the audio signal memory unit when the audio detection unit detects that a voiced section exists, and the audio detection unit does not detect the audio signal. When it is detected that it is a voice section, the image signal is read from the image signal memory unit, the multiplexing unit that synthesizes the read voice signal and the image signal as transmission data, and the transmission data is modulated and output to the transmission path. The present invention is characterized in that it has a transmission device including a modulation section that operates to eliminate unnecessary transmission of a non-voice signal, and can transmit a voice signal and an image signal on the same line, thereby achieving effective use of frequency. You can

According to a fourth aspect of the present invention for solving the above-mentioned problems of the conventional example, in the composite telephone system according to the third aspect, the voice signal memory section for the time required for voice detection by the voice detection section is provided. The transmission device synchronizes the voice detection unit and the voice signal memory unit by delaying the accumulation of the voice signal, and can prevent the voice from being cut off at the receiving side.

According to a fifth aspect of the present invention for solving the above-mentioned problems of the conventional example, in the composite telephone system according to the third aspect, the image signal memory section can store images of two or more screens. When the multiplexing unit reads the image signal for one screen from the image signal memory unit, the image signal encoding unit is a transmission device that encodes the image signal of the next screen, and is always characterized in that You can capture the latest image and send it.

According to a sixth aspect of the present invention for solving the above-mentioned problems of the conventional example, in the composite telephone system according to the third aspect, the image signal encoding section always encodes the input image signal. The coded image signal is stored in the image signal memory unit, and the multiplexing unit is a transmission device that reads the latest image stored in the image signal memory unit at the timing of outputting the transmission data to the modulation unit. The latest image can always be captured and sent.

According to a seventh aspect of the present invention for solving the above-mentioned problems of the conventional example, a demodulation unit for receiving and demodulating transmission data from a transmission line, and an image signal and an audio signal are separated from the transmission data, A separation unit that outputs a blank audio signal in the section of the image signal; an image memory unit that stores the separated image signal; an image signal decoding unit that decodes the image signal of the image memory unit; An image output unit that outputs a decoded image signal, an audio signal decoding unit that decodes the separated audio signal and the blank audio signal, and an audio output unit that outputs the decoded audio signal. It is characterized in that it has a receiving device provided with, and when the audio signal and the image signal are separated and output from the transmission data transmitted through the same line, the time difference of the audio signal can be eliminated.

According to the invention of claim 8 for solving the problems of the conventional example, in the composite telephone system according to claim 7, the image memory section is capable of accumulating images of two or more screens, and an image signal. The decoding unit is a receiving device that repeatedly outputs the image output to the image output unit until the next image signal for one screen is accumulated in the image memory unit, and the image and the sound are appropriate. Can be output to.

According to a ninth aspect of the present invention for solving the above-mentioned problems of the conventional example, in a composite telephone system, a transmitting / receiving device including each part of the transmitting device of claim 3 and each part of the receiving device of claim 7 is provided. It is possible to eliminate wasteful transmission / reception of a non-voice signal, to transmit / receive a voice signal and an image signal on the same line, and to effectively use frequencies.

[0015]

Embodiments of the present invention will be described with reference to the drawings. A composite telephone system (this system) according to an embodiment of the present invention performs coding so that an image signal can be transmitted in a frequency band equivalent to a voice signal at a transmitting side, and a VAD (Voice Activity Detector) is provided.
Section is provided to detect the voiced / unvoiced section of the voice signal,
By inserting and transmitting an image signal in the non-voice section of an audio signal, the audio signal and the image signal can be transmitted on the same line, and the occupied frequency band can be narrowed to achieve effective use of frequencies. It was made possible.

First, a transmitting device of a composite telephone system according to an embodiment of the present invention will be described with reference to FIG. FIG.
It is a functional block diagram of a transmitting device used in the composite telephone system (present system) according to the embodiment of the present invention. As shown in FIG. 1, the transmitter of this system is
A voice input unit 11 for inputting voice, a voice signal encoding unit 13 for converting an analog voice signal into a digital voice signal (voice data), a voice signal memory unit 15 for temporarily storing voice data, and a voice signal VAD unit 16 for detecting voiced / unvoiced sections, and image input unit 12 for capturing images
, An image signal encoding unit 14 for converting an analog image signal into a digital image signal (image data), an image signal memory unit 17 for temporarily storing image data, a composite of voice data and image data, and transmission. It is composed of a multiplexing unit 18 for creating credit composite data and a modulator 19 for modulating the composite data and outputting the modulated data to a transmission path.

Next, each component will be specifically described. Here, a case where a moving image is transmitted as an image signal will be described. The voice signal encoding unit 13 converts the analog voice signal input from the voice input unit 11 into a digital voice signal (voice data), and the converted digital voice signal is stored in the voice signal memory unit 15 and the VAD unit 16. Is output to and.

VAD (Voice Activity Detector) unit 1
6 identifies the voiced section and the non-voiced section from the input and encoded voice signal, and outputs an identification signal indicating “voiced” or “non-voiced” to the multiplexing unit 18. Is. For example, if the input digital voice signal is voiced, "1" is output, and if it is not voiced, "0" is output.

The image input section 12 is for inputting an image, and uses an image pickup device such as a camera for a moving image and an image reading device such as a scanner for a still image or a facsimile image. The audio signal memory unit 15 temporarily stores the digital audio signal (audio data) received from the audio signal encoding unit 13 and outputs the digital audio signal to the multiplexing unit 18. At that time, in the voice signal memory unit 15, the VAD unit 16 delays the voice data by the time required for detecting the voiced / non-voiced section. As a result, the voice data read by the multiplexing unit 18 and the identification signal from the VAD unit 16 can be synchronized with each other, and the voice can be prevented from being cut off.

The image signal encoding unit 14 encodes the analog image signal input from the image input unit 12 including a video camera and converts it into a digital image signal (image data). When transmitting a moving image as an image signal, the image signal encoding unit 14 uses an image information compression technique including a quasi-moving image compression of 10 kbps as an encoding system such as the MPEG system. As a result, the frequency band required for transmitting the image signal can be made substantially equal to the band for the audio signal, and it is possible to transmit using the same line as the audio signal.

The image signal memory unit 17 temporarily stores the encoded image data and outputs it to the multiplexing unit 18, so that the image data for at least two screens can be stored. Has become.

The multiplexing unit 18 synthesizes the audio data from the audio signal memory unit 15 and the image data from the image signal memory unit 17 on the basis of the identification signal from the VAD unit 16 for transmission. Is to create composite data of.
Specifically, when the identification signal from the VAD unit 16 is “voiced”, the multiplexing unit 18 extracts the voice data from the voice signal memory unit 15 and also outputs the voice data from the VAD unit 16. When the identification signal is “non-voice”, the image data from the image signal memory unit 17 is extracted, and the extracted data is combined to be combined data for transmission.
Then, the combined data created by the multiplexing unit 18 is sent to the modulating unit 19, modulated, and output to the transmission path.

That is, in this system, when the voice data is "voiced", voice is transmitted, and conversely, "voiceless".
In this case, the image is transmitted, and the unnecessary transmission of the non-voice information is eliminated, and the image data is inserted in the non-voice portion and transmitted, so that the voice and the image can be transmitted on the same line. is there. In addition, the multiplexing unit 18 also inserts a signal sequence necessary for distinguishing a voice and an image on the receiving side when synthesizing synthetic data.

Next, the operation of the transmitting apparatus shown in FIG. 1 will be specifically described with reference to FIG. FIG. 2 is a timing chart showing the operation of the transmitter shown in FIG.
First, FIG. 2B shows a digital audio signal (audio data) encoded by the audio signal encoding unit 13.
Here, A1, A2, and A3 indicate a voiced section, and B
1, B2, and B3 indicate a non-voice section.

When the voice data of FIG. 2B is input to the VAD unit 16, the VAD unit 16 outputs the identification signal shown in FIG. 2C to the multiplexing unit 18. Where C1, C
2 and C3 are identification signals of "voiced" and are D1 and D2.
Is an identification signal of "no voice". And the VAD unit 1
The voiced / unvoiced discrimination signal from 6 is output with a delay of time t from the signal in (b).

FIG. 2D shows the audio data stored in the audio signal memory section 15. As described above, the audio signal memory unit 15 delays the input audio data by the time t in order to synchronize the identification signal from the VAD unit 16 with the audio data. Therefore, the voiced sections A1, A2, A3 shown in (b) are
In (d), the audio data is delayed by time t and stored as audio data E1, E2, E3, respectively. Further, F1 and F2 are non-voice sections corresponding to B1 and B2 in (b), respectively.

Further, FIG. 2E shows image data stored in the image signal memory section 17, and is G1 to G5.
Each indicate image data for one screen.

Then, the multiplexing unit 18 shows the voice data corresponding to the section of "voiced" in (d) based on the identification signal shown in (c), as shown in FIG. 2 (f). The audio data is extracted and output to the modulator 19. In (f), the combined data output from the multiplexing unit 18 is shown. For example, the multiplexing unit 18 uses the identification signal C1 of (c).
When "(voiced)" is input, the voice signal memory unit 1
The audio data E1 of (d) is fetched from 5 and is output to the modulator 19 as shown in (f).

As shown in (c), the multiplexing unit 18 outputs V
The identification signal from the AD unit 16 changes from "voiced" to "voiceless"
Image signal memory unit 17 shown in FIG.
The image data is fetched from the data inside, inserted after the audio data, and output to the modulator 19. For example, when the identification signal changes from C1 (“voiced”) to D1 (“voiceless”), the image data G1 is read and the voice data E is read.
The image data G1 is output after 1 (see (f)).

Further, in the multiplexing unit 18, before the insertion of the entire one screen is completed while the image data is being captured,
When the identification signal of (c) is switched to "voiced", it is switched to audio data even in the middle of the image data, and the remaining image data is taken in during the next unvoiced section. In the example of FIG. 2, the image data G2 and G4 are divided and inserted. In this way, the multiplexing unit 1
Reference numeral 8 is for obtaining composite data in which image data is inserted in the non-voice section of the audio data, and the composite data is modulated by the modulator 19 and transmitted.

However, as an exception, the data to be first transmitted from the transmitting side to the receiving side is for one screen of image data. As a result, the image data for at least one screen is surely transmitted, and even if the subsequent image data is inserted into the non-voice section and transmitted according to the above-described operation, no image appears on the receiving side. The situation can be prevented.

Here, a method of capturing image data in the transmission device of this system will be described with reference to FIGS. 2 (f) and 2 (a).
This will be described with reference to FIG. In the transmitter of this system, (f)
As shown in (a) and (a), immediately after the output of the image data is started in the multiplexing unit 18, the image signal encoding unit 14
In, the acquisition (encoding) of the image data for the next one screen is started. For example, when the output of the image data G1 is started in the multiplexing unit 18, the image signal encoding unit 14 starts the encoding of the analog image signal G2 and stores the image data G2 in the image signal memory unit 17. It is like this. As a result, the latest image can always be captured and transmitted.

As another method, the image signal encoding unit 14 always encodes the input analog image signal and stores it in the image signal memory unit 17,
The multiplexing unit 18 may fetch the latest one screen of image data from the image signal memory unit 17 in synchronization with the transmission timing of the image data.

Then, the multiplexing unit 18 adds data for distinguishing the voice and the image when creating the synthetic data from the voice data and the image data, but here, for simplicity of explanation, Omitted.

Next, the receiving device in the composite telephone system according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a configuration block diagram of a receiving device used in this system. As shown in FIG. 3, the receiving device in the present system is separated into a demodulation unit 21 that demodulates a received signal received from a transmission line, and a separation unit 22 that separates audio data and image data from the received combined data. An image memory unit 23 for storing image signals, an image signal decoding unit 24 for decoding image data, an image output unit 25 for outputting image data, and an audio signal decoding for decoding separated audio data. It is composed of a unit 26 and a voice output unit 27 that outputs a voice.

The characteristic part of the receiving apparatus will be specifically described. The separation unit 22 separates the audio data and the image data based on the data that distinguishes the audio and the image added to the received data, sends the audio data to the audio signal decoding unit 26, and outputs the image data. Image memory unit 23
To be sent.

Here, when the image data is input, the separating unit 22 sends blank data for a time corresponding to the image data to the audio signal decoding unit 26 as audio data. That is, since the image data is inserted by the amount corresponding to the non-voice section of the voice, if a blank for the image data is inserted as the voice data, a blank equal to the non-voice section is inserted. It is designed to prevent the time lag of. Since the non-voice section is a section that does not originally contain voice information, it is perfectly acceptable to insert a blank on the receiving side.

The image memory unit 23 is for temporarily storing the received image data, and has a capacity for storing at least two screens of the image data. Then, the image memory unit 23 outputs the image data for one screen to the image signal decoding unit 24 when the image for one screen is accumulated, and the same image is stored until the next one screen is accumulated. It continues to output data.

The image signal decoding unit 24 decodes the image data received from the image memory unit 23 by the same method as that used in the image signal encoding unit 14 on the transmission side, and outputs the image. The data is output to the monitor of the unit 25. In the above example, the case where the image data is a moving image has been described, but in the case of a facsimile image, an output unit that prints out on paper or the like may be used. The audio signal decoding unit 26 decodes the audio data sent from the separation unit 22 and outputs it as audio to the speaker of the audio output unit 27.

Next, the operation of the receiving apparatus will be described. When the receiving device according to the present system receives a signal from the transmission path, the receiving device demodulates it in the demodulating unit 21, and the separating unit 2
In 2 the image data and the audio data are separated, the image data is sent to the image memory unit 23, the audio data is sent to the audio signal decoding unit 26, and a blank corresponding to the image data is sent as audio data. Output to the signal decoding unit 26.

Then, the image data is the image signal decoding unit 2
4 is decoded and output to the image output unit 25, and the audio data is decoded by the audio signal decoding unit 26 and output to the audio output unit 27. In this way, the operation of the receiving device in this system is performed.

Next, a transmission / reception device used in the composite telephone system according to the embodiment of the present invention will be described with reference to FIG. FIG. 4 is a configuration block diagram of a transmission / reception device in this system. As shown in FIG. 4, the configuration of the transmission / reception device of the present system has the functions of both a transmission device and a reception device, and the transmission device shown in FIG. 1 and the reception device shown in FIG. 3 are combined. It is composed.

That is, the left half of FIG. 4 is the transmitter,
The configuration is the same as that of each component in the transmitter of FIG. Further, the right half of FIG. 4 is a receiving unit, which has the same configuration as each component of the receiving apparatus shown in FIG. Then, at the time of transmission, the same operation as the transmitting apparatus shown in FIG. 1 is performed, and at the time of receiving, the same operation as the receiving apparatus shown in FIG. 3 is performed.

The memory unit 20 is a combination of the functions of the audio signal memory unit 15 and the image signal memory unit 17 in the transmitter of FIG. 1 and the image memory unit 23 of the receiver of FIG. , The transmission voice data, the transmission image data, and the reception image data are provided.

According to the composite telephone system (present system) of the embodiment of the present invention, the image signal encoding unit 14 for encoding the image signal so that it can be transmitted in the frequency band equivalent to the voice signal to the transmitting side, A VAD unit 16 which detects a voiced / unvoiced section of a voice signal and outputs an identification signal,
Since the multiplexing section 18 for inserting and transmitting image data in the non-voice section of the voice data based on the identification signal from the section 16 is provided, wasteful transmission of the non-voice signal is eliminated, and the voice signal and the image are transmitted. The signal and the same line can be transmitted,
There is an effect that the frequency can be effectively used.

Further, according to the present system, the receiving side separating section 22 separates the audio data from the image data, and further inserts a blank corresponding to the image data into the audio data. There is an effect that the image signal and the audio signal can be separately output on the receiving side, and the audio signal can be output while preventing a time lag.

Further, since the transmitting side is provided with the voice signal memory section 15 for delaying the voice signal in accordance with the output of the identification signal from the VAD section 16, the VAD section 16 is provided.
And the voice data in the voice signal memory section 15 can be synchronized with each other, and it is possible to prevent the voice from being cut off at the receiving side.

Furthermore, on the transmitting side, the multiplexing unit 18
Since the image signal encoding unit 14 captures the image immediately after the output of the image data for one screen is started, the latest image data can be captured at the image transmission timing. .

Further, the data transmitted first from the transmitting side is for one screen of image data, and on the receiving side, the data for one screen that has already been stored is stored until the image data for the next one screen is stored. Is repeatedly output, there is an effect that the phenomenon that an image is not output on the receiving side can be prevented.

[0050]

According to the invention described in claim 1, since the transmitting device is a compound telephone system which inserts an image signal into a voiceless section of a voice signal to synthesize transmission data and transmits the composite data, the voiceless signal is transmitted. It is possible to eliminate wasteful transmission of the data, to transmit the audio signal and the image signal on the same line, and to effectively use the frequency.

According to the second aspect of the invention, the receiving device separates the audio signal and the image signal from the received transmission data, sets the interval of the image signal as a blank audio signal, and outputs the separated image signal, Since it is a composite telephone system that outputs a separated voice signal and a blank voice signal,
When separating and outputting the audio signal and the image signal from the transmission data transmitted on the same line, there is an effect that a time lag of the audio signal can be eliminated.

According to the third aspect of the invention, the voice detecting section detects the voiced section and the non-voiced section from the voice signal, and the multiplexing section reads the voice signal from the voice signal memory section. In the non-voice section, since the composite telephone system has a transmitter that reads an image signal from the image signal memory section and synthesizes it, and modulates the synthesized transmission data in the modulating section and outputs it to the transmission path, There is an effect that the wasteful transmission can be eliminated, the voice signal and the image signal can be transmitted through the same line, and the frequency can be effectively used.

According to the invention described in claim 4, the accumulation of the audio signal in the audio signal memory unit is delayed by the time required for the audio detection in the audio detection unit, and the audio detection unit and the audio signal memory unit are delayed. Since the composite telephone system according to claim 3 has a transmitting device for synchronizing with, there is an effect that it is possible to prevent the voice from being cut off at the receiving side.

According to the fifth aspect of the invention, when the multiplexing unit reads the image signal for one screen from the image signal memory unit, the image signal encoding unit encodes the image signal for the next screen. Since the composite telephone system according to claim 3 is provided with the transmitting device, there is an effect that the latest image can be always captured and transmitted.

According to the sixth aspect of the present invention, the image signal coding section in the image signal memory section always codes the input image signal to store the coded image signal, and the multiplexing section. However, since the composite telephone system according to claim 3 has a transmission device for reading the latest image stored in the image signal memory unit at the timing of outputting the transmission data to the modulation unit, the latest image can always be captured and transmitted. effective.

According to the seventh aspect of the invention, the separation unit separates the audio signal and the image signal, outputs a blank audio signal in the section of the image signal, and the image signal decoding unit decodes the image signal. Is output to the image output unit, and the combined telephone system has a receiving device that decodes the voice signal separated by the voice decoding unit and the blank voice signal and outputs the decoded voice signal to the voice output unit. When separating the audio signal and the image signal from the transmission data and outputting the separated signals, it is possible to eliminate the time lag of the audio signal.

According to the present invention, the image signal decoding unit repeatedly outputs the image output to the image output unit until the image signal for the next one screen is stored in the image memory unit. Since the composite telephone system according to claim 7 is provided with a device, there is an effect that images and sounds can be properly output.

According to the ninth aspect of the invention, there is provided a composite telephone system having a transmitting / receiving device including each part of the transmitting device of claim 3 and each part of the receiving device of claim 7.
It is possible to eliminate wasteful transmission / reception of a non-voice signal, to transmit / receive a voice signal and an image signal on the same line, and to effectively use the frequency.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a transmission device used in a composite telephone system (present system) according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the transmitting device shown in FIG.

FIG. 3 is a configuration block diagram of a receiving device used in the present system.

FIG. 4 is a configuration block diagram of a transmission / reception device in the present system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Audio input part, 12 ... Image input part, 13 ... Audio signal encoding part, 14 ... Image signal encoding part, 15 ... Audio signal memory part, 16 ... VAD part, 17 ... Image signal memory part, 18 … Multiplexing unit, 19… Modulating unit,
20 ... Memory part, 21 ... Demodulation part, 22 ... Separation part,
23 ... Memory unit, 24 ... Image signal decoding unit, 25 ...
Image output unit, 26 ... Audio signal decoding unit, 27 ... Audio output unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 7/14

Claims (9)

[Claims] 1. A composite telephone system comprising a transmission device for synthesizing and transmitting transmission data in which an image signal is inserted in a non-voice section of a voice signal. 2. An audio signal and an image signal are separated from the received transmission data, a section of the image signal is set as a blank audio signal, and the output of the separated image signal and the separated audio signal and the blank audio signal. A composite telephone system having a receiving device for outputting the above. 3. A voice input unit for inputting voice, a voice signal encoding unit for encoding the voice signal from the voice input unit, and a voice signal memory unit for accumulating the encoded voice signal. A voice detection unit that detects a voiced section and a non-voiced section in the encoded voice signal, an image input unit that inputs an image, and an image signal encoding unit that encodes the image signal from the image input unit. An image signal memory section for accumulating the encoded image signal; and a voice signal read from the voice signal memory section when the voice detecting section detects a voiced section, and the voice detecting section. When it is detected that there is no voice section in the image signal, the image signal is read from the image signal memory unit, and the multiplexing unit for synthesizing the read audio signal and the image signal as transmission data and the transmission data by modulating the transmission data. Output to A composite telephone system having a transmitting device having an adjusting section. 4. The accumulation of the audio signal in the audio signal memory section is delayed by the time required for the audio detection section to detect the audio,
The composite telephone system according to claim 3, wherein the transmission device synchronizes the voice detection unit and the voice signal memory unit. 5. The image signal memory unit is capable of accumulating images of two or more screens, and when the multiplexing unit reads an image signal for one screen from the image signal memory unit, the image signal encoding unit 4. The composite telephone system according to claim 3, wherein is a transmitter for encoding the image signal of the next screen. 6. The image signal encoding section always encodes the input image signal and stores the encoded image signal in the image signal memory section, and the multiplexing section outputs the transmission data to the modulation section. The composite telephone system according to claim 3, wherein the composite telephone system is a transmission device that reads the latest image stored in the image signal memory unit at a timing. 7. A demodulation unit that receives transmission data from a transmission line and demodulates it, and a separation unit that separates an image signal and an audio signal from the transmission data and outputs a blank audio signal in the section of the image signal. An image memory unit that stores the separated image signal, an image signal decoding unit that decodes the image signal of the image memory unit, an image output unit that outputs the decoded image signal, and the separated unit. And a voice signal decoding unit that decodes the blank voice signal and a voice output unit that outputs the decoded voice signal. 8. The image memory unit is capable of accumulating images of two or more screens, and the image signal decoding unit is an image output unit until an image signal for the next one screen is accumulated in the image memory unit. 8. The composite telephone system according to claim 7, wherein the composite telephone system is a receiving device that repeatedly outputs the image output to. 9. A compound telephone system comprising: a transmitter / receiver comprising each part of the transmitter of claim 3 and each part of the receiver of claim 7.