JPH03184450A - Method of coping with line echo in facsimile equipment - Google Patents

Abstract

PURPOSE:To prevent a line disconnected due to the reception of an echo by collating the coincidence/noncoincidence of a signal transmitted from its own equipment with a following reception signal and setting the reception waiting state of an original signal from opposite equipment again when the coincidence is obtained. CONSTITUTION:When the transfer of a signal is performed between facsimile equipment, a first FAX message is transmitted from a transmitter T side, and furthermore, after a multi-page signal MPS or procedure interruption MPS (PRI-MPS) being outputted, a response signal waiting state is set. When a certain response signal is received. it is collated whether the response signal is the multi-page signal MPS or the procedure interruption MPS(PRI-MPS), and when they are the same signals i.e., an echo signal, an original response signal from a receiver R is set at a receptable state again. Therefore, it is possible to precisely perform the transmission of a document even on a communication channel with the echo with high signal level or delay quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a line echo handling method for dealing with line echo in a facsimile machine.

(Prior art) Conventionally, as a technology in such a field, there is
There was something described in Japan ITU Association, P, 74-126.

FIG. 2 is a block diagram showing an example of the configuration of a conventional facsimile machine for sending and receiving functions.

This facsimile machine includes a reading section 2 that reads an input document 1, a recording section 3 that prints an image on recording paper, an image processing section 4 that has data compression/expansion functions, a modem 5 that modulates/demodulates data, and a control section. 6, and an operation panel 7. The control unit 6, as described in the above document,
Recommendation T, 3 of the International Telegraph and Telephone Consultative Committee (CCITT)
HDLC (high level data link) specified by
The entire device is program-controlled according to transmission control procedures (protocols) such as control), and includes a CPU (central processing unit) 6a with a built-in timer, a ROM (read-only memory) 6b that stores programs, and a working data storage. RAM (memory that can be read and written at any time) 6c, etc.

In the above configuration, when the input document 1 is set on the reading section 2 of the facsimile device on the side of the transmitter T, the input document 1 is scanned by the reading section 2 and read as a one-dimensional time series signal, and the image processing section Sent to 4. The image processing unit 4 performs -dimensional or two-dimensional data compression in order to reduce the amount of data to be transmitted. This data is stored in modem 5
After being modulated, the signal is transmitted to the facsimile machine on the receiver R side via the communication line 8 and telephone exchange.

In the facsimile machine on the receiver R side, the transmitted data is demodulated by the modem 5 and then decompressed by the image processing section 4. This decompressed data is sent to the recording section 3 and printed as an image on recording paper.

Figures 3 (1) and (2) are flow diagrams for conventional facsimile transmission described in the above-mentioned document, and Figure 4 is a flow diagram for document transmission based on the flow diagrams in Figures 3 (1) and (2). FIG. 2 is a diagram illustrating the exchange of signals between facsimile devices when transmitting a facsimile.

C used in Figure 3 (1), (2>, Figure 4, etc.)
The abbreviations of CHT Recommendation T.30 are as follows:

CED is called station identification, CFR is reception readiness confirmation, CRP is command retransmission, CIG is calling terminal identification, CNG is ring tone,
C3I is called terminal identification, DCN is line disconnection command, DC8
is a digital command signal, DIS is a digital identification signal,
DTC is a digital transmission command, ROM is a message end, EOP is a procedure end, FCF is a facsimile control field, PIF is a facsimile information field, FTT is a training failure, GC is a group command, GI is a group identification, and HDLC is a high-level transmission control procedure. , LC8 is a transmission path adjustment signal, MCF is a message confirmation, MPS is a multi-page signal, NSC is a non-standard function command, NSF is a non-standard function, NSS is a non-standard function setting, PIN is a procedure interruption denial, PIP is a procedure interruption affirmation. , PIS is a procedure abort signal,
PRI-ROM is procedure interrupt EOM, PRI-EOP is procedure interrupt EOP, PRI-MPS is procedure interrupt MPS, RT
N is retraining negative, RTP is retraining positive, TCP is training check, and TSI is transmitting terminal identification.

Also, in FIGS. 3(1) and (2), the blocks indicated by broken lines are optional, Tl, T2. T3 is a timer time (not shown) provided in the control unit 6.

In the "instruction reception" block, the instruction reception subroutine detects an error-free standard instruction, and the judgment block in the flow diagram detects the most recent received standard instruction (
For example, ROM, MPS, etc.). "Compatible with the other receiver" means that the content of the DIS PIF is compatible with the corresponding receiver, and "with a transmission document" means that there is at least one transmission document on the transmitter or receiver side. "Compatible with the other party's transmitter" means that the contents of the DIS PIF are compatible with the other party's transmitter and there is a transmission document. "Response reception" refers to a response reception subroutine that detects standard responses without errors, "Final document" refers to the fact that the final document in the operating mode has been sent, and "Mode setting" refers to the control unit 6 setting the appropriate mode of operation; "three attempts" means that a command is repeated three times without getting an appropriate response; "retransmission capability"
means that the transmitter has the ability to retransmit documents that could not be received with acceptable image quality, "Message carrier reception" means that the message channel carrier was received, and "phase adjustment/training is good" What is phase adjustment/
Training - The TCF signal is analyzed and the results are good.

"Mode change" means that the transmitting device is leaving the currently operating transmitting mode and is requesting reconfiguration of its functions, rNSP
"Request" means that the NSP (non-standard procedure) is "recognized" by a device compatible with the transmitter or receiver that initiated the procedure, and "Good image quality" means that the image quality is determined to be good by some algorithm. "Phase adjustment/training 100 lines" means that it is determined by some algorithm that it is desirable to send out a new phase adjustment/training signal, "Flag" means that a flag has been detected, r "Frame received" means that the device received one complete HDLC frame, rFC3 error.
means that the received HDLC frame has an F'C8 error, "option response" means that the received HDLC frame contains one of the option responses, and "option command" means that the received HDLC frame contains one of the option responses. contains one of the optional commands, ``rCRP option'', which means that the facsimile machine has a CRP option, which allows it to request immediate retransmission of the last command. Furthermore, "local interruption" means that a local device or local operator interrupts the standard facsimile procedure, and "line request" means that a local operator connects a telephone to the line in order to talk to the other party. rPRI-QJ means PRI-ROM, PRI-MPS or PRI-EOP.
is a general term referring to any of the post-message instructions.

Furthermore, in each block of FIG. 3 (1) and (2>),
A non-standard procedure NSP in Note 1 is a procedure that takes less than 6 seconds to complete, and the signals in Note 2 are relevant only to Group 3 equipment.

“Note 3” PRI-EOM, PRI-EOP and PRI
- The MPS post message command is sent when the local interrupt request is bending.

In "Note 4", if an interrupt that causes a procedure interruption occurs at any point during operation, and this interrupt occurs during document transmission, an EOM/RTC signal must be sent before the procedure is interrupted. Become. In the figure, where a slash "/" is used, the terms to the left of the slash are related to groups 1 and 2, and the terms to the right are related to group 3.

Where the symbol () is used, the signal within this symbol is a response to a DIS from a calling device requesting reception. Where the symbol () is used, the signals inside this symbol are optional.

Next, with reference to Figures 3 (1), (2) and Figure 4,
Operations (1) to (8) when transmitting two documents from the transmitter T side to the receiver R side will be explained.

(1) First, in step 50 of FIG.
From the fiR side, non-standard function NSF, called terminal identification C3I
, and a digital identification signal DIS.

(2) On the transmitter T side, the above (
1> is received, and in step 16.17 via steps 12, 13.15, the transmitting terminal identification TSI, digital command signal DO3 or non-standard function setting NSS, and training check TCF signals are output.

(3) The receiver R outputs a reception preparation confirmation CFR in step 56 via steps 51, 53 to 57.

(4) In the transmission 1iT, the reception preparation confirmation CFH signal is received through steps 18 to 21, and the image of the first input document 1 is transmitted as a facsimile message (FAX message) through step 22 and step 23. .Furthermore, step 24, connector ■ and step 25
In step 26' in block BLI, the multi-page signal MPS is outputted via the multi-page signal MPS.

(5) At receiver R, connector F and step 52.5
Upon receiving the FAX message in step 62 via 9.60.61 and the multi-page signal MPS in step 65 via step 63, connector F, steps 52-55, connector ■ and step 64, step 68 -70, and in step 71, a message confirmation MCF signal is output.

(6> At transmitter T, step 2 in block BLI
7, 28. At 26, it is determined whether or not there is a response reception to the multi-page signal MPS, and when the message confirmation MCF signal is received at step 30 via step 29, the message is sent via the connector Step 23
to send the second fax message. Further, in step 32 of block BL2 via step 24, connector 2, and step 25.31, a procedure end EOP signal is output.

(7) At receiver R, connector F and step 52.5
At step 62, the second FAX message is received through steps 9-61. Furthermore, the connector F, steps 52~
When the procedure end EOP signal is received in step 66 via connector 55 and step 64 and 65, a message confirmation MCF signal is outputted in step 71 via steps 68 to 70.

(8) When transmitter T receives the message confirmation MCF signal in step 36, it outputs a line disconnection command DCN signal via connector C in step 37, and disconnects the communication line 8 in step 38. . Through the signal exchange operation as described above, the transmission of the two documents is completed.

On the transmitter T side, if there is a mode change in step 31, a message end ROM signal is transmitted in step 39 in block BLB, and then step 40.
At step 41.39, it is determined whether or not a response has been received. If a response has been received, the process proceeds to step 42, and a procedure interruption denial PI is sent.
Make a determination of N or procedure interruption affirmative PIP.

On the receiver R side, if the command signal is not in the message end ROM in step 67, the line is disconnected in step 72 via connector B in block BL4.

(Problems to be Solved by the Invention) However, the apparatus having the above configuration has the following problems.

In conventional facsimile machines, the echo signal level or When facsimile transmission is performed using the communication line 8 which has a large amount of delay, normal facsimile transmission as shown in FIG. 4 is impossible.

For example, in block BLI of the flow diagram in FIG. 3(2), the transmitter T side sends out the multi-page signal MPS in step 26, then enters a waiting state for a response signal in step 27, and responds within a predetermined waiting time. When no signal is received, the multi-page signal MPS is sent out again in step 26 via step 28. Repeat this operation three times, and if reception is unsuccessful, connect connector C and step 3.
The line is disconnected in step 38 via step 7. if,
If the echo signal of the multi-page signal MPS is received in step 27, for example, steps 39, 30...
The line is disconnected in step 38 via connector C and normal facsimile transmission becomes impossible. The same thing applies to block BL2. This can also occur with BL3 and BL4.

The present invention solves a problem that the conventional technology described above has in that when a communication line has a large echo signal level or a large amount of delay, no consideration has been taken to perform facsimile transmission using the communication line. The present invention provides a method for dealing with line echoes in facsimile machines that solves the problem of impossibility of transmission.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides, after transmitting a transmission signal from either one of the transmitter side and the receiver side to the other.
It enters a waiting state for a response signal, and when the response signal is received within a predetermined waiting time, it proceeds to the next transmission procedure, and when the response signal is not received, the above transmission and waiting state are repeated a predetermined number of times, and the reception is successful. In the facsimile machine, which proceeds to the next transmission procedure and disconnects the line if reception is unsuccessful, the facsimile device checks whether the transmitted signal matches the received signal within the subsequent waiting time; In the case of a match, the process moves to the waiting state, and in the case of a mismatch, the process proceeds to the next transmission procedure.

(Function) According to the present invention, since the line echo countermeasure method for a facsimile device is configured as described above, by checking whether the transmitted signal and the subsequent received signal match/mismatch, if there is a match, then the received If the signal is determined to be an echo, the device goes into a waiting state where it can receive the original signal from the other device.This prevents line disconnection due to echo reception and improves transmission performance.Therefore, The above problem can be solved.

(Embodiment) FIGS. 1(a) to 1(d) show an embodiment of the present invention, and are flow diagrams of the main parts of a line echo countermeasure method in a facsimile machine, and the elements of the conventional method shown in FIG. Common elements are given the same reference numerals. That is, the first
Figures (a) to (d) are blocks BLI to BL4 in Figure 3.
FIG. 3 is a diagram illustrating an example in which this embodiment is applied to each of the following.

In this embodiment, the conventional blocks BLI to BL4 in FIG.
In , when an echo signal is received, a flow is added to ignore it and receive the original signal from the other device again. Then, the program for executing the additional flow is stored in the ROM 6 in the facsimile machine shown in FIG.
The execution function is stored in the CPU 6a.

In FIG. 1(a), in block BLI of FIG.
Step 10 determines whether or not an echo signal is received;
0 is set. In this step 100, it is determined whether or not the multi-page signal MPS or the procedure interruption MPS (PRI-MPS>) is received. If YES, the process returns to step 27, and if there is no NOC>, the process shown in FIG. It has the function of proceeding to step 29.

In FIG. 1(b), in block BL2 of FIG.
On the YES side of step 33, which determines whether or not a response has been received,
A step 110 is provided for determining whether or not an echo signal is received. This step 110 has a function of determining whether a procedure end EOP or a procedure interruption EOP (PRI-EOP) has been received, and if YES, the process returns to step 33, and if NO, the process proceeds to step 35 in FIG. ing.

In FIG. 1(C), in block BL3 of FIG.
On the YES side of step 40, which determines whether or not a response has been received,
A step 120 is provided to determine whether or not an echo signal is received, that is, whether a message end ROM or a procedure interrupt ROM (PRI-ROM) is received.
The S side returns to step 40, and the No side proceeds to step 42 in FIG. 3.

In addition, in FIG. 1(d), in block BL4 of FIG. 3, an echo signal is generated between the No side of step 67, which determines whether or not the message end ROM has been received, and connector B leading to line disconnection step 72. A step 130 is provided for determining the presence or absence of reception. In this step 130, it is determined whether or not the same signal as the signal sent immediately before has been received, and the YES side goes to the connector F, and the NO side goes to the connector B, respectively.

Next, the operation shown in FIG. 1 will be explained with reference to FIGS. 2 to 4.

As shown in FIG. 4, when transmitting and receiving signals between facsimile machines, the transmitter T side transmits the first FAX message in step 23 of FIG. , multipage signal MPS or procedure interrupt MPS (PRI-MPS)
After outputting, in step 27, the process waits for a response signal.

When a response signal of some kind is received in step 27, in step 100 of FIG.
PRI-MPS), and if it is the same signal, that is, an echo signal, it returns to step 27 and can receive the original response signal (message confirmation MCF in Figure 4) from receiver R again. put it in a state. On the other hand, step 10
0, if it is determined that they are not the same signal, the process proceeds to steps 29 and 30 in FIG.
At step 23, the second FAX message is sent.

In this way, since step 100 is provided, step 2
For example, an echo signal is received at step 7, and step 29.30.
. . . and the received echo signal is canceled without proceeding to line disconnection in step 38 via connector C, making it possible to receive the original signal (MCF) from receiver R. . Therefore, accurate document transmission can be performed even on a communication line with a large echo signal level or a large amount of delay.

Similarly, in FIG. 1(b), after sending the second FAX message from the transmitter T and further sending a procedure end EOP or procedure interrupt EOP (PRI-EOP) signal in step 32, step 33 Waits for a response.

If an echo signal is received, it is determined in step 110 and the process returns to step 33, where the state again waits for reception of the original response signal (message confirmation MCF>) from the receiver R, and in step 38 due to echo reception. Almost the same operation is performed at step 120 in FIG. 1(c).

In addition, in FIG. 1(d), when the receiver R side receives some command signal, it sends any signal expected by the command signal (for example, training check TCF, multi-page signal MPS, procedure end EOP, etc.). Since this is not the case, the signal is compared with the signal outputted immediately before by the receiver R in step 130 before proceeding to disconnection of the line in step 72 via connector B. As a result of the comparison, if the signals are the same, the process returns to step 52 via the connector F, and the process waits for the original command signal from the transmitter T to be received again. This prevents disconnection of the line due to echo reception and enables accurate document transmission.

Note that the present invention is not limited to the illustrated embodiment; for example, the second embodiment
The present invention can also be applied to facsimile machines having configurations other than the facsimile machine shown in the figure. Then, in accordance with the facsimile configuration, step 10 in FIG.
By providing steps almost similar to 0 to 130,
Almost the same actions and effects as in the above embodiment can be obtained.

(Effects of the Invention) As described in detail above, according to the present invention, the signal transmitted by the own device and the subsequent received signal are checked for coincidence/mismatch, and if they match, that is, the received signal is echoed. When it is determined that it is a signal, it will wait again to receive the original signal from the other device, so even if the echo signal level or the communication line has a large delay, line disconnection due to echo reception is prevented. Accurate document transmission is possible.

[Brief explanation of drawings]

Figures 1 (a) to (d) are flow diagrams of the main parts of facsimile transmission showing an embodiment of the present invention, Figure 2 shows the countries in which the conventional facsimile equipment is configured, and Figures 3 (1) and (2>) FIG. 4 is a flow diagram of conventional facsimile transmission, which shows the transmission and reception of signals between conventional facsimile devices. 1. Input original, 2. Reading unit, 3.
...Recording unit, 4...Image processing unit, 5...
...Modem, 6...Control unit, 6a...
...CPU, 6b...ROM, 8...
Communication line, 100, 110, 120.130...
・Echo verification step.

Claims (1)

[Claims] After transmitting a transmission signal from either the transmitter side or the receiver side to the other side, it enters a waiting state for a response signal thereto, and when the response signal is received within a predetermined waiting time, it proceeds to the next transmission procedure. , when the response signal is not received, the above-mentioned transmission and waiting state are repeated a predetermined number of times, when the reception is successful, the process proceeds to the next transmission procedure, and when the reception is unsuccessful, the line is disconnected. and a subsequent match/mismatch with the received signal within the waiting time, and if there is a match, the process moves to the waiting state, and if there is a mismatch, the process proceeds to the next transmission procedure. How to deal with line echo on facsimile machines.