JPH05328086A - Modem training control system - Google Patents

Abstract

PURPOSE:To eliminate useless procedures and to provide the transfer control procedure which requires the shorter transfer time by confirming whether or not the training has been a success after sending a training signal and repeating the transmission of training signals again in case of a failure. CONSTITUTION:The training procedure control system can shorten the transfer time in the MODEM for facsimile. In the MODEM performing the training of an equalizer at the re-transmission of information, a protocol control section 9 checks whether or not the direction of training after accepting the correction continuing CTC is set. If it has been set, a MODEM 10 is set to a high-speed transmission mode, sending long training signals. Then the MODEM 10 is set to a low-speed reception mode, checking whether or not the correction continuing response CTR has been accepted. If it has not been accepted, it is assumed that the training is a failure, and the control section 9 checks whether or not the retraining request has been received, thereby sending training signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a training control system for a modem, and more particularly, in a modem for facsimile,
The present invention relates to a training procedure control method capable of shortening transmission time.

[0002]

2. Description of the Related Art Conventionally, CCITT Recommendation V.3 has been used as a modem for facsimile machines. 33, V.I. A high speed modem such as 17 is used. These modems have built-in automatic equalizers. This automatic equalizer is a gain characteristic of telephone line,
The modem on the receiving side automatically recognizes the group delay characteristic and corrects the received signal according to the characteristic. The parameter of the line characteristic is called a tap coefficient. This tap coefficient is created by the receiving modem using the training signal sent from the transmitting modem.

V. The modem recommended by 17 includes two types of training signals, a long training signal and a short training signal. The long training signal is a signal used when initial training and retraining after line connection are required, and the number of symbol times is as follows. Segment1 = 256BAUD Segment2 = 2976BAUD Segment3 = 64BAUD Segment4 = 48BAUD The total is relatively long at 1.393 seconds (1BAUD = 1/2400 seconds). On the other hand, the short training signal is used for resynchronization after successful long training, and is as follows. Segment1 = 256BAUD Segment2 = 38BAUD Segment3 = 0BAUD Segment4 = 48BAUD The total is 142 milliseconds.

Among these, Segment 2 is an equalizer adjustment pattern and is used for forming a tap coefficient, but in the case of a short training signal, the tap coefficient is sufficiently formed because the time is short. I can't afford
Short training is performed using the tap coefficient formed in the previous long training. Therefore, there is a feature that the tap coefficient cannot be formed by the long training due to noise or the like, or if it is incorrect, the tap coefficient cannot be adjusted even by the short training thereafter, so that the image information cannot be received.

FIG. 9 shows a conventional V.V. It is a caller side schematic flow chart when 17 modems are used. This procedure is standardized in CCITT as a transmission control procedure (recommendation T30) for a G3 facsimile having an error correction function (ECM). The meaning of the signal names in the figure is shown in FIG. In FIG. 9, first, when the facsimile machine makes a call in step S70, in step S71, negotiation (confirmation of the function of each person) is performed with the facsimile machine on the receiving side, and then the communication speed of image information, etc. Mode setting (step S72) and training (step S73) are performed to check whether preparations for receiving image information have been completed. (Step S74) If unsuccessful, set the mode (step S7).
The procedure is repeated from 2), and if successful, the process proceeds to step S75. In steps S75 and 76, the short training signal and the image information signal are transmitted, and in step S77, the end of partial page (PPS) and the end of procedure (EOP), which indicate the completion of the transmission of image information, are transmitted.

Here, when the message confirmation (MCF) is received (step S86) and the reception of the image information is confirmed, the disconnection processing (step S88) is performed. If there is an error in the image information on the receiving side, the receiving side will request a partial page (PPR).
Is sent. The transmitting side receives the PPR (step S
78), the process proceeds to step S79. In other cases, in step S87, it is checked whether or not the transmission of PPS and EOP has been tried three times. If it is two times or less, the process proceeds to step S77, and if it is the third time, the process proceeds to step S88.

In step S79, it is checked whether or not it is the fourth retransmission request, and if it is three times or less, the process returns to step S75 to retransmit the image information having an error. If it is the fourth retransmission request, continue correction (CTC) in step S80.
Is transmitted, and in steps S81 and S82, it is checked whether or not the correction continuation response (CTR) is received. If the CTR is not received even after the CTC is transmitted three times, the process jumps to the ending process of step S88. When the CTR is received, step S8
In 3, 84 and 85, long training signal, image information signal, end of partial page (PPS), end of procedure (EOP)
Are sequentially output, and the process returns to step S78 again.

[0008]

FIG. 10 shows an example of a conventional communication procedure according to the flow of FIG. In FIG. 10, after calling and negotiation, the tap coefficient is fixed by long training and image information is transmitted. However, when image information has an error and retransmission is repeated four times, long training starts. Here, if fixing of the tap coefficient fails due to noise, short training and image information transmission will be repeated four times until transfer to long training again. However, since the tap coefficient is not fixed, any transmission will fail, and there is a problem that an unnecessary procedure is repeated.

As an improved technique focusing on this point, there is a technique disclosed in Japanese Patent Laid-Open No. 4-966. In this technique, when image information reception fails after long training, the partial page request signal (PPR) is added with information instructing whether the training should be long or short and the result is returned to the transmitting side. is there.

According to this method, waste of repeating short training and sending of image information is eliminated, but since partial page request signal (PPR) is used, training always involves transmission of image information, and long training fails. In that case, there is a problem that the transmission time becomes long due to useless transmission. It is an object of the present invention to improve the above-mentioned problems of the prior art, eliminate unnecessary procedures, and obtain a transmission control procedure with a shorter transmission time.

[0011]

DISCLOSURE OF THE INVENTION According to the present invention, when retransmitting information, in a modem for training an equalizer, after transmitting a training signal, it is confirmed whether or not the training is successful before transmitting information. In the case of unsuccessfulness, a new procedure is provided for repeating the transmission of the training signal again.

[0012]

With this procedure, even if the training of the equalizer fails, the training of the equalizer can be performed again without sending unnecessary image information.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a flowchart of a transmission control procedure on the transmission side, which represents the outline of the present invention. Referring to FIG. 1, first, in step S1, information is transmitted, and in step S2, it is checked whether or not a retransmission request has been transmitted. If the resend request is not received, the transmission ends, but if the resend request is received, it is checked in step S3 whether or not it is the predetermined number of times.

If it is not the predetermined number of times, step S1
Returning to step 1, the information is retransmitted, but if it is the predetermined number of times, a signal for training the equalizer is transmitted in step S4. In step S5, it is checked whether or not the training is successful. If the training is successful, the information is sent in step S6, and the process returns to step S2. If the training fails, the process returns to step S4 and the training is performed again. By taking such a procedure, the equalizer can be efficiently trained.

Next, an example in which the above procedure is applied to a facsimile machine will be described. FIG. 2 is a block diagram of a facsimile apparatus to which the present invention is applied. The panel 1, the scanner 2, and the printer 3 are connected to the internal bus 14 via the respective control units 4, 5, and 6. A memory 7 for accumulating image information, a system controller 8 for controlling the entire apparatus, a protocol controller 9, and a network controller 11 are connected to the internal bus 14, and a modem 10 connected to the protocol controller 9 is connected.
Is connected to a telephone line 13 via an NCU (network control unit) 12.

FIG. 3 is an internal block diagram of the protocol control unit 9. Command creation unit 21, command analysis unit 25, TC
The F / image information creation unit 22, the TCF / image information analysis unit 24, and the modem mode setting unit 23 are the protocol module control unit 2.
0 is connected to the protocol module control unit 20.
The transmission control procedure is executed by. Further, the command creating section 21 and the command analyzing section 25 are respectively the low-speed transmitting section 2
6, the TCF / image information creating unit 22, and the TCF / image information analyzing unit 24 are connected to the modem 10 via the high-speed transmitting unit 27 and the high-speed receiving unit 28, respectively. The setting unit 23 is connected to the modem 10.

The command creating unit 21 assembles a command to be sent to the partner device according to an instruction from the protocol module control unit 20, and the modem 10 via the low-speed transmission unit 26.
It is sent to the control low-speed channel. The TCF / image information creation unit 22 performs TC processing for compressing the image information read from the memory 7, processing such as frame assembly, or checking whether a channel can be used at this transmission speed.
The F signal is created and sent to the high speed channel of the modem via the high speed transmission unit 27. The command analysis unit 25 receives a command from the control low-speed channel of the modem 10 via the low-speed reception unit 29, and notifies the protocol module control unit 20 of the command. The TCF / image information analysis unit 24 receives the image information or the TCF signal from the high-speed channel of the modem 10 via the high-speed reception unit 28, and performs an error check.

In accordance with an instruction from the protocol module control unit 20, the modem mode setting unit 23 sends to the modem 10 an operation mode of the modem 10 such as the speed of a high-speed channel, or a control signal such as transmission / reception, channel type, training instruction. Information about giving and training failures,
It receives from the modem 10 and notifies it to the protocol module control unit 20. The modem 10 performs operations such as modulation / demodulation of signals of each channel, creation, transmission, and reception of training signals according to an instruction from the protocol control unit 9.

Next, the operation will be described. 4, 5 and 6 are caller side flowcharts of the transmission control procedure of the present invention. First, in step S10, when there is a transmission instruction from the panel control unit 4, the system control unit 8 issues a transmission document reading request to the scanner control unit 5. Scanner control unit 5
Scans the transmission original with the scanner 2, stores it in the memory 7, and notifies the system controller 8 that the reading is completed.

The system control unit 8 makes a call request to the network control unit 11, and the network control unit 11 dials the dial number notified by the system control unit 8 from the NCU 12.
Connect to the receiving facsimile. The protocol control unit 9 sets the modem 10 in the low speed reception mode. Step S1
In Nos. 1 and 12, it is checked whether or not a non-standard function setting (NSF) or a digital identification signal (DIS: CCITT standard function identification signal) indicating the function of the receiving facsimile is received, and if a time-out occurs, Step S
Jump to 31 line disconnection process.

In step S13, the protocol control unit 9
When the non-standard function setting (NSF) is received, the parameter analysis is performed, and the receiving side facsimile displays "Continue correction (CT
C) Check whether there is training reception capability after reception "and notify the contents to the system control unit 8. In step S14, the system control unit 8 notifies the notified reception side facsimile capability and own station capability. Based on the above, the communication mode is set and is notified to the protocol control unit 9. In step S15, the protocol control unit 9 sets the modem 10 in the low-speed transmission mode, and the system control unit 8 instructs "continue correction (CTC)". If you are informed of "training instructions after receiving," set those parameters to non-standard function settings (NSS).
And send it. In FIGS.
17 shows the case where there is the above-mentioned “training instruction after CTC reception” in the 17 mode.

In step S16, the protocol control unit 9 sets the modem 10 in the high-speed transmission mode and sends a long training signal, and in step S17, continuously sends a training check signal (TCF).
In step S18, the protocol control unit 9 causes the modem 10
Is set to the low speed reception mode, and if the reception preparation confirmation (CFR) is received, the process proceeds to step S21, and if not, the process proceeds to step S19.

In step S19, if the training failure (FTT) is received, the process returns to step S14, and if the FTT is not received, the process proceeds to step S20. In step S20, if the number of trials from steps S14 to 17 is two or less, the process returns to step S14, but in the case of the third trial, the process jumps to step S30 to perform the line disconnection process. In steps S21 and S22, the modem 10 is set to the high-speed transmission mode, the short training signal for synchronization is transmitted, the image information is subsequently read out from the memory 7, and is transmitted.

When the protocol control unit 9 finishes sending the image information, it sets the modem 10 to the low speed transmission mode. In step S23, an end of partial page (PPS) and end of procedure (EOP) signal indicating the end of transmission of image information are transmitted, and the modem 10 is set to the low-speed reception mode. In step S24, it is checked whether or not a partial page request (PPR) is received. If it is received, in step S25 it is checked whether or not it is the fourth time, and if it is three times or less, the process jumps to step S21. However, in the case of the fourth time, step S3
Move to 2.

If the PPR is not received in step S24, it is checked in step S26 whether or not the reception disabled (RNR) is received. If the PPR is not received, step S27 is received.
Then, the reception ready (RR) is transmitted, and the process returns to step S26 again. If the RNR is not received in step S26, the protocol control unit 9 checks in step S28 whether a message confirmation (MCF) is received, and if received, jumps to step S30. When the message confirmation (MCF) is not received in step S28, if PPS and EOP are transmitted within two times in step S29, the process jumps to step S23, and if it is the third time, the process proceeds to step S30.

In step S30, the protocol control unit 9
Sets the modem 10 to the low-speed transmission mode and disconnects the line (D
CN) is transmitted, and the system control unit 8 is notified that the transmission has been completed. In step S31, the system control unit 8 issues a termination request to the network control unit 11, and the network control unit 11 sends the line 1
Open 3.

In step S32, the correction is continued (C
TC) to notify the receiving side that training will be performed. In step S33, the protocol control unit 9 issues a "training instruction after receiving the correction continuation (CTC)".
Check whether is set. If it is not set, the processing is the same as the conventional one, the correction continuation response (CTR) is received in step S34, and when the CTR is received, the modem 10 is set to the high-speed transmission mode in step S36 and long training is transmitted. Then, jump to step S42. If the CTR is not received, 3 in step S35.
It is checked whether or not it has been tried twice, and if it is not more than twice, the process returns to step S32, and if it is the third time, the process jumps to step S30 to perform the line disconnection process.

In step S33, "continue correction (CT
C) "training instruction after reception" is set, the modem 10 is set to the high-speed transmission mode in step S37 and a long training signal is transmitted in accordance with the procedure of the present invention. In step S38, the protocol controller 9 is set. Sets the modem 10 to the low-speed reception mode and checks whether or not a continue correction response (CTR) has been received.

If not received, it is considered that the training has failed, and in step S39, the protocol control unit 9
Checks whether a retraining request (eg FTT command) has been received. If received, step S37
Jump to step S21, send the training signal again, and if the training signal is not received, go to step S40. Step S4
In 0, it is checked whether the training has been tried three times, and if it is two or less, the process jumps to step S32 (or step S37), and CTC (or training signal) is transmitted. In the case of the third time, jumping to step S30, the line disconnection process is performed.

Correction continuation response (CTR) in step S38
Is received, it is interpreted as training OK, the modem 10 is set to the high-speed transmission mode in step S41, a short training signal is sent out, the image information is read out from the memory 7 in step S42, and it is sent out. In step S43, PPS and EOP are transmitted, and the process returns to step S24.

FIG. 7 is a flowchart on the receiving side in the present invention. FIG. 7 shows a case where “training instruction after reception of continue correction (CTC)” is set in the mode setting. The operation will be described below with reference to FIG. 7. First, an incoming call is detected in step S50, negotiation is performed in step S51, and then step S5.
Set the mode in 2 and perform long training.

If the training is unsuccessful in step S53, the training fails (FT) in step S54.
T) is sent, the process returns to step S52, and the mode setting is performed again. If the training is successful, a reception preparation confirmation (CFR) is sent in step S55. In step S56, short training and image information reception are performed, PPS and EOP are received in step S57, and it is checked in step S58 whether there is an error in reception.

If there is no error, MCF is determined in step S65.
Is transmitted, the line disconnection process is performed in step S66, and the image information is output to the printer 3. In step S58,
If there is an error in reception, a partial page request (PPR) is transmitted in step S59. Step S60
Then, it is checked whether or not the correction continuation (CTC) is received. If not received, the process returns to step S56, but if received, the process proceeds to step S61.

In step S61, the long training signal is received and training is performed.

In step S62, it is checked whether or not the training is successful. If the training is successful, a correction continuation response (CTR) is transmitted in step S64, and the process returns to step S56. If it fails, in step S63. A retraining request (for example, FTT command) is transmitted, and the process returns to step S61.

In the above-described embodiments, an example in which FTT is used as the retraining request signal is shown.
When the training fails, the transmitting side automatically repeats the long training without sending anything from the receiving side, and thus the retraining request signal is not always necessary.

Further, in this case, the sender may not send the continuation of correction (CTC).

The present invention is applicable to modems with equalizer training, but in particular V.I. It is effective when applied to a modem having long training and short training such as 17 modem. Further, since the success of the training is confirmed by the correction continuation response signal (CTR), it can be carried out for the standard facsimile apparatus with only a slight change in the procedure.

FIG. 8 shows a comparison of procedures between the improved conventional example and the present invention. 30 seconds to transfer image information, P
Sequence of 2 seconds for PR, 1 second for other commands, 1.3 seconds for long training, and 0.142 seconds for short training, and the first long training fails after sending correction continuation (CTC). Is shown. In the conventional example of (a), when the CTC is transmitted and the CTR is received, the long training signal is transmitted. However, even if the training fails here, the image information signal and PPS / EOP are continuously transmitted. On the receiving side,
The PPR is transmitted with a long training instruction, and the transmitting side again transmits the long training signal, the image information signal, and the PP.
S / EOP is sent continuously. If the transmission is successful, MC
Since F is returned, DCN is sent and the line is disconnected. Therefore, in the conventional example, after the correction continuation (CTC) transmission,
It takes 70.6 seconds in total until the line is disconnected (DCN) as shown in FIG.

On the other hand, in the present invention (b), the CTC
Immediately after the transmission, the long training signal is transmitted.
If the training fails, the receiving side sends a retraining request command such as FTT, and the sending side sends the long training signal again. Then, when the training is completed, the CTR is sent from the receiving side. Therefore, the short training signal for synchronization, the image information signal, and the PPS / EOP are continuously transmitted from the transmitting side. If the transmission is successful, the MCF is returned, so DCN is sent and the line is disconnected. Therefore, according to the present embodiment, unlike the conventional example, the image information is not transmitted twice, and after the continuation of correction (CTC) is transmitted, the line is disconnected (D).
CN), the total time is 3 as shown in FIG. 8 (b).
It takes only 8.742 seconds, and the communication time is shorter than that of the conventional example.

[0041]

As described above, according to the present invention, it is possible to eliminate unnecessary procedures and shorten the communication time. Further, this effect is more remarkable as the amount of image information is larger.

[Brief description of drawings]

FIG. 1 is a schematic flowchart of a transmission side of a transmission control procedure of the present invention.

FIG. 2 is a block diagram of a facsimile apparatus to which the present invention is applied.

FIG. 3 is a detailed block diagram of a protocol control unit in FIG.

FIG. 4 is a transmitting side flowchart (part 1) of the procedure according to the present invention.

FIG. 5 is a transmitting side flowchart (part 2) of the procedure according to the present invention.

FIG. 6 is a transmitting side flowchart (part 3) of the procedure according to the present invention.

FIG. 7 is a receiving side flow chart of a procedure according to the present invention.

FIG. 8 is a sequence chart showing a comparison between the present invention and a conventional example.

FIG. 9 is a transmission side flowchart of a conventional transmission control procedure.

FIG. 10 is a sequence chart showing an example of a conventional procedure.

FIG. 11 is an explanatory diagram showing signal names and their meanings.

[Explanation of symbols]

1 ... Panel, 2 ... Scanner, 3 ... Printer, 4 ... Panel control unit, 5 ... Scanner control unit, 6 ... Printer control unit, 7
... memory, 8 ... system control section, 9 ... protocol control section, 10 ... modem, 11 ... network control section, 12 ... network control unit (NCU), 13 ... telephone line, 14 ... internal bus 20 ... protocol module control section, 21 ... Command creation unit, 22 ... TCF / image information creation unit, 23 ... Modem mode setting unit, 24 ... TCF / image information analysis unit, 25 ... Command analysis unit, 26 ... Low speed transmission unit, 27 ... High speed transmission unit, 28
... High-speed receiver, 29 ... Low-speed receiver

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Sakayama 3-7-1 Fuchu, Iwatsuki City, Saitama Prefecture Fuji Zerox Co., Ltd. Iwatsuki Plant (72) Inventor Ken Umezawa 3-7-1, Fuchu, Iwatsuki City, Saitama Prefecture No. Fuji Xerox Co., Ltd. Iwatsuki Office

Claims (1)

[Claims] 1. In a training control method of a modem for training an equalizer at the time of retransmitting information, it is confirmed whether or not training is successful after sending a training signal and before sending information, and if unsuccessful. Is a training control method for modems, in which the training signal is transmitted again.