JPH0482482A - Ghost elimination device - Google Patents

Abstract

PURPOSE:To decide a reception channel after revision momentarily by providing a memory storing a ghost detection component before ghost elimination of a video signal and a memory storing a tap coefficient after ghost elimination to the device. CONSTITUTION:When a reception channel of an external device connecting to a terminal GR is revised, a CPU 5 clears at first a tap coefficient of a transversal filter 2 and fetches a field sequence data via a waveform memory 4 and detects a ghost component based on the data. Then the component is compared with a ghost component for all channels of a memory 16 to decide a current reception channel. Then the tap coefficient after reception channel ghost elimination is read from a memory 117 and fed to the transversal filter 2 to eliminate the ghost component. Thus, the reception channel after revised reception channel is momentarily decided.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ghost removal device that performs ghost removal using an 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 ghosts can be removed and the amount of ghosts remaining after removal can be reduced.

As an example of a conventional ghost removal device, there 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.

In addition, as a ghost removal device using OCR signals,
Television Society Technical Report ROF T896, pp, 3
There are ghost cancellers reported in "1 to 36". This uses a transversal filter in the ghost canceller like the ghost canceller described above, but inputs and outputs of the transversal filter are input to 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 3, 5
is CPU, 2 is transversal filter, ■ is A/D
Converter, 3 is a D/A converter, and 4 is a waveform memory.

The operation of the ghost removal device configured as above will be explained. The input video signal is sent to A/D converter 1
The signals are A/D converted and input to a transversal filter 2 and a waveform memory 4, respectively. The input and output of the transversal filter 2 are connected to C through the waveform memory 4.
Input to PLI5. In the first generation EDTV broadcast,
The WRB signal and the 0 pedestal signal shown in Fig. 4 (a) and (b) are the WRB signal - => 0 pedestal signal -> WRB signal - O pedestal signal = = + Q pedestal signal -> WRB signal = = + Q pedestal signal - 0 WRB signal. It is transmitted in the same horizontal period in a sequence that goes around 8 fields. The signals shown in FIG. 4(C) can be obtained by performing the calculations shown in 12 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 ((F 1-F5)+ (F6-F2)
+ (F3-FT)+ (FB-F4))...
(1) In reality, the signal shown in Fig. 4 (C) is differentiated (
The following ghost removal calculation is performed using the signal shown in d) as a reference signal for ghost detection. MSE (Me
an 5quare Error) method or ZF
(Zero Forcing) method, etc., and these methods sequentially correct on the time axis according to a certain algorithm to finally find the optimal tap coefficient. The output signal of the transversal filter is (Yk), and the reference signal is (R
kl, l - The difference signal between the output signal of the lance versal filter and the reference signal is (Ek), and the total number of taps is M+N+ 1
If so, this is the nth Tashif of Transversal Phil.

The coefficient ((il(l) is modified 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.

(Cil ””' = (Ci) ”' −
β·Ei (3) The CPU 5 performs the synchronous addition and field sequence processing shown in the first two, and then performs the second or third two calculations to repeatedly correct the tap coefficients.

A series of these processes is performed by software, and the processes are repeated until the amount of residual ghost becomes sufficiently small in ghost detection.

Problems to be Solved by the Invention However, in the above-described configuration, the ghost removal device is configured as an adapter, and the output terminal G, which supplies the video signal of another television receiver to the adapter, is configured as an adapter.
When removing ghosts from the video signal from the R terminal,
The R terminal supplies only the input video signal and a GR control signal indicating that the channel has changed. Therefore, if the receiving channel is changed on the connected device side (for example, a television receiver), the change in the receiving channel can be recognized by the GR control signal, but the receiving channel number is not known, so the tap coefficient is memorized for each receiving channel. However, there was a problem in that it was not possible to make a call or call it up instantly.

In view of the above problems, the present invention provides a ghost removal device that can instantly recall tap coefficients from memory by estimating the reception channel number even when the GR terminal is connected.

Means for Solving the tX Problem In order to solve the above problems, the ghost removal device of the present invention includes a memory I that stores ghost detection components before ghost removal of a video signal input from a GR terminal, and a memory I that stores ghost detection components before ghost removal of a video signal input from a GR terminal. It is provided with a memory (2) for storing tap coefficients, and determines the reception channel by comparing the ghost detection component after changing the reception channel on the GR terminal side with the memory.

Effect of the Invention With the above-described configuration, the present invention reads the previously stored tap coefficients after ghost removal from the memory II and instantly adds the tap coefficients.

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 an embodiment of the present invention. In FIG. 1, 1 is an A/D converter that converts the input video signal to digital, 2 is a transversal filter, 3 is a D/A converter that converts the output video signal to analog, and 4 is the input/output of the transversal filter 2. A waveform memory 5 stores signals, a CPU 6, a memory 2 that stores ghost detection components, and a memory 7 that stores tap coefficients after ghost removal.

The operation of the ghost removal device configured as described above will be described below. The input video signal from the GR terminal is A/D converted by an A/D converter 1 and input to a transversal filter 2 and a waveform memory 4, respectively. The input and output of the transversal filter 2 are input to the CPU 5 via the waveform memory 4. Thereafter, field sequence processing is performed according to the first equation to calculate the signal shown in FIG. 4(d). The CPU 5 performs a difference with a reference signal held within the preparatory unit to obtain a ghost detection component. Here, the ghost component in the current reception channel is written into the memory 6. FIG. 2(a) shows the contents written to the memory 6. The memory I6 has ghost component writing areas for n reception channels, and each area is assigned a ghost delay value DEL corresponding to one ghost component and a D/U ratio DU. The ghost components are written to the memory in descending order of D/U ratio. Thereafter, the transversal filter 2 is controlled by performing calculations shown in the second and third equations. At the same time, the tap coefficient at the time of current ghost removal is stored in memory.
Write to 7. FIG. 2(b) shows the contents written to the memory 7. The memory 7 has tap coefficient write areas for n reception channels, and each area has a write area for a total of m taps.

Here, when the reception channel of the external device connected to the GR terminal is changed, the CPU 5 receives a reception channel change signal from the GR terminal, and first clears the tap coefficient of the transversal filter 2. Next, field sequence data is taken in via the waveform memory 4. Ghost components are detected based on this data. Here, comparison is made with ghost components for all channels in the memory I6 to determine the current receiving channel.

Then, the tap coefficient of the receiving channel is read out from the memory 7 and supplied to the transversal filter 2 to perform ghost removal.

As described above, according to this embodiment, even in a system using a GR terminal, ghost removal can be instantaneously performed when switching reception channels.

Effects of the Invention As described above, according to the present invention, by having the memory (2) for storing ghost detection components before ghost removal and the memory (2) for storing tap coefficients after ghost removal, reception after changing the reception channel is possible. Channels can be determined instantly.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a ghost removal device according to an embodiment of the present invention, FIGS. 2(a) and 2(b) are block diagrams of a memory used in the ghost removal device of the present invention, and FIG. 3 is a conventional block diagram. Figure 4 (a) is a signal waveform diagram of the WRB signal, ■・・・・・・A/
D-variable mLH12... Transversal filter, 3... D/A converter, 4... Waveform memory, 5... CPU, 6...・Memory I
, 7...Memory ■. Name of agent: Patent attorney Shigetaka Awano (1 person) Figure Figure (a) (b) Figure Figure □□□

Claims (1)

[Claims] In a device that performs ghost removal using a GCR signal,
Memory I stores the ghost detection component before ghost removal of the video signal input from the GR terminal, memory II stores the tap coefficient after ghost removal, and the ghost detection component after changing the reception channel on the GR terminal side and the above. memory
A ghost removal device is characterized in that it determines a reception channel by comparing it with I and adds a tap coefficient from memory II.