JPH03166853A - Picture information communication control device for general circuit and method - Google Patents

Abstract

PURPOSE: To secure switching to an image communication mode and electrically transmit high-image quality image information for a short time by providing a modem which has a modulating and demodulating function with a plural number of communication speeds and a transmitting and receiving means for a dial-tone multifrequency signal. CONSTITUTION: A modem 2 is connected to a system bus 7 and has a modulating and demodulating function with communication speeds of 9600, 4800 and 2400bps and a transmitting and receiving means for a dial-tone multi-frequency(DTMF) signal. At a 1st stage image control information is sent electrically at 9600bps communication speed to send out a series of binary 0 signals. At a 2nd stage, a bit where an error occurs is calculated and at a 3rd stage, the DTMF signal is used, if an error rate reaches a specific ratio, to adjust a speed with a reception side and to perform electric transmission by reducing its communication speed down to 2400bps. When the error rates does not reach the specific ratio, the image information is transmitted and received as normal. Consequently, switching to image communication mode is made securely, and the image information of high image quality of >=64 gray levels can be transmitted for a short time.

Description

[Detailed Description of the Invention] The present invention utilizes a general switched line (general telephone exchange's) to send and receive frozen image information intended by a user during a voice call within an appropriate time. The present invention relates to an apparatus and method for controlling image information communication in an image information communication system that can perform image information communication.

Yikei Technician recently announced the TTC standard (Japan TTC JJ-40.10.
“Still image video communication system in analog telephone band”, 1
The image telephone according to 988.5.31) uses a dual tone signal of 1633 Hz and 2006 Hz as a switching signal from the voice communication state to the image communication state, and the image information is divided into amplitude and phase at a carrier frequency of about 1747 Hz. Combining the changes in 1 second, -1 7 4 7. It uses a method of electrically transmitting pixels.

However, with the above communication control method, firstly, the system is prone to malfunction due to the double tone included in the whistling part of the voice during a voice call, and secondly, the image information is in an analog format and the amplitude and phase changes. 64 pixels per pixel
It has short points that are difficult to distinguish above Gray Level. Therefore, the purpose of the present invention is to improve the above-mentioned shortcomings by changing the image communication state and communication speed for voice calls, by using DTMF signals for the type of telegrams transmitted, and by using the CCITT recommendations as a modulation method. V. 29 and V. By using the modulation/demodulation method according to 9600.4800.2400 bps specified in 27ter and used in general exchange line facsimile machines, and controlling this appropriately, images having 2 5 6 Gray Level can be transmitted in the communication. The present invention relates to a device and method that can transmit data at a speed faster than that achieved by other methods.

In order to achieve the above object, the present invention provides a system bus having a control and information transmission function between modules, a system control means connected to the bus means and having a system control and interrupt control function; Connected to the bus 9
600bps, 4800bps and 24
A modem having a modulation/demodulation function with a communication speed of 00 bps and having means for transmitting and receiving a dial tone multi-frequency DTMF signal, and a DTMF signal processing means, the modem and the DTM
F signal processing means and general exchange line connection means for connecting the telephone to a general exchange line; a program ROM connected to the system bus and containing a program for controlling communications between the modem and the DTMF signal processing means; and the system bus. R for storing temporary data.
It is characterized by being composed of AM.

Furthermore, the image information communication control method of the present invention increases the communication speed to 9.
a first step of transmitting the image control at 600 bps and sending a series of binary "0"signals; a second step of calculating the bits in error after said first step; and a constant error rate after said second step. When the error rate reaches a certain rate, the speed is adjusted with the receiving side using the DTMF signal, and the communication speed is reduced to 2400 bps, and the image information is transmitted normally. It consists of a third stage that performs transmission and reception.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of the present invention, in which 1 is a general exchange line connection section, 2 is a modem, 3 is a DTMF receiver, 4 is a ROM,
5 is a system control unit, 6 is a RAM, and 7 is a system bus.

As shown in the drawings, the present invention includes a system control unit 5 having a bus structure, a ROM 4, a RAM 6, a modem 2, a DTMF
It consists of a reception m3 and a general exchange line connection section 1.

The system control unit 5 includes a CPU and peripheral circuits (timer, D
MA controller, etc.), and is connected to address, data, control lines, and interlab signal lines on the bus, and is connected to the ROM.
Executes a communication control method using a program.

The ROM4 program is assigned to the CPU's memory map, controls the operation of the entire system, and is used by modem 2 during transmission.
A control procedure is executed to control the DTMF generation circuit built into the DTMF generator.

The RAM 6 is used to store information necessary for temporary storage of the CPU of the system control unit 5, and is allocated to a memory map.

Modem 2 is CCTTV. 29 and V. Built-in modulation/demodulation function and DTMF generation means by 27ter, C
It is mapped to the PU's memory and ■/○, and performs the corresponding operation in a handshaking manner using the internal register and the CPU's control signal for RTS (request to send).In addition, it is modulated and demodulated from the general switched line through the connecting device. Send and receive signals.

When the DTMF receiver 3 receives the signal on the line through the general exchange line connection l and detects a valid DTMF signal, the C
This is notified to the PU using an interrupt method, and 4-bit data (Do-D3) is connected to the bus to notify the CPU.

The general switched line connection unit 1 is composed of a transformer (T) that satisfies the terminal resistance of the terminal and appropriate signal amplification means, and connects the line with a telephone in the initial stage and with a modem in the image communication state. The connection switch is controlled through a CPU control line and a relay.

The amplification means at the transmitting end is a capacitor (C1) and a resistor R.
1, R4, Rll) and an operational amplifier (A1), and the amplifying means at the receiving end is a resistor (R7, R5, R2).
, a capacitor (C2), and an operational amplifier (A2).

Further, the input terminal of the amplification means for the DTMF receiver has a high impedance and serves to adjust only the alternating current component to match the input level of the receiver. Here, the amplification means are capacitors (C3, C4, C5) and resistors (
R3. R6. R8, R9. RIO) and operational amplifier (A
3).

FIG. 2 is a diagram showing the structure of the image control sound used in the present invention, and FIG. 3 is a diagram showing the control procedure of the apparatus to which the present invention is applied.

The ROM4 program is DTMF as shown in Figure 3.
The control procedure shown in FIG. 4 will be performed using the signals.

That is, in the voice communication state, the transmitting side sends out an image control sound consisting of three fields to switch to the image communication state, and the first field is two consecutive DTMF signals, which are used for image communication. If the quality of the network is poor after the training information in FIG. 4 starts, the NA. K
Communication restart due to speed deceleration after a signal, ACK or NAK signal from the receiving side.

The second field is a velocity field, 9 6 0
0 bps, 4 8 0 0 bps and 240
This is a signal that informs the receiving side of the transmission speed of image information at 0 bps. The third field indicates the type of information, including the type of image information to be transmitted (black and white or color image), size,
Indicates whether or not there is text information, and if it is text information, the type of text information, etc. However, when communication resumes depending on the speed after training, the third field is not used and ACK or N
In the case of an AK signal, the second and third fields are not used. The transmission time of the DTMF signal is IO
0 msec, and the no-signal time is 50 msec.
It is.

The terminal that received the image control sound in Figure 4 is 1 0 after receiving it.
An ACK signal must be sent within 0 msec, and the transmitting side that receives the ACK signal continuously trains information that is continuous "0", and the receiving side determines if the bit in which the error occurred is greater than or equal to the correct value. If so, a NAK signal is sent, otherwise an ACK signal is sent.

After receiving the ACK signal, the transmitting terminal transmits image information at the promised communication speed, switches to voice communication state, and returns to NA.
When the K signal is received, the first field of the image control sound is converted into two DTMVs that define communication resumption by speed deceleration.
and the second field is DTMF indicating the reduced speed.
The signal will be sent out after a time delay of 100 ms and training will be performed again.

9600 bps. 4800 bps, 240
The speed is reduced to 0 bps, but if the speed is reduced to 2400 bps, image information is sent out without training again, and then switched to the audio state.

FIG. 5 is a flowchart showing the control procedure on the transmitting side in FIG. 4, and FIG. 6 is a flowchart showing the control procedure on the receiving side in FIG.

First, looking at the control procedure on the transmitting side with reference to FIG. 5, after the voice call is disconnected 10, an image control sound is transmitted 12 at a speed of 9600 bps, and a timer is set for 400 msec 13. If an ACK signal is received within the timeout, a training signal is sent and an additional 4 0
A timer is set for 0 msec, and if an ACK signal is received within the timeout, the image information is electronically transmitted (1
4 to 19, 23), ACK signal cannot be received <MAK signal is received 19, 20, 2400b
After reducing the communication speed to ps and transmitting the image information 21 and 22, the voice call is connected 24.

Next, the control procedure on the receiving side will be explained with reference to FIG.

After the voice call is disconnected 30, if a 9600 bps image control sound is received 31, an ACK signal is sent 32, a timer is set, and if training is received within the timeout 34, 35, errors are calculated up to the last information. If the error is 5% or more, a NAK signal is sent 36 to 39, and if the error is within 5%, an ACK signal is sent and a timer is set 38, 40, 41.

If the image information is received within the timeout, 42, 43, after decoding and storing the image memory until the last information 44;
45. Concatenate voice calls 46.

At this time, if the receiving speed is slowed down from the sending side, 4
7. If it is received at a speed of 2400 bps, the process proceeds in the order after setting the timer 41; if the speed is not 2400 bps, the process proceeds to step 48 and timer setting 49; if the image resume sound is received within the timeout, step 51, sending an ACK step 32 It will proceed as follows.

Furthermore, in the present invention, during communication, on the transmitting side, when the image control sound transmission is completed and when the training information transmission is completed,
It has a msec timer, and if the corresponding reception signal is not received before the timer ends, the image communication state is interrupted and switched to the voice communication state, and the receiving side responds to the image control sound by
It has a timer corresponding to 2 seconds and 8 seconds to 30 seconds upon completion of sending a CK or NAK signal and upon completion of sending a response signal to training information, respectively, and is configured to switch to a voice communication state if the corresponding information is not received. did.

The present invention is configured as described above, and first, by transmitting DTMF signals in a predetermined digital order, it is possible to reliably switch to the image communication mode in the voice state, and to control the communication speed and type of image information. Second, by transmitting image information using a digital transmission method, 6 4 Gray Le, which is difficult to process with existing methods, can be transmitted electronically within a short period of time.
It is possible to transmit high-quality image information that is higher than vel, and thirdly, by inspecting the quality of the network through training, it is possible to adjust the communication speed depending on the quality of the network, and it is possible to transmit clear image information. Fourthly, the modulation/demodulation method used in the present invention is built into a single-chip device that is widely used in general-purpose facsimile machines, so system configuration is easy; and fifthly, the communication speed of facsimile machines is As the speed of communication becomes faster (possible up to 14,400 bps), we can expect the speed of future calls to decrease.

[Brief explanation of the drawing]

Figure 1 is a diagram of the configuration of the present invention, Figure 2 is a diagram of the configuration of image control sounds used in the present invention, Figure 3 is a control procedure diagram of a device to which the present invention is applied, and Figure 4 is a diagram of the control procedure of the device to which the present invention is applied. 5 is a control procedure diagram of the transmitting side in FIG. 3, and FIG. 5 is a control procedure diagram of the receiving side in FIG. <Explanation of symbols of main parts> 1-1-General exchange line connection section 2-Modem 3-D
TMF receiver 4--ROM5-system control unit 6--RAM7--Bus drawing transcription (no change in content) Snoring 4 Usunae 5 Buttocks procedure amendment (method) 1990 L2-I! 3 days

Claims (1)

[Claims] 1. Transmitting or receiving static image information during a voice call using a general switched line, encoding or decoding the received image information or image information for transmission, and converting the image information into In a system that inputs or outputs using a video input/output device, a system bus (7) has a control and information transmission function between each module, and a system control that is connected to the bus means and performs system control and interrupt control functions. Means (5), connected to said bus (7) and having a speed of 9600 bps;
, a modem and DTMF signal processing means (2, 3) having modulation and demodulation functions at communication speeds of 4800 bps and 2400 bps and having means for transmitting and receiving dial tone multi-frequency (DTMF) signals; , 3) and general exchange line connection means (1) for connecting the telephone to the general exchange line, and the modem and DTMF signal processing means (2, 3) connected to the system bus (7).
A general exchange characterized in that it is comprised of a program ROM (4) containing a program for controlling communications, and a RAM (6) connected to the system bus (7) for storing temporary data. Line image information communication control device. 2. In the series of DTMF signals, the first two DTMF signals are used for starting image communication, for restarting communication after speed deceleration, and for mode switching in which the receiving end automatically transmits continuously to the transmitting end, and then the next one DTMF signal 2. The information communication control device according to claim 1, wherein the signal indicates a communication speed, and the next two DTMF signals indicate a type of image information. 3, a system bus (7), a system control means (5) connected to the bus (7), a modem and DTMF signal processing means (2, 3) connected to the bus, and a modem and DTMF signal processing means (2, 3) connected to the bus (7); 2, 3) and a general exchange line connecting means (1) for connecting the telephone to the general exchange line, a program ROM (4) connected to the bus, and a RAM (6) connected to the bus. In the line image information communication control device, the first step is to transmit the image control information at a communication speed of 9,600 bps and send out a series of binary "0" signals, and the second step is to calculate the bit in which an error has occurred after the first step. After the second stage and the second stage, if the error rate reaches a certain ratio, the speed will be adjusted with the receiving side using the DTMF signal, and the communication speed will be reduced to 2400 bps for transmission, so that the error rate will be at a certain ratio. 2. A method for controlling image information communication for a general switched line, characterized in that, if the image information is not reached, a third step is configured to normally transmit and receive image information.