JPH07254944A - Facsimile communication method - Google Patents

Abstract

PURPOSE:To shorten a transmission time of a facsimile equipment having a long preamble wait time by using a usual facsimile modem and a facsimile modem for transmission after retrial with respect to two kinds of facsimiles having a long preamble wait time and a short preamble wait time in a transmission side exchange. CONSTITUTION:When a facsimile 1 having a long wait time sends a call signal, an exchange of its own station detects the call signal and stores a subscriber telephone number to a transmission signal storage section 29 and an opposite exchange is connected to a facsimile equipment 5 able to process the wait time independently of its time length and sends a tone signal to a sender exchange. When detection command control sections 27, 28 detect the tone signal, a control section 27 commands the selection of a proper facsimile modem to a transmission facsimile modem collation section 31 and a control section 28 gives a command of connection of a facsimile modem 21-1 applicable to any wait time processing to a switch connection control section 41. Then the collation section 31 refer to the storage section 29 and a transmission information table 30 to select a facsimile modem 11 making transmission after retrial and commands a switch connection control section 40 to connect a trunk 20 and the modem 11. Then the control section 40 allows a switch circuit network 50 to execute it and the control section 41 uses the circuit network 51 to connect the modem 12-1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a switch,
CCITT V. Facsimile communication in the case where a plurality of types of G3 standard FAX (facsimile) defined in 29 perform communication via a transmission path through which a band-compressed signal, for example, 16 Kbps or 8 Kbps, which is an extremely band-compressed voice signal, is transmitted. Regarding the improvement of the method.

In recent years, a voice signal has also been transmitted to a transmission line between PBXs.
A signal which passes a band-compressed signal of 6 Kbps or 8 Kbps has come to be used, and in this case, V. It is desired that communication between G3 standard FAXes defined in No. 29 is possible and the transmission time is not long although the preamble waiting time is long.

[0003]

2. Description of the Related Art V. of CCITT. G specified in 29
In the FAX of 3 standards, the time from the sending side to sending the transmission preparation signal from the receiving side to the signal from the receiving side and the time at which the receiving side FAX sends a response are discretionary parts, and the above preamble waiting time is Depending on the model, there are the following two types.

The first type has a preamble waiting time of 3
If it takes more than a second, it retries, and if it takes more than 3 seconds, it retries three times, but if it still takes more than 3 seconds, the communication will be terminated. The second type has a preamble waiting time of 4 Up to the second, the same communication is performed (again, if the preamble does not come after 4 seconds, retry is performed).

The delay time due to the transmission path when the transmission path through which the audio signal is band-compressed to 16 Kbps or 8 Kbps is used is longer than the delay time due to the transmission path through which the audio signal is band-compressed at 32 Kbps. In the case of using a transmission line through which a signal band-compressed to 32 Kbps is used, the time required for the preamble signal to arrive from the reception side after transmission of the transmission preparation signal from the transmission side is 3 in any model.
Since it was within seconds, I was able to communicate normally even if the type of FAX changed, but when using a transmission line that passes a signal that has been band-compressed to 16 Kbps or 8 Kbps, after sending a send preparation signal from the sending side, receive The time until the preamble signal comes from the side may be 3 seconds or more.

When the time exceeds 3 seconds, the first type FA
Communication is not possible with X. Also, the audio signal is 32 Kbps
In the case of using a transmission line for passing a band-compressed signal to the device, a voice codec that band-compresses the voice signal to 32 Kbps is used, and the FAX communication is possible by sampling-transmitting the FAX sound source signal. 16 Kbp
When using a transmission line through which a band-compressed signal of s or 8 Kbps is used, an FA is used instead of an audio codec.
Communication is not possible without using an X modem, and a FAX modem has come to be used.

In this FAX modem, only one voice signal is transmitted.
There are one that only allows a FAX signal to pass through a transmission path that allows a signal that has been band-compressed to 6 Kbps or 8 Kbps, and a special FAX modem that allows transmission after a retry operation.

This special FAX modem is a FAX on the transmitting side.
When a preamble signal is returned from the receiving side after sending the transmission preparation signal, it is stored without passing to the transmitting side FAX, and the transmitting side FAX is retried, and the preamble is immediately received when the retry signal is input. By passing the signal of, the preamble wait time will appear within 3 seconds and communication with any type of FAX will be possible (hereinafter, this FAX modem will be referred to as a FAX modem that transmits after retry operation). ).

The G3 FAX in the case of using a transmission line through which a signal obtained by band-compressing a voice signal to 16 Kbps is used is 9600.
G3 FAX is 72 when using a transmission line that passes a signal obtained by band-compressing a voice signal to 8 Kbps by using a bps one.
Transmission of 00 bps is used.

Therefore, the audio signal is transmitted at 16 Kbps or 8K.
G3F is used by using a transmission line that passes a band-compressed signal to bps.
In the case of performing communication by AX, conventionally, a FAX modem that performs transmission after a retry operation is used to enable normal FAX communication even with the above-mentioned first and second types of FAX.

[0011]

However, the second type of fax machine which operates until the preamble waiting time is up to 4 seconds.
In this case, since the communication is performed after the retry regardless of the possibility of the continuous communication, there is a problem that the transmission time becomes longer by about 3 seconds / sheet.

According to the present invention, in the case of using a transmission line for transmitting a signal in which a voice signal is extremely band-compressed, for example, a band-compressed signal of 16 Kbps or 8 Kbps, a FAX of the second type that operates up to a preamble waiting time of 4 seconds is used. The purpose is to provide a facsimile communication method that does not lengthen the transmission time.

[0013]

FIG. 1 is a block diagram showing the principle of the present invention. As shown in FIG. 1, CCITT V. 29
First and second exchanges to which the G3 standard long preamble waiting time (4 seconds) type faxes 1 and 3 and short preamble waiting time type faxes 2 and 4 are connected, respectively. In a communication system in which 100 and 101 are connected by a transmission line 102 that passes a signal obtained by extremely band-compressing a voice signal, the first and second exchanges 100,
101 is provided with a first FAX modem 11 for transmitting after retry operation and a second FAX modem 12 for performing normal operation, which are used when performing FAX communication. When sending
The exchange on the transmission side uses the second FAX modem 12 to perform communication, and an F-type of a type with a short preamble waiting time is used.
At the time of transmission from the AX2, 4, the exchange on the transmitting side uses the first FAX modem 11 for communication, and the exchange on the receiving side uses the first or second FAX modem 11 or 12 to communicate between FAXes. The communication is configured to be performed.

[0014]

According to the present invention, the switch 100 is used when transmitting a fax of a type having a long preamble waiting time, for example, 1.
Is configured to perform communication using the second FAX modem 12 that performs a normal operation, and when transmitting from a fax of a type having a short preamble waiting time, for example, 2, the exchange 100 causes the post-retry operation to perform transmission. Communication is performed using the FAX modem 11 of No. 1.

Therefore, the transmission time is the same as that of the conventional FAX2 having a short preamble waiting time, but the transmission time can be made shorter than that of the conventional FAX1 having a long preamble waiting time.

[0016]

FIG. 2 is a block diagram of a communication system according to an embodiment of the present invention, in which one exchange shows a transmitting side and the other exchange shows a receiving side. FIG. 3 shows a flowchart of the operation in the case of FIG.

In FIG. 2, 1 is a G3 FAX having a preamble waiting time of 4 seconds and 2 is a G3FA having a preamble waiting time of 3 seconds.
X and 5 are G3 FAX whose preamble waiting time may be either 3 seconds or 4 seconds, 11 is a FAX modem for transmitting after retry operation, and 12 and 12-1 are FAs for performing normal operation.
Although it is an X modem, the FAX modem 12-1 on the receiving side may be a FAX modem that performs transmission after a retry operation. Four
0 and 41 are switch connection control units for controlling connection between incoming lines and outgoing lines in response to a connection control signal input by a part of the exchange, and 50 and 51 are switch circuits for performing connection under the control of the switch connection control unit. Network, 27 and 28 are called G3
Detects the FAX tone signal [any of preamble, non-standard function identification signal (NSF), called terminal identification signal (CSI), and digital identification signal (DIS)] to identify and instruct voice communication or FAX communication 2 is a detection / instruction control unit, 29 is a transmission signal storage unit that stores the telephone number of the calling side subscriber, and 30 is the G3 FAX telephone number accommodated in the local exchange as shown in FIG. The transmission information table in which the number of the FAX modem to be selected is written, and 31 is a suitable FA from the transmission signal storage unit 29 and the transmission information table 30.
Transmission FAX modem collation unit for selecting X modem, 2
0 to 24 are trunks, 102 is a voice signal of 16 Kbps
It is a transmission line through which a signal whose band is compressed to 8 kbps is passed.

In this case, assuming that the telephone numbers of the G3FAX1 model are 1001 to 1010 and the telephone numbers of the G3FAX2 model are 1011 to 1020, the transmission information table 30 is as shown in (A), and in the case of the telephone numbers 1001 to 1010, the FAX is shown. Select the modem 11 and call the phone numbers 1011 to 1
In the case of 020, the FAX modem 12 is selected.

The operation of the system shown in FIG. 2 will be described below with reference to the flowchart of the operation shown in FIG. For example, trunk 2
When G3FAX1 connected to 0 sends out a calling signal,
In step 1, the local exchange detects a calling signal, stores the calling subscriber's telephone number 1001 in the transmission signal storage unit 29 in step 2, and sends a dial signal in step 3. Then, the data is input to the exchange on the other side via the voice codec 25, the trunk 22, the transmission line 102, the trunk 23, and the voice codec 26. At step 4, the exchange on the other side detects a dial signal, and, for example, via the trunk 24. Connect to G3FAX5.

Then, in step 5, the G3FAX 5 sends a G3FAX tone signal as a response signal to the transmitting side exchange. In step 6, the sender and receiver are detected.
When the instruction control units 27 and 28 detect the G3 FAX tone signal, in step 7, the detection / instruction control unit 2 on the transmission side is detected.
Reference numeral 7 is a fax modem matching unit 3 which transmits an appropriate fax modem selection.
1, and the detection / instruction control unit 28 on the receiving side instructs the switch connection control unit 41 to replace the voice codec 26 with the FAX.
Instruct to make a connection using the modem 12-1.

Then, in step 8, the transmission FAX modem verification unit 31 transmits the transmission signal storage unit 29 and the transmission information table 3 to each other.
0, the FAX modem 11 is selected, and the switch connection control unit 40 is notified to connect and exchange the trunk 20 and the FAX modem 11 instead of the voice codec 25.

Then, in step 9, the switch connection control unit 40 causes the switch circuit network 50 to execute this, and the switch connection control unit 41 causes the switch circuit network 51 to replace the voice codec 26 and the FAX modem 12-1. Make a connection using.

Then, in step 10, the transmitting side G3F
AX1 sends a transmission preparation signal, receives a response signal, and receives FAX.
Communicate. In step 6, the detection / instruction control unit 27,
If 28 does not detect the G3 FAX tone signal, it is regarded as communication by the telephone terminal, the process proceeds to step 11, and the exchange process using the voice codecs 25 and 26 is performed.

[0024]

As described above in detail, according to the present invention, CCITT V. F of the G3 standard specified in 29
AX has extremely band-compressed voice signal, eg 16K
When communication is performed using a transmission line through which a signal whose band is compressed to bps or 8 Kbps is used, there is an effect that the transmission time of the second type FAX that operates until the preamble waiting time is 4 seconds is not lengthened.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention,

FIG. 2 is a block diagram of a communication system according to an embodiment of the present invention,

FIG. 3 is a flowchart of the operation in the case of FIG.

[Explanation of symbols]

 1 to 5 are G3 FAX, 20 to 24 are trunks, 25 and 26 are voice codecs, 27 and 28 are detection / instruction control units, 29 is a transmission signal storage unit, 30 is a transmission information table, 31 is a transmission FAX modem verification unit, 40 and 41 are switch connection control units, 50 and 51 are switch circuit networks, 100 and 101 are exchanges, and 102 is a transmission line.

Front page continuation (72) Inventor Aiaki Inoue 3-2-1 Sakado, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Network Engineering Co., Ltd.

Claims (1)

[Claims] 1. A first FAX (1, 3) of a kind having a preamble waiting time longer than a predetermined value and a FAX (2, 4) of a kind having a preamble waiting time shorter than a predetermined value are connected, respectively. , Second exchange (100, 101)
However, in a communication system connected by a transmission line (102) for passing a signal in which a voice signal is extremely band-compressed, a retry for use in performing FAX communication with the first and second exchanges (100, 101) First to send after operation
FAX modem (11) and the second F for normal operation
An AX modem (12) is provided, and when transmitting from a fax (1, 3) of a type in which the preamble waiting time is longer than a predetermined value, the exchange on the transmitting side communicates using the second fax modem (12). When transmitting from a fax (2,4) of a type with a preamble waiting time shorter than a predetermined value,
The exchange on the transmitting side uses the first FAX modem (11) for communication, and the exchange on the receiving side uses the first or second communication.
FAX communication (11 or 12) is used to perform communication between FAX machines.