JPH04103267A - Ghost elimination device - Google Patents

Abstract

PURPOSE:To prevent ghost elimination characteristic from being changed by making the relation of a phase of a GCR signal or a vertical synchronizing signal and a phase of a clock signal used for A/D-converting an input video signal constant. CONSTITUTION:A GCR signal or a vertical synchronizing signal or a signal resulting from processing the signal is compared with a waveform data stored in a memory 6 in advance by a CPU 7 and a clock generating circuit 8 whose phase is variable is controlled based on the result of comparison thereby controlling the phase of the clock signal used for A/D conversion. Thus, the relation of the phase of the clock and the GCR signal or the vertical synchronizing signal in the case of A/D-converting a video signal is kept within a prescribed range thereby preventing the ghost elimination performance from being changed due to the phase of A/D conversion.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ghost removal device that performs ghost removal using a GCR signal or a vertical synchronization signal.

Conventional technologyThe first generation of ED''rV broadcasting, which aims to improve image quality while maintaining compatibility with current television systems, was about to begin.
Among these, ghost removal is attracting a lot of attention. Among the required ghost removal performance items are the image quality evaluation value after improvement and the removal time. In other words, this means how quickly ghosts can be removed and the amount of ghosts remaining after removal can be reduced. An example of a conventional ghost removal device is the Technical Report RE 80 of the Television Society of Japan.
-6, pp-9-14, February 1981, there is a ghost cancellation. This detects ghosts by using the differential signal of the leading edge of the vertical synchronization signal unique to television signals as a reference waveform, and performs correlation calculations on the time axis using the detected ghost signals to perform transformer detection. Ghosts are removed by sequentially correcting the tap coefficients of the versal filter. In addition, as a ghost removal device using GCR signals, the Technical Report of the Television Society of Japan ROFT 89-
6, pp. 31-36. This uses a transversal filter in the ghost I/removal section as in the ghost cancel set, but the input and output of the transversal filter are input to the CPU via memory, and synchronous addition is performed.
Performs all ghost removal calculations including processing between fields according to the transmission sequence.

An example of a conventional ghost removal device will be described below with reference to the drawings. FIG. 2 is a schematic block diagram showing the configuration of a conventional ghost removal device. In Figure 2,
10 is an A/D converter that performs A/D conversion of the input video signal W't; 11 is a transversal filter that removes ghosts from the output of the A/D converter 10; 12 is a transversal filter 11 (D 13.14 is a waveform memory that stores the output waveforms of the A/D converter 10 and transversal filter 11; 15 is a waveform memo') 13.14; C controlling the transversal filter 11 using the output
It is PU.

The operation of the τ stress removing device configured as described above will be explained. The input video signal is sent to A/D converter 1
0, and the output signals are input to a transversal filter 11 and a waveform memory 13, respectively.The output of the transversal filter 11 is input to a waveform memory 14, and each waveform memo! 713.14
The output is input to the CPU 15.

In the first generation OHDTV broadcasting, fat, (bl
The key signal indicating K and the O pedestal signal are sent in the same horizontal period in a sequence that goes around in 8 fields: WRB signal → 0 pedestal signal → WRB signal → 0 pedestal signal → O pedestal signal → WRB signal → O pedestal signal → WRB signal. Ru. By performing the calculation shown in equation 1 below on the signals of these 8 fields, the signal shown in FIG. 3(e) can be obtained. However, Fn (n=1 to 8)
represents the nth field signal. Hereinafter, the processing between fields according to the transmission sequence as shown in the first equation will be referred to as field sequence processing.

F=1/4 ((F1-F5)+(F6-F2)
)+ (F3-F7)+ (F8-F4))
...(1) In reality, the signal shown in FIG. 3 (di) obtained by differentiating the signal in FIG. 3(c) is used as the reference signal for ghost detection, and the following ghost removal calculation is performed. MSE (Mean Sq, are Error
) law or ZF (Zer.

Forcing) method, etc., are methods that sequentially correct the tap coefficients on the time axis according to a certain algorithm to finally obtain the optimal tap coefficients. The output signal of the transversal filter is (Yk), the reference signal is (Rk), the difference signal between the output signal of the transversal filter and the reference signal is (Ek), the total number of taps is M+N+1, and f is n of the transversal filter. th tap coefficient C(+)(“
) is corrected based on the following equation 2 in the MSE method and equation 3 in the ZF method. However, α and β are coefficients for determining the amount of correction.

(CI)"") = (C1) "I-a-ΣYk-1
-Ek ・(2) 1(--M'" (Cl) (1") = (CI) β・El
(3) G) - After performing the synchronous addition and field sequence processing shown in the first equation, the CPU 15 repeatedly corrects the tap coefficients by calculating the second or third equation.

A series of these processes is performed by software, and a flow chart thereof is shown in FIG. In this process, the process is repeated until the amount of residual ghost in ghost detection becomes sufficiently small.

Problems to be Solved by the Invention When performing ghost removal with the configuration of a conventional ghost removal device, the phase relationship of the clock signal used when converting an input video signal to a digital video signal with respect to the GCR signal or vertical synchronization signal is The waveform of the digital video signal converted to a digital signal by the A/D converter changes because it changes depending on the temperature characteristics of the generator circuit and the phase of the GCRM 9 or vertical synchronization signal inserted into the input video signal. The ghost removal performance changes due to the waveform change, and in particular, the characteristics of high frequency components of the video signal change.

The present invention solves the above problem, and aims to provide a ghost removal device whose ghost removal performance does not change.

Rounding Means to Solve Problem M In order to solve this problem, the ghost removal device of the present invention uses a GCR signal "8t" or a vertical synchronization signal, or a signal obtained by processing them, and waveform data stored in a memory in advance. The CPU compares the video signal iA/
It is configured to control the phase of the clock signal to be D-converted.

Operation The present invention uses the above-described configuration to convert a video signal into an A/D converter.
During conversion, the tarokk and OCR signal fF, . . . maintain the phase relationship with the vertical synchronization signal within a certain range, thereby preventing the ghost removal performance from changing depending on the phase of the A/Di conversion.

EXAMPLE Hereinafter, a ghost removal device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a circuit configuration of a ghost removal device in an embodiment of the present invention. In FIG. 1, 1 is an A/D converter for A/D converting an input video signal; 24
-j Waveform memory A to which the output of A/D converter 1 is input, 3 is a transversal filter that removes ghosts from the output of A/D converter 1, 4 is waveform memo 'JB to which the output of transversal filter 3 is input. , 5 is a D/A converter that converts the output of the transversal filter 3 to D/A.
A converter, 6 is waveform data memory, 7 is waveform memo!
J214. 8 is a CPU that receives the output of the waveform data memory 6 and controls the transversal filter 3.
This is a phase-variable clock generation circuit that generates a clock signal set to an arbitrary phase by 7 and controls the A/D converter 1 and the D/A converter 5.

The operation of the ghost removal device configured as described above will be described below. Initially, the phase variable clock generation circuit 8 is set to a certain arbitrary phase by the CPU 7,
A tarlock signal is generated from the input video signal, and using the clock signal, the A/D converter 1 converts the input video signal into a digital video signal. The waveform memory A2 receives an OCR signal or a vertical synchronization signal from this video signal and inputs it to the CPU7. The CPU 7 uses the waveform data in the waveform data memory 6 and the GC input in the waveform memory A2.
Compare the R signal or vertical sync signal. As a result of this comparison, the CPU 7 compares the waveform data in the waveform data memory 6 with the GC.
When the correlation with the R signal or the vertical synchronization signal is large, it is determined that the phase relationship between the clock signal and the GCR signal or the vertical signal is appropriate, and the input video signal 'iA/D is determined using the clock signal with this phase relationship. This digital video signal is then used to perform ghost removal. When the correlation between the waveform data of the waveform data memory 60 and the GCR signal or the vertical synchronization signal is small, the CPU 7 stores the clock signal and the GCR signal.
It is determined that the phase relationship between the CR signal or the vertical synchronization signal is inappropriate, and the variable phase clock generation circuit 8 is controlled to change the phase relationship between the clock signal and the OCR signal or the vertical synchronization signal, and then the waveform memory A2 is stored again. Use GCR faith! Or capture the vertical synchronization signal and waveform data memory 6
Compare with the waveform data. Then, this comparison is performed by changing the phase until a phase where the correlation between the wave/shape data in the waveform data memory 6 and the OCR signal or vertical synchronization signal becomes large is found. A/D conversion is performed using the phase clock signal,
Ghost removal is performed using this digital video signal.

In this way, the phase relationship between the GCR signal 8 or the vertical synchronization signal and the clock signal used when A/D converting the input video signal e is made constant, and changes in ghost removal performance are prevented.

Effects of the Invention As described above, according to the present invention, by making constant the phase relationship between the GCR signal or the vertical synchronization signal and the clock signal used when converting the input video signal into A/Dg,
It is possible to solve the problem that the ghost removal performance changes due to the change in waveform when the input video signal qt clock signal is converted into a digital video signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a ghost removal device according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional ghost removal device, and FIG. 3 (at is a waveform diagram of the WRB signal, and (b) is an O pedestal. A signal waveform diagram, (C) is a signal waveform diagram after field sequence processing, (d) is a signal waveform diagram obtained by differentiating (cl), and FIG. 4 is a flowchart of conventional ghost removal processing.・A/D converter, 2... Waveform memory A,
3... Transpersal filter, 4... Waveform memory B15... D/A converter, 6... Waveform data memory. 7...CPU, 8...Clock generation circuit with variable phase. Agent Yoshi Morimoto Private use Figure 3 No. 4

Claims (1)

[Claims] 1. A ghost removal device that performs ghost removal using the GCR signal or vertical synchronization signal of the video signal, which generates a clock signal from the input video signal and whose phase is variable by controlling the phase of the clock signal by the CPU. a clock generation circuit; an A/D converter that converts an input video signal into a digital video signal using the clock signal;
a transversal filter that receives the digital video signal and performs ghost removal under control of the CPU; and a transversal filter that receives the digital video signal and removes ghosts;
a waveform memory A that receives the output of the transversal filter and supplies it to the CPU; and a waveform memory D that converts the output of the transversal filter into an analog output video signal using the clock signal.
/A converter and a waveform data memory that supplies waveform data to the CPU, and controls the phase of a clock signal used when converting an input video signal to a digital video signal to a phase suitable for ghost removal. A ghost removal device configured as follows.