JPH0234083A - Communication system for facsimile equipment - Google Patents

Abstract

PURPOSE:To reduce the intermission of communication by setting a wait time into a time when a procedure signal is sent twice or over based on a detected required transmission time. CONSTITUTION:When a receiver side facsimile equipment 1 receives a procedure signal such as a DCS.NSS signal and a TCF signal, the required transmission time of the signals is detected and a wait time T2 is set to a time while each signal is sent twice or over based on the time. Thus, even if one signal cannot be received at the receiver side depending on the fluctuation of the line state, the signal is received when the line state is recovered at the next retransmission.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a communication system for facsimile machines.

[Prior Art] Facsimile machines conforming to the G3 standard recommended by CCITT are often used.

Figure 5 shows an example of the transmission control procedure of such a facsimile machine.
Sends HD signal and 0IS-NSF signal. The transmitting side receives them and sends the DC5-NSS signal and TC
Sends P signal.

The receiving side determines the result of modem training by detecting data errors in some data transmitted by the TCP signal. Then, if the data error exceeds a predetermined value, an FTT signal is sent.

When the FTT signal is transmitted, the transmitting side shifts down the data transmission rate and retransmits the DC5-NSS signal and TCF signal.

Incidentally, in recent years, facsimile communication using mobile wireless devices such as car telephones has become commonplace. This type of communication requires interference from obstacles in the radio wave propagation path, noise, and
Line conditions tend to deteriorate due to fading, etc., depending on the location of communication and environmental conditions. For this reason, the above-mentioned procedure signal sent by one party may not reach the other party.

[Problem M to be solved by the invention] Now, for example, the above D retransmitted by the transmitter in the above
Assume that the C5-NSS signal and TCF signal do not reach the receiving side due to fluctuations in line conditions. If there is no predetermined response from the receiving side, the transmitting side sends out the same signal again after a certain period of time T4 has elapsed.

On the other hand, the receiving side waits for a certain period of time T after sending the FTT signal.
2, monitor the signal sent from the transmitter.

If a predetermined signal is not received, a DCN signal is sent, the line is disconnected, and the reception operation is discontinued.

The CCITT recommendation stipulates that the constant time T4 is 3 seconds and the waiting time T2 is 6±1 seconds. It is set. On the other hand, the signal transmission time from the transmitting side is typically 1.5 seconds for TCP signals and 1.7 seconds for DOS-NSS signals.

Therefore, the receiving side receives the third D sent from the sending side.
In the middle of the OS-NSS signal, the above-mentioned fixed time T2 elapses, and the reception operation is stopped.

In this way, if the DOS-NSS signal sent by the transmitting side does not reach the receiving side after the receiving side sends out the FTT signal, the receiving side will not be able to receive the next retransmitted DOS-NSS signal.

For this reason, in the past, there was a problem in that communication was likely to be interrupted, especially when line conditions were likely to fluctuate, such as in facsimile communication using a car telephone.

SUMMARY OF THE INVENTION An object of the present invention is to provide a communication system for a facsimile machine that solves the above problems and reduces communication interruptions.

[Means for Solving the Problems] To this end, the present invention provides that, when receiving a procedure signal such as a DOS-NSS signal or a TCF signal, the receiving side detects the required transmission time of the signal, and Based on the required transmission time, the waiting time can be calculated as follows:
This feature is characterized in that it is set to a time at which it is transmitted more than once.

[Operation] Since the waiting time is set to the time during which the transmitting side transmits the procedure signal two or more times, even if one procedure signal cannot be received by the receiving side due to fluctuations in line conditions.

Since the next procedure signal can be received, there are fewer interruptions in communication as in the conventional method.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a system configuration diagram of a facsimile communication system according to an embodiment of the present invention. In the figure, a facsimile device 1.2 is connected to a public telephone network 3, while a facsimile device 4 is connected to a car telephone device 6 via an interface device 5, and each facsimile device M1, 2.4 Communication is carried out between the two.

The facsimile machines 1 and 2 have the same configuration; the scanner 11 reads an original image and extracts image information at a predetermined resolution; the plotter 12 records the image information on recording paper. The encoding/decoding unit 13 encodes the image information to be transmitted and decodes the received image information.

The network control unit 14 performs predetermined call/receive operations on the telephone line, and the modem 15 transmits various procedure signals and image information in transmission control procedures. It controls the modem 15 and transmits and receives image information according to a predetermined transmission control procedure.

The operation display unit 17 displays the operating status of the device, and
This is for the operator to perform various operations. The system control section 18 is composed of a microcomputer system, and controls each section mentioned above to execute predetermined operations of the facsimile machine.

Although not shown, the facsimile machine 4 is not provided with a network control device 14, and the other parts have the same configuration as the facsimile machines 1 and 2. A modem 15 is connected to the interface device 5.

By the way, various procedure signals in the transmission control procedure are CC
It complies with ITT Recommendation (7) V, 20: and is transmitted at a data transmission rate of 300 bps using HDLC7 frames.

FIG. 2(a) shows the frame structure of the DCS-NSS signal, which consists of a preamble with consecutive flags F, an NSS frame, and a DCS frame. Further, as an option, an NSS frame in which RTI information is set and a C3I frame are added.

FIG. 5B shows the structure of one frame of the DC5 and NSS. The information of this one frame is.

It consists of two flags F, an address field AF-control field CF, a facsimile control field FCF, a facsimile information field PIF, a frame check field FCF, and one flag F.

In the above facsimile control field FCF,
Identification information such as DCS-NSS is set.

The facsimile information field PIF is set with the contents of each command, and consists of 6 bytes for an NSS frame and 4 bytes for a DCS frame.

The frame check field FCF consists of 2 bytes, and each of the other fields consists of 1 byte.

With the above configuration, the operation of this embodiment will now be described based on the reception operation of the facsimile apparatus 1.

FIG. 3 shows the receiving operation of this facsimile device 1,
FIG. 4 shows the transmission control procedure in that case.

When the facsimile machine 1 receives a call originating from the facsimile machine 2 or facsimile group W4, first,
A CHD signal and a DIS-NSF signal are sent (process 101), and in response, the other party sends a DO8 signal/N
An SS signal is transmitted (process 202).

In this embodiment, at this time, the facsimile group a2 or facsimile device 4 on the sending side sends information indicating whether it is connected to a normal telephone line or a car phone to the NSS. It is transmitted by signals.

Therefore, if the other party is a normal telephone line (process 103), the NSS signal is used to identify the other party (process 103).
04N), the above-described waiting time T2 is set to 7 seconds, and a timer for monitoring this is set to 7 seconds (process 105).

On the other hand, if the other party is a car phone (Y in process 104)
), and counts the number of bits in both frames of the received DCS-NSS signal (processing 106). Then, the transmission time t of that frame is calculated. That is, Fig. 2 (a
), (b), the NSS frame is 112 bits and the DCS frame is 96 bits, making a total of 208 bits. Further, since the data transmission rate of the procedure signal is 300 bps, the transmission time of the 208 bits is approximately 0.69 seconds. Further, the preamble of this signal is transmitted for one second.

Therefore, if the option frame is not added, the transmission time t of the entire DCS-NSS signal is about 1.69 seconds.

Moreover, as mentioned above, the TCP signal from the transmitting side is 1.
It is transmitted for 5 seconds, and the fixed time until retransmission is 3 seconds. Therefore, in this case, the waiting time T2 is
Set T2=2t+1.5+3 (seconds) and set a timer to monitor this (process 108).

If the modem training check executed using the TCP signal is OK (Y in process 109), a CFR signal is sent (process 110), and a predetermined image information reception operation is executed (process 111).

On the other hand, if the modem training check is not OK (
Step 109 (N), the timer for the standby time T2 is started (Step 112), and the retransmission of the DCS-NSS signal is monitored for the wait time T2 (Step 114, Step 113). Processing 1 from N of 114
13).

During this period, if a DCS-NSS signal is received (processing 1
13 Y), the subsequently transmitted TCP signal is received and a modem training check is performed (process 115). Then, the result is notified in the same manner (proceed to process 109).

By the way, if the other party is facsimile machine 4, the condition of the line 5 may deteriorate and the DC3-NSS signal retransmitted from the sending side may not reach the receiving side and may not be received by the receiving side. .

In this case, the receiving side does not return a CFR signal or FTT signal response, so the transmitting side sends the DCS-NSS signal after 3 seconds.
Resend the signal.

In this case, the receiving side sets rIIJT2 to 72=2t during standby.
+4.5, i.e. in the above example, T2=7.88
(seconds). This causes the sender to then
This means that it is possible to wait until the CS-NSS signal is retransmitted. Furthermore, when the option signal shown in FIG. 2(b) is added, the waiting time T2 is set to be correspondingly longer.

Therefore, the next transmitted signal can be received and a predetermined operation can be performed in the same manner as above.

On the other hand, if the retransmitted DCS-NSS signal cannot be received within the waiting time T2 (Y in process 114), the DCS signal is sent, the line is disconnected, and the receiving operation is stopped.

If the other party is the facsimile machine 2, if the signal is not received within the waiting time T2 of 7 seconds, the receiving operation is similarly stopped.

The case where the facsimile device 1 receives data has been described above, but the facsimile device fi! The same applies to the case where No. 2 receives the information. Although not shown, when the facsimile machine 4 receives the data, the process 103 in FIG.
, 104 are deleted, and processing 106 is executed after processing 102.

As a result, the standby time T2 is set in the same manner as described above, and the same operation is performed.

As described above, in this embodiment, when a car phone is used, when a DCS-NSS signal and a TCF signal are received, the required transmission time of those signals is detected, and based on this, the waiting time is T2 is set to 5 times at which each of the above signals is transmitted twice or more. Therefore, even if one of the above-mentioned signals cannot be received on the receiving side due to a change in the line condition, it will be possible to receive the signal if the two line conditions have recovered the next time it is retransmitted. This reduces communication interruptions that occur in the past.

Further, when the car telephone is not used, the waiting time T2 is set to 7 seconds as before, so that the CCITT recommendation can be complied with.

In addition, in the above embodiment, for convenience, FTT signal and DC
Although the time between the S-NSS signal and the signal was not considered.

The waiting time T2 may be set long enough to take into consideration the time interval between each signal or to receive retransmissions of those signals three or more times.

In addition, we have explained the case of receiving DCS-NSS signals and TCF signals, but in various procedure signals in transmission control, if the receiving side cannot receive the signal and does not respond, the sending side will send the same signal after a certain period of time. The present invention can be similarly applied to various procedural signals in which the signal is retransmitted.

[Effects of the Invention] As described above, according to the present invention, when a procedure signal is received, the required transmission time of the signal is detected, and the procedure signal is transmitted twice based on the detected required transmission time. Since the waiting time is set in the transmission time, even if the receiving side is unable to receive one procedure signal due to changes in line conditions, it can receive the next retransmitted procedure signal, which is easier than before. There are fewer communication interruptions such as

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of a facsimile system according to an embodiment of the present invention, FIGS. 2(a) and (b) are explanatory diagrams of the frame structure of a procedure signal, and FIG. 3 shows a receiving operation of a facsimile machine. FIG. 4 is a time chart of procedure signals during communication in this embodiment, and FIG. 5 is a time chart of procedure signals during conventional communication. 1.2.4...Facsimile device, 5...Interface device, 6...Car phone device, 11...Scanner, 12...Plotter, 13...Encoding/decoding unit, 14... ...Network control device, 15...Modem, 16.
...Communication control unit, 17...Operation display unit, 18...System control unit. Chest diagram (a) (b) NSS:48 DC5:32 diagram

Claims (1)

[Claims] If the receiving side does not return a response to the procedure signal in the transmitted transmission control procedure, the transmitting side retransmits the procedure signal after a certain period of time has passed after sending the procedure signal, while the receiving side transmits the procedure signal according to the procedure described above. In a facsimile communication system that waits for a waiting time set during the period in which the signal should be transmitted and then stops communication if the procedure signal is not received, the receiver side, when receiving the procedure signal, cancels the communication. , a communication system for a facsimile machine, characterized in that the required transmission time of the signal is detected, and the waiting time is set to a time during which the procedure signal is transmitted two or more times based on the detected required transmission time. .