JPH0591348A - Facsimile communication terminal equipment - Google Patents

Abstract

PURPOSE:To prevent the degradation of the transmission picture quality and the use efficiency of a communication line which is accompanied with the state change or the characteristic change of the communication line during the facsim ile communication. CONSTITUTION:A transmission terminal 10 transmits a test pattern to a reception terminal 20 through a communication line 30 before transmission of a picture signal, and the reception terminal 20 calculates a code error rate (r) and obtains a parameter (k) for the code error rate (r) from a preliminarily determined r-k table 24 and not only uses it for decoding control on the reception side but also transmits it to the transmission terminal 10, and the transmission terminal 10 selects and applies systems in accordance with the received parameter (k) so that the picture quality is improved regardless of lees redundancy suppression in the case of the high error rate but redundancy suppression is increased to improve the use efficiency of the communication line in the case of the low error rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile communication terminal device having a modulator / demodulator (hereinafter referred to as a modem) and performing facsimile communication with a connection destination device of a communication line for establishing a connection via an exchange.

[0002]

2. Description of the Related Art Conventionally, in this type of facsimile communication terminal device, after confirming the functions of both transmitting and receiving and setting is completed,
The transmitting terminal transmits a training signal and the following training check (TCF) signal, the receiving terminal performs a training check for adjusting the high-speed modem, and when the adjustment of the high-speed modem is completed, a reception preparation confirmation (CFR) signal Is transmitted to the transmitting terminal.

After receiving the CFR signal, the sending terminal sends a training signal for each page of the manuscript, then sends a facsimile (FAX) message, and on the last page, sends a FAX message followed by an end of procedure (EOP) signal. To do.

This will be described with reference to FIG. FIG. 4 is a signal sequence diagram showing an example of a conventional main procedure.

When the calling terminal calls the called terminal and the called terminal responds with a called terminal identification (CED) signal, the called side digitally identifies (DIS) all the functions of the called terminal.
Notify the calling side with a signal to confirm the function.

When the calling terminal is the sending terminal, in response to receiving the DIS signal, the sending terminal sends a digital command (DCS) signal selected from the received functions from the sending terminal to the called terminal on the called side. And the receiving terminal are determined.

After transmitting the DCS signal, the transmitting terminal transmits a training signal after a predetermined time, and then executes a training check with a TCF signal for adjusting a high speed modem for transmitting a FAX message.

Upon completion of the training check, the receiving terminal sends a reception preparation confirmation (CFR) signal.

When the transmitting terminal receives the CFR signal, it transmits the training signal again, and then the encoded FA is transmitted.
Read the X message from the original and send it.

The encoding method for transmission / reception is determined from the resolution in the image line of the main scanning when confirming the functions of both terminals.

CCITT Recommendation T. In FIG. 4, when the transmission of the message for one page is completed, either the multi-page (MPS) signal in which the original is still transmitted or the procedure end (EOP) signal for notifying the procedure end is transmitted from the transmission terminal.

The receiving terminal returns a message confirmation (MCF) signal as a reception confirmation signal of the MPS signal / EOP signal. The transmitting terminal transmits the original of the next page by FAX with the MCF signal in response to the MPS signal, and transmits a disconnection command (DCN) signal with the EOP signal to proceed to the next phase.

In the facsimile communication, an original signal obtained by scanning an original with a one-dimensional image sensor and photoelectrically converting the original signal on a transmitting side is converted into a black and white signal by a binarizing circuit.
The encoding unit performs redundancy suppression encoding processing by the MH (corrected Huffman) method or the MR (corrected READ) method using the continuity of the white signal or the black signal and the correlation between the lines.
(Electronic Information and Communication Handbook, IEICE 198
8, issued by Ohmsha, see page 2615) When the MH method that uses continuity of a white signal or a black signal in one scanning image line is applied to the processing of the image signal, and then the transmission characteristic from the transmitting terminal to the receiving terminal is good. , The MR system that further suppresses the redundancy is applied by utilizing the correlation with this scanning line to increase the transmission efficiency of the image signal.

In the conventional facsimile communication, when the function setting for determining transmission / reception is 8 dots × 3.85 lines per 1 mm of the scanning line as the resolution, the MH system and the MR system are alternated, that is, the scanning line. One MH for every two
The method is applied and the parameter is set to k = 2. Further, in the case of high resolution of 8 dots × 7 lines per 1 mm of scanning line, the MH method is used with one parameter k = 4 for every 4 scanning lines.
4 is set.

[0015]

The above-mentioned conventional facsimile communication terminal apparatus confirms the function between the transmitting and receiving terminals before transmitting an image by facsimile, and determines the encoding method for each image line according to the terminal performance (resolution). Since it is set by the parameter, the transmission quality of the communication line deteriorates and the transmission image quality deteriorates, and even though the communication line is in good condition and the redundancy is suppressed, the communication speed can be increased. However, there is a problem that it hinders an increase in the utilization efficiency of communication lines.

An object of the present invention is, in a training check of a facsimile communication procedure, a receiving side calculates an error rate of a code based on a test pattern, indexes a preset k parameter corresponding to this error rate and notifies the originating side. Accordingly, it is an object to provide a facsimile communication terminal device that solves the above problems.

[0017]

A basic structure of a facsimile communication terminal device according to the present invention is a facsimile communication terminal device which comprises a modulator / demodulator and performs facsimile communication with a connection destination device of a communication line established through an exchange, A means for transmitting and transmitting a predetermined test pattern on the image transmitting side, and then, when receiving a predetermined k parameter to be returned, switching the encoding method designated by this k parameter for each image line to be transmitted and applying it. On the other hand, the image receiving side calculates the code error rate from the test pattern when the test pattern is received, sets a predetermined k parameter from the code error rate, and transmits it to the transmitting side. There is a means to switch the encoding method specified by the parameter for each image line received and apply it. .

One specific configuration of the facsimile communication terminal device described in the above basic configuration is MH in the encoding system.
It has the function of the G3 model based on the CCITT recommendation that adopts the (corrected Huffman) method and the MR (corrected READ) method, and the k parameter determines the application cycle of the MH method by an encoding method for each image line. The image line has a means for applying the MR method.

Further, one of the means for adding to the configuration of the facsimile communication terminal device is the test pattern and k.
It is a means for transmitting and setting parameters for each original document and before transmitting the image signal of this original document.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of the present invention.

As shown in the figure, a transmitting terminal 10 for transmitting an image signal includes a test pattern generator 11 and a modulator / demodulator 12.
(Modem), parameter receiving unit 13, switching unit 14, one-dimensional coder 15, two-dimensional coder 16, multiplexing unit 17, and coding cycle control unit 18, and a modulator / demodulator 21 (modem), error Bit counter 22, code error rate calculator 2
3, rk table 24, selector 25, one-dimensional decoder,
A two-dimensional decoder 27, a demultiplexing unit 28, and a decoding cycle control unit 29 are connected by a communication line 30 to a receiving terminal 20.

The test pattern generator 11 is the modem 1
2. The test pattern of the total number of transmission bits N is transmitted to the error bit counter 22 via the communication line 30 and the modulator / demodulator 21.

The error bit counter 22 measures the number of error codes n of the received test pattern, and the code error rate calculator 2
3 from the total number N stored in advance, the code error rate r (= n /
N) is calculated.

The rk table 24 is a table for obtaining the parameter k from the code error rate r, and an example is shown in FIG.

FIG. 2 is a comparative explanatory view showing an example of applying the encoding method to the r-k table and the k parameter.

According to FIG. 2, in the rk table, the code error rate r is 10 "-5 power" or less, "-6 power" or less, "-".
K = 2 for each of "7th power" and "-8th power"
4, 6, 8 and the rest are set to k = 1.

The value of the parameter k indicates that the MH method of redundancy suppression coding is applied only once to k image lines. For example, when k = 6, one scan image line is encoded by the MH system, then the following five are encoded by the MR system, and this is repeated. That is, after one scan image line is encoded by the MH system, the next (k-
1) The scanning image lines are coded by the MR system to increase the code redundancy suppression. Therefore, the larger the k parameter value, the smaller the number of transmission codes, the higher the communication speed, and the more efficient use of the communication line.

Now, when the rk table 24 receives the error rate r of "-6 to the power of 10" from the code error rate calculation unit 23, the parameter k = 4 is the modulator / demodulator 21, the communication line 30, and the modulator / demodulator 12. Is transmitted to the parameter receiving unit 13 via the parameter k = 4.
Memorize

The switch 14 of the transmitting terminal 10 first connects the image to be transmitted to the one-dimensional encoder 15.

The one-dimensional encoder 15 scans one input image line and encodes it by the MH method, and the multiplexer 17
The signals are separated by the modulator / demodulator 12, the communication line 30, the modulator / demodulator 21, and the demultiplexing unit 28 and transmitted to the one-dimensional decoder 26.

The selector 25 of the receiving terminal 20 first receives the output of the one-dimensional decoder 26 as an image signal.

Since the two-dimensional encoder 16 and the coding cycle controller 18 of the transmitting terminal 10 receive the parameter k = 4 stored in the parameter receiver 13, the first image line is coded by the MH method and then continued. The three image lines are MR-encoded by the two-dimensional encoder 16, and the encoding cycle control unit 18 repeats the operation of the switching unit 14 and the multiplexing unit 17 in the cycle of every four scanning lines of the parameter k. Control.

In the receiving terminal 20 as well, the two-dimensional decoder 27 and the decoding cycle control unit 29 fetch the parameter k = 4 from the rk table 24 and input it, and the decoding cycle control unit 29 controls the demultiplexing unit 28 to make it one. One scanning line segment to one-dimensional decoder 26
In addition to separating the following three into the two-dimensional decoder 27, the two-dimensional decoder 27 drives the selector 25 so that one scan line segment of the image signal to be received is supplied from the one-dimensional decoder 26 to the subsequent three-dimensional decoder. One scanning line segment is repeatedly received from the two-dimensional decoder 27.

Next, with reference to FIG. 3 together with FIG. 1, a signal transmitting / receiving procedure of the transmitting / receiving terminal will be described.

FIG. 3 is a signal sequence diagram showing an example of the main procedure according to FIG.

First, when the calling terminal 10 calls the called terminal 20 and the called terminal 20 responds with a called terminal identification (CED) signal, the called side has the function of the called terminal 20 with which the called terminal 20 communicates. In order to confirm with the calling terminal 10, the non-standard function identification (NSF) signal including a new function to be added is sent to the calling terminal 10.

When the calling terminal becomes the sending terminal 10, NS
Upon reception of the F signal, the transmitting terminal 10 transmits a non-standard function setting (NSS) signal to the receiving terminal 20 in order to set the function selected from the received signals, and the transmitting terminal 10 and the receiving terminal 20 are determined. ..

The transmitting terminal 10 transmits the training signal after a predetermined time elapses from the transmission of the NSS signal, but a predetermined test pattern is sent from the test pattern generator 11 to the receiving terminal 20 in the subsequent training check (TCF) signal. Send it for a training check. On the other hand, the receiving terminal 20 confirms the reception preparation (CF
R), the error bit counter 22 measures the number of error codes from the received test pattern, and the code error rate calculator 23 outputs the code error rate r.
Index and set the parameter k from the -k table 24,
Send a k-parameter set (KSS) signal to the originating side.

The parameter receiving unit 13 of the transmitting terminal 10 is K
The SS signal is received and notified to the two-dimensional encoder 16 and the encoding cycle control unit 18, the k parameter is set, and the training signal is transmitted, and then the image signal of the first original is changed to the set k parameter. MH / MR according to numerical values
The encoding method is applied and the message is transmitted as a FAX message.

The transmitting terminal 10 that has transmitted the FAX message
When there is a document to be transmitted next time, transmits an MPS signal to notify the receiving terminal 20.

Upon receiving the MPS signal, the receiving terminal 20 prepares to receive the original of the second page and returns an MCF signal for confirmation of reception to the transmitting terminal 10.

When the transmitting terminal 10 receives the MCF signal, it starts from transmitting the test pattern as in the case of the first original. And if the fax message is the last page,
The End of Procedure 3 (EOP) signal is sent instead of the MPS signal.

The procedure after this is the same as the conventional one.

In this embodiment, the application of the MH / MR coding system has been described, but another system may be used. Further, although it has been illustrated and described that the transmission of the test pattern and the setting of the k parameter are executed for each page, in the communication in the same area where the line state is good, it is not necessary to reset the setting for all pages.

As described above, according to the present invention, the code error rate is calculated by transmitting and receiving the test pattern when the transmitting and receiving terminals are connected through the communication line, and the application of the redundancy suppression coding method is set based on this value. Since the k parameter to be set is determined, the image quality and the line usage rate can be optimized. Furthermore, since the detour or channel automatic switching function by effective use of the line changes the state or characteristics of the communication line, there is an opportunity for setting, such as setting the k parameter determination time by the test pattern for each page. Means of increasing are effective.

[0046]

As described above, the present invention has means for indexing the k parameter from the code error rate at the receiving terminal,
By transmitting the test pattern from the transmission terminal, calculating the code error rate at the reception terminal, setting the k parameter and notifying the transmission terminal, redundancy suppression encoding processing according to the state of the communication line can be performed. When the code error rate is high on a bad line, the image quality is prevented from being deteriorated by the minimum redundancy suppression coding process, and when the code error rate is low on the good line, the communication speed is maximized by the redundancy suppression coding process. There is an effect that the communication efficiency can be improved by increasing the use of the communication line.

Further, by finely setting the setting time of the k parameter, there is an effect that it is possible to cope with a change in the state or characteristics of the communication line being connected.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of the present invention.

FIG. 2 is a comparative explanatory diagram showing an example of applying an encoding method corresponding to an rk table and a k parameter value of the present invention.

FIG. 3 is a signal sequence diagram showing an example of a main procedure according to FIG.

FIG. 4 is a signal sequence diagram showing an example of a conventional main procedure.

[Explanation of symbols]

 10 transmitter terminal 11 test pattern generator 12, 21 modulator / demodulator 13 parameter receiver 14 switcher 15 one-dimensional encoder 16 two-dimensional encoder 18 coding period controller 20 receiver terminal 22 error bit counter 23 code error rate Calculation unit 24 rk table 25 Selector 26 One-dimensional decoder 27 Two-dimensional decoder 29 Decoding cycle control unit 30 Communication line

Claims (3)

[Claims] 1. In a facsimile communication terminal device including a modulator / demodulator and performing facsimile communication with a connection destination device of a communication line established through an exchange, an image transmitting side first transmits a predetermined test pattern and then a reply. When a predetermined k parameter is received, the coding method designated by the k parameter is switched and set for each image line to be transmitted and applied, while the image receiving side receives the test pattern. The code error rate is calculated from this test pattern, a predetermined k parameter is set from this code error rate and transmitted to the transmission side, and the coding method indicated by this k parameter is switched for each image line to be received. A facsimile communication terminal device comprising means for setting and applying. 2. MH (Modified Huffman) as the encoding method
Method and CCI that adopts MR (Modified READ) method
It has a function of G3 model based on TT recommendation, and the k parameter has a means for applying the MR method to the image lines during which the application cycle of the MH method is determined by an encoding method for each image line. The facsimile communication terminal device according to claim 1, wherein: 3. A means for transmitting and setting the test pattern and the k parameter for each original document and before transmitting the image signal of the original document.
Alternatively, the facsimile communication terminal device according to claim 2.