JP3397643B2 - Communication device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device such as a facsimile device capable of performing communication in error correction mode (ECM).

[0002]

2. Description of the Related Art Conventionally, in the error correction mode defined in the ITU-T recommendation, the transmitter is set to P
If the receiver is busy when transmitting the PS-Q signal, it transmits the RNR signal. In response to this RNR signal, the transmitter transmits a PR signal and transmits an RR signal until the T5 timer (60 seconds) elapses or until each valid response signal of the MCF signal, the PIP signal or the PIN signal is detected. I was supposed to continue.

[0003]

For this reason, the receiver is
If an error decision is made based on the decoding of the received information without making an error decision by the FCS of the DLC, the decoding must be completed when the reception of the received information is completed.

This is because the above-mentioned PPS-Q on the receiver side.
If the RNR signal is transmitted because the decoding of the received information is not completed when the signal is received, even if a decoding error occurs after that, for example, when the decoding of the received information is completed, the PPR signal is not transmitted. This is because an appropriate operation cannot be obtained because it cannot be transmitted.

According to the present invention, when communication is performed in the ITU-T recommended error correction mode, even if the receiver side does not perform an error check by HDLC but an error check based on decoding of received information, a communication operation due to a delay in decoding is performed. It is an object of the present invention to provide a communication device capable of avoiding the unestablished state of.

[0006]

According to the present invention, in a communication device having communication means in the ITU-T recommendation error correction mode, the transmitter side transmits an RR signal by receiving an RNR signal when transmitting a PPS-Q signal. In the case of shifting to (1), as the reception determination processing of the valid response signal after the transmission of the RR signal, the RNR signal, the MCF signal, the PPR signal,
It is characterized in that each of the PIP signal and the PIN signal is detected.

Further, according to the present invention, in a communication device having a communication means in the ITU-T recommendation error correction mode, when one page of image information is received on the receiver side,
When the error detection is performed by decoding the image information instead of the error check by the HDLC, and the RNR signal is transmitted when the decoding of the image information is not completed at the reception timing of the PPS-Q signal, and then the RR signal is received. Then, when the decoding is not completed yet, the RNR is again set.
It is characterized in that a signal is transmitted, an MCF signal is transmitted when decoding is completed and there is no error, and a PPR signal is transmitted when decoding is completed and there is an error.

Further, in the present invention, in the control method of the communication device having the communication means in the ITU-T recommended error correction mode, the transmitter side shifts to the transmission of the RR signal by the reception of the RNR signal when transmitting the PPS-Q signal. In this case, an RNR signal, an MCF signal, a PPR signal,
It is characterized in that each of the PIP signal and the PIN signal is detected.

With the above-described structure, in the present invention, the receiver is HD when executing the error correction mode communication.
Error check based on decoding of received information is possible instead of error check by FCS signal of LC,
Further, even if the decoding on the receiver side is delayed and a decoding error occurs, the operation in the error correction mode is performed by the proper transmission of the PPR signal, and the communication can be established.

In particular, JBIG (Joint Bi-level Image C
oding Experts Group), MMR (Modified Modified)
In the case of encoding such as Read) encoding, which cannot be decoded when even one bit has an error, it is preferable to actually decode and check the error rather than checking for the error by the status from the modem. Therefore, according to the present invention, an effective error check is performed by enabling an error check based on decoding of received information.
Communication can be performed in an appropriate error correction mode.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the structure of a facsimile apparatus according to an embodiment of the present invention.

The NCU (network control unit) 2 is connected to the terminal of the line in order to use the telephone network for data communication,
It controls the connection of the telephone switching network, switches to the data communication path, and holds the loop. Further, the NCU 2 connects the telephone line 2a to the telephone 4 side if the signal level (signal line 20a) from the control circuit 20 is "0", and connects the telephone line 2a if the signal level is "1". It is connected to the facsimile machine side.
In the normal state, the telephone line 2a is connected to the telephone 4 side.

The hybrid circuit 6 separates the transmission system signal and the reception system signal, sends the transmission signal from the addition circuit 12 to the telephone line 2a via the NCU 2, and sends the signal from the other side via the NCU 2. The signal is received and sent to the modulator / demodulator 8 via the signal line 6a.

The modulator / demodulator 8 complies with ITU-T Recommendation V.6. 8,
V. 21, V.I. 27 ter, V.I. 29, V.I. 17, V.I.
Which performs modulation and demodulation based on 34,
Each transmission mode is designated by the signal line 20c. The modulator / demodulator 8 inputs the signal output to the signal line 20b, outputs the modulated data to the signal line 8a, inputs the received signal output to the signal line 6a, and inputs the demodulated data to the signal line 8b. Output.

The ANSam transmission circuit 10 is a circuit for transmitting an ANSam signal. When an ANSam signal is output to the signal line 20d, the ANSam signal is transmitted to the signal line 10a and then to the signal line 20d. When the signal of the signal level "0" is being output, no signal is output to the signal line 10a.

The adder circuit 12 inputs the information of the signal line 8a and the information of the signal line 10a, and adds the result of addition.
It is output to a. The reading circuit 14 reads an image of a document and outputs the read image data to the signal line 14a. The recording circuit 16 sequentially records the information output to the signal line 20e line by line.

The memory circuit 18 is used to store raw information of read data or encoded information, or to store received information, decoded information, or the like.

The control circuit 20 controls the communication procedure in the ITU-T recommendation error correction mode, particularly in this embodiment, and on the transmitter side,
PPS-Q (Q = EOM, MPS, EOP or NUL
L) When the transmission of the RNR signal is changed to the transmission of the RR signal at the time of transmitting the signal, the RNR signal, the MCF signal, the PPR signal, the PIP signal, and the PIN signal are used as the reception determination processing of the valid response signal after the transmission of the RR signal. Control is performed so as to perform each detection of.

Also, on the receiver side, when one page of image information is received, error detection is performed by decoding the image information instead of error checking by HDLC, and PP
When the decoding of the image information is not completed at the reception timing of the SQ signal, the RNR signal is transmitted, and then the RNR signal is transmitted.
When the R signal is received, the RNR signal is transmitted again when the decoding is not completed yet, the MCF signal is transmitted when the decoding is completed and there is no error, and the PPR signal is transmitted when the decoding is completed and there is an error. Control to send.

2 to 7 are flowcharts showing the operation of the control circuit 20 in this embodiment.

In FIG. 2, the operation starts at S0 and S2
Then, the signal of signal level "0" is output to the signal line 20a to turn off the CML.

In S4, a signal of signal level "0" is output to the signal line 20d, and the ANSam signal is not transmitted.

In S6 and S8, it is judged whether or not the facsimile transmission and the facsimile reception are selected, respectively. When the facsimile transmission is selected, the process proceeds to S12, and when the facsimile reception is selected, the process proceeds to S92, and both are selected. If not, the process proceeds to S10, performs other processing, and S2.
Proceed to.

In S12, a signal of signal level "1" is output to the signal line 20a to turn on the CML. In S14, the V. 21, the image signal is sequentially transmitted in S16, and in S18, it is determined whether or not there is a next page. The post-procedure 21 is executed, and the process proceeds to S2.

If there is a next page, the process proceeds to S22, and it is determined whether or not there is a mode change. If there is a mode change, the process proceeds to S24, where V. Perform 21 intermediate steps,
Proceed to S16.

If there is no mode change, the process proceeds to S26 and 0 is set in the counter for three times retransmission. In S28, the 4th PPR signal detection counter 4th
Set PPR to 0.

Next, in S30, the PPS-MPS signal is transmitted, and in S32, the T4 timer is set to 3 seconds. Then, in S34, it is determined whether or not a significant signal is detected. If a significant signal is detected, the process proceeds to S36, and if no significant signal is detected, the process proceeds to S44.

In S36, S38, S40 and S42, the content of the detected significant signal is determined, and if an RNR signal is detected, the process proceeds to S74, and if a PPR signal is detected, S52.
When the MCF signal is detected, the process proceeds to S16, and the PIP
If a signal or a PIN signal is detected, the process proceeds to S50, and the operator is called, and if a signal other than these signals is detected, the process proceeds to S72.

In S44, it is determined whether or not the T4 timer has timed out, and if not, S3.
When the time is over, the process proceeds to S46.

At S46, the value of Counter is incremented by one. In S48, it is determined whether or not the value of Counter is 3 or more. If it is 3 or more, the process proceeds to S72, and if it is less than 3, the process proceeds to S30.

At S52, the value of the counter 4th-PPR is incremented by one. In S54, the counter 4t
Whether or not the value of h-PPR is 4 is determined. If it is 4, the process proceeds to S56, and if it is not 4, the process proceeds to S62.

In S56, it is determined whether or not to continue the ECM. If the ECM is to be continued, the process proceeds to S58, and if the ECM is not to be continued, the process proceeds to S68.

In S58, the CTC signal is transmitted, and in S60, the CTR signal is received. Furthermore, in S62, a training signal is transmitted, in S64, an error frame is transmitted, and S
At 64, RCP signals are sequentially transmitted, and the process proceeds to S24.

In step S68, the EOR-EOP signal is transmitted, in step S70, the ERR signal is received, and in step S72, the DCN signal is transmitted, and the process proceeds to step S2.

In S74, the T5 timer is set to 60 seconds. In S76, 0 is set in the counter Counter that counts the number of retransmissions three times. In S78, the RR signal is transmitted.

At S80, 4 seconds are set to 3 seconds. Then, in S82, it is determined whether or not a significant signal is detected. If a significant signal is detected, the process proceeds to S36, and if no significant signal is detected, the process proceeds to S84.

At S86, the value of Counter is incremented by one. In S88, it is determined whether or not the value of Counter is 3 or more. If it is 3 or more, the process proceeds to S72, and if it is less than 3, the process proceeds to S90.

In S90, it is determined whether or not the T5 timer has timed out. If the time has expired, the process proceeds to S72. If not, the process proceeds to S78.

In S92, a signal of signal level "1" is output to the signal line 20a to turn on the CML. S94
Then V. In the pre-procedure 21 and S96, the image signal is received.

In S98, the T2 timer is set to 6 seconds. In S100, it is determined whether or not a significant signal is detected. If a significant signal is detected, the process proceeds to S104, and if no significant signal is detected, the process proceeds to S102.

In S104, S106, and S108, the content of the detected significant signal is judged, and if it is a CTC signal, S1
10, the CTR signal is transmitted, and the process proceeds to S96. If the signal is the PPS-Q signal, the process proceeds to S116. If the signal is the EOR signal, the process proceeds to S112.
Proceed to. The ERR signal is transmitted in S112, the DCN signal is received in S114, and the process proceeds to S2.

In S116, the receiver determines whether or not the next information can be received. If the next information can be received, the process proceeds to S118, and if the next information cannot be received, the process proceeds to S120.

In S118, it is determined whether or not there is an error frame in the received frame. If there is an error frame, the process proceeds to S140, the PPR signal is transmitted, and the process proceeds to S96. If there is no error frame, the process proceeds to S130.

In step S120, the RNR signal is transmitted, and in step S122, the T2 timer is set to 6 seconds. S1
At 24, it is determined whether or not a significant signal is detected. If a significant signal is detected, the process proceeds to S128, and if a significant signal is not detected, the process proceeds to S126.

In S126, it is determined whether or not the T2 timer has timed out. If the time has expired, the process proceeds to S2, and if not, the process proceeds to S124. In S128, it is determined whether the detected significant signal is the RR signal or the PPS-Q signal. If the response is a positive response, the process proceeds to S116, and if the response is a negative response, the process proceeds to S2.

In S130, it is determined whether or not it is the last page. If it is the last page, the process proceeds to S132. If it is not the last page, the process proceeds to S134, the MCF signal is transmitted, and the process proceeds to S96.

In S132, it is determined whether or not there is an interrupt. If there is no interrupt, the process proceeds to S134, the MCF signal is transmitted, and the process proceeds to S96. If there is an interrupt, S
Proceed to 136, the PIP signal is transmitted, and then S13
At 8, the operator call is made. After this, the process proceeds to S2.

In the above embodiments, PPS-MPS is used.
The response to the signal was explained, but PPS-MP
Not only S signal, but also PPS-EOM signal, PPS-EO
The present invention can be similarly applied to the P signal and the PPS-NULL signal.

In the above embodiment, the V. Two
1, V.I. 27 ter, V.I. 29, V.I. Although it is assumed that the communication is 17 communication, 8, V.I. The present invention can be applied to the 34 communication.

[0050]

As described above, according to the present invention,
When performing error correction mode communication, the receiver is set to H
Error check based on decoding of received information is possible instead of error check by DLC FCS signal. Furthermore, even if a decoding error occurs on the receiver side and a decoding error occurs, proper transmission of PPR signal is possible. Since the operation is performed in the error correction mode and the communication can be established, especially in the case of JBIG or MM.
When encoding by R or the like is adopted, a smooth communication operation can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the above embodiment.

FIG. 3 is a flowchart showing the operation of the above embodiment.

FIG. 4 is a flowchart showing the operation of the above embodiment.

FIG. 5 is a flowchart showing the operation of the above embodiment.

FIG. 6 is a flowchart showing the operation of the above embodiment.

FIG. 7 is a flowchart showing the operation of the above embodiment.

[Explanation of symbols]

2 ... NCU, 4 ... phone, 6 ... hybrid circuit, 8 ... Modem, 10 ... ANSam sending circuit, 12 ... Adder circuit, 14 ... reading circuit, 16 ... Recording circuit, 18 ... Memory circuit, 20 ... Control circuit.

Claims (3)

(57) [Claims] 1. A communication device having a communication means in the ITU-T recommended error correction mode, wherein the RR is transmitted when a PPS-Q signal is transmitted and an RNR signal is received at the transmitter side.
As the reception determination processing of the valid response signal after signal transmission, RN
R signal, MCF signal, PPR signal, PIP signal, PIN
A communication device characterized in that each of the signals is detected. 2. A communication device having a communication means in the ITU-T recommendation error correction mode, wherein HDL is received when one page of image information is received on the receiver side.
If the error detection is performed by decoding the image information instead of the error check by C and the decoding of the image information is not completed at the reception timing of the PPS-Q signal, the RNR
When the signal is transmitted and then the RR signal is received, the RNR signal is transmitted again when the decoding is not completed yet, and when the decoding is completed and there is no error, MC
A communication device which transmits an F signal, and transmits a PPR signal when decoding is completed and there is an error. 3. A method of controlling a communication device having a communication means in the ITU-T recommended error correction mode, wherein the transmitter side shifts to the transmission of the RR signal by the reception of the RNR signal when transmitting the PPS-Q signal. , The RR
As the reception determination processing of the valid response signal after signal transmission, RN
R signal, MCF signal, PPR signal, PIP signal, PIN
A method for controlling a communication device, wherein each detection of a signal is performed.