JPH01176176A - Teletext receiver - Google Patents

Abstract

PURPOSE:To attain more normal teletext reception by dividing a sent character signal by plural slice levels and extracting a character signal with least error number among them. CONSTITUTION:A character signal is sliced by the combination of a delay section 3 and an analog switch 1. A comparator 7 receives a sliced character signal and a reference voltage from a reference voltage generating section and the timing applying a reference voltage and a timing switching the analog switch 1 are according to the selection signal from a timing generating section 2. The selection signal is generated by counting the clock of a horizontal synchronizing signal, the character signal having error information extracted in this way is corrected sequentially by an error correction section 8 and stored for each slice level in a prescribed area of a buffer RAM 9. A discrimination section 10 fetches sequentially the data stored in the buffer RAM 9, compares and selects error information number and sends a character signal data with least information number. Thus, more normal teletext reception is applied.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention extracts character signals with less error information from character signals with error information in teletext broadcasting,
The present invention relates to a teletext receiver that performs more normal reception.

[Prior Art] A teletext receiver separates a character signal multiplexed into a vertical blanking period of a 1V video signal, that is, a number H of periods from the end of a TV video signal to the start of the next TV video signal. The code is then identified, decoded, stored in memory, and then displayed on a CRT screen.

For code identification, the character signal obtained by applying it to a data slicer is extracted using a code extraction clock, but if there is only one data slicer, it can only be sliced at a specific slice level, so code identification may not be performed normally depending on the slice level. (This can lead to serious errors.)

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a teletext receiver having a character extraction circuit capable of correctly extracting character signals.

[Means for solving problems]

The present invention has been made in order to solve the above-mentioned problems. a plurality of delays and an analog switch l for slicing character signals from the
a reference voltage generation section that generates a reference voltage to be applied to the comparator; a timing generation section that instructs the actuation timing of the analog switch 1 and the analog switch 2 in the reference voltage generation section; and a character signal that passes through the analog switch 1. and the reference voltage, an error correction section that corrects error information of the character signal sent through the comparator, organizes it and sends it out every 8F1 minute, and the character signal from the error correction section. Buffer RA with multiple areas to hold data
M, and a determination section that sequentially extracts, compares and selects the character signal data held in the buffer RAM, and sends out the character signal data with the least amount of error information.

[Effect]

According to the present invention, character signals with less error information can be selected and transmitted from character signals sent from a TV video signal input terminal in the manner described below.

First, a character signal is sliced by a combination of a delay section and an analog switch 1. The plurality of delays are configured to pass character signals in sequence every 8H, and correspondingly, the analog switch 1 is also switched to take out character signals for 8H at every slice level. The sliced character signal and the reference voltage from the reference voltage generator are applied to the comparator. The reference voltage is determined corresponding to the slice level, and the timing of applying the reference voltage and the timing of switching the analog switch 1 are in accordance with the selection signal from the timing generator.

The selection signal is generated by counting the clocks of the horizontal synchronization signal. The character signals with error information extracted in this way are sequentially corrected by the error correction unit, the error information is organized at the head of the character signal data, and the data is stored in a predetermined area of the buffer RAM having multiple areas for each slice level. It is held for a maximum of 8H minutes.

The determination unit sequentially reads the data held in the buffer RAM, compares and selects the number of error information, and transmits the character signal data with the least number of error information, so that more normal teletext reception can be performed. can.

〔Example] Examples of the present invention will be described below.

FIG. 1 shows the circuit configuration of the present invention, which includes a TV video signal input terminal (1), a timing generating section (2) for sending out a selection signal, and a delay section (2) consisting of a plurality of delays. 3) and a slicing section (5) consisting of one analog switch 1 (4), a reference voltage generating section (6) that sends out a reference voltage, and a character signal sliced and taken in by the slicing section and the reference voltage. A comparator (7
), an error correction unit (8) that corrects errors in the 1 and 0 character signals that have passed through the comparator, and a buffer RAM (9) that organizes and stores the error-corrected character signals in units of 88. and coughed.

It consists of a judgment section (10) that extracts character signals from the RAM M, compares and selects them, and sends out the best data, and the timing generation section (2) adds and counts the clock of the horizontal synchronization signal and performs frequency division. It consists of a frequency divider (11) and a counter (12) that sends out a selection signal every time the divided output signal of the frequency divider is counted, and when the count number of this counter exceeds the number of slice circuits. When the vertical synchronization signal causes the contents of the frequency divider and counter to all become zero,
It is set to repeat the process of starting counting from the beginning again.

The slice section (5) connects one end of a delay circuit in which one signal line without a delay and a plurality of delays that operate sequentially with an 8H delay to a TV video signal input terminal (
1), and the other end is connected to a predetermined terminal of analog switch 1 (4).

The reference voltage generation section (6) is set to be able to sequentially send out a plurality of types of generated reference voltages in synchronization with a selection signal from the timing generation section (2) with a voltage dividing circuit (13) that generates a reference voltage. The output side of the analog switch 2 (14) is connected to one terminal of the comparator (7). Note that the reference voltage is set at a value corresponding to the slice level of the character signal.

By the way, the comparator (7) is connected to the TV video signal input terminal (1
) and a predetermined terminal of analog switch 1 (4) are directly connected without a delay, that is, a character signal with error information captured at slice level l and a reference voltage generator (
6) is compared with the reference voltage corresponding to slice level 1, a determination of 1.0 is made, and the character signal with error information is sent to the error correction unit BEST (8), where the error is corrected and the signal is processed for up to 8H. The data is organized and written to a predetermined area of a buffer RAM having multiple areas corresponding to the number of slice levels. After all the data has been written, the determining section compares the number of error information contained in each packet and sends out the character signal with the least number of error information.

Next, the determination section will be explained.

FIG. 2 shows an example of a flowchart of control by the determination unit (lO). Assuming that the slice section (5) is composed of, for example, three slice circuits, in step l, variable a=1 and variable b=2 hold, and in step 2, the first slice circuit of buffer RAM (9) is established. and error information is read from the teletext data held in the second area, and in step 3, the number of error information of both is compared and the number of error information on the side of variable a is smaller than the number of error information on the side of variable If so, the sending count number is set to 1 in step 5, and the process returns to step 2 via the number comparator in step 6. If the number of error information on the variable side is small, it is sent to step 4, variable a is replaced with b, and sent to step 5, where variable s is incremented by 1, and step 6
The process returns to step 2 via .

Next, in step 2, error information is newly read from the teletext data held in the third area, and the error information of the first or second error correction unit that has been compared and remains is detected. The number of information is compared in step 3, and as above, the one with the smaller number of error information is sent to step 5. In step 5, the current addition value 1 is accumulated on the previous addition value 1, and in step 6, the number of additions is calculated. are compared, and if the condition n≦2 is satisfied, the character signal data remaining after completing each of the above-mentioned processes and having the least number of error information is sent out in step 7. When the sending of the character signal data is completed, it is reset in step 8 and returns to the initial state again.

〔effect〕

As described above, the present invention divides an incoming character signal into a plurality of slice levels and captures it, and extracts the character signal with the least amount of error information from among these, thereby enabling more normal teletext reception. Become.

Note that the present invention is economically advantageous because only one expensive error correction unit (BEST) is required.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment according to the present invention, and FIG. 2 is a flowchart of the determination section. In the figure, m-TV video signal input terminal, (2) - timing generation section, (3) - delay section (8) 1 delay. 16H delay, -8X (n-1)H delay),
(4) - analog switch 1, (5) - slice section,
(6) - Reference voltage generation section, (7) - Comparator, (8) - Error correction section, (9) - Hara 7 ARAM, (10) -
Judgment unit, (11)-frequency divider, (12L-power counter, (1
3)--voltage divider circuit, (14)--analog switch 2. Patent applicant: Fujitsu General Ltd. Figure 1 Figure 2

Claims (1)

[Claims] A character signal extraction circuit configuration for extracting a character signal superimposed on a vertical blanking period of a TV video signal includes a plurality of delays for slicing a character signal from a TV video signal input terminal, one analog switch 1, and a comparator. a reference voltage generation section that generates a reference voltage to be applied to the reference voltage, a timing generation section that instructs the actuation timing of the analog switch 1 and the analog switch 2 in the reference voltage generation section, and a character signal passed through the analog switch 1 and the reference voltage. a comparator that compares the character signals, an error correction section that corrects error information of the character signal that has passed through the comparator, organizes and sends it out every 8H minutes, and a plurality of controllers that hold the character signal data from the error correction section. A buffer RAM having an area, and the buffer R
1. A teletext receiver comprising: a determining section that sequentially extracts character signal data held in AM, compares and selects the character signal data, and transmits the character signal data with the least amount of error information.