JPH0252905B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protocol communication control method at the time of starting communication of a facsimile device.

In a facsimile device, after a transmission line is set up with the other party, prior to transmitting facsimile data, the receiving side confirms the function, command information from the sending side and subsequent training, and training from the receiving side. Communication such as post-response, so-called protocol, is performed.

And for this protocol, CCITT
There is a regulation in Recommendation T-30, and therefore, the protocol based on this regulation has conventionally been adopted in most facsimile devices.

The communication procedure according to Recommendation T-30 is shown in Figure 1.

In Figure 1, the right side is from the receiving side R to the sending side S.
The signal sent to the left side is from the sending side S to the receiving side R.
First, NSF (non-standard equipment identification signal), CSI (recipient's telephone number), and DIS (digital identification signal) are transmitted from R to S as initial confirmation signals. Furthermore, among these
According to T-30 above, NSF and CSI are optional signals, and it is optional whether or not to transmit them.

Next, following this initial confirmation signal from R to S, a TSI (sender's telephone number), DCS (digital command signal), and TCF (training check signal) are transmitted from S to R. Until now, the data transmission speed was 300bps by T-30, but this TCF and the training data inserted before it are transmitted at the same transmission speed as the facsimile data to be transmitted afterwards. transmitted at speed. Note that this TSI is also an option.

Then, on the R side, as a post-training response,
A CFR (reception readiness confirmation signal) is transmitted to the S side, and in response, transmission of facsimile data from S to R is started.

By the way, the above T-30 is an international standard, and is therefore determined based on assumptions about the quality of transmission lines and the like from an international perspective.

Therefore, the above-mentioned protocol is also defined with a relatively large margin, and therefore the time spent on it is quite long as shown in FIG.

This figure 2 shows how a facsimile (hereinafter referred to as FAX) is sent after the transmission of the initial identification signal from R to S is completed.
It describes the minimum time required before data transmission starts (called 1 second preamble, followed by TSI+DCS consisting of 360 bits).
Send from S to R at 300bps, prepare for 0.075 seconds, then train for 0.923 seconds and TCF for 1.5 seconds.
send out. Then, after waiting for 0.2 seconds, the 56-bit CFR following the 1 second preamble is read.
Send from R to S at 300bps.

When the CFR is transmitted from R to S, the protocol ends, and there is a waiting time of 0.2 seconds, and training takes 0.923 seconds.
FAX data will be transmitted from S to R.

Therefore, as is clear from Fig. 2, according to the T-30 protocol communication procedure described above, it takes 7.201 seconds at the minimum from the time the initial identification signal is transmitted to the start of fax data transmission. It will become.

On the other hand, when it comes to communications within Japan, the line characteristics are generally good and considerably better than those in other countries, and transmission at a practical speed of 7200bps is possible in most cases. If you look at this differently,
When training at 7200bps, there is almost no fallback, and when training at 9600bps, fallback does not occur as often.

For this reason, when using facsimile equipment that uses the T-30 protocol procedure described above, a lot of time is wasted on the protocol when it is used in places with good line conditions, such as in Japan, which increases transmission costs. The disadvantage was that there was a significant

An object of the present invention is to provide a facsimile communication system that eliminates the above-mentioned drawbacks of the prior art and can significantly reduce the time required for a protocol between predetermined devices installed in a location with good line conditions. be.

To achieve this objective, the present invention uses an initial identification signal to identify whether a receiving facsimile device is a specific destination station, and if so, to prevent the transmission of data for subsequent protocols.
It is characterized in that it is configured to immediately send out the fax data at the same transmission speed as the fax data to be transmitted subsequently, and to perform normal protocol procedures with the receiving side other than the specified partner station.

Embodiments of the facsimile communication system according to the present invention will be described below with reference to the drawings.

FIG. 3 shows an embodiment of the protocol procedure according to the present invention, in which, as in FIG. 1, the right side shows a signal sent from the receiver R to the sender S, and the left side shows a signal sent from the sender S to the receiver R. This figure shows the signal.

First, when a telephone line is set up by an NCU (line control unit), an initial identification signal is transmitted from R to S, followed by NSF, CSI, and DIS. In this embodiment, if the receiving fax machine belongs to a specific group, data indicating this is inserted into the NSF, which is an optional signal in CCITT Recommendation T-30. I'll keep it.

On the other hand, the sending side also analyzes the above data included in the NSF accordingly, and when it is identified, immediately transmits TSI and DCS at the same transmission speed as the fax data to be transmitted subsequently. Sends it from S to R. After that, idle data is sent at the same transmission speed to give the receiving side the time necessary to prepare for reception, and no PIS (Procedure Interruption Signal) is detected from the receiving side by the time the sending ends. sometimes one after another
Start sending fax data and end the protocol.

FIG. 4, corresponding to FIG. 2, explains in an easy-to-understand manner the time from when the initial identification signal is sent until when sending of FAX data is started.

After the transmission of the initial identification signal from R to S is completed,
When the sending side confirms that the other station belongs to a specific group based on the NSF data and that communication using the communication method according to this embodiment is possible, the 360 Bit TSI + DCS is sent at 4800bps, and then the PIS transmission from the receiving side is monitored.
Transmit idle data to give a time of 0.2 seconds, during which time 0.2 if PIS is not received
Immediately start transmitting fax data following seconds of idling data.

Therefore, in this embodiment, the minimum time from receiving the initial identification signal to starting sending fax data is 1.198 seconds, which is significantly shorter than the conventional example shown in Figures 1 and 2. is obtained.

In addition, the above idling data is PIS of 0.2 seconds.
Since this is to prevent data transmission to the receiving modem from being interrupted during standby time, the data may be any data, such as all 0s, all 1s, or the previous TSI,
DCS repeated data may also be used.

Also, on the receiving side, as a result of receiving TSI and DCS,
When a predetermined error rate cannot be obtained, the PIS sent from R to S may be a 462 Hz signal. Therefore, when implementing the communication system according to the present invention, the facsimile device has a generation circuit and a reception circuit for this PIS signal. It is necessary to have the following.

By the way, in the above embodiment, the TSI+DCS data consisting of 360 bits is transmitted only once, but even if these are repeatedly transmitted multiple times, for example 20 times, and the transmission time of the TSI+DCS data is 1.5 seconds. good. By doing so, it is possible to further stabilize data transmission and further reduce the probability of occurrence of fallback. Even in this case, the minimum required time is only (0.923+1.5+0.2)=2.623 seconds.

Further, in this embodiment, even if fallback is performed, it takes much less time than the conventional example shown in FIGS. 1 and 2, and a sufficient time reduction effect can be obtained.

FIG. 5 is a flowchart showing an example of the operation procedure on the transmitting side of the communication system according to the present invention.
After the line is set up by the NCU, NSF and DIS are received at S1 (Step 1, the same applies hereafter).
In the next S2, it is checked by NSF whether the receiving side is compatible with the communication method according to the present invention, that is, whether the receiving side is a specific partner station.

If the judgment result in S2 is NO, that is, the receiving side is not a specific partner station and is not compatible with this sending side, fax data is transmitted using conventional protocol procedures such as Recommendation T-30 toward S3. to go into.

On the other hand, as a result of checking the initial identification signal, if the receiving side is compatible with the transmitting side, the determination result in S2 becomes YES, and in this case, the process proceeds to the next S4.
In S4, a data modem to be used is selected according to the initial identification signal DIS, and in S5, following training, TSI, DCS, and idling data are transmitted. The process then proceeds to S6, sets a 0.2 second timer, and checks in S7 whether the 0.2 second time has elapsed.

When the result in S7 is NO, it goes to S8 and checks whether PIS from the receiving side is detected or not.
During NO, return to S7.

If the result in S8 remains NO and the result in S7 becomes YES, this indicates that PIS was not sent from the receiving side while sending idle data, so S9
Proceed to begin sending the fax data and end the protocol.

On the other hand, if PIS is sent from the receiving side while idling data is being sent due to poor line conditions, when the process advances from S7 to S8, the determination result in S8 will be YES. Therefore, at this time, the process goes to S10, and it is checked whether the transmission speed of the data modem at that time is the lowest speed among the transmission speeds of the modem selectable on the transmitting side.

If the determination result in S10 is NO, the process advances to S11, where a fallback, that is, selection of a modem slower than the modem currently in use, is performed, and the process returns to S5, where data retransmission begins.

If the decision at S10 is YES, meaning that the lowest speed data modem has already been selected, there is no room for fallback, and therefore there is no room for fallback.
Since this means that the fax data cannot be transmitted, the line is disconnected at S12 and the transmission operation is abandoned.

In addition, in this embodiment, the selection of the transmission speed when data transmission is first started from the transmitting side, that is, the selection of the data modem in S4, is based on the DIS from the receiving side. However, instead of this, selection may be made from CSI.

In other words, since this CSI represents the receiving party's telephone number, it is possible to estimate the line characteristics with the other station to a considerable extent based on the contents.
Starting at a lower speed than the modem speed selected by DIS reduces the probability of fallback and further reduces the time required for the protocol.

In addition, in the above embodiment, a signal containing NSF specified in Recommendation T-30 is used as an initial identification signal, but it is also possible to use a signal with a format that does not conform to this specification instead of NSF to identify a specific party. The station may also be identified.

As explained above, according to the present invention,
Since data transmission can be started at high speed from the beginning to a specific partner station while maintaining compatibility with the protocol procedure according to CCITT Recommendation T-30, the time required for the protocol can be significantly reduced, eliminating the shortcomings of the conventional technology. It is possible to provide a facsimile communication system that can reduce transmission costs by reducing transmission costs.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the conventional protocol communication procedure according to CCITT Recommendation T-30, Fig. 2 is an explanatory diagram for understanding the time relationship, and Fig. 3 is an explanatory diagram of the facsimile communication method according to the present invention. , Figure 4 is also an explanatory diagram for understanding the time relationship, Figure 5
The figure is a flowchart illustrating the operation of an embodiment of the present invention. NSF...Non-standard equipment identification signal, CSI...Recipient's telephone number, DIS...Digital identification signal, TSI...
...Sender's telephone number, DCS...Digital command signal, TCF...Training check signal.

Claims (1)

[Scope of Claims] 1. In a facsimile communication system that has a function of sending a procedure abort signal when data transmitted from the other station cannot be received correctly after sending an initial identification signal for starting communication, Following the reception of the initial identification signal, the receiving command signal and the idling data are sequentially transmitted at the same transmission speed as the facsimile data to be subsequently transmitted;
During the transmission of the idling data, the transmission of a procedure interruption signal from the partner station is monitored, and when such a signal is detected, the data transmission rate is reduced by a predetermined value and the reception command signal and idling data are transmitted again. A facsimile communication system characterized in that transmission of facsimile data is started following the idling data only when a procedure interruption signal is not detected by the end of transmission of the idling data. 2. The invention as set forth in claim 1 is characterized in that means is provided for selecting the transmission speed when initially transmitting the reception command signal and idling data in accordance with the initial identification signal of the partner station. Facsimile communication method.