JPS58213576A - Receiving device for television text broadcasting - Google Patents

Abstract

PURPOSE:To indicate to viewers that an incorrectable error occurres in the character code, by displaying a prefixed sign which indicates on a display that an error in the character code is found, in response to the output of a detecting means. CONSTITUTION:When receiving character broadcasting, the character signals are temporarily stored in a buffer memory 5 and signals of a character broadcasting program selected by a program selecting device 10 out of the stored character signals are read out from the buffer memory 5 by a CPU6 and data processed. That is to say, the CPU6 performs error correction and detection against character codes and reads out character codes having no error and character font data corresponding to the error corrected character codes from a character and square type sign font ROM15, and then, transfers them to a pattern memory 7 through a bus line 9. When the CPU6 detects an incorrectable error, reads out the font data of the square sign from the ROM15, and transfers it to the pattern memory 7 through the bus line 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiving device for television teletext broadcasting that is broadcast superimposed on the vertical blanking period of a video signal of a television broadcast radio wave, and in particular to a television teletext broadcasting system using an encoding method. The present invention relates to a receiving device.

Currently, a pattern method and a coding method are being considered as methods for transmitting data such as characters and graphics in television teletext broadcasting. The pattern method refers to a method in which characters and graphic patterns are scanned in the horizontal direction, and the image is separated into dots and transmitted. On the other hand, the encoding method refers to a method in which characters are encoded (this is called a character code), and a figure is a method in which mosaic elements are encoded and transmitted. In our country, there are many types of characters, mainly kanji, so research into pattern systems is progressing, and the To-Baku standard has been created, and it is almost ready for practical use.

However, in the future, it is planned that a complete switch will be made to an encoding system with a much faster transmission rate.

In the encoding method, since the character corresponding to the received character code is displayed based on the received character code, it is necessary to always detect errors in the character code. This is because if the character code is incorrect, a completely different character will be displayed. In particular, in our country, we use ideographic characters, kanji, so the impact of displaying incorrect characters is much greater than in Europe and America, which use phonetic characters, so detecting errors in character codes is essential.

In teletext broadcasting, which is being experimentally broadcasted in Europe and the United States, an 8-bit code with 1 bit of parity added is used for character transmission. In Japan, a unified standard has not yet been created and it has not been determined what kind of code will be used, but information bit 11 and protection bit 5 1
It is highly likely that a 1-5 Hamming code will be used. In any case, there is no doubt that a Hamming code that can correct and detect errors is used.

In the 11-5 Hamming code, 1-bit error correction and 2-bit error detection are possible. Since the 1-pitsu [- error can be corrected, the correct character will be displayed and there will be no problem. However, a 2-bit error can only be detected and cannot be corrected. In the above-mentioned European and American experimental broadcasts, in such a case, a blank display is used in which nothing is displayed in that part. And in the case of our country as well, we believe that such a situation is unavoidable.

However, when a blank display is displayed, it may not be possible to determine whether the blank is actually blank or not, and depending on the text displayed, it may give a big misunderstanding to the viewer. For example, commonly used idioms such as non... and anti...
If you can handle non and anti, it will have completely opposite meanings.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a television teletext receiving apparatus that can clearly display to viewers that there is an uncorrectable error in character codes.

In summary, when an uncorrectable error is detected by decoding a Hamming code, a symbol such as a mouth is written instead of a blank display.

The above objects and other objects and effects of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 1 is a schematic block diagram showing a television teletext receiving apparatus according to an embodiment of the present invention.

In the configuration, the parts that make up the Hiroshi television receiver include a tuner 2 to which an antenna 1 is connected, which is connected to a cathode ray tube 13 via an intermediate frequency amplification circuit 3, a video amplification circuit 16, and an output interface circuit 12. configured. In the character signal receiving section, an intermediate frequency amplifying circuit 3 is connected to a buffer memory 5 via a sampling circuit 4, and the buffer memory 5 is connected to a central processing unit such as a microprocessor (CP).
U) 6, pattern memory 7, color memory 8, program selection device 10, ROM 14, and characters/I-■1 symbol font R
OM15 are respectively connected through the pass line 9,
A succession control circuit 11 is connected to the pattern memory 7 and color memory 8, and the pattern memory 7 and color memory 8 are connected to an output interface circuit 12. In addition to character font data corresponding to character codes, the CPU 6 stores uncorrectable errors in character codes (2-bit errors in the case of the 11-5 Hamming code mentioned above) in the character/1yo symbol font t-ROM 15. CRT 1 when detected
The font data of the +-+ symbol displayed in 3 is stored.

In operation, the television signal received by the antenna 11 and superimposed with a text signal (referring to all signals for text broadcasting) is channel-selected and converted into a video intermediate frequency by the tuner 2, and is further subjected to video intermediate frequency amplification. The circuit 3 amplifies and detects the signal and converts it into a video signal. When receiving normal television broadcasting, this video signal is amplified by the video amplification circuit 16 and sent to the output interface circuit 1.
2 to drive a cathode ray tube 13. On the other hand, in the case of receiving a teletext broadcast, the character signal superimposed on the video signal is separated from the video signal by the extraction circuit 4, and this character signal is further temporarily stored in the buffer memory 5. The buffer memory 5 is configured so that the bit rate of the character signal sent out is determined by the CPU.
Since the data processing speed is much faster than the data processing speed of the CPU 6, it is used to temporarily store character signals and read them out as necessary by the CPU 6 until the next character signal arrives. Among the stored character signals, the signal of the teletext program selected by the program selection device 10 is read out from the buffer memory 5 by the CPU 6 and subjected to data processing.

In other words, the CPU 6 performs error correction and detection on character codes, and converts character font data corresponding to error-free character codes and error-corrected character codes into characters/1.
It is read from the C symbol font ROM 15 and transferred to the pattern memory 7 through the pass line 9. If an uncorrectable error is detected, the II symbol data is read from the character/-1 symbol font ROM 15 and transferred to the pattern memory 7 through the pass line 9.

FIG. 2 is a flowchart showing the operation of the CPU 6 mentioned above. That is, the CPU 6 determines in step S1 whether or not there is an uncorrectable error in the character code. When an uncorrectable error is detected, the process moves to step S3, where the character/[l symbol font font data is read from the character/[l symbol font ROM 15 and transferred to the pattern memory 9 via the pass line 9. If there is no uncorrectable error, proceed to step S2, and write the character/1-1 symbol font ROM.
Character font data corresponding to the character code is read from 15 and transferred to pattern memory 9 through pass line 9.

Further, the CPU 6 transfers the coloring data to the color memory 8 through the pass line 9 for color codes, which are data for coloring characters and the like.

When one screen worth of data is stored in the pattern memory 7 and color memory 8, the readout control circuit 11 sequentially reads out the stored data and displays a character screen on the cathode ray tube 13 via the output interface circuit 12. It will be done.

If an uncorrectable error is detected in the character code, a ``1-'' is displayed on the character screen on the cathode ray tube 13 at the location corresponding to the error, and the viewer can see that some character will be displayed there. It is easy to understand that this is the case. Since teletext is transmitted repeatedly, the same program with a new text signal can be displayed after a short period of time, and code errors tend to occur randomly, so the probability of the same character being mistaken is low, and viewers can understand the correct displayed content. can do.

As described above, according to the present invention, it is possible to eliminate the opportunity to mislead viewers by notifying them that a transmission error has occurred. In addition, the symbol indicating that an uncorrectable error has been detected can be included in the ROM for character font data, which is absolutely necessary for the encoding method, so there is no particular cost increase; This has the effect that accurate display of teletext can be realized using the standardization method.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing a television teletext receiving apparatus which is an embodiment of the present invention, and FIG. 2 is a block diagram showing a system for detecting errors in character codes and transmitting font data of characters or error display symbols. 3 is a flowchart showing the operation procedure of the CPU 6. FIG. In the figure, 1 is an antenna, 2 is a tuner, 3 is an intermediate frequency amplification circuit, 4 is a character signal handling circuit, 5 is a buffer memory, 6 is a central processing unit, 7 is a pattern memory, 8 is a color memory, and 9 is a Pass line, 10 is a program selection device,
11 is a read control circuit, 12 is an output interface circuit,
13 is a cathode ray tube, 14 is a ROM, and 15 is a character/[1 symbol 7 on (~ROM, respectively)].

Claims (1)

[Scope of Claim] A device that receives character signals for television teletext broadcasting that are broadcast superimposed on the vertical blanking period of video signals of television broadcast radio waves, and displays them on a display such as a cathode ray tube. The character signal includes a character code in which a character to be transmitted is encoded, the character code is configured with a code system capable of error detection, and means for detecting errors in the character code; means for displaying, in response to the output of the means, a predetermined symbol indicating that an error in the character code has been detected at a location on the display where the character of the character code in which the error has been detected should be displayed; A television teletext receiving device comprising: