JP2000134508A - Ghost removing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize ghost removing processing with the high speed and high precision by improving the precision to judge whether or not a GCR(reference signal for ghost cancel) bar waveform fetched for the ghost removing processing is normal. SOLUTION: A waveform check circuit 1-6 is provided with not only a first judging circuit 2-3 for judging the offset of a burst signal and a second judging circuit 2-10 for judging the integrated result of a GCR signal but also a third judging circuit 2-5 and a fourth judging circuit 2-6 being two kinds of level judging circuits for judging signal levels before and after the rising of the GCR signal. Thus, even a signal whose judgment is difficult such as the case with a proximate and oversized ghost signal can be accurately judged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ghost eliminator used for various video equipment such as a television (TV) receiver for handling TV video signals and for removing ghost or waveform distortion. It is another object of the present invention to provide a ghost removing apparatus which can improve the processing accuracy and speed up the processing.

[0002]

2. Description of the Related Art In recent years, TV video signals in which a ghost canceling reference signal (GCR signal) is inserted have been broadcast in order to improve the image quality of TV broadcasting. On the receiver side,
The ghost canceling reference signal is extracted, and the ghost is removed based on the signal. Since this GCR signal is described in detail in Japanese Patent Application No. 1-69179, a detailed description is omitted here.

FIG. 2 shows a conventional example of a ghost removing device based on the above-described principle. The analog video signal input from the input signal line L1-1 is input to a timing signal generation circuit 1-1, which generates necessary timing signals such as a system clock and a waveform sampling pulse. The input video signal is also input to the S / N measurement circuit 1-2, and the S / N measurement circuit 1-2 determines the S / N of the input video signal.
Is measured and the measurement result is output.

An input video signal is supplied to an A / D conversion circuit 1-
A / D conversion is performed in 3. Actually, sampling is performed at a sampling frequency of 4 fsc (where fsc is a color subcarrier frequency, fsc = 3.58 MHz). The signal is subjected to removal of a waveform distortion component such as a ghost in a transversal filter circuit 1-4. Transversal filter circuit 1
The tap coefficient sequence of 4 corresponds to blocks 1-5 to 1-9 described below.
Is rewritten at any time to a value calculated to cancel the ghost.

[0005] A waveform capturing circuit 1-5 receives a signal for a predetermined period (for example, one scanning line) including a ghost removal reference signal (GCR signal) from the input and / or output of the transversal filter circuit 1-4. Extraction and 4-field difference processing are performed to obtain a GCR bar waveform. Which of the input and / or output of the transversal filter circuit 1-4 the signal to be captured by the waveform capturing circuit 1-5 is determined by the control algorithm of the subsequent processing circuit 1-9. The waveform check circuit 1-6a determines whether the GCR bar waveform obtained by the waveform capture circuit 1-5 is normal or not.

Next, a conventional waveform check will be described with reference to FIG. 3 (block diagram of a waveform check circuit) and FIG. 4 (a diagram showing a relationship between a GCR waveform and a timing signal).

The GCR signals (the GCR waveform shown in FIG. 4A and the pedestal waveform shown in FIG. 4B) read by the waveform capturing circuit 1-5 are subjected to four-field difference processing, so The GCR bar waveform shown in FIGS. 4C and 4D in which the synchronization signal and the burst signal are canceled out. This is the correctly captured GCR bar waveform. The signal of FIG. 4D has the same waveform as that of FIG. This inversion processing is performed by the absolute value conversion circuit 2-4 shown in FIG.

Here, there are cases where the clock and the synchronous reproduction system are disturbed by jitter included in the video signal, signal disturbance generated by scene switching on the broadcast station side, impulse noise due to disturbance, or ghost. is there. In such a case, the result of the burst signal canceling process in the waveform capturing circuit 1-5 described above is not good, and FIG.
A residual component of the burst signal cancellation as shown by a may occur, and a correct GCR bar waveform cannot be obtained.

[0009] It is considered that the remaining component of the above-described burst signal cancellation and the previous ghost component exist in the section where Ba is generated. Therefore, in the conventional waveform check circuit shown in FIG. 3, first, the pre-ghost component is removed through the band-pass filter 2-1 having the fsc component pass characteristic. Next, in the section in which the timing signal shown in FIG. 4F is "L", the burst component integration circuit 2-2 performs integration to detect the Ba component and obtain a Ba component detection value (integrated value). Then, the first determination circuit 2-3 compares the Ba component detection value with the Ba component determination value, and determines whether the waveform obtained by the waveform capturing circuit 1-5 is normal. (It is determined to be normal when Ba component detection value ≦ Ba component determination value.)

The output of the absolute value conversion circuit 2-4 is input to first and second amplitude value integration circuits 2-7 and 2-8. These circuits perform integration processing of input signals. For example, the first amplitude value integration circuit 2-7 performs the integration processing of the input signal during the section in which the timing signal of FIG. 4G indicates “L”, and the second amplitude value integration circuit 2-8 similarly performs the processing of FIG. 4 (h) performs the integration process in the section of “L”. As a result, a signal integrated value before and after the rise of the GCR bar waveform signal in which the noise component is reduced is obtained.

In the following difference processing circuit 2-9, a difference processing of the two integrated values is performed. Based on the obtained difference result, the second judgment circuit 2-10 compares the difference result with the difference judgment value and obtains the GC obtained by the waveform acquisition circuit 1-5.
A determination is made as to whether the R bar waveform is normal.
(It is determined to be normal when the difference result ≧ the difference determination value.)

It should be noted that if the judgment level values used in the judgment processing of the first and second judgment circuits 2-3 and 2-10 are controlled in accordance with the S / N obtained by the S / N measurement circuit 1-2, , Each S /
More accurate determination according to the N conditions can be realized. At the time of high S / N, control is performed such that the Ba component determination value is made smaller and the difference determination value is made larger than at the time of low S / N.

From the judgment results of the first and second judgment circuits 2-3 and 2-10, the waveform judgment circuit 1
Comprehensive judgment is made as to whether the waveform obtained in -5 is normal. When all of the two determination results are determined to be normal, the comprehensive determination circuit 2-11a determines that the waveform is a normal GCR bar waveform.

The delay circuit 2-12 is a circuit for delaying the signal supplied from the waveform capturing circuit 1-5 by the time required for the above processing. Waveform capture circuit 1 with comprehensive judgment circuit 2-11a
When it is determined that the signal waveform supplied from -5 is normal, the gate circuit 2-13 opens, and the signal (GCR bar waveform signal) supplied from the waveform capturing circuit 1-5 is output to the next stage.

Returning to FIG. 2, the output signal of the waveform check circuit 1-6a is subjected to waveform conversion in a waveform conversion circuit 1-7 so as to have a waveform suitable for the subsequent arithmetic processing. The converted signal and the ideal reference waveform signal generated by the ideal reference waveform generation circuit 1-8 are input to the next arithmetic processing circuit 1-9.

In the arithmetic processing circuit 1-9, arithmetic processing is executed based on an algorithm for obtaining a tap coefficient sequence (tap gain sequence) of the transversal filter circuit 1-4, and a tap coefficient sequence for removing a ghost is provided. Is required. In this arithmetic processing, the measurement result of the S / N measurement circuit 1-2 functions as one of the control elements.

The tap coefficient sequence obtained by the above processing is set in the transversal filter circuit 1-4 at an appropriate timing. By passing the video signal through the transversal filter circuit 1-4, a video signal with reduced waveform distortion components such as ghost can be extracted. The video signal that has passed through the filter circuit 1-4 is D / A converted by the next D / A conversion circuit 1-10. The video signal returned to the analog signal is output from the output line L1-2.

The apparatus performs a ghost removal operation by repeating the above operation and sequentially updating the tap coefficient sequence.

[0019]

However, in the above-described conventional example, even if the waveform before and after the rising edge of the GCR signal is distorted due to ghost interference or the like, even if the GCR signal waveform does not allow normal ghost removal processing, the GCR signal waveform cannot be processed. However, there is a possibility that the signal is determined to be a normal GCR signal.

In the above case, there is a case where there is a ghost before excessively close proximity. This will be described below using the waveform shown in FIG. FIG. 5A shows an ideal GCR bar waveform. In the conventional example, FIG.
In the section where each of the signals (c) is “L”, the acquired GCR signals are integrated, and the level determination is performed using the resulting difference value. The purpose of this process is to determine the level difference before and after the rise of the GCR signal. Here, in the case of the waveform shown in FIG. 5D in the ghost state before excessively close proximity, since the ghost level is large, it is impossible to perform the ghost removal processing.
The level difference obtained from the section in which the signal of (c) is “L” is determined to be an appropriate level difference. (FIG. 5
This is almost the same as the level difference obtained from the ideal GCR bar waveform shown in FIG. )

For this reason, in the conventional example, although the ghost state cannot be processed, the waveform check circuit 1-6a determines that the signal is normal, and the ghost removal processing is not stable and sometimes diverges. There was a fear that.

The present invention improves the accuracy of determining whether or not a GCR waveform captured for ghost removal processing is normal (prevents erroneous determination of the captured waveform).
It is an object of the present invention to provide a ghost removing device that operates efficiently at high speed.

[0023]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a ghost removing apparatus for removing a ghost by using a ghost canceling reference signal (GCR signal) inserted into a video signal. A timing signal generating circuit for generating a timing signal necessary for signal processing from an incoming video signal, and an S / N ratio of the incoming video signal.
And a transversal filter circuit that removes a ghost from the incoming video signal and outputs the ghost signal by updating the tap coefficient sequence as needed.
A waveform capturing circuit for extracting and storing a predetermined period including the GCR signal from the input and / or output of the transversal filter circuit, and a signal captured by the waveform capturing circuit is a GCR bar waveform signal at a predetermined timing. A waveform check circuit for determining whether or not there is, and the capture signal determined to be normal by the waveform check circuit is supplied, a reference timing is detected, and based on this timing, synchronous addition and waveform of the capture signal are performed. A waveform conversion circuit for performing conversion, an ideal reference waveform generation circuit for generating an ideal reference waveform, a signal output from the waveform conversion circuit, and an arithmetic process using a signal output from the ideal reference waveform generation circuit. The tap coefficient sequence for canceling the ghost, and A ghost elimination device including an arithmetic processing circuit for writing a tap coefficient sequence as needed, wherein a determination is made in a waveform check circuit based on an integrated value of a remaining component of a burst signal cancellation component of a signal fetched by the waveform fetch circuit. A determination circuit, and a second determination circuit that obtains each integrated value of signals before and after the rising timing of the signal captured by the waveform capturing circuit and performs determination based on a difference between the two integrated values. A determination is made based on a comparison result between a level of the signal captured by the waveform capturing circuit and a first reference level in a predetermined section before the rising of the signal captured by the waveform capturing circuit. 3 and the rising timing of the signal captured by the waveform capturing circuit. A fourth determination circuit for performing a determination based on a comparison result between the level of the signal captured by the waveform capturing circuit and a second reference level in a predetermined section after the lifting, and determination by the first to fourth determination circuits; A general judgment circuit for judging that the signal fetched by the waveform fetch circuit is a normal GCR bar waveform signal based on the result, wherein the criterion of the first to fourth judgment circuits is determined by the S / N measurement A ghost elimination device characterized by performing control in accordance with a measurement result of a circuit.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to two types of waveform check processing conventionally performed in a waveform check circuit.
By newly adding two types of level determination processes (level determination processes of signals before and after the rise of the GCR signal) and comprehensively determining a total of four types of determination results, the determination accuracy of the waveform check circuit is improved, It is to achieve the purpose.

In the present invention, the configuration and operation contents other than the waveform check circuit are almost the same as those of the conventional example.
The configuration and operation of the waveform check circuit will be mainly described, and detailed description of the other components will be omitted.

Waveform check circuit 1-6 according to one embodiment of the present invention
Will be described with reference to FIG. The difference from the conventional example is that, in addition to the first judgment circuit 2-3 for judging the cancellation of the burst signal and the second judgment circuit 2-10 for judging the integration result of the GCR signal, which have been used conventionally, In addition, a third determination circuit 2-5 and a fourth determination circuit 2-6, which are two types of level determination circuits for determining a signal level before and after the GCR signal rises, are provided.

The signal input to the waveform check circuit 1-6 is input to the bandpass filter circuit 2-1, the absolute value conversion circuit 2-4, and the delay circuit 2-12. Bandpass filter circuit 2-
In step 1, filter processing is performed to pass only the burst signal component (fsc), and unnecessary components other than the burst signal component such as noise and a previous ghost are removed.

The output of the band-pass filter circuit 2-1 is subjected to integration processing in the burst signal integration circuit 2-2 while the timing signal in FIG. The result of the integration is determined by the first determination circuit 2-3. The output of the absolute value conversion circuit 2-4 is equal to the third and fourth determination circuits 2-5,2-
6. Input to the first and second amplitude value integrating circuits 2-7 and 2-8.

The third and fourth determination circuits 2-5 and 2-6 compare a set reference level with an input GCR signal and perform determination processing. In the third determination circuit 2-5, the signal before the rise of the GCR signal (the signal shown in FIG. 4 (g) and FIG.
), The level determination value L (see FIG. 5D)
And a comparison determination process with the captured GCR signal. In addition, the section after the rise of the GCR signal (FIG. 4 (h), FIG. 5 (c)
In the section where the signal shown in FIG.
(See FIG. 5D) and a comparison determination process between the captured GCR signal. The respective determination results are output from the third and fourth determination circuits 2-5 and 2-6.

In the first and second amplitude value integrating circuits 2-7 and 2-8, the input signal is integrated. For example, the first amplitude value integrating circuit block 2-7 outputs the signal shown in FIG. 4 (g) and FIG.
In the section indicating L ″, the input signal is integrated, and the second amplitude value integration circuit 2-8 similarly performs the processing shown in FIG. 4 (h) or FIG. 5 (c).
Is performed in the section where is "L". As a result, the integrated value of the signal level before and after the rise of the GCR signal in which the noise component is reduced is obtained. The next difference processing circuit 2-9 performs a difference process on the integrated values. Based on the obtained difference result, the second determination circuit 2-10 determines the captured GC
It is determined whether the R bar waveform is normal.

The judgment level value used in the above judgment processing (processing by the first to fourth judgment circuits) is controlled according to the S / N obtained by the S / N measurement circuit 1-2. Therefore, more accurate determination according to each S / N condition is realized.

In the general judgment circuit 2-11, it is judged whether or not the signal is a normal GCR signal from four kinds of judgment results (judgment results by the first to fourth judgment circuits). If it is determined that the signal is normal, a signal for opening the gate circuit of block 2-13 is transmitted. The delay amount of the delay circuit 2-12 is set so as to correct the delay of the processing system in the blocks 2-1 to 2-11. Subsequent processing is the same as in the conventional example.

As described above, in this embodiment, in addition to the first determination circuit 2-3 for determining the cancellation of the burst signal and the second determination circuit 2-10 for determining the result of integrating the GCR signal, A third determination circuit 2-5, which is two types of level determination circuits for determining a signal level before and after the GCR signal rises, a fourth determination circuit
By providing the determination circuit 2-6, accurate determination can be performed even for a signal that is difficult to determine, such as an excessively close ghost signal. Therefore, in the present embodiment, it is possible to improve the accuracy of determining whether the GCR waveform captured for the ghost removal processing is normal or not, and it is possible to perform the ghost removal operation at high speed and efficiently.

[0034]

As described above, the ghost elimination apparatus of the present invention can accurately judge a signal that is difficult to judge, such as an excessively close ghost signal. Therefore, the ghost removal device can improve the accuracy of determining whether the GCR waveform captured for the ghost removal process is normal or not,
Ghost removal operation can be performed efficiently at high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a main part of the present invention.

FIG. 2 is a block diagram showing a conventional ghost removing device.

FIG. 3 is a block diagram showing a conventional waveform check circuit.

FIG. 4 is a diagram showing a relationship between a GCR waveform and a timing signal.

FIG. 5 is a diagram illustrating a GCR waveform determination process.

[Explanation of symbols]

 1-2 S / N measurement circuit 1-6 Waveform check circuit 2-1 Band pass filter circuit 2-2 Burst signal integration circuit 2-3 First judgment circuit 2-4 Absolute value conversion circuit 2-5 Third judgment circuit 2 -6 4th judgment circuit 2-7 1st amplitude value accumulation circuit 2-8 2nd amplitude value accumulation circuit 2-9 Difference processing circuit 2-10 2nd judgment circuit 2-11 Total judgment circuit 2-12 Delay circuit 2- 13 Gate circuit

Claims (1)

[Claims] 1. A ghost removing device for removing a ghost by using a ghost canceling reference signal (GCR signal) inserted into a video signal, wherein a timing signal required for signal processing is generated from an incoming video signal. A timing signal generating circuit, an S / N measuring circuit for measuring the S / N of the incoming video signal, and a tap coefficient sequence being updated as needed to remove ghosts from the incoming video signal. A transversal filter circuit for outputting, a waveform capturing circuit for extracting and storing a predetermined period including the GCR signal from an input and / or output of the transversal filter circuit, and a signal captured by the waveform capturing circuit; A waveform check circuit for determining whether or not the signal is a GCR bar waveform signal at a predetermined timing; A waveform conversion circuit for detecting a reference timing, performing synchronous addition and waveform conversion of the captured signal based on the timing, and an ideal reference for generating an ideal reference waveform. A waveform generation circuit, performs a calculation process using a signal output from the waveform conversion circuit and a signal output from the ideal reference waveform generation circuit, and sets the tap coefficient sequence for canceling a ghost, A ghost elimination device comprising: an arithmetic processing circuit that writes the tap coefficient sequence to a transversal filter circuit as needed; a waveform check circuit, based on an integrated value of a residual component of a burst signal cancellation component of a signal fetched by the waveform fetch circuit. A first determination circuit for performing determination, and a rising timing of a signal captured by the waveform capturing circuit. Then, a second determination circuit that obtains each integrated value of the signal before and after the rising and determines based on a difference between the two integrated values, and a rising timing of the signal captured by the waveform capturing circuit, A third determination is performed based on a comparison result between the level of the signal captured by the waveform capturing circuit and the first reference level in a predetermined section before the rise.
A determination circuit based on a comparison result between a level of a signal captured by the waveform capturing circuit and a second reference level in a predetermined section after the rising with respect to a rising timing of the signal captured by the waveform capturing circuit. 4th judgment
And a comprehensive determination circuit that determines that the signal captured by the waveform capturing circuit is a normal GCR bar waveform signal based on the determination results of the first to fourth determination circuits, A ghost elimination device, wherein the criterion of the fourth determination circuit is controlled according to the measurement result of the S / N measurement circuit.