JPH09149292A - Ghost removal device - Google Patents

Abstract

(57) Abstract: A ghost removing device capable of efficiently removing a ghost is provided. A transversal filter 3 removes a ghost from a video signal and outputs it. The memory circuit 7 is a GCR extracted from the input signal or output signal of the filter 3.
The waveform data of the signal is updated and stored. The processing device CPU calculates the filter coefficient set in the filter 3. The sequence number storage circuits 16 and 17 store the sequence number of the updated latest waveform data and the sequence number of the waveform data previously sent to the processing device CPU. Only when it is determined that the latest waveform data has been updated, the latest waveform data and the waveform data paired with the latest waveform data are sent to the processing device CPU, and the waveform is displayed during the period when it is determined that the latest waveform data has not been updated. Avoid sending data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ghost eliminating device used in various video equipment such as a television receiver that handles television video signals.

[0002]

2. Description of the Related Art In recent years, in order to improve the image quality of television broadcasting, a television video signal in which a ghost removing reference signal (GCR signal) for removing ghost or waveform distortion is inserted is broadcast. On the receiver side, this GCR signal is taken out and the ghost is removed based on the taken out GCR signal. The GCR signal is, as shown in Table 1,
8 field sequence method, and they are shown in FIG.
The waveforms are as shown in (a) to (h).

[0003]

[Table 1]

For further details of the GCR signal, see, for example, Japanese Patent Application No. 1-69179 (Japanese Patent Application Laid-Open No. 2-290398).
No.), the description thereof is omitted here.

FIG. 2 is a block diagram showing an example of a conventional ghost removing device. In FIG. 2, the incoming analog video signal is input to the timing generation circuit 1 and the A / D conversion circuit 2. The timing generation circuit 1 generates necessary timing signals such as a system clock and a waveform sampling pulse. The A / D conversion circuit 2 A / D converts the input video signal. As an example, the A / D conversion circuit 2 performs sampling at a sampling frequency of 4 fsc (where fsc is a color subcarrier frequency, fsc = 3.58 MHz).

The digital video signal output from the A / D conversion circuit 2 is input to the transversal filter 3. The transversal filter 3 removes a waveform distortion component such as a ghost as described later. The output of the transversal filter 3 is input to the D / A conversion circuit 4. D
The A / A conversion circuit 4 outputs the input digital video signal to D /
A conversion and output.

The select circuit 5 selects an input signal to the transversal filter 3 or an output signal from the transversal filter 3 according to an algorithm used to calculate a filter coefficient in the transversal filter 3. For example, when the division method is used as the algorithm, the input signal to the transversal filter 3 is required, when the ZF method is used, the output signal from the transversal filter 3 is required, and when the correlation method is used. Requires both the input and output signals of the transversal filter 3.

The gate circuit 6 receives the GCR signal extraction pulse output from the timing generation circuit 1 to generate a GCR signal.
A signal including a signal for a predetermined period is gated from the select circuit 5 and input to the memory circuit 7. The memory circuit 7 stores the GCR signal input from the gate circuit 6 in an area designated by the sequence number of the GCR signal output from the timing generation circuit 1. Note that the above processing always operates according to the television signal, regardless of the operating status of the program of the processing device CPU.

The GCR signal output from the memory circuit 7 is input to the processing unit CPU and processed as follows.
The 4-field difference processing circuit 8 includes the timing generation circuit 1
3 by reading the latest GCR waveform data and the GCR waveform data paired with the latest GCR waveform data from the memory circuit 7 based on the latest sequence number of the GCR signal from FIG. Obtain a GCR bar waveform as shown in i). The GCR waveform data includes the first field and the fifth field, and the second field and the sixth field.
A field, a third field and a seventh field, and a fourth field and an eighth field are paired respectively.

The error check circuit 9 determines whether the GCR bar waveform obtained by the 4-field difference processing circuit 8 has an error. That is, it is determined whether the burst signals have been canceled out, are below a certain level before the rise of the GCR bar waveform, or are above a certain level after the rise of the GCR bar waveform. The peak search circuit 10 performs differential filter processing on the input GCR bar waveform in order to eliminate the jitter component due to the influence of ghost, noise, etc.
The maximum position is detected. In the subsequent processing, since the maximum position is processed as the reference position, the jitter component can be eliminated.

The synchronous adder circuit 11 is a peak search circuit 1
With the position obtained by 0 as a reference, the input GCR bar waveform is subjected to 1-clock difference processing and synchronously added. The acquisition frequency check circuit 12 checks whether the GCR bar waveform has been acquired a predetermined number of times. If the number of acquisitions is less than or equal to the predetermined number, the above processing is repeated. This improves S / N. The averaging circuit 13 divides the data, which has been subjected to the synchronous addition processing a predetermined number of times, by the number of times to obtain an average value. The data output from the averaging circuit 13 is input to the arithmetic circuit 14.

The arithmetic circuit 14 includes the GCR waveform generation circuit 1
From 5, the pre-calculated ideal ghost removing reference waveform (reference GCR waveform) is input. The arithmetic circuit 14 calculates a filter coefficient for setting the transversal filter 3 based on the GCR bar waveform from the averaging circuit 13 and the reference GCR waveform from the GCR waveform generating circuit 15.
The filter coefficient thus obtained is set in the transversal filter 3, and the ghost of the video signal input to the transversal filter 3 is removed. By repeating the above operation and sequentially updating the tap gain (filter coefficient) of the transversal filter 3, the ghost of the video signal is removed.

[0013]

By the way, in the above-mentioned conventional ghost removing device, the GC by the processing device CPU is used.
Since the waveform acquisition processing of the R signal is performed at high speed, the GCR waveform acquisition processing is executed many times within one field. That is, during the period until the GCR waveform data of the memory circuit 7 is updated, the same waveform data is taken in many times. Therefore, the S / N of the GCR waveform cannot be sufficiently improved even though the synchronous addition process is performed. As a result, although the GCR waveform data is fetched a large number of times, it is affected by the noise component and causes a wrong filter coefficient to be set in the transversal filter 3, so that stable ghost removal processing cannot be realized. There was a problem.

The present invention has been made in view of such a problem, and even if the number of times the GCR waveform data is taken in is reduced, an ghost is efficiently set without setting an incorrect filter coefficient in the transversal filter. It is an object of the present invention to provide a ghost removing device that can remove the ghost.

[0015]

In order to solve the above-mentioned problems of the prior art, the present invention eliminates ghosts by using a ghost elimination reference signal that is inserted in a video signal and transmitted in a predetermined field sequence. A ghost removing device that removes ghosts from an incoming video signal with a predetermined tap coefficient set and outputs the resulting filter circuit (3).
From the input signal or output signal of the filter circuit,
Waveform data storage means (7) for extracting a predetermined fixed period including the ghost removing reference signal and updating and storing each waveform data based on the field sequence.
And a calculation processing means (CPU) for calculating a tap coefficient to be set in the filter circuit based on the output waveform data from the waveform data storage means and setting the tap coefficient in the filter circuit at any time. In the removing device, the first sequence number storage means (16) for storing the sequence number of the latest waveform data updated in the waveform data storage means and the sequence number of the waveform data previously sent to the arithmetic processing means are stored. A second sequence number storage means (17) for storing,
By comparing the sequence numbers of the second sequence number storage means, the latest waveform data is paired with the latest waveform data in the arithmetic processing means only when the waveform data storage means determines that the latest waveform data has been updated. The period during which the waveform data is sent and it is determined that the waveform data storage means has not updated the latest waveform data,
There is provided a ghost elimination device characterized in that the arithmetic processing means is provided with a control means (18, 19) for controlling so as not to send waveform data.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A ghost removing apparatus of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of the ghost removing device of the present invention. In FIG. 1, the same parts as those in FIG. 2 are designated by the same reference numerals.

In FIG. 1, the incoming analog video signal is input to the timing generation circuit 1 and the A / D conversion circuit 2. The timing generation circuit 1 generates a necessary timing signal such as a waveform sampling pulse. The A / D conversion circuit 2 A / D converts the input video signal. A /
As an example, the D conversion circuit 2 has a sampling frequency of 4 fsc (where fsc is a color subcarrier frequency, and fsc = 3.58 MH).
Sampling is performed in z).

The digital video signal output from the A / D conversion circuit 2 is input to the transversal filter 3. The transversal filter 3 removes a waveform distortion component such as a ghost as described later. The output of the transversal filter 3 is input to the D / A conversion circuit 4. D
The A / A conversion circuit 4 outputs the input digital video signal to D /
A conversion and output.

The select circuit 5 selects an input signal to the transversal filter 3 and / or an output signal from the transversal filter 3 according to an algorithm used to calculate a filter coefficient in the transversal filter 3. For example, as an algorithm,
When using the division method, the transversal filter 3
When the ZF method is used, an input signal to
The output signal from the transversal filter 3 is required, and when the correlation method is used, both the input and output signals of the transversal filter 3 are required.

The gate circuit 6 receives the GCR signal extraction pulse output from the timing generation circuit 1 to generate a GCR signal.
A signal including a signal for a predetermined period is gated from the select circuit 5 and input to the memory circuit 7. The memory circuit 7 stores the GCR signal input from the gate circuit 6 in an area designated by the sequence number of the GCR signal output from the timing generation circuit 1. Note that the above processing always operates according to the television signal, regardless of the operating status of the program of the processing device CPU.

The GCR signal output from the memory circuit 7 is input to the processing unit CPU via the gate circuit 19. The gate circuit 19 uses the latest GCR waveform data newly written in the memory circuit 7 and the GCR paired with the latest GCR waveform data.
Only the waveform data is gated and input to the 4-field difference processing circuit 8. When the latest GCR waveform data is written in the memory circuit 7, the latest sequence number is stored in the sequence number storage circuit 16. The sequence number storage circuit 17 stores the sequence number sent to the 4-field difference processing circuit 8 last time. The comparison control circuit 18 compares the sequence numbers of the sequence number storage circuits 16 and 17, controls the gate circuit 19 only when the sequence numbers are different from each other, and the memory circuit 7 controls the pair of pairs of GCR waveform data to be a 4-field difference processing circuit. Make sure to enter 8.

That is, when the GCR signal of the first field shown in FIG. 3A is updated, the gate circuit 19 forms a pair with the GCR waveform data of the first field.
The GCR waveform data of the fifth field shown in (e) is gated and input to the 4-field difference processing circuit 8. At this time, the sequence number storage circuits 16 and 17 store the sequence number 1 which is the updated latest sequence number and is the previously transmitted sequence number. Therefore, the gate circuit 19 is closed until the sequence number of the sequence number storage circuit 16 is updated, and data is not input to the 4-field difference processing circuit 8. Next, when the GCR signal of the second field shown in FIG. 3B is updated, the sequence number storage circuit 16 stores the sequence number 2 and the sequence number storage circuit 1
Since the values of 6 and 17 are different, the gate circuit 19 forms a pair with the GCR waveform data of the second field.
The 6th field GCR waveform data shown in (f) is gated and input to the 4-field difference processing circuit 8.

As described above, one pair of GCR waveform data is always input to the 4-field difference processing circuit 8 only when one of the pairs of GCR waveform data is updated. Further, during the period when it is determined that the latest GCR waveform data has not been updated, the GCR waveform data is not sent to the 4-field difference processing circuit 8. Comparison control circuit 1
8 and the gate circuit 19 are the transversal filter 3
The GCR waveform data is input to the processing device CPU that operates as a calculation processing unit for calculating the tap coefficient to be set at any time and setting it at any time, and operates as a control unit that controls not to input the GCR waveform data.

Then, the 4-field difference processing circuit 8 in the processor CPU performs difference processing using the pair of input GCR waveform data to obtain a GCR bar waveform as shown in FIG. 3 (i). The error check circuit 9 uses the GC obtained by the 4-field difference processing circuit 8.
Determine if there is an error in the R bar waveform. That is, it is determined whether the burst signals have been canceled out, are below a certain level before the rise of the GCR bar waveform, or are above a certain level after the rise of the GCR bar waveform. The peak search circuit 10 performs differential filter processing on the input GCR bar waveform in order to eliminate a jitter component due to the influence of ghost, noise, etc., and detects the maximum position. In the subsequent processing, since the maximum position is processed as the reference position, the jitter component can be eliminated.

The synchronous adder circuit 11 is a peak search circuit 1
With the position obtained by 0 as a reference, the input GCR bar waveform is subjected to 1-clock difference processing and synchronously added. The acquisition frequency check circuit 12 checks whether the GCR bar waveform has been acquired a predetermined number of times. If the number of acquisitions is less than or equal to the predetermined number, the above processing is repeated. This improves S / N. The averaging circuit 13 divides the data, which has been subjected to the synchronous addition processing a predetermined number of times, by the number of times to obtain an average value. The data output from the averaging circuit 13 is input to the arithmetic circuit 14.

The arithmetic circuit 14 includes the GCR waveform generation circuit 1
From 5, the pre-calculated ideal ghost removing reference waveform (reference GCR waveform) is input. The arithmetic circuit 14 calculates a filter coefficient for setting the transversal filter 3 based on the GCR bar waveform from the averaging circuit 13 and the reference GCR waveform from the GCR waveform generating circuit 15.
The filter coefficient thus obtained is set in the transversal filter 3, and the ghost of the video signal input to the transversal filter 3 is removed. By repeating the above operation and sequentially updating the tap gain (filter coefficient) of the transversal filter 3, the ghost of the video signal is removed.

In the ghost removing apparatus of the present invention described above, only the latest pair of GCR waveform data can be fetched at all times, and the filter coefficient of the transversal filter 3 can be calculated based on it, so the number of fetching GCR waveform data can be increased. Even if the number is small, ghosts can be efficiently removed without setting wrong filter coefficients in the transversal filter 3.

Although the sequence number storage circuits 16 and 17 and the comparison control circuit 18 are provided outside the processing unit CPU in this embodiment, these circuits may also be provided in the processing unit CPU, and the present invention is not limited thereto. Various changes can be made without departing from the spirit of the invention.

[0029]

As described in detail above, the ghost removing apparatus of the present invention includes first sequence number storage means for storing the sequence number of the latest GCR waveform data updated in the GCR waveform data storage means, By comparing the sequence numbers of the first and second sequence number storage means with the second sequence number storage means for storing the sequence number of the GCR waveform data previously sent to the arithmetic processing means for computing the tap coefficient, Only when it is determined that the latest GCR waveform data has been updated in the GCR waveform data storage means, the latest GCR waveform data and the GCR waveform data paired with the latest GCR waveform data are sent to the arithmetic processing means.
The control means for controlling the arithmetic processing means so as not to send the GCR waveform data during the period when it is determined that the latest GCR waveform data has not been updated in the CR waveform data storage means. Even if the number of times of capturing is small, it is possible to efficiently remove ghosts without setting wrong filter coefficients in the transversal filter.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

FIG. 3 is a diagram showing a GCR signal.

[Explanation of symbols]

1 Timing Generation Circuit 2 A / D Conversion Circuit 3 Transversal Filter (Filter Circuit) 4 D / A Conversion Circuit 5 Select Circuit 6, 19 Gate Circuit 7 Memory Circuit (Waveform Data Storage Means) 8 4 Field Difference Processing Circuit 9 Error Check Circuit 10 Peak search circuit 11 Synchronous addition circuit 12 Capture count check circuit 13 Average circuit 14 Arithmetic circuit 15 GCR waveform generation circuit 16, 17 Sequence number storage circuit (sequence number storage means) 18 Comparison control circuit CPU processing device (arithmetic processing means)

Claims (1)

[Claims] 1. A ghost removing device for removing a ghost by using a ghost removing reference signal which is inserted into a video signal and transmitted in a predetermined field sequence, and an incoming video signal with a predetermined tap coefficient set. From the input signal or the output signal of the filter circuit, which removes more ghosts and outputs, a predetermined fixed period including the ghost removal reference signal is extracted, and each waveform data based on the field sequence is extracted. With the waveform data storage means for updating and storing, and the output waveform data from the waveform data storage means,
In a ghost elimination device comprising a calculation processing means for calculating a tap coefficient for setting in the filter circuit and setting the tap coefficient in the filter circuit at any time, the latest waveform data updated in the waveform data storage means. Sequence number storage means for storing the sequence number of the waveform data, second sequence number storage means for storing the sequence number of the waveform data transmitted last time to the arithmetic processing means, and the first and second sequence numbers. By comparing the sequence numbers of the storage means, the latest waveform data and the waveform data paired with it are sent to the arithmetic processing means only when it is determined that the waveform data storage means has updated the latest waveform data. Period when it is determined that the waveform data storage means has not updated to the latest waveform data Is ghost canceling apparatus characterized by being configured to provide a control means for controlling so as not to send the waveform data to said processing means.