JPH03183270A - Ghost eliminating device - Google Patents

Abstract

PURPOSE:To considerably shorten the processing time and to eliminate an influence of the variance due to disturbance of an input signal by synchronously adding a GCR signal or a vertical synchronizing signal by a CPU and transferring this signal to a RAM after field sequence processing and switching the repeatedly read-out signal and the input signal of a ghost eliminating device. CONSTITUTION:An input video signal is inputted to a ghost eliminating circuit 3, and a CPU 6 repeatedly takes in the input video signal and sufficiently performs synchronous addition to improve S/N. Thereafter, field sequence processing is performed, and the signal is transferred to a RAM 1 and is written. Hereafter, a switching circuit 2 selects the (b) side to repeatedly read out the RAM 1. The CPU 5 calculates the difference from a preliminarily prepared internal reference signal to control a ghost eliminating circuit.

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 or a vertical synchronization signal.

Conventional Technology The first generation of EDTV broadcasting, which aims to improve picture quality while maintaining compatibility with current television systems, is about to begin, and ghost removal is attracting a lot of attention. Image quality evaluation value after improvement to ghost removal performance required in this,
There is an item for 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, the Technical Report of the Television Society RE80-6, pρ,
There is a ghost canceller reported on 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 slope coefficients of the versatile filter.

In addition, as a ghost removal device using OCR signals, the Technical Report of the Television Society of Japan ROFT89-6, pp. 31
There is a ghost canceller reported in -36. 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 the 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 FIG. 3, 5 is a CPU, 12 is a transversal filter,
The operation of the ghost removal device configured as one or more of the following will be described: 20 is an A/D converter, 21 is a D/A converter, and 22 is a waveform memory. The input video signal is
The signals are A/D converted by an A/D converter 20 and input to a transversal filter 12 and a waveform memory 22, respectively. The input and output of the transversal filter 12 are input to the CPU 5 via the waveform memory 22. In the first generation EDTV broadcast, the WRB signal and 0 pedestal signal shown in Fig. 4 (a) and (b) are WRB signal → O pedestal signal → WRB signal → O pedestal signal → ○ pedestal signal → WRB signal → O pedestal signal. The signal is transmitted in the same horizontal period in a sequence of 8 fields of signal → WRB signal. The signal shown in FIG. 4(C) 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) 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)+ (FB-F4))...(1)
Actually, the following ghost removal calculation is performed using the signal shown in FIG. 4(A) obtained by differentiating the signal shown in FIG. 4(C) as a reference signal for ghost detection. Generally, M S E (Mea
n 5quare Error) method or Z F (Z
Er.

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 (Ykl, the reference signal is (Rkl), 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+N+1, then the n-th tap coefficient of the transversal filter is C(1) <
IIl is modified based on the following equation 2 in the MSE method and equation 3 in the ZF method. However, C7β is a coefficient for determining the amount of correction.

(Ci) ”−” = (Ci) ”'1α・Σ
Yk-4-Ek (2) k=-M (C1l +*-11= (Ci l (nl-
β-E i ·- · (3) After performing the synchronous addition and field sequence processing shown in the first equation, the CPU 5 performs the second
The tap coefficients are repeatedly corrected by calculating the equation or the 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.

In the conventional configuration, when the S/N of the input video signal is low, synchronous addition of 8 fields as shown in equation 1 alone can no longer separate the ghost and noise when the amount of residual ghost reaches a level almost equal to the noise signal level. Discrimination becomes impossible, and this level becomes the performance limit for ghost removal.Therefore, in order to reduce the amount of residual ghosts and improve ghost removal performance, sufficient synchronous addition must be performed for the reasons stated above. /N must be improved.

However, the processing time increases in proportion to the number of synchronous additions, resulting in a longer ghost removal time. Furthermore, each time the correction is made, the input signal is
This means that there is instability in the operation, such as divergence, due to re-importing the data into the PU. That is, when corrections are made sequentially on the time axis, the optimal solution for the tap coefficient is determined according to a fixed procedure while oscillating, so it is easily affected by noise and other disturbances. If the tap coefficients are affected and the combination of tap coefficients becomes a tap coefficient sequence that causes divergence, the output of the transversal filter 12 will diverge.

Problems to be Solved by the Invention In order to reduce the residual amount of ghosts as much as possible and improve the ghost removal performance with the configuration of the conventional ghost removal device, it is necessary to perform sufficient synchronous addition to improve the S/N ratio. It won't happen. On the other hand, increasing the number of synchronous additions results in a longer ghost removal time. Furthermore, since corrections are made sequentially on the time axis, not only does the ghost removal time increase, but also the influence of external disturbances becomes more likely, increasing the possibility of divergence. In view of the above-mentioned problems, the present invention reduces the amount of ghosts remaining after ghost removal as much as possible, and also significantly shortens the removal time compared to the conventional method in which a signal is captured every time the tap coefficient is successively corrected. We propose a ghost removal device that can improve stability.

Means for Solving the Problem In order to achieve this objective, the OCR signal or vertical synchronization signal is subjected to synchronous addition and field sequence processing in the CPU, and then transferred to the RAM, and this RAM is repeatedly read out and ghost removed. The apparatus is configured to switch the input signal of the apparatus and input it to the ghost removal means.

In the present invention, once synchronous addition and field sequence processing are performed using the above-described configuration, this signal is repeatedly read out in the RAM to perform ghost removal calculations. This greatly reduces processing time without having to import signals each time the tap coefficients are successively corrected, and by providing a sufficient number of synchronous additions, the S/N ratio is sufficiently improved, and fluctuations due to disturbances in the input signal are avoided. Avoid being influenced.

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 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. Regarding the ghost removal device configured as above,
The operation will be explained 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 taken into the CPU 5 via the memory 4. The CPU 5 repeatedly takes in input video signals and performs sufficient synchronous addition to improve the S/N ratio. Thereafter, the Felton-Kens process shown in equation 1 is performed to calculate No. 13 shown in FIG. 4(d). This signal is transferred from CP tJ 5 to RAMI for writing. After this, the switching circuit 2 selects the b side and repeatedly reads out the RAMI. This RAMI signal is taken into the CPU 5 in the same way as when the input video signal was first taken in. The CPU 5 calculates a difference between the signal and the reference signal stored in the preparator, and performs calculations shown in equations 2 and 3 to control the ghost removal circuit 3.

A flowchart of the processing at this time is shown in FIG.

Here, if we assume that N fields are required for synchronous addition, M times for correction circuits, and L fields for ghost detector calculation + stamp coefficient correction, then when comparing the configuration of the conventional method and the present invention when all processing is performed, , the processing time ratio α is as shown in the fourth equation below.

α−N+M*L/ (N+L)*M ・・・・・・
・(4) Here, as a value for boat fishing, synchronous addition is 128 fields, number of corrections is 20 times, ghost detection + calculation → -
If we consider the case where the tap coefficient is corrected by one field, α becomes 1/17, which is a significant reduction.

Hereinafter, specific embodiments of the present invention will be briefly described with reference to the drawings. FIG. 2 is a block diagram showing a specific embodiment of the present invention. In FIG. 2, IO is a GCR signal sampling circuit, 11 and FIFO 112 are transversal filters, 13 is a selector, and 14 is a counter. O.C.
The R signal extraction circuit 10 generates a gate pulse signal during the period when the GCR signal is superimposed. The input video signal is input to the transversal filter 12 with the switch 2 selecting the C side. Transversal filter 12
The input and output of gate pulse signal period selector 1
3 supplies the counter output to the memory address,
It is written to memory 4 by DMA processing. After this memory 4
The address from the CPU is supplied to the CPL 15, which performs synchronous addition and field sequence processing as shown in the first equation. All of these are processed by software inside the CPU. After performing this series of processing a necessary number of times, select b with switch 1 and transfer it to PIFO II. After the transfer is completed, switch 1 is switched to the d side and the FIFO
II repeatedly outputs the signal read out and written by the CPU 5. On the other hand, the switch 2 is also switched to the d side at the same time, and the transversal filter 12 has FIFO II.
The output of is input. After transferring to FIFO II in this way, by using the FIFOI signal, it is possible to process signals that have already been subjected to synchronous addition and field sequence processing each time, reducing processing time and providing stability as if using a fixed signal source. It becomes possible to operate it.

Effects of the Invention As described above, according to the present invention, after performing -degree synchronous addition and field sequence processing, this signal is switched with the input video signal for use, thereby significantly shortening the processing time and improving stability. It becomes possible to remove ghosts by raising the level.

[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 block diagram of a specific embodiment of the ghost removal device of the present invention, and FIG. 3 is a block diagram of a conventional ghost removal device. The block diagram, Fig. 4 (fa) is a signal waveform diagram of the WRB signal, Fig. 4 (b) is a signal waveform diagram of the O pedestal signal, and Fig. 4 (C) is a signal waveform diagram after field sequence processing. Figure (d) is a signal waveform diagram obtained by differentiating (C), Figure 5 is a flowchart of conventional ghost removal processing, and Figure 6 is a flowchart of ghost removal processing of the present invention. , 2... Switching circuit, 3... Old ghost removal circuit, 4... Memory, 5... CPU, 10... GCR signal extraction circuit, 11...FIFO112...
...Transversal filter, 13...Selector, 14...Counter.

Claims (1)

[Claims] A ghost removal device that performs ghost removal using a GCR signal or a vertical synchronization signal, comprising means for performing ghost removal, and means for switching the input of the ghost removal device between an input video signal of the ghost removal device and an output signal of a RAM; A memory that captures the input signal and output signal of the ghost removal means, and a memory that captures the signal of the memory and performs processing between fields according to a synchronous addition and transmission sequence and a ghost removal operation so as to enable a ghost removal operation. The RAM is configured with a CPU that performs
1. After transferring the signal after synchronous addition and processing between fields according to the transmission sequence, the switching means inputs this signal to the ghost removal means. removal device.