JP2754012B2 - Facsimile communication method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a facsimile communication method.

[Prior art] The control procedure in a conventional facsimile machine is CCITT.
It is specified by Recommendation T.30.

Fig. 6 shows the conventional G3 defined in CCITT Recommendation T.4.
FIG. 9 is a schematic diagram showing a specific example when two pages are transmitted in the facsimile mode.

In the figure, each signal of training / TCF (training check) and training / PIX (facsimile image information) is transmitted at high speed by CCITT recommendation V27ter (phase operation modulation / demodulation method) or CCITT recommendation V29 (quadrature modulation / demodulation method). Other signals are control signals, and CC
Transmission is performed at a relatively low speed according to ITT recommendation V21 (FSK modulation / demodulation method with a transmission speed of 300 b / s).

Here, when the transmission speed of the control signal is 300 b / s, NSF / CSI / DIS, NSS / TSI / DCS, NSC / CIG / DTC have a facsimile information field, but other control signals are It does not have a facsimile information field (in the error correction mode ECM, other control signals also have a facsimile information field).

For example, the format of an MCF (message confirmation signal) at a transmission rate of 300 b / s is configured as shown in FIG.

First, after the preamble signal is transmitted for about 1 second, 2
A byte flag (01111110 _B ) is sent. afterwards,
Address Field (11111111 _B), control field (11001000 _B), a facsimile control field (in the case of the MCF, 00110001 _B) is sent, further 2-byte frame check sequence FCS, and flags are raised.

Here, the time t ₁ required for the preamble is approximately 1 second as described above. Also, the time t ₂ required for the actual signal portion
Is a total of 8 bytes, so (8 × 8) / 3
00 = 0.21 seconds.

[Problems to be Solved by the Invention] By the way, for example, when noise is mixed during transmission of MCF and this data is corrupted, the transmitter cannot receive MCF. Will be resent. On the other hand, since the receiver has transmitted the MCF, it is ready to receive a high-speed signal. However, what is sent here is a 300 b / s MPS, and the receiver that received this MPS can identify that it has received a 300 b / s signal, but what kind of signal was received Often cannot be identified.
Then, after this, the receiver is ready to receive the 300 b / s signal by receiving the 300 b / s signal, but at this time, the transmitter has already finished the triple transmission of the MPS, DCN
(A disconnection command signal). For this reason,
The receiver side receives the DCN and cannot continue facsimile transmission.

When the receiver is ready to receive a high-speed signal and receives a control signal of 300 b / s, it detects that the control signal has been received by detecting the preamble signal, and sends the signal after this. In some cases, the incoming facsimile control field FCF can be received.

However, also in this case, if a part of the HDLC information field such as the FCF is broken, the MPS cannot be received, and the transmitter sends the DCN after the triple transmission of the MPS.
Therefore, facsimile transmission cannot be continued.

On the other hand, even if the receiver could receive the first MPS, but the cutter operation did not end, the MCF could not be transmitted, and if the second or later MPS from the transmitter was broken, the receiver The side cannot receive the MPS and the transmitter cannot receive the MCF, so the DCN is transmitted, and the facsimile transmission cannot be continued.

Further, even in a facsimile apparatus in which the cutter operation is completed in a short time, a timer for waiting for the reception of a command signal after receiving a high-speed signal such as facsimile image information has a maximum of 6 seconds. If the signal is broken twice, one retransmission operation requires about 4 seconds, so that the time is over and transmission becomes impossible.

As described above, the conventional facsimile apparatus has a drawback in that only one or two data of the control signal following the preamble signal are damaged, and subsequent communication becomes impossible.

Further, even when communication can be maintained by retransmission of the Q signal (MPS, EOP, EOM), one retransmission operation requires about 4 seconds, so that there is a disadvantage that the processing is delayed as a whole.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a facsimile communication method that can continue communication even when a part of data of a control signal is broken and can process the data quickly.

[Means for Solving the Problems] In the present invention, in a facsimile communication method, a transmitting device receives a procedure signal of a facsimile communication procedure at a receiving device, and the transmitted procedure signal is transmitted based on a signal from the receiving device. According to the identification result, the receiving device transmits a procedure signal including a plurality of frame data having the same content following the preamble signal, and the receiving device is transmitted following the preamble signal. When one frame data in frame data having the same content is correctly received, it is determined that the procedure signal has been normally received.

[Operation] In the present invention, in the transmission of one procedural signal in one transmission, if the receiving side does not correctly receive the procedural signal, the procedural signal composed of a plurality of frame data having the same content following the preamble signal in one transmission When the receiving side correctly receives one frame data of a plurality of frame data having the same content transmitted following the preamble signal, it determines that the procedure signal has been normally received. Thus, the probability that the procedure signal is correctly received can be increased, and as a result, the error termination of the communication can be prevented as much as possible. In the present invention,
Compared to a case where a plurality of procedural signals are always transmitted in one transmission, the time required for communication of the procedural signals can be reduced. Further, the preamble signal need only be transmitted at the beginning of the procedural signal. The transmission time of the procedural signal can be reduced as compared with the case where the preamble signal is transmitted before each transmission of the frame data.

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

First, each component of the facsimile apparatus will be described.

In order to use the telephone network for data communication and the like, the NCU (network control device) 2 connects to the terminal of the line, controls connection of the telephone exchange network, switches to a data communication path, performs looping, Is held. Also, NCU2
If the signal level from the control circuit 30 is 0, the telephone line 2a is connected to the telephone set 4; if the signal level from the control circuit 30 is 1, the telephone line 2a is connected to the facsimile apparatus (FIG. 1). At the right side of the NCU2).
In a 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 16 to the telephone line 2a via the NCU 2, and transmits the signal from the other party to the V29 via the NCU 2
These are sent to the demodulator 20 and the V21 demodulator 18.

The reading circuit 8 sequentially reads image signals for one line in the main scanning direction from a transmission original and creates a signal sequence representing binary values of white and black. The reading circuit 8 includes an image pickup device such as a CCD (charge coupled device) and an optical device. The system is composed of:

The encoding circuit 10 encodes the read data (MH (Modified Huffman) encoding or MR (Modified Read) encoding).

V27ter or V29 modulator 12 is a known CCITT recommendation V27ter
(Differential phase modulation) or V29 (quadrature modulation).

The V21 modulator 14 is a modulator that performs modulation based on the known CCITT recommendation V21, and modulates a procedural signal from the control circuit 30.

The addition circuit 16 is a circuit that adds the outputs of the modulators 12 and 14.

The V21 demodulator 18 performs demodulation based on the known CCITT recommendation V21.

V27ter or V29 demodulator 20 is a known CCITT recommendation V27ter
Alternatively, demodulation based on V29 is performed.

The decoding circuit 22 is a circuit that decodes demodulated data from the demodulator 20 (MH decoding or MR decoding).

The recording circuit 24 is a circuit for sequentially recording the decoded white and black signals output from the decoding circuit 22 on plain paper line by line.

The noise detection circuit 26 takes in the received signal transmitted from the hybrid circuit 6 and detects the impulse noise included in the signal. When the impulse noise is detected, the signal level becomes "1". The signal is output to the control circuit 30.

The control circuit 30 performs overall control of the facsimile machine.

In the above-described configuration, the facsimile apparatus transmits the same signal twice after the preamble signal for some facsimile control signals, so that a good communication state can be obtained with respect to data destruction due to noise or the like. It is supposed to be maintained.

In this case, an example of the transmission operation of the preamble signal and the control signal will be specifically described. First, when a byte pack interrupt request is sent from the V21 modulator 14, flag pattern data as a preamble signal is transmitted. I do. After continuously sending the flag for 1 second, address information, control information, FCF information, 2-byte FCS,
The flag patterns are transmitted sequentially. Then, the address information, the control information, the FCF information, the 2-byte FCS, and the flag pattern are sequentially transmitted again.

Therefore, after the preamble signal, for example, MCF
Are transmitted, and the other party only needs to receive one of them, and even if one of the MCFs is broken, communication can be maintained.

In addition, the time required for transmitting this control signal is 0.21 seconds per transmission as described above, and even if this is transmitted twice,
Since it is 0.42 seconds, there is no delay in processing.

In this embodiment, the same signal is transmitted twice only for a single frame signal, and NSF / CSI /
DIS, NSS / TSI / DCS, and NSC / CIG / DTC are transmitted only once after the preamble signal.

Also, in this embodiment, instead of transmitting the same signal twice for all single frame signals,
Only in the following cases, the same signal is transmitted twice after the preamble signal.

(A) When the frequency of occurrence of the impulse noise exceeds a predetermined value based on the output of the noise detection circuit 26 that detects the impulse noise generated in the received signal, after a predetermined time has elapsed from the detection of the impulse noise When sending.

(B) The case where the facsimile control signal is transmitted once or a predetermined number of times, but the response signal cannot be received, and the facsimile control signal is further retransmitted.

(C) After the transmission of the facsimile control signal, if a retransmission facsimile control signal is received, despite the fact that the apparatus is ready to receive a high-speed signal from the other party, a return signal for the received facsimile control signal is transmitted. Case.

(D) After the transmission of the facsimile control signal, if a retransmission facsimile control signal is received despite the fact that the apparatus is ready to receive a command signal from the other party, a return signal for the received facsimile control signal is transmitted. Case.

As described above, by transmitting the same signal twice under certain conditions, communication can be performed by a normal protocol at normal times, and the procedure time can be shortened, and further, there is no function as in this embodiment. Smooth processing can be ensured even for a conventional facsimile machine. In general, even when a conventional facsimile apparatus receives a procedure signal, it does not malfunction even if the same signal is received twice after the preamble signal. Therefore, when the line condition is poor, by using the function of the present embodiment, it is possible to reduce troubles in communication with the conventional facsimile machine.

 Next, the operation of the above embodiment will be described.

FIGS. 2 (1) and 2 (2) are flowcharts showing a control operation when a single frame procedure signal is transmitted.

First, the head address of the transmission data memory space TD is set in the address pointer of the modem (S1). Then, address information (specifically, FF _H ), control information (specifically, 03 _H ), and FCF information are set (S 2, S 3, S 4) sequentially from the top address of the memory space TD.

In addition, "0" is set to the flag TE indicating that one single frame transmission has been completed (S5).

Next, it is determined whether the same signal is transmitted twice following the preamble signal (S6). Here, when transmitting the same signal for the second time due to the factors described in the above (B) to (D), the counter C1 is set to “2” (S
7) Conversely, when transmitting the same signal for the first time, "1" is set to the counter C1 (S8). When the same signal is transmitted for the first time, since the frame is the last frame, " _13H " is set to the address of the control information (S9). Further, "1" is set to the flag TM indicating that the flag is being transmitted (S10).

When an interrupt request is issued from the V21 modulator 14, a routine name "V21TI" to be jumped is set (S11).

Next, the control circuit 30 sends a transmission request signal RTS to the V21 modulator 14.
Is turned on (S12), and the transmittable signal CTS from the V21 modulator 14 is turned on.
Is detected as "1" and turned on (S13),
Since the preamble signal is transmitted for one second, the timer T0 is set to one second (S14). When the time expires (S15), the timer T0 is set to 3 seconds (S1).
6). In this embodiment, when there is much impulse noise, valid data is transmitted after the impulse noise is in the non-detection state.However, the timer T0 determines that the impulse noise is in the non-detection state. This is to escape this state when detection is not possible.

Then, if the line has many impulsive noises (S1
7) In the case of detecting impulsive noise (S1
8) If the timer T0 has timed out (S1
9) Instruct to transmit the same signal twice after the preamble signal (S22).

When a new impulse noise is detected (S2
0), if the timer T0 times out (S21),
It instructs that the same signal be transmitted twice after the preamble signal (S22).

Next, set to "2" to the counter C1 because sending twice the same signal following the preamble signal (S23), since not a further final frame is set to "03 _H" as the control information in the memory space TD ( S24).

Next, since the transmission of the flag ends, "0" is set to the flag TM (S25).

When the flag TE becomes "1" (S2
6), the RTS of the V21 modulator 14 is turned off (S27). Also, V21
If the CTS of the modulator 14 is "0" (S28), the instruction to transmit the same signal twice due to the above-described factor (A) is canceled (S29).

FIG. 3 is a flowchart showing a “V21TI” routine executed when an interrupt request is issued from the V21 modulator 14.

First, when the flag TM is "1" (S36), a flag pattern is output (S38), "1" is set to a flag FT for transmitting FCS (S40), and the process returns to the start.

If the flag TM is "1" in S36 and it is determined from the comparison between the contents of the pointer of the modem and the address that the transmission of one signal has not been completed (S42),
After outputting the contents of the pointer of the modem (S44), the pointer is incremented (S46) and the process returns to the start.

In S36, when the flag TM is "1" and it is determined that transmission of one signal has been completed based on a comparison between the contents of the pointer of the modem and the address in the memory space (S4).
2) If the counter FT for sending FCS is "0" (S48), this is incremented by one (S50), and the FCS
Is transmitted (S52), and the process returns to the start.

If the counter FT is "1" (S54), it is incremented by one (S56), the second byte of the FCS is transmitted (S58), and the process returns to the start.

If the counter FT is not “0” or “1”,
A flag pattern is transmitted (S60), the counter C1 is decremented by one (S62), and when the counter C1 becomes "0" (S64), the flag TE indicating that one transmission of the procedure signal has been completed is set to "TE". 1 "(S66), and returns to the start. When the counter FT becomes "1" in S64, it is necessary to transmit the same frame once again. In this case, the address of the memory space is set to the pointer of the modem (S68), and since the next frame is the last frame, " _13H " is set as control information (S7).
0), initialize the counter FT (S72), and return to the start.

FIGS. 4 (1) to (7) are flow charts showing transmission / reception operations in the facsimile apparatus.

First, the CML is turned off (S80), and then "1000" is set in a counter CT for measuring 5 seconds with a 5ms timer (S82). Then, the timer interrupt of 5 ms is prohibited (S84), and 3 is set in the impulse counter IC (S8).
6). That is, in this embodiment, if the impulse noise is detected “3” times within 5 seconds, it is determined that the line is a line with a large amount of impulsive noise.

Next, "0" is set to a flag IL indicating that the first impulsive noise has been detected, indicating that the impulse noise has not been detected (S88). "0" indicating that there is not much is set (S90).

Further, "0" indicating non-existence is set in the flags JA to JD indicating that the conditions (A) to (D) that require the same signal to be transmitted twice are present, and the same signal is set. Is transmitted once (S92).

Then, when facsimile transmission is selected (S9
4) First, enable the 5 ms interrupt operation (S96), turn on the CML (S98), and perform the pre-procedure (S10).
0), and an image signal is transmitted (S102). If there is no next original (S104), the counter CS for counting the number of EOP transmissions is set to "1" (S106), and the EOP is transmitted (S108). This is processed by the subroutine shown in FIG. The same processing is performed by this subroutine when transmitting a single frame signal thereafter.

If no response signal is received within three seconds (S110), the counter CS is incremented by one (S11).
2) If the value of the counter CS is "3" (S114),
If the same signal is transmitted twice (S116), the value of the counter CS is not "3" (S114), and if it is "4" (S118), DN
C is transmitted (S120). This returns to the start. If a response signal is received within 3 seconds from the transmission of the EOP (S110), the instruction to transmit the same signal twice according to the conditions (B) to (D) is canceled (S122), and the DNC is reset. Send it (S120).

If there is a next document in S104, if there is a mode change (S124), the counter CS is set to "1" (S126), EOM is transmitted (S128), and a response signal is sent within three seconds. If no counter is received (S130), the counter CS
Is incremented by one (S132). If the value of the counter CS is "3" (S134), transmission of the same signal is instructed twice (S136), and the value of the counter CS is not "3" (S134). ),
If it is "4" (S138), a DNC is transmitted (S120). If the response signal is received within 3 seconds after the transmission of the EOM (S130), the instruction to transmit the same signal twice according to the conditions (B) to (D) is canceled (S140), and the process before S100 is canceled. Return to the procedure.

If there is no mode change in S124, the counter CS
Is set to “1” (S142), and the MPS is transmitted (S14).
4) If no response signal is received within 3 seconds (S14
6), the counter CS is incremented by one (S148). If the value of the counter CS is "3" (S150), the same signal is transmitted twice (S152), and the value of the counter CS becomes "3". "
If not (S150), but is "4" (S154), a DNC is transmitted (S120). If a response signal is received within three seconds from the transmission of the MPS (S146), the instruction to transmit the same signal twice under the conditions (B) to (D) is canceled (S156), and the image in S102 is canceled. Return to signal transmission.

Also, when facsimile reception is selected in S158, 5 ms
Is performed (S160), and CML is turned on (S162). Then, 35 seconds are set in the initial identification timer T1 (S164), and 3 seconds are set in the timer T4 (S166). Next, NSF / CSI / DIS is transmitted (S168), and NSS / TSI / DCS cannot be received (S170). When the timers T1 and T4 time out (S172 and S174), the process returns to the start.

Further, when NSS / TSI / DCS is received (S168), when TCF reception is not good (S176), FTT is transmitted (S17).
8) Set 6 seconds in timer T2 (S180) and set NSS / TSI / D
Wait for CS to be re-received (S182).
When the time of T2 expires (S184), the process returns to the start.

Further, NSS / TSI / DCS is received (S170, S182). If TCF reception is good (S176), CFR is transmitted (S186), and 6 seconds is set to timer T2 (S188). Here, when a low-speed signal is received without receiving a high-speed signal (S190), transmission of the same signal is instructed twice (S194).
Proceed to S180, set 6 seconds in timer T2, and set NSS / TSI / DCS
It waits for re-reception (S182). Further, the timer T2 times out (S196) without receiving any of the high-speed signal and the low-speed signal (S190, S192), and returns to the start.

On the other hand, when the high-speed signal is received (S190), the instruction to transmit the same signal twice is canceled (S198), and the high-speed signal is received (S200). Next, 6 seconds are set to the timer T2 (S202), and when a command is received (S204),
If this is EOP (S206), the MCF is transmitted (S208), and 6 seconds are set in the timer T2 (S210). And EO
When the command of P is received (S212, S214, S216),
An instruction to transmit the same signal twice is issued (S218), and the process returns to S208 to retransmit the MCF.

If the timer T2 times out without receiving a command (S220, S222) or receives a DCN in S214, the process returns to the start.

When the MPS is received instead of the EOP in S206 (S224), the MCF is transmitted (S226), and the timer T2 is set to 6 seconds (S228). Then, when the high-speed signal is received (S230), the process returns to S198 and shifts to the receiving operation of the next page.
If a low-speed signal is received (S232), the timer T2
Is set to 6 seconds (S234). If an MPS command is received (S236, S238, S240), an instruction to transmit the same signal twice is issued (S242), and the process returns to S226 to retransmit the MCF. I do. In addition, the timer T2 times out without receiving a high-speed signal, a low-speed signal, or a command signal (S244, S2
46) When the DCN is received in S238, the process returns to the start.

Also, EOP and MPS are not received in S206 and S224, and EOM
Is received (S248), the MCF is transmitted (S250), and 6 seconds are set in the timer T2 (S252). Then, when a command is received (S254) and this is NSS / TSI / DCS (S256), the instruction to transmit the same signal twice is canceled (S2).
58), and return to S176. If an EOM command is received (S260), an instruction to transmit the same signal twice is issued (S262), and the process returns to S250 to retransmit the MCF. When the timer T2 times out without receiving a command (S264), or when receiving other than NSS / TSI / DCS or EOM (S256, S260), the process returns to the start.

If facsimile transmission or facsimile reception is not selected (S94, S158), other processing is performed (S266).

FIG. 5 is a flowchart showing an interrupt routine for determining whether a line has a large amount or a small amount of impulsive noise.

This interrupt takes one time every 5 ms.

First, when the timer of 5 seconds by the counter CT expires (S268), the flag ID for identification indicating that the line has less impulsive noise is set to "0" (S270), and the flag IL is set to "0". Set (S272).

When the timer for 5 seconds by the counter CT has not expired (S268), the flag IL is “0” (S274), and when the impulse noise is detected (S2).
76) The flag IL is set to “1” (S278), and the counter is set.
The CT is decremented by one (S280), and the process returns to the start.

If no impulse noise is detected in S276, one impulse counter IC is decremented with the flag IL set to “0” (S280), and the process returns to the start.

Further, when the flag IL is “0” in S274 and the impulse noise is not detected (S282), since the detection and non-detection of the impulse noise have been confirmed once, the impulse counter IC is decremented by one (S284). ). Then, the flag IL is set to “0” (S286), and when the impulse counter IC becomes “0” (S290), the flag ID is set to “1” (S292), and the counter CT is set to “1000”. It is set (S294), "3" is set in the impulse counter IC (S296), and the process returns to the start.

If the impulse noise is detected in S282 and the impulse counter IC is not “0” in S290, the process proceeds to S280, in which the counter CT is decremented by one and returns to the start.

The present invention is not limited to the above-described embodiment. For example, the condition for transmitting the same signal twice can be variously adopted, and in some cases, the same signal may be transmitted three or more times. Good. Further, the number of times may be changed according to the situation.

Further, the present invention can be similarly applied to multi-frame transmission. In this case, any one of the signals of the multi-frame may be specified, and this signal alone may be transmitted a plurality of times.

[Effects of the Invention] According to the present invention, in the transmission of one procedural signal in one transmission, if the reception side is not correctly received, a plurality of frame data having the same content follows the preamble signal in one transmission. When the receiving side correctly receives one frame data of a plurality of frame data having the same content transmitted following the preamble signal, the receiving side determines that the procedure signal has been normally received. Therefore, the probability that the procedure signal is correctly received on the receiving side can be increased, and as a result, the communication can be prevented from ending with an error as much as possible.

Further, according to the present invention, it is possible to reduce the time required for communication of the procedure signal as compared with a case where a plurality of procedure signals are always transmitted in one transmission, and the preamble signal is added at the beginning of the procedure signal. It is only necessary to transmit, and it is possible to reduce the transmission time of the procedural signal as compared with the case of transmitting the preamble signal before transmitting each of the plurality of frame data.

[Brief description of the drawings]

FIG. 1 is a block diagram of a facsimile apparatus showing one embodiment of the present invention. FIGS. 2 (1) and 2 (2) are flowcharts showing a control operation when a single frame procedure signal is transmitted in the embodiment. FIG. 3 is a flowchart showing a “V21TI” routine executed when an interrupt request is issued from the V21 modulator. FIGS. 4 (1) to (7) are flow charts showing transmission / reception operations in the facsimile apparatus. FIG. 5 is a flowchart showing an interrupt routine for determining whether a line has a large amount or a small amount of impulsive noise. FIG. 6 is a schematic diagram showing a specific example when two pages are transmitted in the conventional G3 facsimile mode defined in CCITT recommendation T.4. FIG. 7 is a schematic diagram showing a configuration of an MCF format at a transmission speed of 300 b / s. 2 ... NCU, 16 ... Addition circuit, 24 ... Recording circuit, 26 ... Impulsive noise detection circuit, 30 ... Control circuit.

Claims (4)

(57) [Claims] In a facsimile communication method, a transmitting apparatus transmits a procedure signal of a facsimile communication procedure to a receiving apparatus, and based on a signal from the receiving apparatus, the transmitted procedure signal is not correctly received by the receiving apparatus. According to the result of the identification, a procedure signal consisting of a plurality of frame data having the same content is transmitted following the preamble signal, and the receiving device transmits the frame data having the same content transmitted following the preamble signal. A facsimile communication method, wherein when the one frame data is received correctly, it is determined that the procedure signal has been normally received. 2. The transmission device according to claim 1, wherein the transmitting device detects an impulse noise generated in a received signal, and when the frequency of occurrence of the impulse noise exceeds a predetermined value, the transmitted procedure signal A facsimile communication method characterized in that the receiving device identifies that the data is not correctly received. 3. The transmitting procedure according to claim 1, wherein the transmitting apparatus transmits the procedure signal when the response signal of the procedure signal cannot be received from the receiving apparatus despite transmitting the procedure signal a predetermined number of times. A facsimile communication method comprising identifying that a signal is not correctly received by the receiving device. 4. The transmission device according to claim 1, wherein, after transmitting the procedure signal, the transmission device shifts to a state of receiving a high-speed signal from the reception device.
A facsimile communication method comprising: when receiving a procedure signal from the receiving device, identifying that the transmitted procedure signal is not correctly received by the receiving device.