JP3140202B2 - Ghost removal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ghost removing apparatus for removing a ghost using a GCR signal.

[0002]

2. Description of the Related Art First-generation EDTV broadcasting has been started to improve image quality while maintaining compatibility with the current television system. Or divergence is a problem. These phenomena are considered to be unstable factors and fatal defects for the ghost removing device.

A conventional ghost removing device will be described below. FIG. 3 is a block diagram showing a configuration of a conventional ghost removing device. In FIG. 1, reference numeral 1 denotes a transversal filter that removes a ghost component multiplexed on an input video signal, 2 denotes a ghost detection circuit that detects a ghost component based on a GCR waveform, and calculates a coefficient of the transversal filter 1; A GCR signal take-in circuit, 4 is a synchronization separation circuit that separates a vertical synchronization signal V and a horizontal synchronization signal H from an input video signal, and 5 is a GCR signal insertion position 18H, 281H from the vertical synchronization signal V and the horizontal synchronization signal H. 18H and 281H detection circuits for detecting the signal.

Next, the operation of the conventional device will be described. The input video signal is output through the transversal filter 1. At this time, a ghost component multiplexed on the input video signal is removed by the transversal filter 1. Further, the input video signal is input to the sync separation circuit 4, where the vertical sync signal V and the horizontal sync signal H are separated. 1
The 8H, 281H detection circuit 5 uses the vertical synchronizing signal V and the horizontal synchronizing signal H to output the GCR signal insertion positions 18H, 2H,
81H is detected.

[0005] Next, a GCR waveform is captured by a GCR signal capturing circuit 3 based on the detection signal, and a ghost detection circuit 2 detects a ghost component based on the GCR waveform, and the coefficient data of the transversal filter 1 is converted. The calculated ghost component is removed by writing the coefficient data to the transversal filter 1. FIG. 4 shows the signal waveform of each part, and FIG. 4A shows one horizontal period in which a GCR signal is inserted in a part of the input video signal. (B) shows the horizontal synchronizing signal H, and the falling or rising edge of the horizontal synchronizing signal is used as a reference point for the GCR.
The signal is captured. (C) shows the captured GCR signal.

[0006]

However, in the above-described conventional configuration, the synchronization separation performance of the synchronization separation circuit 4 is lower than that of the GC.
There is a problem that the position detection of the R signal is not sufficient. That is, as shown in FIG. 4 (b), the horizontal synchronization signal H separated from the synchronization has a jitter component. In particular, when there are many ghost components, this jitter component extends to several microseconds. The horizontal synchronization signal H is G
As a reference point for taking in the CR signal, the jitter component remains in the signal after taking in the GCR signal as shown in FIG. For this reason, there has been a problem that accurate capturing cannot be performed, and a ghost removing function is deteriorated and a divergence phenomenon is caused.

Therefore, an object of the present invention is to provide an accurate GCR signal by using a jitter-free GCR signal acquisition timing.
An object of the present invention is to provide a ghost eliminator capable of capturing a CR signal and improving a ghost elimination function.

[0008]

A ghost eliminator according to the present invention comprises a synchronizing separating means for separating an input video signal into horizontal and vertical synchronizing signals, and a detecting means for detecting an insertion position of a GCR signal based on these separated synchronizing signals. Means for capturing a GCR waveform based on the detection signal of the detecting means, ghost detecting means for detecting a ghost component from the captured GCR waveform and calculating coefficient data of a transversal filter, A transversal filter that removes a ghost component of the input video signal from the input video signal, and reproduces a system clock synchronized with the color phase by extracting a color burst signal from the input video signal. Horizontal sync signal to reproduce the horizontal sync signal based on the A signal reproducing unit, and a monitoring unit that monitors a change in a GCR detection signal output from the GCR waveform capturing unit, and resets the horizontal synchronous reproducing unit when the monitoring unit detects a sudden change in the GCR signal. Thereafter, the insertion position of the GCR signal is detected using the horizontal synchronization signal reproduced by the horizontal synchronization signal reproducing means.

[0009]

According to the structure of the present invention, the GCR signal is monitored by the monitoring means, and when there is a sudden change, the horizontal synchronous reproducing means is reset to the horizontal synchronous position from the synchronous separating circuit. The insertion position of the GCR signal is detected using the horizontal synchronizing signal reproduced in step (1).
The position where the signal is taken in is detected, and a divergence phenomenon or the like due to erroneous detection of the taken-in position can be prevented.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a circuit configuration of a ghost removing device according to an embodiment of the present invention. In the figure, the same reference numerals as those in FIG.
When the input video signal is output from the transversal filter 1 as in the conventional apparatus, the ghost component multiplexed with the input video signal is removed by the transversal filter 1. In order to control the transversal filter 1, a GCR
It is necessary to extract a signal and detect a ghost, and the GCR signal capturing circuit 3 and the ghost detecting circuit 2 perform these processes. Here, it is important to stably detect the position of the GCR signal always at the same position.

Therefore, in the present invention, a horizontal synchronizing signal serving as a reference for detecting a GCR signal is reproduced. This means that the broadcasting station always has a stable cycle based on the burst signal, that is, one horizontal period is 4 fsc (1
4.2MHz) is managed as 910 times,
It is intended to take advantage of this. Therefore, FIG.
As shown in FIG. 7, a burst lock circuit 6 for extracting a color burst signal and reproducing a system clock synchronized with the color phase, a quadruple circuit 7 for increasing the system clock output from the burst lock circuit 6 to four times the frequency, A horizontal synchronizing signal reproducing circuit 8 for reproducing a horizontal synchronizing signal based on a reference, and a microcomputer 9 for monitoring the state of a GCR detection signal output from the GCR signal capturing circuit 3 are provided.

The operation of the embodiment of the present invention will be described. First, the horizontal synchronizing signal H and the vertical synchronizing signal V are separated from the input video signal by the sync separation circuit 4. This horizontal synchronizing signal H is, as shown in FIG.
It has a jitter component equal to or greater than one clock width of fsc. In particular, for a video signal having a strong ghost component, the jitter component is further increased. On the other hand, the burst lock circuit 9 detects a burst clock fsc phase-synchronized with the input video signal from the input video signal. The frequency fsc is raised to four times the frequency by the quadruple frequency multiplier 7, and becomes 4fsc shown in FIG.

Next, the microcomputer 9 stores the GCR detection signal from the GCR capture circuit 3 and determines whether the ghost has changed abruptly or the video has been interrupted. When such an abnormality occurs, the lock is released by the synchronization separation circuit 4, and H cannot be detected for a certain period of time. When that happens,
The time interval between H ′ and H reproduced by the horizontal synchronizing signal reproducing circuit is shifted, and the microcomputer 9 detects the GC with the shifted time position.
The R signal is captured. After detecting this abnormality, when the synchronization of the input video signal is stabilized and the same GCR signal can be captured several to several tens of times, the microcomputer 9 outputs the signal shown in FIG.
A reset signal of the horizontal synchronizing signal reproducing circuit 8 shown in FIG.

The horizontal synchronizing signal reproducing circuit 8 comprises an infinite loop counter for counting 910 clocks of 4 fsc, which is one horizontal period, and the infinite loop counter is reset by a reset signal from the microcomputer 9.
The microcomputer 9 captures the horizontal synchronization signal H at the time when the microcomputer 9 determines that the GCR signal can be captured without temporal fluctuation, sets that signal as the time origin, and thereafter, reproduces the horizontal synchronization signal H ′ reproduced by the infinite loop counter (FIG. d)) is output. Therefore, the reproduced horizontal synchronizing signal H ′ has no jitter and is a reference signal synchronized with the input video signal.

Therefore, based on the reproduced horizontal synchronizing signal H 'and vertical synchronizing signal V, the 18H and 281H detecting circuits 5
The CR signal insertion position is detected. Since the insertion position of the GCR signal is detected by a horizontal synchronization signal containing no jitter, the insertion position is always detected at the same stable position. For this reason, erroneous detection of the position where the GCR signal is captured is eliminated, and divergence can be prevented.

[0016]

According to the ghost removing device of the present invention,
The GCR signal is monitored by the monitoring means, and when there is an abrupt change, the horizontal synchronizing reproduction means is reset to the horizontal synchronizing position from the sync separation circuit, and thereafter the GCR signal is reproduced by using the horizontal synchronizing signal reproduced by the horizontal synchronizing reproduction means. Since the insertion position of the signal is detected, the capture position of the GCR signal is detected by the horizontal synchronizing signal without jitter, and the divergence phenomenon due to the erroneous detection of the capture position can be prevented, and the ghost removal function is enhanced. be able to.

[Brief description of the 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 diagram showing waveforms of respective units in the embodiment device.

FIG. 3 is a block diagram illustrating a configuration of a conventional ghost removal device.

FIG. 4 is a diagram showing waveforms at various parts in a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transversal filter 2 Ghost detection circuit 3 GCR signal taking-in circuit 4 Sync separation circuit 5 18H, 281H detection circuit 6 Burst lock circuit 7 Quadruple circuit 8 Horizontal synchronization signal reproduction circuit 9 Microcomputer (monitoring means)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/21

Claims (1)

(57) [Claims] 1. Synchronization separation means for separating an input television signal into horizontal and vertical synchronization signals, detection means for detecting an insertion position of a GCR signal based on the separated synchronization signals, and a detection signal based on the detection signal of the detection means. And a ghost detecting means for detecting a ghost component from the fetched GCR waveform and calculating coefficient data of a transversal filter, and removing a ghost component of the input television signal based on the coefficient data. A ghost eliminator provided with a transversal filter, comprising: reproduction means for extracting a color burst signal from an input television signal and reproducing a system clock synchronized with a color phase; and a system clock reproduced by the reproduction means. Synchronization signal reproducing means for reproducing a horizontal synchronization signal Monitoring means for monitoring a change in a GCR detection signal output from the GCR waveform capturing means, and resetting the horizontal synchronous reproduction means when the monitoring means captures a sudden change in the GCR signal; Is a ghost removing device for detecting the insertion position of the GCR signal using the horizontal synchronizing signal reproduced by the horizontal synchronizing reproducing means.