JPH0686101A - Ghost elimination device - Google Patents

Abstract

PURPOSE:To eliminate a ghost signal without effect of jitter. CONSTITUTION:The device is provided with a burst lock circuit 11 locking a color burst of an input video signal. Then a horizontal synchronizing signal just after the lock signal of the burst lock circuit 11 is obtained is extracted by an horizontal synchronizing signal extract circuit 13. Then a horizontal synchronizing signal H'' is generated by a horizontal synchronizing signal recovery circuit 14 based on a color burst signal by taking the extracted horizontal synchronizing signal as a reference origin. A GCR signal is extracted based on the generated horizontal synchronizing signal H'' and a separated vertical synchronizing signal and the signal is set to a transversal filter 2 as coefficient data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ghost removing device for removing a ghost by using a GCR signal (ghost cancellation reference signal).

[0002]

2. Description of the Related Art First-generation EDTV broadcasting, which aims to improve image quality while maintaining compatibility with current television systems, has been started, and ghost elimination is a major improvement.
FIG. 3 is a block diagram showing the configuration of a conventional ghost removing device. In the figure, an input video signal is applied to an input terminal 1, and this signal is applied to a transversal filter 2, a GCR signal acquisition circuit 3 and a sync separation circuit 4.
The sync separation circuit 4 separates the horizontal and vertical sync signals of the input signal, and outputs the respective outputs of 18.281H.
It is given to the detection circuit 5. The 18.281H detection circuit 5 is a detection circuit for detecting 18H and 281H of each frame, and its output is given to the GCR signal acquisition circuit 3. G
The CR signal receiving circuit 3 receives 18H and 28 based on this signal.
The GCR signal inserted in 1H is extracted, and its output is given to the ghost detection circuit 6. The ghost detection circuit 6 calculates and sets the coefficient data of the transversal filter 2 based on this GCR signal. In this way, when a ghost is added to the input video signal, the ghost is removed by the transversal filter, and a ghost-free signal is obtained at the output terminal 7. FIG. 4 shows the signal waveform of each part, and FIG. 4A shows a part of the input video signal in which the GCR signal is inserted. (B) has shown the horizontal synchronizing signal extracted from this.

[0003]

However, in such a conventional ghost elimination device, the sync separation performance of the sync separation circuit 4 is not sufficient for detecting the position of the GCR signal. That is, as shown in FIG. 4B, the horizontal sync signal separated by sync has a jitter component, and its rising and falling points slightly change. Especially when there are many ghost components, this jitter component spreads to several μs. Since this horizontal synchronizing signal serves as a reference point for capturing the GCR signal, a jitter component remains after capturing the GCR signal as shown in FIG. 4 (c). Therefore, the conventional ghost removing device has a drawback that the GCR signal cannot be accurately captured and the ghost removing performance is deteriorated. In the worst case, transversal filter 2
Was diverged and the image could not be reproduced.

The present invention has been made in view of such conventional problems, and it is technically possible to generate a GCR signal capture timing without jitter and thereby capture the GCR signal. It is an issue.

[0005]

The present invention includes a transversal filter for eliminating ghosts of an input video signal, a sync separation circuit for detecting a horizontal sync signal and a vertical sync signal of a television signal, and a television signal. A burst lock circuit that extracts the color burst signal and locks the phase, and a horizontal sync signal that generates a horizontal sync signal based on the burst signal output from the burst lock circuit with the horizontal sync signal after being locked by the burst lock circuit as the origin. Generating means, GCR signal extracting means for extracting the GCR signal based on the horizontal synchronizing signal generated by the horizontal synchronizing signal generating means and the vertical synchronizing signal obtained by the sync separating circuit, and the ghost extracted by the GCR signal extracting means. Ghost detection that sets the coefficient data of It is characterized in that it comprises a circuit.

[0006]

According to the present invention having such characteristics, the color burst signal is extracted from the color burst included in the input video signal and the phase is locked. The horizontal sync signal output from the locked sync separation circuit after locking is used as a reference origin to generate a horizontal sync signal based on the burst signal output from the burst lock circuit based on this signal. The horizontal scanning period including the GCR signal is extracted based on the horizontal synchronizing signal thus generated and the extracted vertical synchronizing signal, and the GCR signal is extracted to remove the ghost.

[0007]

1 is a block diagram of a ghost removing apparatus according to an embodiment of the present invention. In this embodiment, the same parts as those in the conventional example described above are designated by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, the input terminal 1 is connected to the burst lock circuit 11 in addition to the transversal filter 2, the GCR signal acquisition circuit 3 and the sync separation circuit 4. The burst lock circuit 11 detects the color burst signal included in the input video signal and locks the phase, and outputs a signal of a constant color subcarrier frequency (f _SC = 3.579545 MHz). This signal is given to the quadruple multiplication circuit 12. When locked at the same time, a lock signal is given to the H extraction circuit 13. The H extraction circuit 13 extracts the horizontal sync signal of the sync separation circuit 4 immediately after the lock signal is applied, and its output is applied to the horizontal sync signal reproduction circuit 14 as H '. The horizontal synchronizing signal reproducing circuit 14 is a counter which receives a clock signal of 4f _SC from the quadrupling circuit 12 and counts this clock signal. Here, one horizontal scanning period is a period of 4f _SC (69.8
It is managed as 910 times that of 4127nS). In this embodiment, this relationship is utilized to reproduce the horizontal sync signal. That is, the horizontal synchronizing signal reproducing circuit 14 is composed of a counter that counts this 4f _SC and 910 clocks. An accurate horizontal synchronizing signal can be obtained from the output of this counter. This signal H ″ is detected by the 18 · 281H detection circuit 5
Given to. Here, the quadruple multiplication circuit 12 and the H extraction circuit 13
The horizontal synchronizing signal reproducing circuit 14 constitutes a horizontal synchronizing signal generating means for generating a horizontal synchronizing signal based on the burst signal output by the burst lock circuit, with the horizontal synchronizing signal after being locked by the burst lock circuit as an origin. is doing.

The vertical sync signal output from the sync separation circuit 4 is applied to the 18.281H detection circuit 5. 1
The 8.281H detection circuit 5 extracts the signals of 18H and 281H in one frame based on these input signals, and its output is given to the GCR signal acquisition circuit 3. The GCR signal capturing circuit 3 is a capturing circuit for capturing a GCR signal based on this signal and an input video signal. Other configurations are similar to those of the conventional example.

Next, the operation of this embodiment will be described with reference to FIG. First, when an input video signal is applied to the input terminal 1, the burst lock circuit 11 extracts the color burst signal and locks the phase, so that an accurate color burst signal is output. By multiplying this signal by 4 in the 4 × circuit 12, a signal of frequency 4f _SC as shown in FIG. 2A is obtained. Further, the separated horizontal synchronizing signal H is obtained from the synchronizing separation circuit 4. Then, when the burst lock circuit 11 locks at time t ₁ , the horizontal synchronizing signal immediately after that is extracted by the H extraction circuit 13 as shown in FIGS. 2A to 2D, and the signal H ′ is output. It Time t ₂ is a falling point of the H 'is used as the origin of the incorporation of the horizontal synchronizing signal. After that, the horizontal synchronizing signal reproducing circuit 14 multiplies by 4
The signal of f _SC is counted, and as shown in FIG. 2E, a horizontal synchronizing signal H ″ whose output is accurately inverted in one horizontal scanning period is obtained. In FIG. 2B, the horizontal synchronizing signal H has jitter. Since it occurs, its rising and falling points fluctuate left and right on the time axis, but with reference to time t ₂ which is the falling point of the first horizontal synchronizing signal, subsequent horizontal synchronizing signals are stored in this ghost elimination device. By creating it, a signal without jitter can be obtained. By this signal H ″ and the vertical synchronizing signal V, 18H and 2
81H is detected, which captures the GCR signal.
By doing so, an accurate GCR signal without jitter can be taken in, whereby the count data set in the ghost detection circuit 6 is set in the transversal filter 2.
In this way, the ghost can be removed without the influence of jitter.

[0010]

As described in detail above, according to the present invention, the horizontal synchronizing signal is reproduced based on the color burst signal. Therefore, an accurate horizontal synchronizing signal can be reproduced without the influence of jitter, and a GCR signal is taken in based on this, so that a ghost can be removed without the influence of jitter.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a ghost removing device according to an embodiment of the present invention.

FIG. 2 is a time chart showing a waveform of each part of the ghost removing device of the present embodiment.

FIG. 3 is a block diagram showing a configuration of a conventional ghost removing device.

FIG. 4 is a time chart showing the operation of a conventional ghost removing device.

[Explanation of symbols]

 1 Input Terminal 2 Transversal Filter 3 GCR Signal Capture Circuit 4 Sync Separation Circuit 5 18 ・ 281H Detection Circuit 6 Ghost Detection Circuit 7 Output Terminal 11 Burst Lock Circuit 12 4 Multiplication Circuit 13 H Extraction Circuit 14 Horizontal Sync Signal Reproducing Circuit

Claims (1)

[Claims] 1. A transversal filter for removing a ghost of an input video signal, a sync separation circuit for detecting a horizontal sync signal and a vertical sync signal of a television signal, and a color burst signal included in the television signal. A burst lock circuit for phase locking; a horizontal sync signal generating means for generating a horizontal sync signal based on a burst signal output from the burst lock circuit with the horizontal sync signal after being locked by the burst lock circuit as an origin; GCR signal extraction means for extracting a GCR signal based on the horizontal synchronization signal generated by the horizontal synchronization signal generation means and the vertical synchronization signal obtained by the synchronization separation circuit; and a ghost extracted by the GCR signal extraction means. Set the coefficient data in the transversal filter. Ghost canceling apparatus characterized by comprising a strike detection circuit.