JPH1174983A - Data communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To complete transmission preparation in fall back sequence of about one time even when the quality of a communication line is not so good by setting a data signal speed that is close to the preceding data signal speed as an initial value and deciding a data signal speed to perform communication this time. SOLUTION: A preceding speed storing part 15 stores a data signal speed which is adopted in the past in each transmission destination. When a data signal speed deciding part 14 is started for the first time, the preceding data signal speed is set to a data signal speed value that becomes a processing object. When the data signal speed value is less than six, the data signal speed value is increased. That is, if the preceding data signal speed value is, e.g. three, it is increased up to four as one step. In this way, when a data signal speed value of this time is decided by increasing the preceding data signal speed value by one step, a communication speed is successively increased by one stage each and an optimum communication speed can be selected in such a case that the quality of a communication line is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication apparatus having an ability to select a data signal speed stepwise according to the transmission quality of a communication line.

[0002]

2. Description of the Related Art For example, a facsimile apparatus provided with a modem capable of designating a plurality of data signal rates examines the transmission quality of a communication line before data transmission / reception starts, and determines an optimum transmission rate (hereinafter referred to as a data signal rate). ). Such selection of the data signal rate is based on ITU-T Recommendation T.30. 30
This is performed by the TCF (training check) signal, which is determined by the training of the modem of the transmitter / receiver, and by controlling the reduction of the data signal speed on the transmitter side. Such a series of data signal speed reduction operations is called a fallback sequence.

[0003]

However, the above prior art has the following problems to be solved. The selection of the data signal rate is performed in advance by comparing the capability of the device on the transmitting side with the capability of the device on the receiving side. In addition, communication is performed on a trial basis at the data signal rate determined in this manner, and as a result,
If the speed is determined to be inappropriate, a fallback sequence is performed. However, this fallback sequence includes the ITU-T Recommendation T.30. T determined by 30
It requires a procedure for transmitting and receiving CF signals, FTT signals, DCS signals, and the like. Therefore, for example, in the case of a facsimile machine,
One fallback sequence requires a procedure time of at least 4 seconds or more. For this reason, for example, if the quality of the communication line is poor even if the capacity of the transceiver is high, if the speed is reduced one step at a time from the high data signal speed, a lot of procedure time due to the fallback sequence will be spent. Become.

On the other hand, there is a method in which a user manually sets in advance the data signal speed available on the line for each destination in order to avoid such a frequent occurrence of the fallback sequence. However, such methods involve the complication that the user has to set the optimal data signal rate. Moreover, once the setting is made, there is a problem that data transmission is continued at a low data signal rate even when the quality of the communication line is improved.

[0005]

The present invention employs the following structure to solve the above problems. <Configuration 1> A data signal rate determining unit that switches a preset initial value of the data signal rate stepwise according to the transmission quality of the communication line to determine the data signal rate for performing the current communication, And a previous speed storage unit for storing the data signal speed determined at the time of communication, wherein the data signal speed determination unit refers to the previous data signal speed stored in the previous speed storage unit, A data signal speed that is close to the data signal speed of the data communication is set to an initial value, and a data signal speed for performing the current communication is determined.

<Structure 2> In the data communication apparatus described in Structure 1, the data signal speed determination unit sets a data signal speed one step higher than the previous data signal speed stored in the previous speed storage unit to an initial value. A data communication rate for performing the current communication.

<Structure 3> In the data communication device according to structure 1, the data signal speed determination unit sets the previous data signal speed stored in the previous speed storage unit to an initial value,
A data communication device for determining a data signal speed for performing a current communication.

<Structure 4> In the data communication apparatus according to any one of Structures 1 to 3, the previous speed storage unit stores the data signal speed determined in the previous communication separately for each transmission destination. A data communication device characterized by storing

<Structure 5> A data signal rate determining section for switching the preset initial value of the data signal rate stepwise according to the transmission quality of the communication line to determine the data signal rate for performing the current communication. And a data signal speed history storage unit that stores the data signal speed determined in the past communication, and the data signal speed determination unit searches for the content stored in the data signal speed history storage unit. A data signal rate that is close to the data signal rate determined most frequently is set as an initial value, and a data signal rate for performing the current communication is determined.

<Structure 6> In the data communication apparatus according to Structure 5, the data signal rate determining section searches the contents stored in the data signal rate history storage section to determine the data determined most frequently. A data communication device, wherein a data signal speed one step higher than a signal speed is set as an initial value, and a data signal speed for performing current communication is determined.

<Structure 7> A data signal rate determining section for switching the preset initial value of the data signal rate stepwise according to the transmission quality of the communication line to determine the data signal rate for the current communication. And a data signal speed history storage unit that stores the data signal speed determined in the past communication, and the data signal speed determination unit searches for the content stored in the data signal speed history storage unit. A data signal speed that is close to the fastest data signal speed determined in the past as an initial value and determines a data signal speed for performing current communication.

<Structure 8> In the data communication device according to Structure 7, the data signal rate determining section searches the contents stored in the data signal rate history storage section to determine the fastest data determined in the past. A data communication device, wherein a data signal speed one step higher than a signal speed is set as an initial value, and a data signal speed for performing current communication is determined.

<Structure 9> A data signal rate determining section for switching the preset initial value of the data signal rate stepwise according to the transmission quality of the communication line to determine the data signal rate for performing the current communication. And a data signal speed history storage unit that stores the data signal speed determined in the past communication, and the data signal speed determination unit searches for the content stored in the data signal speed history storage unit. A data communication apparatus characterized in that a data signal rate close to the average value of data signal rates determined in the past is set as an initial value, and a data signal rate for performing current communication is determined.

<Structure 10> In the data communication apparatus according to Structure 9, the data signal rate determining section searches the contents stored in the data signal rate history storage section to determine the data signal rate determined in the past. A data signal speed one step higher than the average value of the data communication is set as an initial value, and a data signal speed for performing the current communication is determined.

<Structure 11> A data signal rate determination unit that switches a preset initial value of the data signal rate stepwise according to the transmission quality of the communication line and determines the data signal rate for the current communication. And storing the data signal speed determined in the past communication and the presence or absence of execution of a fallback sequence when determining the data signal speed,
A data signal speed history storage unit, and the data signal speed determination unit determines that the initial value of the data signal speed is determined to be the actual data signal speed without a fallback sequence, and that the case continues for a preset number of times or more. A data communication device characterized in that when it is determined, a data signal speed close to the data signal speed is set as an initial value, and a data signal speed for performing current communication is determined.

<Structure 12> In the data communication apparatus according to Structure 11, the case where the data signal rate determination unit determines the initial value of the data signal rate to the actual data signal rate without a fallback sequence is set in advance. When it is determined that the data signal rate has continued for more than the number of times, a data signal rate one step higher than the data signal rate is set as an initial value, and the data signal rate for performing the current communication is determined. Communication device.

<Configuration 13> In the data communication apparatus according to Configuration 11, the case where the data signal rate determination unit determines the initial value of the data signal rate to the actual data signal rate without a fallback sequence is set in advance. A data communication apparatus characterized in that when it is determined that the communication has continued for more than the number of times, the data signal rate is set to an initial value and the data signal rate for performing the current communication is determined.

<Structure 14> A data signal rate determining unit for switching the preset initial value of the data signal rate stepwise according to the transmission quality of the communication line to determine the data signal rate for the current communication. And a communication data storage unit for storing communication data including a data signal speed determined at the time of the latest communication and an error rate when communication is performed at the data signal speed, and the data signal speed determination unit Referring to the communication data storage unit, if the error rate at the latest determined data signal rate is equal to a predetermined appropriate value, the data signal rate is set to an initial value, and the error rate is set. If the error rate is equal to or less than the appropriate value, the data signal rate one step higher than the data signal rate is set as the initial value.
A data communication apparatus characterized in that a data signal speed for a current communication is determined by setting a data signal speed lower by a step to an initial value.

<Structure 15> A data signal rate determining section for switching the preset initial value of the data signal rate stepwise according to the transmission quality of the communication line to determine the data signal rate for the current communication. And a communication data storage unit for storing communication data including a data signal speed determined at the time of the latest communication and an error rate when communication is performed at the data signal speed, and the data signal speed determination unit With reference to this communication data storage unit, when the error rate at the latest determined data signal rate is equal to or more than a predetermined appropriate value, the modulation method is changed to another modulation method having better communication stability. A data communication device, characterized in that:

<Structure 16> A data signal rate determination unit that switches a preset initial value of the data signal rate stepwise according to the transmission quality of the communication line to determine the data signal rate for the current communication. And a communication data storage unit for storing communication data including a data signal speed determined at the time of the latest communication and an error rate when communication is performed at the data signal speed, and the data signal speed determination unit If there is an image error at the most recently determined data signal speed with reference to the communication data storage unit, the data signal speed that is lower by a predetermined number of steps than the data signal speed is set to the initial value. A data signal rate for performing the current communication.

<Structure 17> A data signal rate determining unit that switches the preset initial value of the data signal rate stepwise according to the transmission quality of the communication line to determine the data signal rate for the current communication. And a communication data storage unit for storing communication data including a data signal speed determined at the time of the latest communication and an error rate when communication is performed at the data signal speed, and the data signal speed determination unit Refers to the communication data storage unit, sets the data signal speed corresponding to the error rate at the latest determined data signal speed to the initial value, and determines the data signal speed for performing the current communication. A data communication device, comprising:

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. <Embodiment 1> FIG. 1 is a functional block diagram of the apparatus of Embodiment 1. INDUSTRIAL APPLICABILITY The present invention can be used for various data communication devices capable of increasing and decreasing the data signal speed stepwise. Here, a specific description will be given using a facsimile machine as an example. The apparatus shown in the figure is a functional block diagram of the main part of the facsimile apparatus. Prior to the description, the overall configuration of the facsimile apparatus will be described first.

FIG. 2 is a block diagram showing the configuration of the entire facsimile apparatus. The apparatus shown is connected to a telephone line 1 and includes a reading unit 2, an image processing unit 3, a modem 4, a line connection unit 5, a control unit 6, and a control panel 7. The reading unit 2 is configured by an image scanner or the like, reads a transmission original,
This is a part for converting to image data. The image processing unit 3 is a part that performs an operation of compressing image data to perform facsimile transmission and the like, and an operation of expanding the image data when receiving the image data.

The modem 4 is a part that performs processing for sending out data to be transmitted to the telephone line 1 using a predetermined protocol. A line control unit (NCU) 5 is an interface for connecting the telephone line 1 and the modem 4, is called a network control unit, and controls outgoing calls and incoming calls. The control unit 6 has a built-in CPU and various storage devices, and performs operations as described later to control the facsimile machine. The operation panel 7 is a portion provided with keys for the user to set operating conditions, communication speed, and other settings of the facsimile machine.

Returning to FIG. 1, the specific configuration of the control unit will be described. As shown in this figure, the control unit 6 includes a modem setting unit 11, a communication control unit 12, a capability storage unit 13 of a receiver, a data signal speed determination unit 14, and a previous speed storage unit 15. The modem 4 is composed of, for example, a digital facsimile modem, and the communication mode is defined in ITU-T Recommendation T.3. 30 and a transmission control procedure for facsimile messages specified in the V recommendation. The specific transmission speed will be described later with reference to FIG.

The modem setting section 11 is a section for setting a communication mode and various settings for the modem 4. Communication control unit 1
Reference numeral 2 denotes a part for controlling the entire facsimile apparatus. The capability storage unit 13 of the receiver is a memory for analyzing the DIS signal received from the partner receiver during the execution of the facsimile communication procedure and temporarily storing the data signal speed capability included therein. This is composed of, for example, a 4-bit memory. Note that the DIS signal is a digital identification signal.

The previous speed storage section 15 is a section for storing the data signal speed previously adopted for each transmission destination. The data signal speed determination unit 14 is a unit that performs the operation of determining the data signal speed according to the present invention based on the information stored in the capability storage unit 13 of the receiver and the previous speed storage unit 15.
Specifically, this is constituted by a predetermined program of a processor for controlling the facsimile machine.

FIG. 3 is a diagram for explaining the contents of the previous data signal speed recording. As shown in FIG. 1, the content of the data signal speed record stored in the previous speed storage unit 15 shown in FIG. 1 represents, for example, the data signal speed at the previous transmission for each transmission destination. The method of displaying the data signal speed is represented by numbers 1 to 6 determined according to the capability of the modem.

FIG. 4 is an explanatory diagram showing the relationship between the V recommendation and the data signal speed value. As shown in the figure, the data signal rate indicated by the V. recommendation is, for example, V.V. 27 of 2.4 kbp
s to V. Six levels of switching are possible within a range of 33, 14.4 kbps. Values 1 to 6 are set for these data signal speeds. This value is used as the data signal speed record shown in FIG. As a result, the data signal speed storage portion at the time of the previous transmission has a storage capacity of 3 bits. Note that a destination that has never been transmitted is initialized to the maximum value 6 of the data signal speed of its own device.

Next, the operation of the apparatus of the present invention will be described with reference to FIG. FIG. 5 is a flowchart showing an operation main routine of the apparatus according to the first embodiment. In a normal facsimile apparatus, a facsimile communication procedure is started, and when the phase B process is performed, the data transmission speed is determined.
Here, the operation from the start of the phase B will be described. The operation of the other parts is the same as the conventional one.

First, in step S1, a destination is specified in the previous speed storage unit 15 shown in FIG. Thereby, the setting is made so that the previous data signal speed of the corresponding destination can be read. Next, in step S2, the data signal speed determination unit 14 is initialized. To set a new data signal speed, the previous data is cleared. Next, in step S3, a DIS is received from the partner device. This is a process of receiving information about the data transmission / reception capability from the partner device. Thus, in step S4, the data signal speed capability of the receiver is extracted and stored in the capability storage unit 13 of the receiver. Then, the process proceeds to a data signal speed determination process according to the present invention.

That is, in step S5, the data signal speed determination unit 14 starts. FIG. 6 shows the operation of the data signal speed determination unit. It should be noted that if this main routine is described in advance with respect to the subsequent procedure, step S5
When the data signal speed is determined in step S6, it is determined in step S6 whether the value of the data signal speed is 0. If the data signal speed value is equal to or greater than "1", that is, if the data signal speed value is equal to or greater than the minimum speed, the process proceeds to step S7, where a DCS signal is transmitted to determine a new speed.

At step S8, a TCF signal is transmitted to perform a training check. In step S9, a response signal is received, and it is determined in step S10 whether the response signal is an FTT signal. If it is an FTT signal, a fallback sequence is performed. That is, the process returns to step S5, and the data signal speed determination process is performed again. When the data signal speed is determined by performing the processing up to step S10 in this manner, the process proceeds to step S11,
Thereafter, message transmission and communication completion processing are performed, and the previous data signal speed record is updated in step S12.

That is, in FIG.
Then, the destination and the current data signal speed are stored, and the process ends. If the data signal speed value becomes "0" in step S6, the process proceeds to step S13.
In this case, the call is disconnected because communication is impossible at any data transmission speed. DCN for that
A signal is sent in step S13, and the process ends.

The DCN signal means a disconnection command. The FTT signal is a training failure signal. The TCF signal is a training check signal. Further, the CFR signal is a reception preparation confirmation signal.
Thereafter, this signal is used to shift to the phase C message transmission.

Next, the operation of the data signal speed determination unit will be described with reference to FIG. First, in step S14 of FIG.
After starting this communication, the data signal speed determination unit 14 determines whether or not it has been started for the first time, that is, whether or not it has been restarted. If it is started for the first time, the process proceeds from step S14 to step S15, where the previous data signal speed value is set to the data signal speed value to be processed. And step S
Proceeding to 6, it is determined whether the data signal speed value is "6". If the data signal speed value is less than "6", the process proceeds to step S17, where the data signal speed value is incremented. That is, if the previous data signal speed value is "3", it is increased by one step to "4".

Next, in step S18, it is determined whether the data signal speed value is within the capability range of the partner. If the capacity exceeds the partner's ability range, such setting is impossible, so the process proceeds to step S19, and the maximum value of the partner's data signal speed is set to the current data signal speed value. On the other hand, if the data signal speed value is within the range of the partner's capability, the value set in this way is determined as the data signal speed value to be used for the current transmission. If the data signal speed value is "6" in step S16, the data signal speed value cannot be further incremented.
Jump to 18.

Thus, the previous data signal speed value is set to 1
If the data signal speed value of this time is determined after the stage increment, if the quality of the communication line is improved, the communication speed is sequentially increased by one stage to select the optimum communication speed. it can. In addition, if it is determined that the data signal speed value that has been incremented this time is inappropriate, it is possible to return to the optimum value in one fallback sequence, thereby preventing a long time from being spent in the fallback sequence. it can.

If it is determined in step S14 in FIG. 6 that the restart is performed, the process proceeds to step S20. The restart is an example in which a fallback sequence is performed in step S10 of FIG. At this time, decrement processing for lowering the data signal speed value set so far by one rank is performed. Then, in a step S21, it is determined whether or not the data signal speed is "0".

If the data signal speed is "0", it is determined that there is no appropriate signal speed to be transmitted, and the process is terminated.
If it is not "0", the process proceeds to step S22, and it is determined whether or not the data signal speed is within the capability range of the other party. If it is within the capability range of the opponent, the process is terminated as it is. If it exceeds the capability range of the opponent, step S2
Returning to 0, the data signal speed value is decremented again.

<Effect of Specific Example 1> As described above, the previous data signal speed is stored for each transmission destination, and the current transmission speed is stored within the range of the capability of the transceiver. Since the training was performed by selecting the speed one level higher than the previous data signal speed and using this as the initial value,
Even if the quality of the communication line is poor, transmission preparation is completed in about one fallback sequence. Further, if the quality of the communication line is improved as compared with the related art, the speed is automatically increased, and the optimum communication speed can be selected.

It should be noted that control may be performed so as to initialize not only the speed one step higher than the previous data signal speed but also a speed close to the previous speed. The speed close to the previous speed is a range of several stages around the previous speed, preferably two to three stages or less. If the fallback sequence is speeded up due to the performance improvement of the device, or if a method that allows more detailed selection of stages appears, for example, the data communication speed should be initialized to several steps higher or lower than the previous speed. The same effect can be obtained even if the control is performed as described above. If you initially set the speed higher than the previous speed,
This has the effect of quickly reaching the highest possible communication speed. If the speed is initially set to a speed lower than the previous speed, communication can be started more reliably even if the communication environment deteriorates.

<Embodiment 2> FIG. 7 shows a functional block diagram of the apparatus of Embodiment 2. This device includes a data signal speed history storage unit 16 instead of the previous speed storage unit 15 of the device of the first embodiment.

FIG. 8A is a diagram for explaining the contents of the data signal speed history. (B) shows an explanatory diagram of a frequency distribution extraction result. In this specific example, the data signal speed history as shown in FIG. 7A is stored in the data signal speed history storage unit 16 shown in FIG. 7 for each transmission destination. FIG.
As shown in (a), this information includes the previous communication, the previous communication, the previous communication,..., The N previous communication, and so on.
For each communication, the data signal speed value at that time and the presence or absence of fallback are recorded.

As described above, the data signal speed value is, for example, any one of "1" to "6". The presence / absence of fallback indicates, for example, whether or not the data signal speed value was determined without a fallback sequence when training was performed using the previous data signal speed value as an initial value. When the data signal speed value is determined without the fallback sequence, the content is set to "0", and when the fallback sequence is performed even once, the content is set to "1". by this,
The data signal speed history has a data signal speed value of 3 bits,
The presence / absence of fallback is 1 bit, which is the content of 4 × N words.

This data is searched while the pointer is advanced in order from the oldest history position (the communication N times before in this figure) to the latest history position (the communication one time before), as shown in FIG. The frequency distribution is extracted, and the data signal speed value setting is determined as described later.

As a result, for example, as shown in FIG.
The frequency distribution at which communication was performed can be obtained. For example, as shown in this figure, it can be seen that, for a particular destination, the case where the data signal speed value is "4" is the most common, and the case where the data signal speed value is "3" or "5". The apparatus shown in FIG. 7 operates based on such data.

FIG. 9 shows an operation main routine of the apparatus of the second embodiment. This processing is different from the operation of the device of the first embodiment shown in FIG. 5 in the steps S1 and S12 and the operation of determining the data signal speed in step S5. First, in step S1, a destination is specified in the data signal speed history storage unit 16 in advance. As a result, necessary data is extracted. The data signal speed is determined based on such data.

In step S12 in FIG. 9, when the current data signal speed is finally determined, the contents stored in the data signal speed history storage section 16 are updated in order to reflect the content in the data signal speed history. Processing is performed. Since the storage capacity of data itself is limited by the limitation of hardware, as shown in FIG. 8A, for example, data signal histories are stored only from the latest one to the Nth previous one. Therefore, at the time of the update, the one before one is two times before, the one before two times three times, and the one before N-1 times is N
The content will be updated as before.

Next, using FIG. 10 and FIG.
Of the data signal speed determination unit (step S5 in FIG. 9)
Will be described. In step S1 of FIG. 10, first, it is determined whether or not the restart is performed. For the first speed setting,
The process proceeds from step S1 to step S2. In step S2, the frequency for each speed value is obtained from the data signal speed history. This is a process for obtaining data having contents as shown in FIG. Next, the process proceeds to step S3, where the data signal speed value is set to the speed value having the maximum frequency. For example, FIG.
In the case of (b), the data signal speed value is initialized to "4".

Next, in step S4, a value of -N is set to the history pointer. As a result, FIG.
The process of reading the data shown in (a) from the oldest history is started. The non-fallback history counter is cleared. This non-fallback history counter is a counter that counts how many times a data signal rate without fallback has been set until recently. In step S5, it is determined whether the history pointer is smaller than "0". When the history pointer becomes “0”, the data reading process is finished because the previous data has been read.

When the process proceeds from step S5 to step S6, first, the data signal speed value is read from the history storage unit.
Then, it is determined whether or not the data signal speed value set this time matches the data signal speed value to be counted. If they do not match, to read the next data, step S11
Proceed to. If they match, the fallback history of the data signal speed value is read (step S8).

Here, as shown in FIG. 8A, when there is a fallback history, that is, when the content is "1", the process proceeds to step S12, and when it is "0", the process proceeds to step S1.
Go to 0. If it is "0", the non-fallback history counter is incremented. That is, this counts that the data signal rate has been used once without non-fallback. By performing the loop processing from step S5 to step S11, it is possible to detect, for example, the communication performed immediately before, for example, several times immediately before, at a constant data signal speed, in a non-fallback state, that is, without fallback. When communication is performed several times without fallback, it can be determined that communication can be performed stably at the data signal speed value.

However, when such a non-fallback setting has not been made in the last few times, it can be understood that the data signal speed value is not always appropriate. In step S9, if there is a fallback, the non-fallback history counter is cleared. With this configuration, the counter is reset to "0" when there is at least one fallback, and the result is displayed on the counter only when the non-fallback processing is performed several times continuously. .

If it is determined in step S5 that all data has been read, the flow advances to step S13 to determine whether the non-fallback history counter is "3" or more. That is, when the non-fallback processing is performed three times in succession, it is determined that the data signal speed is a stable speed. Note that, in this case as well, specific example 1
Similarly to the above, the training is performed from the speed one step higher than the speed. That is, in step S14, the data signal speed value is incremented to set an initial value of the data signal speed.

In FIG. 11, it is first determined in step S15 whether the speed thus set is within the range of the partner's ability. If it is not within the opponent's ability range,
Proceeding to step S16, the data signal speed value is set to the highest value of the data signal speed of the other party. If it is within the capability range, the process proceeds to step S17, where the fallback flag is cleared and the process ends.

If it is determined in step S1 in FIG. 10 that the vehicle is to be restarted, the process proceeds to step S18 in FIG.
Here, the fallback flag is turned on, and in step S19, the data signal speed value is decremented. In step S20, it is determined whether or not the data signal speed value is not "0". If the speed value is not "0", the process proceeds to step S21 to determine whether or not the data signal speed value is within the range of the other party's ability. I do. As a result, if the performance is equal to or lower than the partner's capability, the process is terminated. If the capability is out of the partner's capability range, the process returns to step S19, and the data signal speed value is further decremented. In this way,
In the case of fallback processing, resetting is performed while sequentially decrementing the data signal speed value.

<Effect of Specific Example 2> According to this specific example,
The history of the data signal speed and the fallback from the immediately preceding communication to the communication up to N times before are stored, and the next data signal speed is predicted according to this history, and if the non-fallback process is performed several times continuously, Since the data signal speed is set to an appropriate value and the initial setting is performed, it is possible to perform the initial setting in consideration of the past history even more than in the first specific example.
Other operations and effects are the same as those of the first embodiment.

In the case of the specific example 2, the data signal speed is tabulated by the frequency distribution, but a method of taking an average value or a maximum value is also possible. Of course, this can be applied not only to the facsimile apparatus but also to various data communication terminals having fallback control. Further, the example in which the history of the data signal speed and the like are stored for each transmission destination has been described. However, it is also possible to uniformly apply the data signal speed history of the device itself without specifying the communication partner. In this case, the self-receiver capability declaration T.D. which does not declare a data signal speed exceeding the determined initial value of the data signal speed. If this data signal speed declaration is deleted from the 30 DIS signals, this application can be applied even at the time of data reception.

Further, although an example has been shown in which the data signal speed is decremented each time training fails, a method may be employed in which the training check is repeated several times before fallback. Alternatively, a predetermined data table for initial setting of the optimum data signal speed from the past data signal speed history may be prepared and referred to. In this case, a typical pattern can be arranged, and the initial setting of the data signal speed can be performed according to the pattern.

The data signal speed history and the presence / absence of the fallback sequence are stored to determine the initial value of the data signal speed. Settings can also be made. Further, the data signal speed one step higher than the initially set data signal speed is always set as the initial value. However, depending on the case, this is not performed, and the data signal speed set initially or one step higher than the initially set data signal speed is used. It is also possible to select to execute communication in a state where the line quality is stable, such as setting the lower data signal speed as an initial value.

<Embodiment 3> FIG. 12 shows a functional block diagram of the apparatus of Embodiment 3. This device includes a communication data storage unit 17 instead of the previous speed storage unit 15 of the device of FIG. Here, the following data is stored.

FIG. 13 is a diagram for explaining the contents of the communication data of the third embodiment. Here, data such as the telephone number of the partner station, communication date, communication result, data signal speed, and error rate are stored. The error rate indicates the number of error frames / the number of transmission frames. That is, when communication is performed at a predetermined data signal speed, the frequency of occurrence of an error is displayed here as an error rate. If fallback occurs and communication is performed at multiple data signal rates,
It is preferable to record the error rate for each data signal speed. In this specific example, an initial value of the data signal speed is selected based on the communication data as described above.

First, FIG. 14 shows an operation flowchart (part 1) of the third embodiment. In step S1, communication data relating to a partner station to be transmitted is called from the communication data storage unit. That is, the communication data as shown in FIG. 13 stored in the communication data storage unit 17 shown in FIG. 12 is read. If there is, the process proceeds from step S2 to step S3. If not, the process proceeds to step S8.

In step S3, it is determined whether or not the communication data has been normally terminated. If the operation is normally completed, the process proceeds to step S4, and the error rate at the final data signal speed of the communication data is obtained. Then, in step S5,
The error rate is compared with a predetermined value k to determine what state the error rate is in. When the error rate is smaller than the predetermined value k, that is, when the error rate is relatively low, the data signal rate is determined to be an appropriate value, and the data signal one step higher than the final data signal rate of the communication data is determined in the same manner as the above processing. Initialize the speed as your maximum capacity.

On the other hand, if it is determined in step S5 that the error rate is not smaller than the predetermined value k, step S9
To determine whether the error rate is greater than a predetermined value K. If it is larger, the process proceeds to step S10, and the data signal speed one stage lower than the final data signal speed of the communication data is set as the self-maximum capacity. That is, when the error rate is high, it is determined that the data signal speed is not appropriate, and the speed one rank lower is set as the initial value.

On the other hand, if the error rate is equal to or lower than K, the final data signal speed of the communication data is set to its own maximum capability in step S11. That is, although it is inappropriate to go up, it is not necessary to go down (0 ≦ k <
If the value K) is set to K, an appropriate data signal speed is selected in steps S6, S10, and S11. If it is determined in step S3 that the communication data has not been completed normally, the process proceeds to step S3.
From 3, the process proceeds to step S <b> 7, and the data signal speed one stage lower than the final data signal speed of the error-terminated communication is set as the self maximum capacity. That is, in this case, the previous communication does not end normally, and the data signal speed is inappropriate, so that the initial value is set to a value lowered by one stage.

If it is determined in step S2 that there is no communication data for the partner to be transmitted,
The maximum speed is set as the maximum capacity of the apparatus in the initial setting of the apparatus by the same processing as that of the related art (step S8). Steps S7 and S
When the processes of 8, S6, S10, and S11 are completed, the process proceeds to the next training process in any case.

FIG. 15 shows an operation flowchart (part 2) of the embodiment 3, and FIG. 15 (a) shows a procedure following the processing of FIG. (B) shows a procedure following the processing of (1).
First, in (a), in step S12 in the figure, the maximum data rate of the partner device is compared with the maximum data rate of the partner apparatus confirmed by the pre-communication procedure, and the lower data signal rate is determined as the data signal rate of the transmission start. . Next, in step S13, transmission of image data is started after the phase matching / training. That is, the process proceeds to the process of the phase C here. In step S14, the current communication data is stored in the storage unit, and if the communication data of the same partner station is stored, it is overwritten. Thus, the communication data is updated.

If it is determined in step S3 of FIG. 14 that the answer is N, the process can proceed to the process shown in FIG. 15B instead of proceeding to step S7 of FIG.
In (b), it is considered that the state of the line is actually extremely bad. If the processing has been performed using the 34 modulation method, it is determined whether an error has occurred in the pre-communication procedure (step S15). And if there is an error here, it is another protocol,
A protocol for performing stable communication even when the line condition is worse, for example, V.40. Switching to the 17 modulation system is performed. That is, V. The maximum data signal speed in the 17 modulation method is initialized as the self-maximum capacity (step S16).

In step S15, the V.V. 34
If it is determined that an error has not occurred in the modulation method, the process proceeds to step S17, and the data signal speed one stage lower than the final data signal speed of the error-terminated communication is set as its own maximum capacity. In other words, in this case, the processing is continued with the previous protocol.

<Effect of Specific Example 3> According to the specific example described above, based on the past communication data, the optimal initial value of the data signal rate is selected from the error rate at the time of frame transmission. It is possible to set an appropriate data signal speed according to the condition at an early stage. Other effects are the same as those in the specific examples 1 and 2. In addition, when the line condition is poor, transmission by another method is enabled by changing the protocol, so that a more appropriate data signal speed can be set.

<Embodiment 4> In Embodiment 3, the method of initially setting the data signal speed at the start of transmission on the calling side according to the contents of the communication data stored in the storage unit on the calling side has been described. However, the same can be done in the called device.

FIGS. 16 and 17 show flowcharts (parts 1 and 2) of a modification of the fourth embodiment. The configuration of the device on the called side is the same as that of the device on the calling side, but the operation is as shown in FIG. 16 and FIG. FIG.
6 and 17 correspond to the flowcharts shown in FIGS. 14 and 15 on the calling side. Therefore, only the part different from the calling side will be described below.

First, in step S1 of FIG. 16, when the calling ring rings, the other party's telephone number information arriving with the calling ring is received and stored in the storage unit. Then, in step S2, the communication data for the partner transmitting station to be received is read from the communication data storage unit. That is, the called side recognizes the other party's telephone number, and refers to the communication data indicating the past communication contents stored in the communication data storage unit in advance for each telephone number.

In step S3, it is determined whether or not there is corresponding communication data relating to the partner station to be received. If there is communication data, the process proceeds to step S4. If not, the process proceeds to step S8. Subsequent processing is exactly the same as the processing in the calling device shown in the third embodiment.

FIG. 17A shows a process when it is determined that the latest communication data has ended in error as a result of the determination in step S4 of FIG. In this case, the data signal rate one step lower than the final data signal rate of the communication in which the error has ended is selected as the self-maximum capacity. This processing is referred to as step S20. FIG. 17B is a process performed when an error occurs in the pre-communication procedure, and corresponds to FIG. 15B.

On the other hand, a process corresponding to the process on the calling side shown in FIG. 15A is shown in FIG. Here, in step S12, the self-maximum capability is transmitted to the calling side by a pre-communication procedure. The transmitter on the calling side determines the lower transmission rate as the transmission rate at the start of transmission by comparing the capability declaration of the receiver with its own maximum capacity. The other processes are exactly the same as the corresponding processes on the calling side.

<Effect of Specific Example 4> As described above, the negotiation is quickly established by indicating the appropriate self-maximum capability from the called side to the calling side, and the optimum data signal speed is initialized. In this way, not only the calling side but also the called side can perform the same processing as in the specific example 3 to optimize the data signal speed.

<Specific Example 5> ITU-T Recommendation V. In the control channel specified in ITU-T Recommendation T.34. Transmission / reception of a procedure signal for facsimile communication specified in 30 is performed. This control channel is provided not only at the start of facsimile communication but also at the end of transmission of each page. V. In the case of facsimile communication of No. 34, this control channel is provided with an ECM (error correction mode). If there is an error frame in the image data in the primary channel for transmitting image data, the receiving side issues a PPR signal (partial page request signal) and transmits the error frame information to the transmitting side. The sender is
The corresponding error frame is retransmitted to the receiving side in the next primary channel.

At this time, the transmitting side transmits the error frame at the same transmission rate as the immediately preceding transmission rate or at one step lower than the previous transmission rate. This control is continued until there is no error in the image data, that is, until an MCF (receive without error) signal is sent from the receiving side to the transmitting side. However, even if retransmission is performed at the same transmission rate as before or at a transmission rate one step slower, the error of the image data may not be eliminated. Here, if the retransmission of the error frame continues, the communication period is extended by that much. In this specific example, such a case is rescued.

FIG. 18 is a block diagram of a facsimile apparatus for carrying out the fifth embodiment. In FIG. 18, a facsimile machine 21 (hereinafter referred to as a calling station) on the calling station side indicated by a dashed line is provided with a scanner 22 for reading information on a transmission document 22A and a reception copy 23A for receiving information received from the called station. The printer reads the information read by the printer 23 and the scanner 22, and processes the information as image information into the line memory 2.
4 and a recording processing unit 25b that processes image information to be printed received from the line memory 24 and transmits the information to the printer 23. Note that the reading / recording processing unit 25 is configured by the reading processing unit 25a and the recording processing unit 25b.

The calling station 21 also stores image information to be transmitted to the called station in the line memory 2 according to the data compression mode.
The image information compression / decompression unit 26, which receives the image data from the called station and decompresses the processed image data, compresses the image data while reading out the image data from the called station, / Communication buffer RAM (random access memory) 28 for recording image data as a transmission buffer when transmitted via data bus 27
And the image data recorded in the communication buffer RAM 28 by a modem / NCU (network control unit).
When transmitting via the interface 29 and modulating the image data and the control signal to be transmitted and receiving the image data and the response signal from the called station, the modem 30 for demodulating the image data and the response signal, the NCU 37 and Is provided.

The communication buffer RAM 28
When receiving data from the called station, it becomes a reception buffer,
The image data and the response signal demodulated by the modem 30 are stored. The stored image data and response signal include an address /
The data is transmitted to the image information compression / decompression unit 26 via the data bus 27. Also, the modem 30 has 8 and V.I. 34
Modem with the function of

The calling station 21 further includes a CPU (control means) 31 for performing system control of the entire calling station 21, management of each signal flow, communication control, general control of network control, and the like.
And a program ROM (read only memory) for storing program data of the CPU 31 and a table described later.
32 and a communication management information storage RAM for storing the number of one-page transmission frames, the number of error frames, and the error rate described below.
33, a mechanism control unit 35 and an operation display unit 3 connected to the address / data bus 27 via the interface 34.
6 are provided.

The mechanism control unit 35 controls a driver, a medium detection sensor, and the like in accordance with an instruction from the CPU 31. The operation / display unit 36 has a man-machine interface function, and conveys operation contents (operation instructions) of main devices involved in facsimile communication to the CPU 31, and receives contents display status of the devices from the CPU 31 to a panel (not shown). indicate.

FIG. 19, FIG. 20, and FIG. 21 are operation flowcharts of the device of the fifth embodiment. First, the operator inputs a telephone number using the operation / display unit 36 shown in FIG. The CPU 31 transmits the information to the interface 3
Recognize through 4. Thus, the CPU 31 performs a calling process in step S1. After calling, the CPU 31 sends out a CNG signal in step S2. Next, in step S3, the CPU 31 waits for an ANSam signal from the called station. When receiving the ANSam signal, the CPU 31
Means that the called station's modem is 8 Recognize that the modem is capable of communication. Thus, the process proceeds to step S4. Otherwise, the process proceeds to step S9.

At step S9, NSF. (CSI) .D
When an IS signal is received, T. other than 34 Thirty transmission controls are performed. If this signal has not been received, the process proceeds to step S10 to detect a timeout. If the timeout has occurred, the process proceeds to step S11, where the line is disconnected and the operation is terminated. On the other hand, if the timeout does not occur, the process returns to step S2.

In step S4, the CPU 31 informs the called station of the CM in order to notify the modulation mode of the CPU 31.
Send a signal. The called station sends a JM signal to indicate which is valid for the modulation mode of the calling station. This is detected by the CPU 31 in step S5. In step S6, a CJ signal is transmitted. Thereafter, the process proceeds to step S7, where the modem 30 34 Go to phase 2 operation.

This V. In phase two, both modems exchange their modulation options,
The line characteristics are measured by the line probing signal. Further, the symbol rate, the presence or absence of pre-emphasis, the usable data rate, the carrier frequency, and the transmission level of each transmitter are exchanged, and the process proceeds to the next step S8. Step S8
Then, V. 34. Phase 3 is executed. In phase 3, training of the equalizer and the echo canceller is performed based on the symbol rate and the carrier frequency. Then, FIG.
The process proceeds to step S12 shown in FIG.

In step S12, the CPU 31 starts a control channel timer, and proceeds to step S12.
Proceed to 13. Further, the CPU 31 checks whether the modem 30 has finished exchanging modulation parameters and training, and has entered the data mode. If the mode is the data mode, the process proceeds to step S14; otherwise, the process proceeds to step S17. In step S14, the CPU 31
U.T. In accordance with the procedures set forth in
(CSI)-Transmission and reception of procedure signals such as DIS, NSS, DIS, and CFR are performed with the called station.

Further, it is checked whether the procedure has been completed. If the procedure has been completed, the process proceeds to step S15; otherwise, the process proceeds to step S17. In step S17, it is determined whether or not the control channel timer has timed out. If not a timeout, the process proceeds to step S13, and the control channel is continued. On the other hand, when a timeout occurs, the process proceeds to step S18, and a line disconnection process is performed. And
Thereafter, a communication error process is executed in step S19.

On the other hand, from step S14 to step S15
When the process proceeds to step (c), the CPU 31 reads information on the determined transmission rate from the modem 30. Then, the transmission rate is stored in the communication management information storage RAM 33. This transmission rate is assumed to be A. Thereafter, in step S16, the image data is transmitted as primary channel data for one page.

Next, the process proceeds to step S20 shown in FIG. Here, the modem 30 enters the control channel. At the beginning of the control channel, the modulation parameters that are essentially communicated are transformed, trained,
Determine the data rate at which communication is possible. The CPU 31 starts the control channel timer in step S20, and determines in step S21 whether the control channel has entered the data mode.

When the exchange of the modulation parameters and the training are completed and the mode is changed to the data mode, the process proceeds to step S22. Otherwise, the process proceeds to step S34. Step S34 is processing to determine whether or not the timer for the control channel has timed out. If not, the process returns to step S21. If a timeout has occurred, the process proceeds to step S35, where a line disconnection process is performed, and a communication error process is performed in step S36.

On the other hand, when the process proceeds from step S21 to S22, the CPU 31 reads out information on the determined transmission rate from the modem. Further, the communication management information storage RAM 33
As the transmission rate A. Then, step S2
In step S3, the CPU 31 sets the T.T. 30 according to the post command (PPS / EOP, PPS / MPS, PP
S.EOM).

Further, the flow advances to step S24 to check whether a response to the post command has been received. If no response has been received, the process proceeds to step S33. In step S33, it is determined whether the post command has been tried three times. That is, the post command transmission in step S23 is tried three times. If no response is received after three attempts, the process proceeds to step S35. When the response is received, the process proceeds to step S25.

In step S25, it is determined whether an MCF signal has been received. If an MCF signal has been received, the flow advances to step S29 to determine whether there is one or more untransmitted images. If there is, step S30
The image data for one page is transmitted using the primary channel data. Otherwise, step S3
Proceeding to 1, the DCN transmission is performed, and in step S32, a line disconnection process is performed.

If it is determined in step S25 that the MCF has not been received, the process proceeds to step S26. Step S
At 26, it is determined whether a PPR signal has been received.
If a PPR signal has been received, the process proceeds to step S27. Here, the transmission rate A stored in step S22 is read from the communication management information storage RAM. Then, a transmission rate two lower than the transmission rate is set in the modem. Thereafter, the process proceeds to step S28, where the primary channel data is retransmitted. In the case of this retransmission, there is retransmission of a partial page and the like.

The above is the operation of the device of the fifth embodiment. During the above operation, in step S22, the facsimile apparatus stores information corresponding to the control channel transmission rate, that is, the data signal rate described in the first to fourth embodiments. If the data is to be retransmitted based on the image data transmission error, in step S27, the data signal speed is initialized to a speed two steps lower than the stored transmission rate A. This increases the rate at which retransmitted image data is transmitted to the called station without error.

In the above step S27, the transmission rate which is two steps lower than the stored transmission rate is forcibly initialized in the modem. For example, if the line condition is very bad, the previous transmission rate The transmission rate may be set to three steps lower than the transmission rate. Initial settings may be made so as to be close to the previous transmission rate and slightly lower than that.
Needless to say, this specific example 5 and the following specific example 6 can also be applied to various communication apparatuses other than the facsimile apparatus.

<Effect of Specific Example 5> As described above, in this specific example, when an error occurs during transmission of image data,
When retransmitting the image data or partial image data, the speed is set to two or more steps lower than the data signal speed at the time of the error, so that the error occurrence rate at the time of retransmission decreases. Thus, retransmission can be performed reliably. Thereby, the communication time can be shortened.

<Embodiment 6> FIG. 22 is a flowchart showing the operation of the apparatus of Embodiment 6. As described above, when retransmitting image data, a transmission rate can be set in consideration of an error rate in addition to a method of uniformly lowering the transmission rate by two steps. That is, in this specific example, an example will be described in which the data signal speed according to the error rate is initialized at the time of retransmission.

For this purpose, first, in step S15 in FIG.
In addition, processing for storing the number of transmission frames of one page as the number B of transmission frames of one page in the communication management information storage RAM is added to step S22 of FIG. Further, FIG.
The process shown in step S27 is changed as shown in FIG. That is, the following table is stored in the program ROM 32.

FIG. 23 is a table explanatory diagram of the error rate and the number of fallbacks. As shown in this figure, in this specific example, the number of fallbacks indicating how many steps the transmission rate is reduced is made to correspond to the error rate of the page in which the error has occurred. In the example of the figure, the fallback number is “1” when the error rate is 0.3, the fallback number is “2” when the error rate is 0.8, and the fallback number when the error rate is more than 0.8. Is "3".

That is, if the error rate is somewhat low, data retransmission is performed at a transmission rate one step lower than the immediately preceding transmission rate. If the error rate is about 0.8, retransmission is performed at a two-step lower transmission rate. If the error rate is higher than this, retransmission is performed at a three-step lower transmission rate. Make these settings.

Next, the operation of the apparatus will be specifically described with reference to the flowchart of FIG. First, in step S26, when a PPR signal is received, the process proceeds to step S37. In step S37, the CPU 31 reads the number of image error frames from the PPR signal. Then, the number of error frames C is stored in the communication management information storage RAM.

Next, in step S38, the number B of transmission frames per page and the number C of error frames are read from the RAM for storing communication management information. Then, the result of dividing C by B is set as an error rate D, and stored in the communication management information storage RAM.

Next, in step S39, the error rate D is read from the RAM for storing communication management information, and is compared with the data a1: 0.3 in the ROM. In step S40, it is determined whether or not the error rate D is smaller than a1, that is, 0.3. If the error rate is low, step S41
Then, the transmission rate A is read from the communication management information storage RAM, and a transmission rate one step lower than the transmission rate A is set in the modem.

On the other hand, if it is determined in step S40 that the error rate D is not smaller than 0.3, step S42
Then, the error rate D is read from the communication management information storage RAM and compared with the data b1: 0.8 in the ROM. That is, in step S43, it is determined whether the error rate D is lower than 0.8. If it is lower than 0.8, step S44
Then, the transmission rate A is read from the communication management information storage RAM, and a transmission rate two steps lower than the transmission rate A is set in the modem.

On the other hand, if it is determined in step S43 that the error rate D is not smaller than 0.8, step S4
Proceeding to 5, the transmission rate A is read from the communication management information storage RAM, and a transmission rate three steps lower than the transmission rate A is set in the modem.

As described above, an appropriate threshold of the error rate is set, and how many steps the transmission rate is reduced in accordance with the error rate is determined in advance. As a result, retransmission at a lower transmission rate is performed as the error rate increases. The correspondence with the number of fallbacks can be set to an optimum value by an experiment or the like.

<Effect of Specific Example 6> As described above, according to this specific example, when an image data transmission error occurs,
Since retransmission of image data is performed by setting a low transmission rate according to the error rate, the rate of occurrence of errors due to retransmission is further reduced, and as a result, communication time can be shortened.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an apparatus according to a first embodiment.

FIG. 2 is a block diagram of the entire facsimile machine.

FIG. 3 is an explanatory diagram of the contents of previous data signal speed recording.

FIG. 4 is an explanatory diagram showing a relationship between a V recommendation and a data signal speed value.

FIG. 5 is a flowchart of an operation main routine of the apparatus according to the first embodiment.

FIG. 6 is an operation flowchart of a data signal speed determination unit.

FIG. 7 is a functional block diagram of an apparatus of a specific example 2.

FIG. 8A is a diagram for explaining the content of a data signal speed history,
(B) is an explanatory diagram of a frequency distribution extraction result.

FIG. 9 is a flowchart of an operation main routine of the apparatus according to the second embodiment.

FIG. 10 is an operation flowchart (part 1) of a data signal speed determination unit.

FIG. 11 is an operation flowchart (part 2) of the data signal speed determination unit.

FIG. 12 is a functional block diagram of an apparatus according to a third embodiment.

FIG. 13 is a diagram illustrating the contents of communication data according to a third specific example.

FIG. 14 is an operation flowchart (part 1) of the third embodiment.

FIG. 15 is an operation flowchart (part 2) of the third embodiment.

FIG. 16 is a flowchart of a modification of the specific example 4 (part 1).
It is.

FIG. 17 is a flowchart (part 2) of a modification of the specific example 4.
It is.

FIG. 18 is a block diagram of an apparatus according to a fifth embodiment.

FIG. 19 is an operation flowchart (part 1) of the device of the specific example 5;

FIG. 20 is an operation flowchart (part 2) of the device of the specific example 5;

FIG. 21 is an operation flowchart (part 3) of the device of the specific example 5;

FIG. 22 is an operation flowchart of the device of Example 6;

FIG. 23 is an explanatory diagram of a table of the number of errors and the number of fallbacks.

[Explanation of symbols]

 Reference Signs List 1 telephone line 4 modem 5 line connection unit (NCU) 6 control unit 8 modem setting unit 12 communication control unit 13 receiver capacity storage unit 14 data signal speed determination unit 15 previous speed storage unit

Claims (17)

[Claims] 1. A method for switching an initial value of a preset data signal speed stepwise according to the transmission quality of a communication line,
A data signal speed determination unit that determines a data signal speed for performing the current communication, and a previous speed storage unit that stores the data signal speed determined in the previous communication, the data signal speed determination unit includes: With reference to the previous data signal speed stored in the previous speed storage unit, a data signal speed close to the previous data signal speed is set as an initial value, and a data signal speed for performing the current communication is determined. A data communication device, comprising: 2. The data communication device according to claim 1, wherein the data signal speed determination unit sets a data signal speed one step higher than the previous data signal speed stored in the previous speed storage unit to an initial value. A data communication device for determining a data signal speed for performing the current communication. 3. The data communication device according to claim 1, wherein the data signal speed determination unit sets the previous data signal speed stored in the previous speed storage unit to an initial value and performs the current communication. A data communication device for determining a data signal rate of a data signal. 4. The data communication device according to claim 1, wherein the previous speed storage unit stores the data signal speed determined at the time of the previous communication separately for each destination. A data communication device characterized by storing. 5. The method according to claim 1, wherein the preset initial value of the data signal speed is switched stepwise according to the transmission quality of the communication line.
A data signal speed determination unit that determines a data signal speed for performing the current communication, and a data signal speed history storage unit that stores the data signal speed determined in the past communication, the data signal speed determination unit Retrieves the contents stored in the data signal speed history storage unit, sets a data signal speed close to the data signal speed determined at the highest frequency to an initial value, and sets the data for the current communication. A data communication device for determining a signal speed. 6. The data communication device according to claim 5, wherein the data signal speed determination unit searches the contents stored in the data signal speed history storage unit and determines the data signal determined at the highest frequency. A data communication device, wherein a data signal speed one step higher than the speed is set as an initial value, and a data signal speed for performing the current communication is determined. 7. A data signal rate initial value set in advance is switched stepwise according to the transmission quality of a communication line.
A data signal speed determination unit that determines a data signal speed for performing the current communication, and a data signal speed history storage unit that stores the data signal speed determined in the past communication, the data signal speed determination unit Searches the contents stored in the data signal speed history storage unit, sets a data signal speed close to the fastest data signal speed determined in the past as an initial value, and sets a data for performing the current communication. A data communication device for determining a signal speed. 8. The data communication device according to claim 7, wherein the data signal speed determination unit searches the contents stored in the data signal speed history storage unit and determines the fastest data signal determined in the past. A data communication device, wherein a data signal speed one step higher than the speed is set as an initial value, and a data signal speed for performing the current communication is determined. 9. A data signal rate initial value set in advance is switched stepwise according to the transmission quality of a communication line.
A data signal speed determination unit that determines a data signal speed for performing the current communication, and a data signal speed history storage unit that stores the data signal speed determined in the past communication, the data signal speed determination unit Search the contents stored in the data signal speed history storage unit, set the data signal speed close to the average value of the data signal speed determined in the past as the initial value, and perform the current communication. A data communication device for determining a data signal rate. 10. The data communication device according to claim 9, wherein the data signal speed determination unit searches the contents stored in the data signal speed history storage unit and determines the data signal speed determined in the past. A data communication device, wherein a data signal speed one step higher than an average value is set as an initial value, and a data signal speed for performing current communication is determined. 11. An initial value of a preset data signal speed is switched stepwise according to the transmission quality of a communication line.
A data signal rate determination unit that determines the data signal rate for this communication, the data signal rate that was determined in the past communication, and whether a fallback sequence was executed when the data signal rate was determined. A data signal speed history storage unit, wherein the data signal speed determination unit determines that the initial value of the data signal speed is determined to be the actual data signal speed without a fallback sequence, and the case continues for a preset number of times or more. And a data signal speed that is close to the data signal speed is set as an initial value, and a data signal speed for performing the current communication is determined. 12. The data communication apparatus according to claim 11, wherein the data signal rate determining unit determines the initial value of the data signal rate to be the actual data signal rate without a fallback sequence, and the number of times the data signal rate is determined in advance is a predetermined number of times. When it is determined that the communication is continued, a data signal speed one step higher than the data signal speed is set as an initial value, and a data signal speed for performing the current communication is determined. apparatus. 13. The data communication device according to claim 11, wherein the data signal rate determining unit determines the initial value of the data signal rate to be the actual data signal rate without a fallback sequence, and the number of times the data signal rate is determined in advance is A data communication apparatus characterized in that when it is determined that the communication is continued, the data signal rate is set to an initial value and the data signal rate for performing the current communication is determined. 14. An initial value of a preset data signal speed is switched stepwise according to the transmission quality of a communication line,
A data signal speed determination unit that determines the data signal speed for this communication, and a communication that includes the data signal speed determined during the latest communication and the error rate when communication is performed at that data signal speed A communication data storage unit for storing data, the data signal speed determination unit refers to the communication data storage unit, the error rate at the latest determined data signal speed, a predetermined appropriate value When the error rate is equal to, the data signal speed is set to an initial value. When the error rate is equal to or less than the appropriate value, the data signal speed one step higher than the data signal speed is set to the initial value. In the above case, a data communication speed is set to an initial value by setting the data signal speed one step lower than the data signal speed to determine a data signal speed for performing the current communication. 15. An initial value of a preset data signal speed is switched stepwise according to the transmission quality of a communication line.
A data signal speed determination unit that determines the data signal speed for this communication, and a communication that includes the data signal speed determined during the latest communication and the error rate when communication is performed at that data signal speed A communication data storage unit for storing data, the data signal speed determination unit refers to the communication data storage unit, the error rate at the latest determined data signal speed, a predetermined appropriate value In the above case, a data communication device is changed to another modulation method having better communication stability. 16. An initial value of a preset data signal speed is switched stepwise according to the transmission quality of a communication line,
A data signal speed determination unit that determines the data signal speed for this communication, and a communication that includes the data signal speed determined during the latest communication and the error rate when communication is performed at that data signal speed A communication data storage unit for storing data, the data signal speed determination unit refers to the communication data storage unit, and when there is an image error at the latest determined data signal speed, the data signal speed determination unit A data communication apparatus characterized by setting a data signal speed lower by a predetermined stage than a speed as an initial value and determining a data signal speed for performing current communication. 17. A method of switching a preset initial value of a data signal speed stepwise according to transmission quality of a communication line,
A data signal speed determination unit that determines the data signal speed for this communication, and a communication that includes the data signal speed determined during the latest communication and the error rate when communication is performed at that data signal speed A communication data storage unit for storing data, the data signal speed determination unit refers to the communication data storage unit, and initializes a data signal speed corresponding to the error rate at the latest determined data signal speed. A data communication device, wherein the data communication speed is set to a value to determine a data signal speed for performing the current communication.