JP2522550B2 - Communication control method of communication terminal device - Google Patents

Description

The present invention relates to a communication control system for a communication terminal device such as a facsimile device.

[Prior Art] In a communication terminal device, for example, a facsimile device,
Modem (modulator / demodulator) when the distance from the exchange is long
Since the adaptive automatic equalizer in the above cannot completely equalize the line condition, a fixed equalizer such as a cable equalizer was manually inserted to improve the quality of communication data.

[Problems to be solved by the invention] However, if an equalizer is inserted depending on the distance from the exchange, even if the line from the station to the own facsimile machine can be equalized, the loss of the line from the station to the other party Since the equalization of the group delay and the like due to the passage of the filter in the central office and the exchange changes each time, the only option is to rely on the adaptive automatic equalizer in the modem.

In addition, the image quality may be disturbed by an error when the image communication is started only by determining the transmission speed by checking the characteristic of the line by the training check.

In view of this, the present invention automatically equalizes the line during data communication by automatically varying the equalization property due to training failure on the other side during transmission and automatically detecting the error during error reception. An object of the present invention is to provide a communication control method for a communication terminal device that can be held well and can perform high-quality data communication.

In addition, it is also an object of the present invention to provide a communication control method for a communication terminal device that can change the sample rate and can perform higher quality data communication.

Furthermore, when transmitting or receiving information on multiple pages, if a bit error occurs on the first page, the equalization characteristics are automatically changed on and after the second page to maintain good line equalization. It is an object of the present invention to provide a communication control method for a communication terminal device capable of performing high quality data communication.

[Means and Actions for Solving the Problem] The invention corresponding to claim (1) is provided with a first equalization characteristic changing means which is provided on a transmission path to a line and which changes the equalization characteristic,
A second equalization characteristic changing means provided on the receiving path from the line for changing the equalization characteristic is provided. At the time of transmission, a training check is first transmitted, and if a training failure is received from the other side, the sample rate is fixed. As it is, the first equalization characteristic changing means is controlled to increase the equalization characteristic and the training check is transmitted again, and the training check can be transmitted with the sample rate fixed up to a preset number of times. When the training is confirmed to be successful, the information transmission starts. When receiving, the training check is first received, and if an error occurs in the reception, the training failure is transmitted to the other party and the automatic equalization function is sent to the other party. If there is not, the second equalization characteristic changing means is controlled to increase the equalization characteristic and the next training check is received. It will be waiting.

Therefore, at the time of transmission, if the other party fails in training, the equalization characteristic is changed so as to increase and the training check is transmitted again, so that the line equalization state is eventually reached and high quality data transmission becomes possible. If an error occurs during reception, the equalization characteristic is changed so as to increase when the other party does not have an automatic equalization function, so that high quality data reception is possible in this case as well.

Further, in the invention corresponding to claim (2), when the training failure is continuously received from the other party even when the training check is transmitted a preset number of times during the transmission,
This is to reduce the sample rate and reduce the number of transmissions to zero to start transmitting the training check again, and start transmitting information when successful training is confirmed.

In the invention corresponding to claim (3), when a plurality of pages of information are transmitted or received, if a bit error occurs during transmission or reception of the nth information, a fallback occurs at the (n + 1) th transmission or reception. To reduce the sample rate and increase the equalization characteristic by controlling the first equalization characteristic varying means or the second side when the other party does not have an automatic equalization function.
In order to increase the equalization characteristic by controlling the equalization characteristic changing means.

Therefore, even if an error occurs in the transmission or reception of the first page, 2
From the pages onward, it is possible to improve the quality of data communication.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.
In this embodiment, the invention is applied to a facsimile machine.

In FIG. 1, L ₁ and L ₂ are public lines, and the ends of the lines L ₁ and L ₂ are connected to the common contacts of the contact switches 11 a and 11 b of the line switching relay circuit 11. The contact switches 11a, 11
One fixed contact of b is connected to one winding of the matching transformer 12, and the other fixed contact is connected to the external telephone 13.

The other winding of the matching transformer 12 is connected to the 2-wire-4 wire conversion circuit 14.

Reference numeral 15 is a modem (modulation / demodulation device), which is provided with a first equalization characteristic changing means for changing the equalization characteristic in the transmission path between the modem 15 and the conversion circuit 14, and in the reception path. Similarly, second equalization characteristic changing means for changing the equalization characteristic is provided.

The first equalization characteristic changing means selects a transmission side amplitude equalization circuit 16 having four stages of equalization characteristics and one equalization characteristic from the equalization circuit 16 in order to equalize the line length of the cable. The transmission amplitude equalization selection switch 17 is configured to operate.

The second equalization characteristic varying means selects a reception side amplitude equalization circuit 18 having four stages of equalization characteristics and one equalization characteristic from the equalization circuit 18 in order to equalize the line length of the cable. A reception amplitude equalization selection switch 19, a group delay equalization circuit 20 for correcting the group delay, and a group delay equalization selection switch 21 for selecting whether to perform reception via the equalization circuit 20. ing.

Further, 31 is a CPU (central processing unit) that constitutes the main body of the control unit, 32 is a ROM (Read Only Memory) in which program data for the CPU 31 to control each unit is stored, and 33 is image information read by the scanner. Various memories such as a memory for storing the information, a memory for storing the information compressed for transmitting the image information, a memory for storing the received information, a memory for storing the expanded information for printing out the received information, and the like. RAM (random access
Memory), 34 is an input / output port, 35 is a dial button, one-touch key, speed dial key, communication start key,
A keyboard portion provided with various keys such as a reset key, and 36 are peripheral circuits such as a scanner for reading a document and a printer for printing out the received information.

The CPU 31, the ROM 32, the RAM 33, the input / output port 34, the keyboard unit 35, the peripheral circuit 36 and the modem 15 are
They are connected via a bus line 37 and a data bus line 38.

The control signal from the input / output port 34 is respectively supplied to the transmission amplitude equalization selection switch 17, the reception amplitude equalization selection switch 19, the group delay equalization selection switch 21 and the equalizer 15a provided in the modem 15. There is. Also the CPU
The control signal from 31 is directly supplied to the line switching relay circuit 11.

The CPU 31 is programmed so as to perform the control shown in FIG. 2 when transmitting a TCF (training check) performed prior to image communication.

That is, the value of the counter N provided in the RAM 33 is set to "1".
Then, the modem 15 is controlled to first send TCF to the other side. Then, it is checked whether or not the training is successful by the response from the other party. If the training is successful, it is determined that the line is equalized and communication is started. That is, transmission of image information is started.

If the response is training failure (FTT), the transmission amplitude equalization level is strengthened. That is, the transmission amplitude equalization selection switch 17 is switched to increase the equalization characteristic. Here, the number of TCF transmissions valid at the same sample rate is x, and x
= 2, N = 1, so N = 1 + 1 = 2, and then the TCF is transmitted again to the other side without fallback. The sample rate is 9,600 bps first, and then 7,20 bps.
It is assumed that 0 bps, the next is 4,800 bps, and the last is 2,400 bps.

Therefore, the second TCF transmission is also performed at 9,600 bps. Then, it is checked again whether the training is successful. If the training is successful, it is determined that the line is equalized and communication is started.

If the response is training failure (FTT), the transmission amplitude equalization level is strengthened, but since N = 2 = x, fallback occurs. That is, the communication speed is 7,20
Drop to 0 bps. Then, since x is not set to "1" at x = 2, the equalization level is reset. That is, the transmission amplitude equalization selection switch 17 is switched to return to the initial state. Then, the TCF is transmitted to the other party again with the communication speed lowered.

After that, as long as the training failure continues in this way, the equalization characteristic is changed at the same sample rate, the TCF is transmitted twice, the sample rate is changed, and the control is repeated.

When x = 1 is set, that is, when the TCF transmission count is set to 1, the equalization level is changed and fallback is simultaneously performed without resetting the changed equalization level so that TCF transmission is repeated. Has become.

The CPU 31 is programmed so as to perform the control shown in FIG. 3 when receiving the TCF from the other party.

That is, when the TCF is received from the other party, the contents are checked and it is determined whether or not there is an error. If there is no error, it is determined that the training is successful and communication is started. That is, the reception of image information from the other party is started. If there is an error, it is checked whether or not the other party, which is the sender, has the same automatic equalization function as that of its own station. If the other party also has the same automatic equalization function, the other party changes the equalization characteristic for the line, so that the other station does nothing. This is prohibited in the own station because the characteristics may be overcompensated if the automatic equalization function is activated in both.

However, if the other party does not have an automatic equalization function, the reception amplitude equalization selection switch 19 is switched to enhance the amplitude equalization level or the group delay equalization selection switch 21 is switched to perform group delay correction. Change the characteristics to improve the reception status and receive the TCF from the other side again. In this way, the equalization characteristics are gradually changed until the training is successful.

Further, the CPU 31 performs the reception control shown in FIG. 4 when the reception of the image information from the other party is started after the training is successful.

That is, when the image reception of one page is completed, it is checked whether or not there is an image to be received, and if there is no image, the communication is terminated. If there is an error, it is checked whether or not an error has occurred in the received contents of one page, and if there is an error, the reception amplitude equalization selection switch 19 is switched to strengthen the amplitude equalization level or group delay. The equalization selection switch 21 is switched to perform group delay correction to change the equalization characteristic and improve the reception state. Thus, the reception of the next page is started.

Although FIG. 4 has described the case of reception, it goes without saying that this control can be applied to the case of transmitting a plurality of pages to the other party.

In this embodiment having such a configuration, at the time of transmission, the TC is sent to the other party at a sampling rate of 9,600 bps.
Send F (training check). As a result, when FTT (training failure) is received as a response from the other party, the transmission amplitude equalization selection switch 17 is switched to enhance the transmission amplitude equalization level and improve the reception state. Then, the TCF is sent again to the other party at the same sample rate. If the training is successful, communication of normal image information is started.

However, when the FTT response comes again, this time, the sample rate is changed, the communication speed is reduced to 7,200 bps, the transmission amplitude equalization level is returned to the initial state, and the TCF is transmitted to the other side.
If the training is successful, communication of normal image information is started.

In this way, at the time of transmission, image information transmission is started after TCF transmission is used to equalize the line with the other party and improve the line condition. Can be held satisfactorily and high quality data communication can be performed.

Also, when receiving the TCF, the line equalization with the other party is attempted to improve the line condition before the image information reception is started, so the line equalization is well maintained when receiving the image information. Therefore, high quality data communication can be performed.

Further, even after the transmission or reception of the image information is started, if an error occurs in the first page, the equalization characteristic of the line is further improved in the transmission or reception of the image information of the second and subsequent pages, so that the error occurrence is prevented. There is no higher quality data communication.

Although the present embodiment has been described with the present invention applied to a fax machine, the present invention can also be applied to other communication terminal devices.

[Effects of the Invention] As described in detail above, according to the present invention, the equalization characteristic is automatically changed by the training failure of the other side at the time of transmission, and the equalization characteristic is automatically changed by the error detection at the time of reception. As a result, the equalization of the line can be favorably maintained during the information communication, and high quality data communication can be performed. In addition, the sample rate can also be changed to enable higher quality data communication. Furthermore, when transmitting or receiving information on multiple pages, if a bit error occurs on the first page, the equalization characteristics are automatically changed on and after the second page to maintain good line equalization. This enables high quality data communication.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a circuit block diagram of a facsimile machine, FIG. 2 is a flow chart showing training check transmission control by CPU, and FIG. 3 is training check reception control by CPU. Flow chart, 4th
The figure is a flow chart showing the image information reception control by the CPU. 15 ... Modem, 16 ... Transmission side amplitude equalization circuit, 17 ... Transmission amplitude equalization selection switch, 18 ... Reception side amplitude equalization circuit, 19 ... Reception amplitude equalization selection switch, 20 ... Group delay Equalization circuit, 21 …… Group delay equalization selection switch, 31 …… CPU (central processing unit), 32 …… ROM (read only memory).

Claims (3)

(57) [Claims] 1. A first equalization characteristic changing means provided on a transmission path to a line for changing an equalization characteristic, and a second equalization characteristic changing means provided on a reception path from the line for changing an equalization characteristic. Equalization characteristic variable means is provided, and at the time of transmission, a training check is first transmitted, and when a training failure is received from the other side, the first equalization characteristic variable means is controlled while the sample rate is fixed and the equalization characteristic is increased. And send the training check again,
It is possible to transmit a training check with a fixed sample rate up to a preset number of times, and if successful training is confirmed during that time, information transmission will be started. When an error is confirmed in the reception, a training failure is transmitted to the other party, and when the other party does not have an automatic equalization function, the second equalization characteristic varying means is controlled to increase the equalization characteristic and the next training check is performed. A communication control method for a communication terminal device, characterized in that it waits for reception of a message. 2. A first equalization characteristic changing means provided on a transmission path to the line for changing the equalization characteristic, and a second equalization characteristic changing means provided on a reception path from the line for changing the equalization characteristic. Equalization characteristic variable means is provided, and at the time of transmission, a training check is first transmitted, and when a training failure is received from the other side, the first equalization characteristic variable means is controlled while the sample rate is fixed and the equalization characteristic is increased. And send the training check again,
It is possible to transmit a training check with this sample rate fixed up to a preset number of times, and even if the training check transmission of this set number of times is performed, if the training failure reception from the other side continues, When the sample rate is reduced and the number of transmissions is set to zero to start sending the training check again, if training success is confirmed during that time, information transmission starts, and when receiving, the training check is received first and an error occurs in that reception. When the occurrence of the above is confirmed, a training failure is transmitted to the other side, and when the other side does not have an automatic equalization function, the second equalization characteristic changing means is controlled to increase the equalization characteristic to receive the next training check. A communication control method for a communication terminal device, which is characterized by waiting. 3. A first equalization characteristic changing means provided on a transmission path to the line for changing the equalization characteristic, and a second equalization characteristic changing means provided on a reception path from the line for changing the equalization characteristic. When a plurality of pages of information are transmitted or received, if a bit error occurs during transmission or reception of the nth information, (n
+1) Fallback at the time of transmission or reception of the first sheet to lower the sample rate and increase the equalization characteristic by controlling the first equalization characteristic changing means, or the second when the other party has no automatic equalization function. A communication control system for a communication terminal device, characterized in that the equalization characteristic varying means of (1) is controlled to increase the equalization characteristic.