JPH0575820A - Facsimile communication method - Google Patents

Abstract

PURPOSE:To provide a simplified facsimile communication method by which the usage charge of a public line network can be reduced and transmission efficiency can be improved. CONSTITUTION:The telephone number of a station to be communicated is made to a specified identifying means ID, and a means 1 for storing and reproducing the ID and the contents of the facsimile function of this called station is provided, and prior to the communication of CNG and CED being communication standard procedures between a calling station and the called station, prescribed signals f1, f2 are communicated between the calling station and the called station 2, and the success or the failure of the communication is confirmed 3, and when the communication fails, the communication is performed between the calling station and the called station in conformity to usual facsimile transmission procedure including the communication standard procedure 4, and when the communication succeeds, the usual facsimile transmission procedure is omitted, and operation is shifted to the protocol control of the procedure of the training of a MODEM 6, and the transmission of required information can be performed quickly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile communication method capable of shortening communication time.

[0002]

2. Description of the Related Art A conventional standard protocol procedure for a facsimile will be described with reference to FIG. 5 showing an example of a G3 / G2 machine procedure.
After calling off-hook on the calling station side and starting dialing, CNG
(1100Hz ± 38Hz), CED (2100Hz ±
Communication is started by a handshake of 15 Hz).
Here, CNG is a signal notifying the called station side that it is in the transmitting state, and CED is a signal notifying the calling station side that it is in the receiving state. After that, it is a signal from the called station to inform the calling station of information such as the type of modem, I / O speed, recording paper width, etc., as a function of the calling station when receiving, the preamble and NSF. ), CS
I (identification number of the own device to notify the calling station side when receiving), D
IS (similar to NSF but of G3 specifications) is transmitted until it is reliably received at the calling station. In the illustrated example, it is repeated twice. After that, the calling station side similarly informs the preamble and NSS (what kind of transmission conditions at the called station side at the time of transmission ... For example, modem speed, I / O speed, document width, etc.), Our specifications), T
SI (identification number of the own device to notify the called station side at the time of transmission),
DCS (similar to NSS but with G3 specifications) is sent. As a result, the procedure between transmission and reception is completed, and thereafter, the training of the modem is started.

That is, a high-speed modem requires an equalizer for correcting the distortion of the transmission line, and generally follows a difference in distortion amount due to a difference in connection state and a gradual change in distortion after connection. An adaptive equalizer that operates to cancel them is used. In such an adaptive equalizer, training for equalizer adjustment is performed as training of a modem before data transmission / reception. There are CCITT recommended V27ter modem and CCITT recommended V29 modem as the modem. The V27ter modem is an 8-phase differential phase modulation (PSK) standardized modem for transmitting at 4800 bit / s on a general public line network, and has a fallback function (auxiliary function that backs up basic functions).
Therefore, the operation of 2400 bit / s is possible. V29
The modem was standardized to be used for point-to-point 4-wire dedicated telephone line type line 9600
In a bit / s quadrature amplitude modulation (QAM) mode modem,
This also enables the operation of 7200 bit / s and 4800 bit / s by the fallback function. Also, during modem training, TCF (signal for modem training check) is issued and CFR (signal for notifying the calling station side that modem training has succeeded) or FI.
T (a signal notifying the calling station side that the modem training has failed) is output. If you fail, you will be retrained. Then, the process shifts to data transmission and demodulation.

[0004]

As described above, conventionally, both the calling station side and the called station side have a handshake function for information such as model confirmation, modem speed, document width, and linear speed. Therefore, in addition to the time required for the original image transmission, the time for this is always required, and the usage fee for the public line becomes high.

That is, when looking at the standard procedure of the protocol,
When the communication partner is known in advance, it is not necessary to send from the preamble on the called station side to DIS and from the preamble on the calling station side to DCS. In other words, the transmission time for this purpose is not always necessary and may be omitted.

Similarly, from training to CFR, if the operation of the modem is surely guaranteed, it can be omitted. Alternatively, it suffices to train the modem while transmitting data, and at least the time from the start of training to the start of retraining is not essential.

Furthermore, since the modem always operates from the beginning every time a new signal comes in, it takes a considerable time to enter a stable state.

[0008]

According to a first aspect of the present invention, in a facsimile communication method for encoding and transmitting image and character information from a calling station to a called station through a public line network, the called station communicating A telephone number is used as a specific identification means ID, and a means for storing and reproducing this ID and the facsimile function contents of the called station is provided, and for communication of CNG and CED which is a standard communication procedure between the calling station and the called station. First, a predetermined signal is communicated between the calling station and the called station to confirm the success or failure of communication, and when communication by this predetermined signal is not established, a normal facsimile transmission procedure including the communication standard procedure is issued. Communication is performed between the calling station and the called station, and when communication by a predetermined signal is established, the normal facsimile transmission procedure is omitted and the protocol control, which is the modem retraining procedure, is entered. It was so.

According to the second aspect of the present invention, the default destination of the normal facsimile transmission procedure is changed to the protocol control, which is the modem retraining procedure of the first aspect of the invention, instead of the modem control procedure. The procedure was changed to protocol control, which is a training / TCF procedure.

In these inventions, in the invention described in claim 3, when dialing the calling station, the telephone number of the called station is used as a specific identification means ID for the called station such as modem speed, document width and line density. The contents of the facsimile function on the other side are stored and reproduced, and in the invention of claim 4, a means for identifying a predetermined signal other than CNG on the called station side and a predetermined signal other than CED on the calling station side. In the invention of claim 5, the transmission order and the identification order of the predetermined signals between the calling station side and the called station side are arbitrary. ..

Further, in the invention according to claim 6, when the modem is retrained or shifted to training by the omitted procedure, it is discriminated whether the modem type is the modem V27ter or the modem V29, and the identified modem type is set. The demodulation operation is performed accordingly.

Further, according to the present invention, when the modem on the called station side for demodulating the transmitted facsimile signal is in a normal communication state, the tap value of the equalizer in the modem is held and a new value is set. It is determined whether or not to use this tap value held at the time of starting communication, and when it is determined to use it, the modem is started to operate normally starting from this tap value.

[0013]

When the calling station and the called station mutually know the other party, the telephone number of the called station is used as a specific identification means ID to store and reproduce the facsimile function contents to control communication. The communication procedure can be simplified by handshaking using only a predetermined signal and omitting the normal facsimile transmission procedure and shifting to the protocol control which is the procedure of retraining or training / TCF of the modem. As a result, the required information can be transmitted promptly, the usage fee of the public line network can be reduced, and the transmission efficiency can be improved.

In particular, according to the invention described in claim 7, the modem does not need to always operate from the beginning every time a new signal is input, and by using the held tap value of the equalizer,
It is possible to train and stabilize the modem efficiently in a short time.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in FIG. 5 are designated by the same reference numerals. 1 is based on the method of FIG.
9 shows a protocol procedure of a system of this embodiment instead of the system.

First, in the present embodiment, when dialing at the calling station, in the case of a known called station, as shown in the process, the telephone number of the called station is identified by a specific identifying means. It has a storage / reproduction function of storing the facsimile function contents on the called station side such as the modem speed, the document width, and the line density as an ID, and reproducing and checking it if already stored.

Next, CNG, CE, which is a communication standard procedure,
Prior to the communication of D, as shown in the process, a predetermined signal f
_A handshake for communicating ₁ and f ₂ between the calling station and the called station is performed. In this case, for example, f ₁ = 2100 Hz, f ₂
A signal of = 1100 Hz may be used and a conventional BPF (band filter) may be used instead. Alternatively, another frequency signal may be used, and in short, the frequency signal generating means and the frequency signal detecting means may be held together. The called station side may be provided with means for identifying a predetermined signal f ₁ other than CNG and means for transmitting a predetermined signal f ₂ other than CED to the calling station side. Further, in the illustrated example, the calling station side detects f ₂ after sending out f ₁ as the identification and transmission order of the predetermined signals f ₁ and f ₂ as described above. F ₂ at the calling station within the time indicated by
Alternatively, the order may be reversed so that f ₁ is transmitted from the calling station side after detecting (the former is more preferable).

Next, as shown in the processing, the success or failure of communication by the predetermined signals f ₁ and f ₂ is checked. If this communication is not established, as described in the processing, the above-mentioned C
Communication is performed between the calling station and the called station according to a normal facsimile transmission procedure starting from NG and CED communication.

On the other hand, when the result of the processing judgment shows that the communication is established, the normal facsimile transmission procedure is omitted and
Modem training / TCF procedure (process) to move to protocol control, or training /
The TCF is also omitted, and processing (processing) for shifting to protocol control, which is a procedure for modem retraining, is performed.

As the modems used on the called station side, there can be a modem V27ter and a modem V29. Therefore, prior to the training or retraining transition, it is possible to identify which modem is used by the processing. To perform a training operation according to the identified type of modem.

FIG. 2 shows an example of identification processing of the modem V27ter / V29. In this processing example, for example, a filter having a high Q is used as a BPF (bandpass filter) for detecting a carrier frequency, 1800 Hz (or 1700 Hz or no signal) is detected, and which is determined. is there. After the determination, the training process is sequentially performed on the divided segments 2 to 5 according to the training sequence of each modem, and the TCF is output.

Since the procedure after the training is basically the training of the modem, it is preferable to control so that the stable state is achieved as soon as possible. The modem configuration and operation for that purpose will be described with reference to FIGS. FIG. 3 shows a PSK or QAM type modem (modem V
27 ter or V29 may be used). That is, the band pass analog filter 1, the A / D converter 2, the AGC circuit 3, the complexization processing circuit 4, the automatic equalizer 5, the phase synchronization circuit 6, the determination circuit 7, and the P /
A memory 10 is added to the automatic equalizer 5 in addition to a demodulation system configuration for demodulating received data by the S conversion circuit 8 and the descrambler 9 into reproduced data. This memory 10 holds the tap value (coefficient) of the automatic equalizer 5 at the time of communication in a normal state, and when the new communication is started, the contents of the automatic equalizer 5 are instantly displayed. It replaces the contents.

That is, as shown in FIG. 4, when the modem on the called station side that demodulates the transmitted facsimile signal is in a normal communication state (equalizer coefficient setting is performed by a normal method, segment 2 to segment 2). If the result of training every 5 is normal), the tap value of the automatic equalizer 5 is held in the memory 10. Then, when you start a new communication,
Whether or not this state value is used is determined by whether or not it is the normal method. If it is not the normal method, the coefficient setting of the automatic equalizer 5 is normally performed as described above. The coefficient of the rectifier 5 is called from the memory 10 (a trigger signal is generated by the detection of the segment 1 during training), and the coefficient is set by instantaneously replacing the coefficient.
It is to shift to training as it is. Therefore, it is not necessary for the modem to always perform the coefficient setting operation every time a new signal is input, and the modem training can be performed efficiently in a short time.

[0024]

As described above, the present invention identifies the telephone number of the called station by paying attention to the fact that it is not necessary to always perform all the standard procedures of the protocol when the communication partner is known in advance. The content of the facsimile function is stored and reproduced as the identification means ID of the above and used for communication control, and the normal facsimile transmission procedure is omitted by the establishment of the handshake using only a predetermined signal, and the modem retraining or training / training / Since the protocol control, which is the TCF procedure, is performed, the communication procedure can be effectively simplified, the required information can be transmitted quickly, and the usage fee of the public line network can be reduced and transmitted. It is possible to ensure efficiency improvement.

In particular, according to the invention described in claim 7, the modem does not always have to operate from the beginning every time a new signal is received, and the tap value of the equalizer held in the normal communication state is used. Thus, it is possible to efficiently train and stabilize the modem in a short time, and it is possible to further improve the transmission efficiency.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a protocol procedure of an embodiment of the present invention.

FIG. 2 is a flowchart showing a modem identification process.

FIG. 3 is a block diagram showing a configuration of a receiving unit of a modem.

FIG. 4 is a flowchart showing the equalizer coefficient processing.

FIG. 5 is an explanatory diagram showing a protocol procedure of a conventional example.

[Explanation of symbols]

 5 equalizer

Claims (7)

[Claims] 1. In a facsimile communication method of encoding and transmitting image and character information from a calling station to a called station through a public line network, the telephone number of the called station to be communicated is used as a specific identification means ID. A means for storing and reproducing the facsimile function contents of the called station is provided, and a predetermined signal is called between the calling station and the called station prior to the communication of CNG and CED which is a standard communication procedure between the calling station and the called station. The communication between the calling station and the called station is performed by confirming the success or failure of the communication by communicating with the station, and when the communication by the predetermined signal is not established, the communication is performed between the calling station and the called station according to the normal facsimile transmission procedure including the communication standard procedure. Do
A facsimile communication method characterized in that, when communication by a predetermined signal is established, a normal facsimile transmission procedure is omitted and a protocol control, which is a retraining procedure of a modem, is performed. 2. In a facsimile communication method for encoding and transmitting image and character information from a calling station to a called station through a public line network, the telephone number of the called station to be communicated is used as a specific identification means ID. A means for storing and reproducing the facsimile function contents of the called station is provided, and a predetermined signal is called between the calling station and the called station prior to the communication of CNG and CED which is a standard communication procedure between the calling station and the called station. The communication between the calling station and the called station is performed by confirming the success or failure of the communication by communicating with the station, and when the communication by the predetermined signal is not established, the communication is performed between the calling station and the called station according to the normal facsimile transmission procedure including the communication standard procedure. Do
When the communication by the predetermined signal is established, the normal facsimile transmission procedure is omitted and the modem training / TCF is performed.
Facsimile communication method characterized in that the protocol control, which is the procedure of, is performed. 3. At the time of dialing of the calling station, the telephone number of the called station is used as a specific identification means ID to store and reproduce the facsimile function contents of the called station such as modem speed, document width, and line density. The facsimile communication method according to claim 1, wherein the facsimile communication method is performed. 4. The called station side is provided with means for identifying a predetermined signal other than CNG and means for transmitting a predetermined signal other than CED to the calling station side. The facsimile communication method according to 1 or 2. 5. The facsimile communication method according to claim 4, wherein the transmission order and the identification order of predetermined signals mutually between the calling station side and the called station side are arbitrary. 6. When the retraining of the modem or the shift to the training by the omitted procedure, the type of the modem is identified as the modem V27ter or the modem V29, and the demodulation operation is performed according to the identified type of the modem. The facsimile communication method according to claim 1 or 2, characterized in that. 7. The tap value of the equalizer in the modem is held when the modem of the called station that demodulates the transmitted facsimile signal is in a normal communication state, and is held when a new communication is started. 3. The facsimile communication according to claim 1, wherein it is determined whether or not the tap value is used, and when it is determined that the tap value is used, the modem is started from this tap value to bring the modem into normal operation. Method.