JPH04170161A - Ghost elimination device - Google Patents

Abstract

PURPOSE:To reduce the arithmetic time by using a signal resulting from a GCR(Ghost Cancel Reference) signal subject to synchronization addition and field sequence processing in place of an input video signal with switching and implementing hardware arithmetic operation as the convolution arithmetic operation through the use of a transversal filter. CONSTITUTION:A GCR signal is subject to synchronization addition by a CPU 5 and field sequence processing, then the result is transferred to a RAM 1, and the signal read from the RAM 1 is used in place of an input signal of the ghost elimination device through a changeover circuit and inputted to a ghost elimination circuit 3. That is, the signal subject to synchronization addition and field sequence processing is read by the RAM 1 and ghost elimination calculation in an FIR(Finite Impulse Response) filter section is implemented. Thus, in the case of the hardware operation by using a transversal filter, since the S/N is sufficiently improved at first synchronization addition, the synchronization addition at convolution calculation is not required. Thus, the tap coefficient of an IIR(Infinite Impulse Response) filter is momentarily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to Ghost Cancel Referen
The present invention relates to a ghost removal device that performs ghost removal using a ce (OCR) signal.

Conventional Technology The first generation of EDTV broadcasting, which aims to improve image quality while maintaining compatibility with current television systems, is about to begin, and ghost removal is attracting a lot of attention. Among the requirements for ghost removal performance are image quality evaluation after improvement and removal time. In other words, this means how quickly the amount of ghosts remaining after removal can be reduced (ghosts can be removed).

An example of a conventional ghost removal device is a ghost canceller reported in "Television Society Technical Report RE80-6.pp, 9-14, February 1980." 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. Further, as a ghost removal device using a GCR signal, there is a ghost canceller reported in "Television Society Technical Report ROFT 89-6.pp, 31-36, June 1989."

This uses a transversal filter in the ghost canceller like the ghost canceller described above, but the input and output of the transversal filter are taken into the CPU via memory, and synchronous addition is performed between fields according to the transmission sequence. Perform all ghost removal calculations including processing in .

An example of a conventional ghost removal device will be described below with reference to the drawings. FIG. 3 is a schematic block diagram showing the configuration of a conventional ghost removal device. In Figure 2,
5 is CPU, 7 is transversal filter, 6 is A
8 is a D/A converter, and 9 is a waveform memory.

The operation of the ghost removal device configured as above will be described below. The input video signal is A/D
The signals are A/D converted by a converter 6 and input to a transversal filter 7 and a waveform memory 9, respectively. The input and output of the transbar → Nord filter 7 are input to the CPU 5 via the waveform memory 9. First generation E
In DTV broadcasting, the WRB signal and 0 pedestal signal shown in Figure 4 a and b are the WRB signal 90 pedestal signal I+wR.
B signal c3Q pedestal signal c>o pedestal signal 9W
The RB signal φO pedestal signal φWRB signal is transmitted in the same horizontal period in a sequence that goes around eight fields.

The signal shown in FIG. 4C can be obtained by performing the calculation shown in equation 1 below on the signals of these 8 fields. However, Fn=(n-1 to 8) represents the signal of the nth field. 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((Fl-F5)+(F6-F2)+(
F3-F7)+ (F8-F4)1... (1) Actually, the signal shown in Figure 4D, which is obtained by differentiating the signal in Figure 4C, is used as the reference signal for ghost detection, and the following ghost removal calculation is performed. I do.

Generally, there is a division method as a method for determining the tap coefficients of a transversal filter, and this method determines the optimal tap coefficients on the frequency axis according to a certain algorithm. The transfer characteristic of the nearby ghost region (part of the FIR filter) of the output signal g from the transversal filter is set to 0.
1. If the transfer characteristic of the normal ghost region (part of the IIR filter) is 02, and the frequency characteristic of the GCR signal is R, then FI
The transfer characteristic H1 of a part of the R filter is H1=R/Gl... (2)
The transfer characteristic H2 of a part of the 11R filter is H2=1/(
1+G2/G1) ... (3) Or, expressed in the time domain, the tap coefficient h of a part of the IIR filter
2 is h2=g*hl...
(4) However, hl is a tap coefficient of a part of the FIR filter determined from equation (2), and * represents a convolution operation.

Problems to be Solved by the Invention However, in the above configuration, since the CPU performs the convolution calculation for calculating the tap coefficients of a part of the FIR filter, when the number of samples is 1024 or 2048, the calculation process is This has the problem of being time consuming and causing problems in practice.

In view of the above-mentioned problems, the present invention provides a ghost removal device that significantly reduces the calculation time by performing the convolution calculation in hardware using a transversal filter.

Means for Solving the Problems In order to solve the above problems, the ghost removal device of the present invention synchronously adds GCR signals in a CPU, performs field sequence processing on them, transfers them to a RAM, and combines signals read out from the RAM with ghosts. The configuration is such that the input signal of the ghost removal device is switched and inputted to the ghost removal circuit.

Operation According to the above-described configuration, the present invention reads out the signal after -degree synchronous addition and field sequence processing in the RAM, and performs ghost removal calculation for a part of the FIR filter. As a result, when a calculation is performed in hardware using a transversal filter, by sufficiently improving the S/N during the first synchronous addition, there is no need for synchronous addition during the convolution calculation.

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

FIG. 1 is a schematic block diagram of the circuit configuration of a ghost removal device in a first embodiment of the present invention.

In FIG. 1, 1 is a RAM, 2 is a switching circuit, 3 is a ghost removal circuit, 4 is a memory, and 5 is a CPU. The operation of the ghost removal device configured as described above will be described below.

Initially, the switching circuit 2 selects the a side, and the ghost removal circuit 3 receives an input video signal. The input and output of the ghost removal circuit are connected to the CPU via memory 4.
It will be incorporated into 5. The CPU 5 repeatedly takes in input video signals and performs sufficient synchronous addition to improve the S/N ratio.

Thereafter, the field sequence processing shown in equation 1 is performed to calculate the signal shown in FIG. 4d. This signal is sent to the CPU
5 to RAM1 for writing. After this, the switching circuit 2 selects the b side and repeatedly reads the RAMI. Next, the CPU 5 calculates the formula (2) and the FIR
By calculating the transfer function of the filter and performing inverse Fourier transform, the tap coefficients of the nearby ghost region are found.

This tap coefficient is written into the ghost removal circuit 3. Here, the ghost in the vicinity is removed.

Thereafter, by taking in the output from the ghost removal circuit 3 from the memory 4, calculation of equation (4) is performed on the hardware, and the tap coefficient of the IIR filter for ghost removal in the normal section is determined. This tap coefficient is written into the ghost removal circuit 3. Here, the ghost in the normal portion is removed.

Finally, when the switching circuit 2 is selected to the side a, the input video signal is input to the ghost removal circuit 3, and a video signal from which ghosts have been removed is obtained. A flowchart of the above processing is shown in FIG.

As described above, by switching the input signal to the ghost removal circuit between the input video signal and the memory, the I
The tap coefficients of the IR filter can be found instantly.

Effect of the invention As described above, according to the present invention, -degree synchronous addition is performed.

After field sequence processing, this signal can be switched with the input video signal and the convolution operation can be performed in hardware using a transversal filter, making it possible to significantly shorten the calculation time. .

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a ghost removal device according to an embodiment of the present invention, FIG. 2 is a flowchart of a ghost removal process of the present invention, FIG. 3 is a schematic block diagram of a conventional ghost removal device, and FIG. Figure a is a signal waveform diagram of the WRB signal,
The figure C is a signal waveform diagram of the O pedestal signal, the figure C is a signal waveform diagram after field sequence processing, and the figure d is a signal waveform diagram of the O pedestal signal.
FIG. 3 is a signal waveform diagram obtained by differentiating . 1...RAM, 2...Switching circuit,
3...Ghost removal circuit, 4...Memory, 5...CPU, 6...A/D,
7... Transversal filter, 8...
...D/A, 9...Waveform memory. Name of agent: Patent attorney Akira Okaji and 2 others -1.〇-

Claims (1)

[Claims] In a device that performs ghost removal using a GCR signal, FIR (Finite Impulse Responses)
e) Filter and IIR (InfiniteImpul)
means for removing ghosts using a filter (seResponse); means for switching the input of said ghost removing means between an input video signal of a ghost removing device and an output signal of a RAM; and a memory for taking in input signals and output signals of said ghost removing means. , a CPU that takes in the signal from the memory and performs a ghost removal operation using the division method, transfers the signal from the CPU to the RAM after performing inter-field processing according to the synchronous addition and transmission sequence, and performs the ghost removal operation using the division method. After giving the tap coefficient of the FIR filter determined by , the switching means inputs this signal to the ghost removing means, and the output signal from the ghost removing means is given as the tap coefficient of the IIR filter. Ghost removal device.