JPH06125442A - Data transmission speed selecting device - Google Patents

Abstract

PURPOSE:To accurately discriminate the line condition and to reduce the transmission speed in accordance with this discrimination. CONSTITUTION:A check timing detecting part 11 issues an instruction to an EQ monitor 10 for each line, at intervals of a prescribed time, or at each time of error line detection to output the line quality indication value to a speed change discriminating part 12. This part 12 discriminates whether it is necessary to change the transmission speed or not based on the supplied quality indication value at each time of the end of reception of picture information of one page. If it is necessary, an instruction is issued to a protocol control part 13 to send a signal (FTT) for fall back. The transmission station falls back by this signal FTT.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission rate selection device, and more particularly to a data transmission rate selection device capable of selecting a data transmission rate according to the quality of a communication line in a data transmission device capable of setting a plurality of transmission rates. Regarding the device.

[0002]

2. Description of the Related Art In a data transmission device such as a facsimile device, if the transmission speed is too high for the quality of the line, an error may occur during data transmission and the correct image may not be reproduced on the receiving side. In this case, it is sufficient to reduce the data transmission rate in advance to transmit the data, but this is not desirable because the transmission time is too long.
Therefore, a method of detecting an error in data and reducing the transmission rate (fallback) when an error occurs can be considered.

As an example of such a system, the communication quality is estimated by detecting an error in the received image information data, and counting the number of errors for each original document. There is a system in which the transmission speed is switched to a low speed when it exceeds the limit (Japanese Patent Publication No. 62-60873).

[0004]

The above-mentioned conventional method has the following problems. In the above method, the number of image signals of one line is counted while two synchronous codes (EOL) added to the head of one line and transmitted are detected. If the detected number of image signals is smaller than the number of image signals planned for one line, the
The line is judged as an error line.

However, if the sync code cannot be detected due to line noise or the like, the number of image signals detected for one line, that is, the number of image signals between the sync signals increases, so that even if there is an error, It is possible that it cannot be detected.

In the method which determines whether the number of error lines is greater than a predetermined value for each original, if there is a sync code detection error as described above, the number of error lines is less than the actual number of error lines. Only can be detected.

As described above, although the number of error lines for one document is originally larger than the planned number, fallback may not be performed correctly, and the transmission rate is selected accurately in accordance with the line quality. There was a problem of lacking.

The object of the present invention is to solve the above problems,
An object of the present invention is to provide a data transmission rate selection device capable of surely performing fallback and reproducing a correct image when the line quality is poor by highly accurate error detection means.

[0009]

SUMMARY OF THE INVENTION To solve the above problems and to achieve the object, the present invention is scheduled to receive image information from an eye quality monitor that outputs a quality instruction value according to the line quality. At the timing of reading the quality instruction value,
It is characterized in that the read quality indicator value is compared with a reference value to judge the quality of the line condition and the transmission rate is set for receiving the image information of the next page.

[0010]

According to the present invention having the above characteristics, the line quality can be reliably detected by the output of the eye quality monitor (hereinafter referred to as EQ monitor) while receiving the image information. The image information of the next page can be received by setting an appropriate transmission rate by comparison with the reference value.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram of the essential parts showing the hardware configuration of a facsimile machine incorporating the data transmission rate selection device of the present invention.

In the figure, a network control unit (NCU) 1 is connected to the end of the line, and a modem 2 is connected to this NCU 1. The modem 2 has an EQ monitor (not shown) that outputs a line quality detection signal. This EQ monitor outputs a quality instruction value indicated by a number from 0 to 7, for example, according to the line quality. The larger the quality instruction value, the better the line quality.

The modem 2 is connected to the system controller 3 of the main body of the facsimile, and the system controller 3 is further connected.
Is connected to a bus 4 of a microcomputer including a CPU 5 and storage devices such as ROM 6 and RAM 7. A reading device 8 and a printer 9 are connected to the bus 4 to read a transmission document and print out a reception document.

The reception operation of the facsimile apparatus having the above configuration will be described below. First, the line quality determination process for determining whether or not to reduce the transmission rate will be described with reference to the flowchart in FIG. Here, whether or not the transmission rate needs to be reduced is determined based on the output of the EQ monitor read at the scheduled time intervals during the reception of the image information.

In FIG. 3, in step S1, a monitoring timer in which a predetermined timer value is set for measuring the timing of reading the output signal of the EQ monitor is started. When it is determined in step S2 that the time set by the timer value has elapsed (timeout), the process proceeds to step S3.

In step S3, the instruction value of the EQ monitor is read and compared with the line condition determination reference value. This reference value for judging the line status is a value which is experimentally determined in advance, and is a value which is experimentally judged that a line error is less likely to occur if the quality indicator value of the EQ monitor is larger than the reference value. In step S4, it is determined whether or not the line condition is good based on the comparison result.

When it is determined that the line condition is bad, the process proceeds to step S5, and the value of the defect counter for counting the number of times the line condition is detected is incremented by "1". After adding "1" to the value of the counter, the process proceeds to step S6 and adds "1" to the value of the total check counter for counting the total number of times the quality instruction value is read from the EQ monitor.

When it is determined in step S4 that the line condition is good, step S5 is skipped and direct step S
Go to 6.

In step S7, it is determined whether the image information for one page has been received. If the determination in step S7 is affirmative, the process proceeds to step S8, and the ratio of the value of the defective counter to the value of the total check counter is calculated.

In step S9, it is determined whether or not the ratio is larger than the update determination value. If the ratio is larger than the update judgment value, it is judged that there is a high risk that a line error will occur, and the process advances to step S10 to set a flag for reducing the transmission rate.

The operation of reducing the transmission rate is performed by determining the state of the flag as described later, sending a retraining affirmative signal RTP according to the result, and rechecking the reception of the training check signal TCF.
If the ratio is smaller than the update determination value, the current transmission rate is maintained as it is.

As described above, in the embodiment shown in FIG. 3, the time-out signal of the monitoring timer is used as the trigger for reading the quality instruction value from the EQ monitor. However, the present embodiment is not limited to this, and the code EOL added to the line head of the image information is used as a trigger, and the quality instruction value is read from the EQ monitor each time the code EOL is detected. Good.

Further, a means for detecting an error line may be provided, and the quality instruction value may be read from the EQ monitor by using the error line detection signal as a trigger. As a means for detecting an error line, a general detection means for determining an error can be used when the number of pixels per line is other than a prescribed number (for example, 1728 for A4 size).

In the example of using the code EOL as a trigger and the example of reading the quality indicator value of the EQ monitor by using the error line detection signal as a trigger, the detection result of the code EOL and the error line determines whether or not the transmission rate is changed. It is not directly used for such judgment. It is merely used as a signal for activating the operation of comparing the quality indicator value of the EQ monitor with the reference value and determining whether to change the transmission rate based on the comparison result. Therefore, even if the code EOL or the error line cannot be temporarily detected due to line noise or the like, it does not directly affect the determination of the transmission rate change.

Further, in the above-mentioned example, the transmission speed is reduced based on the ratio of the number of times the line status defect is detected to the total number of times the quality instruction value of the EQ monitor is read. As a result of reading the value, if the quality instruction value is lower than the reference value even once, the transmission rate may be reduced.

When the line status is judged by one-time judgment, it is desirable to judge at the timing closest to the reception of the next page. For example, when the control return signal RTC indicating the end of receiving the image information currently being received is received, E
It is preferable to read the quality indicator value of the Q monitor.

The control return signal RTC consists of a sequence of a plurality of (six) codes EOL sent from the transmitting side. The receiving side can be configured to judge that the control return signal RTC has been received when the number of arbitrarily set numbers or more is detected in the continuous code EOL. For example, when three or more code EOLs are detected, this is returned to the control return signal RTC.
The control return signal RTC can be identified even if one to three code EOLs are temporarily not detected due to line noise.

Next, the image information receiving operation including the above-mentioned transmission rate processing will be described with reference to the general flowcharts of FIGS. In FIG. 4, in step S101,
The receivable transmission rate, for example, the maximum transmission rate that can be set by the receiving station is set. In step S102, the non-standard function signal NSF or the digital identification signal DIS is transmitted.
In step S102, the receivable transmission rate is declared.

In step S103, the reception of the non-standard function setting signal NSS or the digital command signal DCS is awaited.
If the determination in step S103 is affirmative, step S1
At 04, it is determined whether or not the transmission rate of the transmitting station and the transmission rate set by the receiving station match. In the case of affirmative determination, the process proceeds to step S105, and it is determined whether or not the training signal and the training check signal TCF have been received. If the training signal and the training check signal TCF can be received, step S107.
Then, the reception preparation confirmation signal CFR is transmitted.

On the other hand, when the transmission rate does not match between the receiving station and the transmitting station, and when the training signal or the training check signal TCF is not received, the determinations in step S104 and step S105 are negative and the process proceeds to step S106. Training failure signal F
TT is transmitted and the process returns to step S103. The calling side can fall back in response to the training failure signal FTT.

After the reception preparation confirmation signal CFR is transmitted, in step S108, image information reception is started at a transmission speed that is matched by the protocols of the receiving station and the transmitting station. In step S109, the line quality determination process described with reference to the flowchart of FIG. 3 is performed.

In step S110 of FIG. 5, it is determined whether or not a flag for reducing the transmission rate is set in the processing of step S10 of the line quality determination processing. If this determination is affirmative, the process proceeds to step S111 to set a low transmission rate.

In step S112, the Q command, that is, the multi-page signal MPS and the message end signal EO.
Wait for M, procedure end signal EOP, etc. If one of these signals is detected, the process proceeds to step S113 to determine whether the quality of the received image information is good. If the quality is good, the process proceeds to step S114 and the retraining affirmative signal R
When the TP is sent and the quality of the received image information is poor,
In step S115, the retraining negative signal RT
Send N.

In this way, when it is determined by the line quality determination process that the line state is bad, step S113
Even when the image information quality judgment result in (2) is good, the retraining affirmative signal RTP is sent out and the process returns to the phase B to judge the transmission rate and confirm the training check signal.

On the other hand, if the determination in step S110 is negative, the process proceeds to step S116 to wait for the Q command. Q
If a command is detected, the process proceeds to step S117,
It is determined whether the quality of the received image information is good. If the quality is good, the procedure goes to step S118 to send the message confirmation signal MCF. If the quality of the received image information is bad, the procedure goes to step S119 to send the retraining negative signal RTN.

After sending the retraining negative signal RTN, the retraining positive signal RTP, and the message confirmation signal MCF, the protocol is continued in accordance with the regulations.

That is, the retraining negative signal RTN
Alternatively, after sending the retraining affirmative signal RTP, the process returns to step S102. And the subsequent step S10
In step 4, the transmission rate set in step S111 is compared with the transmission rate supplied from the transmitting station to determine whether or not to send the training failure signal FTT. The transmission rate is changed by the fallback operation of the transmitting station, and the processing of step S106 is performed until the value reaches a desired value, and the training failure signal FTT is transmitted.

In the present embodiment, an example in which the transmission rate is lowered by judging that the line condition is bad is shown.
It is also possible to return to the phase B by the retraining affirmative signal RTR without lowering the transmission rate at 11, and check the line quality by the training check signal TCF.

Next, a function for performing the operation of this embodiment will be described. FIG. 1 is a block diagram showing the functions of the essential parts for performing the operation of this embodiment. In the figure, the check timing detection unit 11 has a function of measuring the timing of reading the line quality instruction value of the EQ monitor 10 provided in the modem 2. That is, as described above, the check timing detection unit 11 has any one of the timer means for detecting a predetermined time interval, the means for detecting the synchronization code EOL, the error line detection means, and the image information reception completion detection means. , The read signal is supplied to the EQ monitor 10 when the respective detection target signals are detected.

When the read signal is supplied, the EQ monitor 10 outputs a line quality instruction value corresponding to the line quality at that time in response to the read signal. This line quality instruction value is supplied to the speed change determination unit 12. The speed change determination unit 12 compares the supplied line quality instruction value with a reference value, and if the result is judged to be worse than the standard value, the transmission speed decreases at the time when reception of one page of image information is completed. Output a command.
The protocol control unit 13 outputs a protocol signal for returning to the phase B again to check the line quality, that is, a signal RTP in response to the transmission rate lowering command.

Further, the speed change judging unit 12 may output a transmission speed lowering command when it is judged by the line quality instruction value of the EQ monitor even once that the line condition is bad, or as described above. The transmission speed lowering command may be output based on the ratio of the number of times of detection of a defective line status to the total number of checks during reception of information.

[0042]

As is apparent from the above description, according to the present invention, the transmission rate is changed according to the line quality detected by the EQ monitor, so that it is not affected by the line noise and can be changed depending on the line condition. Therefore, the transmission rate can be changed reliably.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main function of a facsimile apparatus showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a hardware configuration of a facsimile apparatus showing an embodiment of the present invention.

FIG. 3 is a flowchart showing a line quality determination operation.

FIG. 4 is a general flowchart (part 1) of a receiving operation.

FIG. 5 is a general flowchart (No. 2) of the receiving operation.

[Explanation of symbols]

1 ... NCU, 2 ... modem, 3 ... system control unit,
10 ... EQ monitor, 11 ... Check timing detection unit, 12 ... Speed change determination unit, 13 ... Protocol control unit

Claims (2)

[Claims] 1. A data transmission rate selection device of a data transmission device having an eye quality monitor for outputting a quality instruction value according to line quality, wherein a scheduled timing during image information reception from the eye quality monitor. Means for reading the quality instruction value with, a speed change determination means for comparing the read quality instruction value with a reference value and outputting a transmission speed reduction command when the line condition is bad, and a response for the transmission speed reduction command. And a protocol control means configured to execute a protocol procedure for shifting to Phase B. 2. A data transmission rate selection device of a data transmission device having an eye quality monitor for outputting a quality instruction value according to line quality, wherein a scheduled timing during image information reception from the eye quality monitor. Means for reading the quality instruction value with, a speed change determination means for comparing the read quality instruction value with a reference value and outputting a transmission speed reduction command when the line condition is bad, and a response for the transmission speed reduction command. And a protocol control unit configured to send a protocol signal for causing the transmitting station to perform a fallback operation after receiving one page of image information being received. Selection device.