JPH04183179A - ghost remover - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a ghost removal device that performs ghost removal using a ghost removal reference signal (OCR signal).

2. Prior Art The first generation of HDTV 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. The performance of a ghost removal device is determined by how quickly it can remove ghosts and reduce the amount of ghosts remaining after removal. 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.

In addition, as a ghost removal device using CR multiplied signal, [Television Society Technical Report ROF T89-6,
There is a ghost canceller reported in p p, 3l-36J. This uses the same transversal filter as the ghost canceller in the ghost canceller, but the input and output of the transversal filter are taken into the CPU via memory, and the fields are processed according to the synchronous addition and transmission sequence. The CPU performs all of the ghost removal calculations, including the processing in between.

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, 1
5 is a CPU, 12 is a transversal filter, 11 is an A/D converter, 13 is a D/A converter, and 14A and 14B are waveform memories.

The operation of the ghost removal device configured as above will be explained. The input video signal is sent to A/D converter 1
1, the signals are A/D converted and input to the transversal filter 12 and the waveform memory 14A, respectively. The input and output of the transversal filter 12 are the waveform memory 1
It is input to the CPU 15 via 4A and 14B. In the first generation HDTV broadcasting, the WRB signal and 0 betestal signal shown in Fig. 4(a) and (b) are WRB signal → O petestal signal - 6 WRB signal → 0 petestal signal - 00 betestal signal → WRB signal → 0 betestal signal. The signal rumors are transmitted in the same horizontal period in a sequence that goes around in eight fields of the WRB signal. By performing the calculation shown in equation 1 below on these 8 field signals, the signal shown in FIG. 4(C) can be obtained. However, Fn (n=1 to 8) is the nth
Represents field signals. 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) Actually, the signal shown in Figure 4 (C) obtained by subtracting the signal in Figure 4 (C) by one clock is The following ghost removal calculation is performed using the reference signal for ghost detection. MSE (Mean 5quare Error) is generally used as a method to find the tap coefficients of a transversal filter.
Law or ZF (Zer.

Forcing method and the like, these methods sequentially correct on the time axis according to a certain algorithm to finally find the optimal tap coefficient. If the output signal of the transversal filter is fYkli quasi-4N (Rkl), and the difference signal between the output signal of the transversal filter and the reference signal is (Ekl), and the total number of taps is M + 1, then n of the transversal filter is equal to tap coefficient (:1i
)(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.

(Ci) “”Kudzu)= ((il (l
−α ・Σ Yk−i ・Ek・・・・・・(2)
k=-River(niB tl'll = (Ci) !I
ll −β・Ei・・・・・・
(3) After performing the synchronous addition and field sequence processing shown in the first equation, the CPU 15 repeatedly corrects the stamp coefficient by calculating the second or third equation. 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.

However, when the S/N of the input video signal is low, the level difference between the ghost signal and the noise signal becomes small with only 8-field sequence processing, and ghosts may not be correctly identified, resulting in more residual ghosts or unstable control. This causes the transversal filter 12 to diverge and oscillate.

Therefore, a method of performing synchronous addition in order to separate ghosts and noise has also been considered. However, increasing the number of synchronous additions increases the time required for one successive equalization. FIG. 5 shows a flowchart of the process.

Problems to be Solved by the Invention In the conventional configuration, in order to reduce the amount of residual ghosts and to operate stably, it is necessary to sufficiently perform synchronous addition to improve the S/N ratio. There was a problem in that if data was fetched every time and synchronous addition and sequence processing were performed, the removal time would become longer.

In view of the above-mentioned problems, the present invention aims to provide a highly stable ghost removal device that minimizes the amount of remaining ghosts and shortens the removal time. Means for Solving the Problems Solving the above-mentioned problems In order to do this, the ghost removal device of the present invention includes means for extracting the ghost removal reference signal (OCR signal) of the input video signal from the insertion lines (18H, 281H) and subjecting it to averaging processing (synchronous addition) and sequence processing;
It is equipped with means for updating the signal every 8 fields and means for switching and inserting the processed signal into 18H and 281H of the input video signal.
It is configured so that the signal can be replaced with an improved signal.

Effect of the Invention With the above configuration, the present invention replaces and uses the ghost removal reference signal with one that has been subjected to averaging processing (synchronous addition) and sequence processing, so that the removal time can be reduced compared to performing new synchronous addition for each sequential processing. .

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 diagram of a circuit configuration of a ghost removal device according to an embodiment of the present invention. In FIG. 1, 1 is an A/Di converter, 6 is a transversal filter, 2 is a D/A converter, 3 is a ghost removal reference signal averaging (synchronous addition), a sequence processing circuit, 31 memories, 32 It consists of 1 memory and 33 averaging sequence processing circuits. 4 is a switching circuit, 5 is a synchronization separation/timing generation circuit, 7 is a waveform memory, 8 is a waveform memory, and 9 is a CPU that performs ghost removal control.

Next, the operation of the ghost removal device configured as described above will be explained. An input video signal is A/D converted and digitized by an A/D converter 1. The signal is input to the a side of the switching circuit 4 and also to the memory 31 of the ghost removal reference signal averaging (synchronous addition)/sequence processing circuit 3. The input video signal is connected to a synchronization separation/timing generation circuit 5, where signals indicating 18H and 281H are generated. Further, a clock signal having four times the frequency synchronized with the ghost signal for operating the transversal filter, A/D, D/Aitag, etc. is also generated by the PLL. Averaging (synchronous addition) of the ghost removal reference signal The sequence processing circuit 3 improves the S/N of the ghost removal reference signal. 18H, 281 from the output of A/D converter 1
The H signal is taken into the memory 31 by DMA. The captured signals are averaged by an averaging processing/sequence processing circuit 33. This process follows the following equation.

For 8 consecutive fields, F=1/4 ((F 1-F5)+ (F6-F2)+
(F3-F7)+ (F8-F'4))...
Calculate (4). FN--N=field number Calculate the average of the results of (4) for a set of eight consecutive fields with m=1. However, m is the set number of a set of 8 fields. This result is stored in memo 1J32 every time m is updated.
Transferred by MA. This transfer occurs at the beginning of the field. The contents of the memory 32 are DM during the 18H and 281H periods.
A is read out and sent to the b side of the switching circuit 4. The switching circuit 4 is switched between a and b by signals indicating 18H and 281H of the synchronous separation/timing circuit 5. Therefore, the input signals of the transversal filter 6 are 18 H, 28
Only the 1H portion is averaged and replaced with a sequenced ghost removal reference signal.

The CPU 9 calculates tap coefficients for removing ghosts by the MSE method, the ZF method, the net removal method, etc. using the averaged and sequentially processed ghost removal signals taken into the waveform memory and the waveform memory 8. Ghosts are removed by modifying the tap coefficients of the transversal filter 6.

The output of the transversal filter 6 is converted into an analog signal by the D/A converter 2 and output as a video signal from which ghosts have been removed.

FIG. 2 shows a flowchart of ghost removal processing in this configuration. In the ghost removal device of this configuration, the 41f signal, which is the basis for ghost removal, is averaged (synchronized addition) and the S/N is improved in the sequence processing circuit 33, and the ghost removal reference signal sent from the 18H1281H broadcasting station is Ghosts can be removed at high speed because of the process of replacing the ghost.

For example, if one cycle of sequential equalization for ghost detection, calculation, and tamping coefficient correction takes 16 m5 ec and ghost removal can be performed in 10 times, and if initial averaging is performed for 64 fields, then 64 x 16 msec + 16 m5 ec XIO =
It can be removed in 1184 msec. In contrast, in the conventional method, (64X16msec +16m5ec)X10=10
400 m5ec is required.

Effects of the Invention As described above, according to the present invention, the ghost removal reference signal is replaced with one that has been subjected to averaging processing (synchronous addition) and sequence processing. Removal time can be shortened. Furthermore, since only the ghost removal reference signal portion of the input signal is replaced, the original video signal portion is not affected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a ghost removal device in an embodiment of the present invention, FIG. 2 is a flowchart of ghost removal processing in an embodiment of the invention, and FIG. 3 is a block diagram of a conventional ghost removal device. The subsequent signal waveform diagram (d) is a one-clock difference signal waveform diagram from (C). FIG. 5 is a flowchart of a ghost removal device in a conventional ghost removal device. 1...A/D converter, 2...D/A converter, 3...Averaging/sequence processing circuit, 3
1...Memory, 32...Memory, 33
...Average sequence processing circuit, 4...
switching circuit, 5... synchronization separation/timing circuit,
6... Transversal filter, 7...
... Waveform memory, 8... Waveform memory, 9...
...cpu. Name of agent: Patent attorney Akira Okaji and two others i;;
4 Lj tb) Ze'rope child's star signal (C) θ field sequence
) 7 clock number 5

Claims (1)

[Claims] The ghost removal reference signal is used as the reference signal for ghost removal,
In a device that performs ghost removal by modifying the tap coefficients of a digital transversal filter, a ghost removal reference signal sent out by a broadcasting station is sent to an insertion line (1
8H, 281H) and performs averaging processing (synchronous addition)/sequence processing; means for updating every 8 fields; means for reading out signals with improved S/N by averaging; and 18H, 281H. What is claimed is: 1. A ghost removal device comprising means for switching and inserting signals, and detecting ghosts using averaged signals and performing tap correction calculations to remove ghosts.