JPH0767169B2 - Signal processor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a signal processing device capable of preventing waveform deterioration of a character multiplex signal superimposed on a television signal.

(Prior Art) In recent years, broadcasting is performed by superimposing a character multiplex signal obtained by digitizing character (still image) information such as news, weather forecast, or additional information of a normal broadcast program in a vertical blanking period of a television signal. Teletext is being implemented.

This character multiplex signal is for displaying one still screen with about 50,000 pixels of vertical 204 × horizontal 248, for example, and the pattern data and character code data forming this still screen are shown in FIG. As described above, a predetermined horizontal scanning line in a vertical blanking period for each predetermined unit (packet) (for example, the 14th to 16th and 21st horizontal scanning lines in the case of an odd field, the 277th to 279th in the case of an even field). And the 284th horizontal scanning line)
Overlaid with a color burst.

In addition, each data packet has 3 bytes (24
(Bit) synchronization part and 34 bytes (272 bits) data part. The synchronization part is a clock run-in (CR) and a byte unit used by the receiving side to synchronize bit units. A framing code (FC) used for synchronization, and the data portion is composed of pattern data, character code data, and an error correction signal (for example, Hamming code).

Further, the signal level of the data "1" in the character multiplex signal is about 70% of the white level of the video signal in the television signal, and the signal level of the data "0" is set to be substantially equal to the pedestal level of the video signal. ing.

On the other hand, on the side receiving such a character multiplex signal, the pattern data of the program designated by the keyboard or the like is decoded, or the character code data is decoded by converting it into pattern data by a character generator or the like, and the decoded data is sent. After being written in the display memory once, it is displayed on the receiving tube as a teletext screen or mixed with an ordinary TV screen.

(Problems to be solved by the invention) By the way, the band width has been remarkably increased due to the recent improvement in image quality of VTRs (video tape recorders).
In a high-quality VTR that realizes more than 0 TV lines, the character multiplex signal as described above can be recorded and reproduced as it is.

However, when dubbing is performed by using such a high-quality VTR to reproduce a television signal on which a character multiplex signal is superimposed and record it in another VTR, waveform deterioration of the character multiplex signal due to this dubbing occurs.

Here, the waveform (especially the peak value) of the character multiplex signal as described above is set to a predetermined signal level as described above.

For this reason, there is a problem in that an error in reproducing and decoding the character multiplex signal whose waveform is deteriorated by the dubbing as described above increases, and correct character broadcasting cannot be reproduced.

Further, a television signal recorded by the high image quality VTR as described above may be subjected to sharpness correction and color correction using an editing machine such as a video processor.

Here, the sharpness correction and the color correction are performed by variably operating the frequency characteristics of the television signal so as to emphasize or soften the contour of the image or change the color tone of the image.

Therefore, when sharpness correction or the like is applied to a television signal on which the above-described character multiplex signal is superimposed, not only the video signal but also the frequency characteristic of the character multiplex signal is changed, and such a character multiplex signal is generated. There is a problem that decoding will increase the number of errors significantly.

(Means for Solving the Problem) The present invention has been made in view of the above circumstances, and an object thereof is to provide a signal processing device capable of preventing deterioration of a character multiplex signal.

In order to achieve this object, the present invention provides an input terminal to which a television signal in which an information signal having a byte-unit or a synchronization unit for synchronizing byte units is superimposed on a predetermined portion, and an input terminal One signal line and the other signal line respectively connecting the terminal and the output terminal, and a detection means for detecting the average value of the synchronization section related to the information signal,
A waveform shaping circuit that is provided on the other signal line, and performs waveform shaping by slicing the signal level of the television signal supplied at a slice level that varies according to the average value detected by the detection means, A switch circuit that selectively switches the one signal line and the other signal line to connect to the output terminal, and a television that switches the switch circuit at a predetermined timing and is supplied through the one signal line. A signal processing device comprising a switch control circuit for interposing a waveform-shaped information signal supplied to the information portion of the John signal via the other signal line.

(Embodiment) A preferred embodiment of the signal processing apparatus according to the present invention will be described in detail below with reference to FIGS. 1 to 5.

In the present embodiment, the present invention is applied to a video processor. The input terminal 1 of the video processor conforms to the NTSC system, and as described above, a character multiplex signal is superimposed in the vertical blanking period. Then, the reproduced television signal (composite television signal) is supplied.

The supplied television signal is an automatic gain control circuit (AG
After being gain control in C) 2, is supplied to the clamp circuit 3 is pedestal clamp is sent to one of the signal lines l ₁ and the other signal line l _2.

A video signal processing circuit 4 and a delay line 5 are provided on the _one signal line l ₁ , and the video signal processing circuit 4 extracts a luminance signal and a color signal from the supplied television signal and Not Performs sharpness correction on the luminance signal and color correction on the color signal according to the operation of the operation unit (volume). And this video signal processing circuit 4
Re-synthesizes the luminance signal, the color signal, the synchronizing signal, and the color burst and outputs them to the delay line 5 as a composite television signal.

The delay line 5 adjusts the time of the signal processing speed in the other signal line l ₂ described later and the signal processing speed in the one signal run-in l ₁ , and is output from this delay line 5. The television signal is transmitted to the output terminal 7 through the one acquisition terminal 6a and the movable terminal 6b of the switch circuit 6.

A data slice circuit 8 and a filter circuit 9 are provided on the other signal line l ₂ , and the slice level in the data slice circuit 8 is set by a slice level setting circuit 10.

Here, the slice level setting circuit 10 detects the average level of the clock run-in (CR) and the framing coat (FC) in the character multiplex signal, and automatically sets the slice level according to the detected average level. It is a variable setting.

That is, the slice level setting circuit 10 includes first and second monomultis 101 and 102, first to third switch circuits 103, 104 and 105, an integrating circuit 106 and a slice level holding capacitor 107 as shown in FIG. The output of the first mono-multi 101 controls the switching of the first switch circuit 103 and triggers the second mono-multi 102, and the output of the second mono-multi 102 is provided. The second and third switch circuits 1
It is designed to control switching of 04 and 105.

The first mono-multi 101 is a sync separation circuit 11 to which a television signal as shown in FIG. 3 (A) is supplied.
Triggered by the horizontal retrace pulse shown in FIG. 7B, which is extracted in FIG. 7, the output shown in FIG.

The output of the first mono-multi 101 is supplied to the first switch circuit 103, and the first switch circuit 103 is opened during the high level period of the output of the first mono-multi 101.

As a result, the direct current 108 having a predetermined level connected to the first switch circuit 103 is connected to the integrating circuit 106, and the preset level of the integrating circuit 106 is set as shown in FIG. 3 (E). .

On the other hand, the output of the second mono-multi 102, which is triggered by the fall of the output of the first mono-multi 101, is shown in FIG.
As shown in FIG. 5, the high level is maintained during the period corresponding to the synchronizing portion of the character multiplex signal, and while the output of the second monomulti 102 is at the high level, the second and third switch circuits 10 are
4,105 is opened.

Here, the television signal output from the clamp circuit 3 is supplied to the second switch circuit 104,
The synchronizing portion of the character multiplex signal multiplexed with the television signal passes through the second switch circuit 104 and the integrating circuit 1
Supplied to 06.

This integrator circuit 106 is a synchronization part of the character multiplex signal, that is, a clock run-in (CR) and a framing code (FC).
Is integrated and an integrated output (average value) as shown in FIG. 3 (E) is supplied to the capacitor 107 via the buffer amplifier 109 and the third switch circuit 105.

Then, the output of the second mono-multi 102 also falls at the same time when the synchronizing portion of the character multiplex signal ends, and the second and third switch circuits 104 and 105 are closed.

Therefore, the integrated output at the end of the synchronizing section is held in the capacitor 107, and the hold level is supplied to the data slice circuit 8 via the buffer amplifier 110 as a slice level.

Thus, in this embodiment, paying attention to the fact that the bit pattern of the synchronizing part does not change even if the bit pattern of the data part changes, and the slice level is set according to the average value level of the synchronizing part in the character multiplex signal. By variably setting, optimum slicing can be performed according to the degree of waveform deterioration of the input television signal. In this technical idea, it goes without saying that the signal to be superimposed on the input television signal is not limited to the character multiplex signal, but may be an information signal having a synchronizing portion.

As the slice level setting circuit 10, for example, the character multiplex signal is once decoded to detect the error rate, and the slice level is set so that this error rate is minimized, or the slice level is set by manual operation of the volume. It may be set.

Further, the filter circuit 9 shapes the waveform as shown in FIG. 4B so that the character multiplex signal sliced as shown in FIG. 4A has a predetermined frequency spectrum. The television signal output from the filter circuit 9 is sent to the other input terminal 6c of the switch circuit 6 with a time delay.

On the other hand, the television signal output from the clamp circuit 3 is supplied to the sync separation circuit 11, and the sync separation circuit 11 receives the horizontal sync signal (H.sync) and the vertical sync signal (V) from the supplied television signal.・ Sync) is extracted and output.

Each of the extracted synchronization signals is supplied to the switch control circuit 12, and the switch control circuit 12 generates a switching signal that causes the switch circuit 6 to perform a switching operation based on each of the supplied synchronization signals and supplies the switching signal to the switching circuit 6. To do.

The switching timing of the switch circuit 6 by this switching signal is the character multiplex portion in the television signal, that is, in the present embodiment, the 14th to 16th portions within the vertical blanking period.
And the 21st horizontal operation period, and the 277th to 279th and 28th
It is connected to the fourth horizontal operation period terminal 6c, whereby the waveform shaping transmitted through the other signal line during the vertical retrace period of the television signal transmitted through the one signal line is performed. The character multiplexed signal thus generated is time-division multiplexed.

According to the video processor having the above-described configuration, by slicing only the character multiplex signal and shaping the waveform, the output terminal can be obtained despite the sharpness correction or the like performed by the video signal processing circuit 4. It is possible to always keep the waveform of the character multiplex coupling superimposed on the television signal output from No. 7 constant.

Therefore, it is possible to significantly reduce the occurrence of an error at the time of decoding due to the waveform deterioration of the character multiplex signal.

Further, by connecting the VTR on the reproducing side to the input terminal 1 and the VTR on the recording side to the output terminal 7 for dubbing, it is possible to prevent the waveform deterioration of the character multiplex signal at the time of dubbing. When performing such dubbing, the video signal processing circuit 4 is unnecessary.

Further, in the present embodiment, by providing the automatic gain control circuit 2 in the input stage, even if the signal level of the input television signal deviates from the predetermined level, it is automatically adjusted to the predetermined range. Further, it is possible to perform more optimal slicing of the character multiplexed signal.

By the way, in the above embodiment, the video signal processing circuit 4 is
Although the synchronizing signal is added in the above, as shown in FIG. 5, the waveform-shaped horizontal synchronizing signal (H.sync) and vertical synchronizing signal (V.sync) extracted from the synchronizing separation circuit 11 are added.
The television signal output from the switch circuit 6 circuit may be combined at 13.

As a result, not only the character multiplex signal but also the waveform deterioration of each synchronization signal can be prevented.

In this case, the video signal processing circuit 4 is configured so that the synchronizing signals are not combined.

(Effect of the invention) As is apparent from the above description, according to the present invention, even if the data content represented by the information signal changes, the bit pattern of the synchronization unit does not change, so the average of the synchronization unit By detecting the value, the amplitude value of the information signal can be obtained, and the slice level can be varied accordingly to slice the signal level of the television signal to perform waveform shaping. As a result, even if the signal level of the information signal changes, the information signal can always be sliced at the optimum slice level, so that even if the information signal whose waveform has been deteriorated is supplied, the information signal can be correctly distinguished from the high level and the low level. There is a remarkable effect that the waveform shaping can be performed.

[Brief description of drawings]

1 is a block diagram showing an embodiment of a signal processing device according to the present invention, FIG. 2 is a circuit diagram showing a slice level setting circuit, and FIGS. 3 (A) to 3 (E) are shown in FIG. FIGS. 4A and 4B are time charts showing the operating state of the slice level setting circuit, FIG. 4A is a time chart showing the operating state of the filter circuit, and FIG. 5 is another embodiment of the signal processing device according to the present invention. A block diagram and FIG. 6 are waveform diagrams showing a general television signal on which a character multiplex signal is superimposed. 1 ... Input terminal, 6 ... Switch circuit, 7 ... Output terminal, 8 ... Data slice circuit (waveform shaping circuit), 10 ... Slice level setting circuit, 12 ... Switch control circuit, l ₁ ... One side Signal line, l ₂ ... the other signal line.

Claims (1)

[Claims] 1. An input terminal to which a television signal in which an information signal having a byte-unit or a synchronization unit for synchronizing byte-unit is superposed on a predetermined portion is supplied, and the input terminal and the output terminal are respectively connected. One signal line and the other signal line, detecting means for detecting the average value of the synchronizing part relating to the information signal, and the other signal line provided on the other signal line, depending on the average value detected by the detecting means. And a waveform shaping circuit that performs waveform shaping by slicing the signal level of the television signal supplied at a slice level that is variable, and selectively switches to the output terminal by switching between the one signal line and the other signal line. Information of the television signal supplied via the one signal line by switching the switch circuit to be connected and this switch circuit at a predetermined timing. Min to a signal processing apparatus characterized by comprising a while interpolating switch control circuit waveform shaping information signal supplied via the other signal lines.