JPH01181278A - Facsimile communication system - Google Patents

Abstract

PURPOSE:To count accurately a burst error over plural lines by inserting an identification code for prescribed plural lines of picture information to be sent and applying error line count by the burst error at the receiver side. CONSTITUTION:In the case of MH coding, white 0 and black 0 runs for each 5-line, for example are inserted. An LC 5 being a normal reception line counter for each 5-line is cleared and an OKLIN being a total normal reception line counter during one-page reception and an NGLIN being an error line counter during one page are cleared. Then white 0 black 0 line length is received next to an EOL, decoding is continued not being each 5th line and till the EOL comes, and whether or not the reception of the decoded line is normal is discriminated depending whether the picture element number is 1728 or not after the arrival of EOL. Thus, even with a long burst error below 5 lines, the error lines are counted accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field] The present invention relates to a facsimile communication system, and particularly to a facsimile communication system that can detect error lines.

Conventionally, in facsimile communication, when demodulating (hereinafter referred to as decoding) during reception, in the case of size A4, 172
Lines that can be decoded into 8-bit information are considered normal, lines that are not are counted as error lines, and when there are many error lines in one page, an RTN signal is sent to the sending side. However, when burst errors occur on multiple lines, it is not possible to accurately count the error lines.

For example, if noise occurs from the 7th line to the 9th line, the beginning of the 7th line and the last part of the 9th line will be decoded and lines 7 to 9 will be mistaken for an error line. There were many cases.

〔the purpose〕

It is an object of the present invention to provide a facsimile communication system that eliminates the drawbacks of the above-mentioned conventional example and can accurately count the number of error lines.

〔Example〕

FIG. 1 is a control circuit diagram of the facsimile machine of this embodiment.

In the figure, 10 is a league for reading originals, 12 is a printer 1 for recording received images or copied images, 14 is a CPU for controlling the entire facsimile machine, 16 is a ROM that stores a control program for the CPU 14, and 18 is for controlling the CPU 14. A RAM that stores necessary data, such as the count value of a counter that counts the number of error lines, the state of flags, etc., and image data; 20 is a kneader/decoder that encodes and decodes image signals; 22 is an image signal and control signal; A modem 24 that performs modulation and demodulation connects the communication line 28 to the telephone 26,
This is an NCU that switches whether to connect to the modem 22 or not.

FIG. 2 shows a diagram of the correlation between raw image data and MH code data in which white 0 and black O runs are inserted every 5 lines of this embodiment when converted into MH code. Now, as an example, line 7 and line 8
Consider the case where a burst error occurs between lines.

In this case, since the pixels after demodulation≦1728, the 7th and 8th lines are mistaken for the 1st line. In other words, the error line is determined to be 1 line instead of 2 lines. FIG. 3 shows a flowchart of error line counting in this embodiment to improve this problem. This corresponds to a part of FAX reception processing.

In FIG. 3, LC5, which is a normal reception line counter for every 5 lines, is cleared at Sl, and 0KLIN, which is a total normal reception line counter during one page reception, and NGLIN, which is an error line counter during one page, are also cleared. Every 5 lines in S2? I judge that.

Did this receive a run length of white 0 black 0 after EOL? This is a judgment based on the following (see Figure 2). If it is not every 5th line, the process goes to S3 and decoding is continued until the EOL is reached. When the EOL is reached, it is determined whether or not the reception of the decoded line is normal based on whether the number of pixels=1728.

If it is normal, the process passes through S6, where the normal reception line counter for every 5 lines and one page is incremented by 1, and the process returns to S2. 82 every 5 lines) and have all 5 lines been received normally? is judged at 87, and if it is normal, the process advances to S9<32. 87 eO3 if error line is included
8<Proceed to S2, and in S8, the error line among the five lines is calculated and added to the total error line counter for one page. LC5, which is a normal line counter for every 5 lines, is also cleared and the process goes to S2. This makes it possible to accurately count error lines even when there is a long burst error of 5 lines or less.

In this embodiment, the white 01 black θ run length is inserted at the beginning of one line of information, but it can also be added at the end of one line of information.

In this embodiment, it is weak against burst errors of 5 lines or more, but every 5 lines is white 0 black 0, and every 10 lines is white 0 black 0.
If white is 0 and black is 0, burst errors of 10 lines or less can be accurately counted. However, adding line count information increases the amount of overall image information to be transmitted, which has the disadvantage of increasing transmission time.

Further, the identification code may be expressed by a code other than white 01 black 0 that is not included in the image signal code, or by a series of EOLs.

〔effect〕

As explained above, an identification code is inserted into each predetermined number of lines of image information to be transmitted, and this is used as an identification signal.
By counting error lines based on burst errors, the receiving side has the effect of being able to accurately count burst errors that span multiple lines.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the facsimile machine of this embodiment. Figure 2 is a correspondence diagram of image information and codes, FIG. 3 is a diagram showing a control flowchart.

Claims (1)

[Claims] A facsimile communication system characterized in that the image information is transmitted by inserting an identification code signal every predetermined number of lines of image information, and the receiving side identifies whether or not an error line exists based on the code signal.