JPH1169119A - Communication terminal equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide communication terminal equipment whose communication time is substantially reduced by not conducting communication at a data rate higher than a decided data rate as an optimum data rate at once in the preliminary procedure at start of communication to suppress production of a communication error in the communication terminal equipment such as a facsimile equipment. SOLUTION: The terminal equipment is provided with a modem 5 whose data rate is set at the start of communication and revised on the way of communication respectively, a RAM 3 that stores the data rate set by the modem 5 in the preceding procedure, and a CPU 1 that controls the communication so that it is conducted at a data rate below the data rate stored in the RAM 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication terminal device such as a facsimile device, and more particularly to a communication terminal device according to Recommendation V.34 of ITU-T (International Telecommunication Union-Telecommunication Standardization Sector). And a communication terminal using a modem capable of changing a data rate (communication speed) during communication.

[0002]

2. Description of the Related Art Generally, a communication terminal device for performing data communication such as a facsimile device converts a digital signal into a voice signal at the time of transmission and transmits the signal to a general public telephone line, and receives a voice signal from a general public telephone line at the time of reception. A modem is provided for receiving signals and converting them to digital signals.

[0003] In the case of performing data communication with a conventional communication terminal device, a modulation / demodulation device based on a half-duplex system such as the ITU-T (International Telecommunication Union-Telecommunication Standardization Sector) recommendation V.17 communication procedure is used. When using and performing facsimile communication, the V.17 communication procedure is used in accordance with the procedure stipulated in T.30, which is a facsimile communication procedure of the general G3 standard.

[0004] However, an ultra-high-speed communication procedure (hereinafter referred to as V.34 communication procedure) having a maximum communication speed (data rate) of 33.6 Kbps based on the recommendation V.34 has also been put to practical use.
34 In the communication procedure, at the start of communication, it is possible for the receiving side to specify the data rate according to the current line conditions, specifically, S / N, bandwidth, etc. Is determined to perform transmission at the data rate specified on the receiving side. Also, in this V.34 communication procedure, during communication, no error is detected on the receiving side, etc.
When the line condition is improved, it is possible to increase the data rate, and the transmitting side is changed to perform transmission at the data rate specified by the receiving side. When data communication is performed in the V.34 communication procedure, it is necessary to determine the actual data rate by performing communication in the same V.8 communication procedure.

Next, a conventional V.34 communication procedure will be described with reference to a schematic diagram of FIG. 4 showing transmission and reception of signals at the start of the communication. However, when executing the V.34 communication procedure, the data rate is first determined by the V.8 communication procedure as described above.
Divided into stages.

In the phase 1 network interaction, mutual capability is confirmed between the transmitting and receiving devices. The calling side (calling side) device sends out a calling tone CNG or a function indication signal CI. When the call is received, the receiving device returns a modified response tone ANSam indicating that the transmitting device has the function of the V.8 communication procedure.
By receiving the modified response tone ANSam, the transmitting device can call the menu signal CM indicating the capability of its own modem.
Is sent. Upon receiving the calling menu signal CM, the receiving device selects the highest capability from the capabilities of the modems of both the transmitting and receiving devices, and sends out a common menu signal JM indicating that. Note that the transmitting apparatus sends a CM termination signal CJ as a response to the common menu signal JM. Thus, the phase 1 ends.

[0007] Thereafter, in phase 2, line probing is performed. Signal INFO between both transmitting and receiving devices
Thus, information such as a modem capability, a line probing result, and a data mode modulation parameter is exchanged. After transmitting and receiving the tones A and B, line probing is executed. This line probing is performed in order to detect the state of the line at the receiving device by transmitting the probing signals (L1, L2) from the transmitting device, whereby the receiving device receives the S / N of the line at that time and The bandwidth and the like are determined. According to this result, the receiving side device transmits again the modem capability, the line probing result, the data mode modulation parameter, and the like by the signal INFO.

Next, in phase 3 equalizer training, a training signal TRN is transmitted from the transmitting device. By receiving the training signal TRN, the data rate is determined in the receiving device. Then, in the final training of the phase 4, the speed change request signal PPh is transmitted and received between the two, and finally the speed designation signal MPh is transmitted and received to determine the data rate. After this, ITU-T
Facsimile communication conforming to Recommendation T30 is performed.

FIG. 5 is a schematic diagram showing signal transmission / reception (inter-page procedure) when the data rate is not changed at a page break during communication of image data.

At the time when transmission of one page of image data (Image Data) is completed, a normal procedure for transmitting the next page of image data (Image Data) is started from the transmitting apparatus, and signal Sh is output. The signal Sh is also transmitted from the receiving device, and the image data (Image Data) of the next page is transmitted from the transmitting device in a normal procedure.

FIG. 6 shows transmission / reception of a signal when a change in data rate is requested from the transmission side device at a page break during communication of image data (Image Data) (inter-page procedure).
FIG.

When transmission of one page of image data (Image Data) is completed, first, a transmission-side device transmits a speed change request signal PPh, and in response thereto, the reception-side device also transmits a speed change request signal PPh. Eventually, the speed designation signal MPh is transmitted and received between the two, the data rate is determined, and the image data of the next page is transmitted.

FIG. 7 shows the transmission and reception of a signal when a change in data rate is requested from a receiving apparatus at a page break during communication of image data (Image Data) (inter-page procedure).
FIG.

When the transmission of one page of image data (Image Data) is completed, a normal procedure for transmitting the next page of image data (Image Data) is started from the transmitting apparatus, and the signal Sh is output. However, the receiving device transmits a speed change request signal PPh, and the transmitting device also transmits the speed change request signal PPh, and finally, the speed designation signal MPh is transmitted and received between the two devices. The data rate is determined, and image data (Image Data) of the next page is transmitted.

As described above, in the conventional V.34 communication procedure and the V.8 communication procedure as a pre-procedure thereof, the data rate can be changed at the start of communication and during communication. Therefore, when no error is detected in the transmitted data, it is possible to increase the data rate and transmit the next page, but it takes time to transmit and receive a signal for changing the data rate, and such a time is required. If the data rate is increased in this manner, there is a high possibility that an error will occur. In this case, the procedure shown in FIGS. 6 and 7 is repeated to lower the original data rate. Need to retransmit.

[0016]

If an error is not detected in the data received by the receiving side during execution of data communication such as facsimile communication by the V.34 communication procedure as described above, a request from the receiving side is issued. By doing so, subsequent communication can be performed at a data rate higher than the data rate at that time, but when the data rate is increased in such a manner, the possibility of occurrence of an error increases. In this case, the data rate is reduced in response to a request from the receiving side and recommunication is performed. If no error is detected at that time, the data rate is increased again.

As a result, conventionally, an error occurs when the data rate is increased as described above, so that retransmission at a lower data rate and retransmission and an increase in the data rate are repeated. As a result, there is a problem that the communication time becomes longer.

The present invention has been made in view of such circumstances. For example, in a communication terminal device such as a facsimile device, communication is performed at a data rate higher than a data rate once determined to be optimal in a pre-procedure at the start of communication. To prevent communication errors from occurring,
An object of the present invention is to provide a communication terminal device capable of substantially reducing communication time.

[0019]

According to a first aspect of the present invention, there is provided a communication terminal apparatus comprising: a modem capable of setting a data rate by a pre-procedure prior to an original communication; Storage means for storing the data rate set in the previous procedure, and control means for performing communication only at a data rate equal to or less than the data rate stored in the storage means when the data rate is changed during communication. It is characterized by.

In the first aspect of the communication terminal apparatus of the present invention, communication is performed only at a data rate equal to or lower than the data rate set in the pre-procedure and stored in the storage means. A situation in which the data rate is increased and errors frequently occur is avoided.

Further, in the communication terminal device according to the present invention, in the first aspect, the control means may change the data rate during the communication with the data rate stored in the storage means and after the change by the modem. The data rate is compared with the data rate, and only when the former is smaller than the latter, it can be recognized.

In the second aspect of the communication terminal device of the present invention, the data rate stored in the storage means is compared with the data rate after the change by the modem, and when the former is smaller than the latter, Since a change in the data rate during communication is recognized, if an error occurs due to deterioration of the line condition after the start of communication, the data rate is automatically reduced to a data rate at which no error occurs.

Further, in the communication terminal device according to the second aspect of the present invention, the control means may be arranged such that the control means performs
Attempts to change the data rate so as to increase the data rate when a predetermined amount of data is transmitted without error and to reduce the data rate when the number of errors has reached the predetermined number. It is characterized by.

According to the third aspect of the communication terminal apparatus of the present invention, the data rate is increased when a predetermined amount of data is transmitted without error, and when the number of error occurrences reaches a predetermined number. Therefore, communication is performed at an optimum data rate within a range equal to or less than the data rate set in the previous procedure.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is a block diagram showing a configuration example of an embodiment in which a communication terminal device according to the present invention (hereinafter, referred to as the present device) is embodied as a facsimile device.

In FIG. 1, reference numeral 1 denotes a CPU (Central Processing Unit) which functions as a control unit of the facsimile apparatus, and a ROM (Read) in which a program for controlling the operation of the entire facsimile apparatus is stored in advance. Only Memor
y) functions as a storage unit for storing data necessary for control by the CPU 1, for example, data such as a data rate set in a pre-procedure by the modem 5 described later, or data that requires temporary storage during operation. RAM (Random Acc
ess Memory) 3 is connected.

The CPU 1 has an NCU (Network Control Uni
t) 4, Modem 5 is connected. The NCU 4 is controlled by the CPU 1 to control a connection between the line L and the facsimile machine, and has a function of transmitting a dial pulse corresponding to a telephone number of a communication partner and a function of detecting an incoming call. The line L is connected to a general public telephone line (not shown).

The modem 5 modulates and demodulates the transmission / reception data, specifically modulates the transmission data into an audio signal and sends it to the line L via the NCU 4, and conversely, converts the audio signal received from the line L via the NCU 4 Demodulates to a digital signal. Although there are products with various capabilities as the modem 5, in this example,
Assume that the modem is capable of V.34 communication procedures. Generally, a modem capable of the V.34 communication procedure is capable of changing the communication speed during communication, and at the same time, based on a signal received from a communication partner, the state of the communication line at that time, specifically, S / S Data such as N and bandwidth can be externally monitored as status.

Note that the modem 5 is provided with a CONF register 51 that stores a data rate used in actual communication.

The CPU 1 further includes a reading unit 6, an image memory 7,
A codec 8, a recording unit 9, an operation unit 10, a display unit 11, and the like are connected. The reading unit 6 reads a document image using, for example, a CCD image sensor. Image memory 7
Stores image data read by the reading unit 6 and image data received from the outside via the line L and the modem 5. The codec 8 encodes the image data to be transmitted and decodes the received image data. The recording unit 9 records the received image data or the image data read by the reading unit 6 on recording paper (paper). The operation unit 10 includes ten keys for inputting numbers such as telephone numbers, one-touch keys, abbreviated keys, operation keys for instructing various operations, and the like. The display unit 11 includes a CRT display or an LCD (Liquid Crystal Display) that displays various information such as a telephone number input by operating the operation unit 10.

Next, with respect to the operation of the facsimile apparatus as the present invention having the above-described configuration, an actual control procedure by the CPU 1 when the present invention is a receiving side (called side) apparatus will be described with reference to FIG. And a flowchart shown in FIG. In the following description, it is assumed that the transmitting (calling) device also has the same function as the device of the present invention.

First, when there is an incoming call, the CPU 1 sequentially performs the processing of phase 1, phase 2 and phase 3 in the same procedure as that of the conventional example shown in FIG. 4 (steps S11 and S11).
12, S13). As a result, in the phase 2, the line probing is performed as described above, and the optimum data rate at that time is determined and stored in the CONF register 51 of the modem 5. The CPU 1 reads the data rate stored in the CONF register 51 and stores the data rate in an appropriate area of the RAM 3 (Step S14).

Next, by exchanging the speed designation signal MPh in the phase 4, the communication speed (data rate) with the transmitting side device is exchanged.
Is determined (step S15), and the CPU 1 further performs a handshaking process with the transmitting device (step S16), and receives the facsimile image data (step S17).

The first one after the communication is started in this way.
When the reception of the image data of the page is completed and the termination procedure is performed next ("YES" in step S18), the communication process is terminated.

If the termination procedure is not performed ("NO" in step S18), the inter-page procedure without changing the data rate shown in FIG. 5 is executed (step S19). Then, while receiving the image data of the next one page, the CPU 1 checks whether the condition for increasing or decreasing the data rate is satisfied during that time.
(Step S20). More specifically, the condition for increasing the data rate is only when two consecutive error frames are not received at the time of reception. In this case, the data rate is increased by one step. Conversely, conditions for lowering the data rate include a case where a PPR signal is received four times during transmission and a case where a preset number of error frames is received.

The PPR signal is a partial page request signal, and indicates that the message was not successfully received, and that the frame specified in the corresponding facsimile information field needs to be retransmitted.

However, even if the condition for changing the data rate as described above is satisfied ("YES" in step S20), if the condition for increasing the data rate is satisfied, the CP
U1 is read from the CONF register 51 of the modem 5
The data rate is increased only when the data rate does not exceed the data rate stored in the memory ("YES" in step S21)
. In this case, the newly determined data rate is set in the CONF register 51 of the modem 5 while receiving the next one page of image data (step S22). On the other hand, if the conditions for changing the data rate are not met (step
(“NO” in S20), the image data of the next one page is received as it is (step S31).

Then, in either step S22 or S31, if the termination procedure is executed after the reception of one page of image data is completed (step S23 or S32).
"YES"), the communication ends. However, if the termination procedure is not executed ("NO" in step S23 or S32) and the setting for changing the data rate is made ("YES" in step S21), the data shown in FIG. If the inter-page procedure for changing the data rate is executed (step S24) and the setting for changing the data rate is not made,
(“NO” in step S20 or S21), the inter-page procedure that does not change the data rate shown in FIG. 5 is executed (step S33).

Thereafter, the processing from step S20 is repeated until the termination procedure is executed, in other words, until the communication processing of the image data of all pages to be communicated is completed. As a result, in the pre-procedure of the phase 2, the modem 5
If the communication error occurs within the range that does not exceed the data rate stored in RAM 3 and is within that range, communication will be performed at a lower data rate, and the data rate will be Such a situation that communication errors frequently occur can be avoided.

When the communication is once completed and the communication is started again, the optimum communication speed (data rate) at the time of starting the communication is newly determined by the modem 5 by the same processing as described above. Needless to say.

[0041]

As described in detail above, according to the communication terminal apparatus of the present invention, communication at a data rate higher than the data rate set as the optimum in the previous procedure is prohibited, so that occurrence of communication errors is suppressed. Thus, the communication time is substantially reduced.

Further, since the data rate can be changed within a range not exceeding the data rate set as the optimum by the previous procedure, if an error occurs due to deterioration of the line condition after the start of communication, By lowering the data rate, errors can be avoided, and when the line condition is restored, it is possible to raise the data rate within a range that does not exceed the data rate that was set optimally by the previous procedure. Communication takes place at the highest data rate that does not occur.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of an embodiment when a communication terminal device of the present invention is embodied as a facsimile device.

FIG. 2 is a flowchart showing an operation procedure of the communication terminal device according to the present invention.

FIG. 3 is a flowchart showing an operation procedure of the communication terminal device according to the present invention.

FIG. 4 is a schematic diagram for explaining a V.8 communication procedure as a pre-procedure of a general V.34 communication procedure.

FIG. 5 is a schematic diagram for explaining a general V.34 communication procedure.

FIG. 6 is a schematic diagram for explaining a general V.34 communication procedure.

FIG. 7 is a schematic diagram for explaining a general V.34 communication procedure.

[Explanation of symbols]

1 CPU, 3 RAM, 5 modem, 51 CONF register,
L Communication line.

Claims (3)

[Claims] 1. A communication method comprising: a modem capable of setting a data rate in a pre-procedure prior to an original communication; and a modem capable of changing the data rate in the middle of the communication; and a storage unit for storing the data rate set by the modem in the pre-procedure. A communication terminal device comprising: control means for performing communication only at a data rate equal to or lower than the data rate stored in the storage means when changing the data rate in the middle. 2. The control means compares a data rate change during communication with a data rate stored in the storage means and a data rate after the change by the modem, wherein the former is smaller than the latter. 2. The communication terminal device according to claim 1, wherein the communication terminal device is allowed to recognize only in a certain case. 3. The control means increases a data rate when a predetermined amount of data is communicated without error during communication, and decreases the data rate when the number of errors has reached a predetermined number. 3. The communication terminal device according to claim 2, wherein each of the communication terminals attempts to change the data rate.