JP3114165B2 - Facsimile communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile communication method, and more particularly to an improvement in transmission speed.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram of a general facsimile machine. The signal from the line 4 is taken into the signal processing unit 18 via the modem 14. This signal is decoded by the encoding / decoding circuit unit 12 and is output to the print output unit 2.
6 is printed. On the other hand, when transmission is performed, a document is read from the image reading unit 28 and encoded by the encoding / decoding circuit unit 12. The encoded data is transmitted to the modem 14 and the line controller 6 by the signal processor 18.
Is sent to the line 4 via. The facsimile communication is performed as described above.

[0003] In facsimile communication, a method is employed in which training communication is performed before image data is transmitted to determine the line status (referred to as TCF check) and the transmission speed is determined. Hereinafter, regarding this TCF check,
The operation will be described with reference to the operation flowchart on the receiving side (FIG. 3).

First, the communication speed is set to 96 on both the transmitting side and the receiving side.
Set to 00 bps (step S1). The transmitting side sends a training start signal to the receiving side. In response, the receiving side resets the timer in the signal processing unit 18 (Step S2). The transmitting side continues to transmit “0” for 1.5 seconds following the start signal. If the receiving side continues to receive “0” until the timer measures 1 second (step S5), the receiving side sends a CFR signal as good line condition (step S5).
9) Then, it proceeds to image data reception (step S10).

However, if "1" is received on the way, the timer is reset (step S4). Therefore, unless “0” is continuously received for one second, the process does not shift to image data reception. If the training is completed before the timer measures 1 second (step S6), an FTT signal is transmitted (step S7), and the communication speed is reduced to 7200 bps (step S8). Then, again at this communication speed, step
Execute S2 and below. When the communication speed is reduced, the number of errors is reduced, and if the timer measures one second, the process proceeds to image data reception (step S10). Even if the communication speed is reduced, if "0" cannot be continuously received for one second (step S6), an FTT signal is transmitted (step S7).
Further, the communication speed is reduced to 4800 bps (step S8). Hereinafter, the same processing is repeated, and when the line condition is poor, the communication speed is reduced to the minimum communication speed of 2400 bps.

[0006] As described above, the TCF check is performed, and when the line condition is poor, transmission is performed at a reduced communication speed. As a result, reliable communication can be performed even if the line condition is poor.

[0007]

However, the conventional facsimile communication method as described above has the following problems.

In recent years, in facsimile communication, an error correction mode (ECM) may be used in order to transmit data accurately. This ECM is
Data consisting of 256 bits is regarded as one frame, and 25
The transmission is performed with six frames as one block. After transmission, the frame in which an error has occurred is transmitted from the receiving side to the transmitting side by parity checking or the like, and only the frame in which the error has occurred is retransmitted. Thus, data can be transmitted accurately.

By the way, in the conventional communication method, E
Regardless of whether a CM is used or not, the criterion of the TCF check is fixed. When the ECM is used, there is an error repair function, so that a slight transmission error is allowed. Nevertheless, there has been a problem that the determination is made stricter than necessary, and the communication speed is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a facsimile communication method capable of solving the above problems and improving the transmission speed when a transmission method having an error recovery function is used.

[0011]

SUMMARY OF THE INVENTION A facsimile communication method according to the present invention provides a method for improving the line condition by training communication.
The check for rejection is made when the sender sends a fixed
Continuation signal for the predetermined transmission time,
The training signal is constant during the predetermined receiving time
If the transmission is continued, it is judged that the line status is good, the image data is divided into units having a predetermined size and transmitted, and if a transmission error occurs in each unit, it is retransmitted. When performing the above, the predetermined receiving time is shortened.
Therefore, the feature is that the criterion for judging the line condition in training communication as good is lowered.

[0012]

In a case where image data is divided into units having a predetermined size and transmitted, and when a transmission error occurs in each unit and retransmission is performed, a predetermined reception time is shortened.
This lowers the standard for determining the line condition in training communication as good. As a result, a reduction in communication speed can be prevented.

[0013]

FIG. 1 is a flowchart showing a facsimile communication method according to an embodiment of the present invention. The hardware configuration is the same as in FIG.

First, the signal processing unit 18 determines that the transmission mode is EC
It is determined whether the mode is the M mode (step S1). In the case of the ECM mode, the timer time-up time Q as the reception time is set to 0.8 seconds (step S2). In the case of the ECM mode, the timer time-up time Q as the reception time is set to 1.0 seconds (step S2). S3).

Next, the communication speed is set to 96 on both the transmitting side and the receiving side.
Set to 00 bps (step S4). The sender is a trainee
Sending a signaling signal to the receiving side. In response, the receiving side
Reset the timer in the signal processing unit 18 (step S
Five). The transmitting side follows the alignment signal,Constant training
Signal"0"As the predetermined transmission time
Continue transmitting for 1.5 seconds. On the receiving side, the timer counts Q seconds.
If “0” continues to be received until measurement (step S8),
As the line condition is good, CFR is transmitted (step S12),
The process proceeds to data reception (step S13). In ECM mode,
In step S8, the timer times out in 0.8 seconds.
Step. If not in ECM mode, time out in 1.0 second
Step. In other words, the line status is better in ECM mode.
Is low.

If "1" is received on the way,
The timer is reset (Step S7). Therefore, unless “0” is continuously received for Q seconds, the operation does not shift to image data reception. If the training ends before the timer measures Q seconds (step S9), the signal processing unit 18
The TT is transmitted (step S10), and the communication speed is reduced to 7200 bps (step S11). Then, step S5 and subsequent steps are executed again at this communication speed. When the communication speed is reduced, the number of errors is reduced, and if the timer measures Q seconds, the process proceeds to image data reception (step S13). Even if the communication speed is lowered, if "0" cannot be continuously received for Q seconds (step S9), an FTT is transmitted (step S1).
0), and further reduce the communication speed to 4800 bps (step S1)
1). Hereinafter, the same processing is repeated, and when the line condition is poor, the communication speed is reduced to the minimum communication speed of 2400 bps. As described above, in the case of the ECM, the criterion for determining that the line status is good is reduced by shortening the time-up time of the timer. The use of the ECM has an automatic error recovery function, so that accurate communication can be performed even if the line state is slightly poor. Therefore, according to this embodiment, EC
In M, there is no possibility that the speed is unnecessarily reduced.

In the above embodiment, the time for the time-up in the ECM is set to 0.8 seconds. However, an appropriate time can be set according to the case.

[0018]

According to the facsimile communication method of the present invention, image data is divided into units having a predetermined size and transmitted, and when a transmission error occurs in each unit, transmission is performed by a method of retransmission. To reduce the prescribed reception time
Accordingly, the standard for judging the line status in training communication as good is lowered. As a result, in the communication method having the error correction function, it is possible to prevent a reduction in communication speed due to a line condition.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a facsimile communication method according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a general facsimile machine.

FIG. 3 is a diagram showing a flowchart of a conventional facsimile communication method.

[Explanation of symbols]

 2 ... facsimile machine 4 ... line 18 ... signal processing unit

Claims (1)

(57) [Claims] 1. A picture communication method smell before data transmission by performing a training communication check the quality of the channel condition, when the line condition is bad for transmitting image data and drop the transmission rate
In order to check the line status by training communication,
The transmitter sends a certain training signal to the receiver.
The transmission is continued during the fixed transmission time, and the receiving side
During the communication time
When the line status is judged to be good, the image data is divided into units having a predetermined size and transmitted,
When transmission is performed by a method of retransmission when a transmission error occurs in each unit, the predetermined reception time should be shortened.
Accordingly, you lower the criteria for determining the line status in the training communicates with good, facsimile communication method characterized by.