JPS6317387B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data communication system, and more particularly to a composite media communication system in which voice and still images in addition to normal character data are communicated over the same line and the same terminal.

The data of coded digital signals such as characters and figures is usually transmitted via facsimile or data communication on paper, documents, or memory media, which allows for sufficient thinking time and when the user is not present. Communication is also possible. On the other hand, real-time communication by telephone or the like is important because it allows people to directly check each other's voices and communicate with each other. Furthermore, by adding video signals to real-time communications, it becomes possible to hold conferences, lectures, etc. between distant points using television.

However, while conventional data communication devices are used to handle only character data, voice is transmitted by telephone, and images are communicated separately by facsimile and television. Therefore, in order to aim for more advanced and effective communication,
A communication system that handles these media in a composite manner is desirable, and advances in sound synthesis technology and semiconductor integration technology are making composite media communication possible.

By the way, communication in which coded digital signal data such as characters and graphics and analog signal audio data are mixed on the same communication channel has rarely been carried out in the past. However, there are two ways to communicate using the same communication channel: digital data communication mode,
A method is known in which voice communication modes are clearly separated and humans can switch between the modes. In that case, voice communication (communication by real voice) is performed in a human-to-human relationship.

In recent years, speech synthesis technology has reached a practical level and is being effectively used in various fields, such as outputting stylized sentences as voice. Speech synthesis technology enables not only human-to-human communication, but also center device-to-human communication.
Voice communication has also become possible between humans and processing devices including computers.

On the other hand, when transmitting images via telephone lines,
If you try to transmit this as a digital signal, the amount of information is large, so at a line speed of 1200 b/s, for example, it will take 10 minutes to several minutes to transmit an image on one television screen.
Must be sent for 10 minutes or more. In the future, if digital lines become widespread, high-speed transmission will become possible, but this is expected to be more than 10 years away.

On the other hand, a problem when transmitting a still image from the transmitting side and playing it back on television at the receiving side is that the signal band that can be transmitted by the telephone line is 4K.
Hz, whereas television signals are 4-6M
The point is that it requires a frequency band of Hz.

Furthermore, in the future, it is expected that flexible disks (product name: floppy disks) will be widely used as portable storage devices in terminal devices. , conventional flexible disk devices for data communication cannot be shared as they are.

The purpose of the present invention is to solve these problems by making it possible to transmit not only character data but also voice and still images over the same line, and by making it possible to share a flexible disk device for recording these composite media. The object of the present invention is to provide a data communication system that allows terminal devices to be made at low cost.

The data communication system of the present invention is a data communication device that performs data communication via a telephone line and stores data using a flexible disk device. Data is transmitted and received as an analog signal, and the analog signal is stored as it is in the flexible disk device and then outputted. A sub-memory separate from the flexible disk device is provided, and audio and still image data are stored in the sub-memory. It is characterized by temporarily storing and converting the time axis.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a data communication system showing an embodiment of the present invention, and FIG. 3 is a signal processing waveform diagram in FIG. 1.

In the data communication system of the present invention, FM modulation data transmitted at low speed over a telephone line in a band of approximately 4KHz is temporarily recorded in a secondary memory on the receiving side, and then read out at high speed and stored on a flexible disk with approximately 5M.
Record as a Hz signal. When transmitting data, the data is read out from the flexible disk and written into the secondary memory at high speed, then read out at low speed and sent to the line. This made it possible to transmit not only text data but also audio and still images over the same line, and also made it possible to share the flexible disk device for recording text data and audio and still images.

In Figure 1, 1 is the input/output terminal to the line, 2
3 is an analog secondary memory, 3 is a flexible disk device, 4 is a signal converter, 5 is a television receiver 6 is a VTR (video tape recorder). Note that a transmitting/receiving circuit is connected before the sub memory 2. FIG. 3a shows a write signal to the sub memory 2, FIG. 3b shows a read signal from the sub memory 2, FIG. 3c shows a write signal to the flexible disk 3, and FIG. 4d shows a signal in the signal converter. The signals after conversion are shown.

The terminal device shown in FIG. 1 has a unified configuration in which all the circuits are of an analog type.

When this terminal device receives a still image, an FM-modulated signal in a band of about 4 KHz is input from the line to the analog sub-memory 2 via the input/output terminal 1.
The analog sub-memory 2 has, for example, two lines.
These line memories receive data alternately, and while one of them is receiving data, the other one is reading it out at high speed. If we plot the write signal to secondary memory 2 over 30 seconds, for example,
Although the waveform is a single period waveform as shown in FIG. 3a, multiple waveforms appear in the signal read out from the sub-memory 2 at high speed as shown in FIG. 3b. The analog signal read from the sub memory 2 is then transferred to the flexible disk 3 and recorded thereon. The write signal at this time has a waveform as shown in FIG. 3c. In this way, all the data for one screen is recorded on the flexible disk 3, and when this is to be further reproduced and output to the television receiver 5, the data for one screen is read out at a high speed of 1/60 seconds.
The signal converter 4 converts FM modulation data in a band of approximately 5 MHz.
send to When the signal converter 4 receives this, it converts it into a video signal as shown in FIG. 3d, and then outputs the still image to the television receiver 5.

Furthermore, even when using a VTR 6, still images can be recorded and reproduced by performing signal processing in exactly the same manner.

The head of a flexible disk device is usually for digital signals and has a wide gap and a low maximum magnetic flux density in the core, but by using a head for a VTR, it is possible to record and play back still image data and character data. can. However, the flexible disk device 3 must be used for still image data and character data.

Further, as the sub memory 2, an analog IC memory can be used. In this case, recording and reproduction speeds can be converted by converting the sampling frequency.

Furthermore, in the future, SIT (Static Induction)
Transistor Logic) memory is put into practical use,
This can be used as the secondary memory 2.

FIG. 2 is a block diagram of a data communication system showing another embodiment of the present invention, and FIG. 4 is a signal processing waveform diagram in FIG. 2.

In FIG. 2, 7 is an A/D converter, 8 is a D/D converter, and 8 is a D/D converter.
This is the A conversion section, and the other symbols are the same as in FIG. The terminal device shown in FIG. 2 has all its circuits integrated into digital processing, and performs D/A conversion and A/D conversion when inputting and outputting data to and from lines and equipment used.

When this terminal device receives a still image, if the FM modulated signal input from the line is plotted over, for example, 30 seconds, it will have a single period waveform as shown in Figure 4a, but it will be digitalized by the A/D converter 7. When converted into a signal, for example, as shown in Figure 4b,
It becomes a PCM code. This digital signal is then
The information is recorded on the flexible disk 3 in a digital signal format by a conventional flexible disk device (see FIG. 4c).

During playback, after data is read from the flexible disk device 3 to the secondary memory 2, the fourth
As shown by the pulse waveform in FIG. d, data is read from the secondary memory 2 at high speed. Next, the high-speed digital signal is converted into an analog signal by the D/A converter 8, and then converted into a video signal shown in FIG. 4e by the signal converter 4 and output to the television receiver 5.
Exactly the same processing is performed when outputting to the VTR6.

In addition, when transmitting a still image, by connecting the D/A converter 8 to the line transmission circuit, the digital signal stored in the flexible disk device 3 can be read out at high speed and written to the sub memory 2 at high speed. After that, it is read out at low speed, converted into an analog signal (FM modulated signal) by the D/A converter 8, and then sent to the line.

Therefore, in FIG. 2, a normal digital signal disk can be used as is as the flexible disk 3. Further, an IC memory is used as the sub-memory 2, and data is repeatedly read out at high speed and data is continuously sent out at a speed that matches the synchronization signal of the television receiver 5.
Furthermore, the signals to be recorded on the flexible disk 3 may be separated into a luminance signal and a color difference signal, and these may be determined in consideration of image quality.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a data communication system showing an embodiment of the present invention, Fig. 2 is a block diagram of a data communication system showing another embodiment of the invention, and Figs. 3 and 4 are respectively similar to Fig. 1. and a signal processing waveform diagram of FIG. 2. 1: line input/output terminal, 2: sub memory, 3: flexible disk, 4: signal converter, 5: television receiver, 6: VTR, 7: A/D converter,
8: D/A conversion section.

Claims (1)

[Claims] 1 Data communication equipment that communicates data via telephone lines and stores data using flexible disk devices, which not only stores character data as digital signals, but also transmits and receives voice and still image data as analog signals. , the analog signal is stored as it is in the flexible disk device and then outputted, a sub-memory separate from the flexible disk device is provided, audio and still image data are temporarily stored in the sub-memory, and the time axis is A data communication method characterized by conversion.